ARTICLE | doi:10.20944/preprints201706.0004.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: hydroxyapatite, xenografts; implant design; implant surface
Online: 1 June 2017 (06:19:41 CEST)
The aim of the present study was to monitor implant stability after sinus floor elevation with two biomaterials during the first 6 months of healing by a resonance frequency analysis (RFA), and how physico-chemical properties affect the implant stability quotient (ISQ) at the placement and healing sites. Bilateral maxillary sinus augmentation was performed in 10 patients in a split-mouth design using a bobine HA (BBM) as a control and porcine HA (PBM). Six months after sinus lifting, 60 implants were placed in the posterior maxilla. The ISQ was recorded on the day of surgery from RFA at T1 (baseline), T2 (3 months), and T3 (6 months). Statistically significant differences were found in the ISQ values during the evaluation period. The ISQ (baseline) was 63.8±2.97 for BBM and 62.6±2.11 for PBM. The ISQ (T2) was ~ 73.5±4.21 and 67±4.99, respectively. The ISQ (T3) was ~ 74.65±2.93 and 72.9±2.63, respectively. All the used HAs provide osseointegration and statistical increases in the ISQ at baseline, T2 and T3 (follow-up), respectively. The BBM, sintered at high temperature with high crystallinity and low porosity, presented higher stability, which demonstrates that variations in the physico-chemical properties of a bone substitute material clearly influence implant stability.
ARTICLE | doi:10.20944/preprints202309.1333.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: dental implant; implant surgery; soft tissue management; immediate implant placement; early implant placement; connective tissue graft
Online: 19 September 2023 (16:29:43 CEST)
The clinical requirement for a good esthetic result for immediate implant placement is the absence of dehiscence in the anterior facial alveolar bone. In the presence of a dehiscence, it is recommend-ed to use a connective tissue graft in addition to immediate implant placement or to change to ear-ly implant placement. However, the literature focusing on dehiscence is scarce, and the influence of different placement times and combined use of connective tissue graft on postoperative esthetics in cases with dehiscence is unclear. Therefore, we quantitatively evaluated the pre-extraction de-hiscence morphology and postoperative changes in the facial tissue of implants in three groups: immediate implant placement (Group I), immediate implant placement with connective tissue graft (Group IC), and early implant placement (Group E). Fifty-two implants were obtained (20 in Group I, 16 in Group IC, and 16 in Group E). A wider dehiscence increases the risk of soft tissue regression, which was one reason for choosing early implant placement. A combination of imme-diate implant placement and connective tissue graft, or early implant placement, tended to result in less soft tissue regression due to the thicker postoperative facial soft tissue volume.
ARTICLE | doi:10.20944/preprints202305.0593.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Implant stability; Implant stability quotient; Periotest value; Implant stability test; Prospective study; Elderly patient
Online: 9 May 2023 (08:08:15 CEST)
As medical care aiming to maintain the quality of life for elderly patients is increases, implant treatment for elderly patients is increasing worldwide. Therefore, we aimed to investigate implant stability and the reliability of different measuring devices according to implant placement site and duration in patients aged over 65 years. The study evaluated 60 implants in 60 patients aged ≥ 65 years. The implant placement sites were divided into six evenly distributed sections (n=10) i.e., maxillary right- posterior, A; maxillary anterior, B; maxillary left-posterior, C; mandibular right-posterior, D; mandibular anterior, E; mandibular left-posterior, F. Participants visited the hospital seven times: preoperatively, 1V; implant surgery, 2V; stitch removal, 3V; 1-month follow-up, 4V; 2-months follow-up, 5V; before final-restoration delivery, 6V; and after final-restoration delivery, 7V. The implant stability was evaluated with the Osstell Mentor (ISQ), Periotest M (PTV), and Anycheck (IST). The mean values of ISQ, PTV, and IST were analyzed (α=.05). ISQ, PTV, and IST results of 5V and 6V were significantly higher than those of 2V (P<.05). The lowest ISQ results occurred in E location at 5V and 6V (P<.05). In all mandibular locations, IST results of 7V were significantly higher than those of 2V, 3V, 4V, and 5V (P<.05). ISQ results were negatively correlated with PTV and positively correlated with IST, and PTV was negatively correlated with IST. By considering various factors that affect implant stability, the appropriate implant load application time was determined. This could help increase the implant success rate in elderly patients. And as a diagnostic device for implant stability for evaluation of osseointegration in elderly patients, Anycheck was also able to prove its relative reliability compared to Osstell ISQ Mentor and Periotest M.
ARTICLE | doi:10.20944/preprints202308.0797.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Chlorhexidine Gel; marginal bone loss; Peri-implantitis; implant survival rate; implant decontamination; dental implant complication.
Online: 10 August 2023 (09:09:13 CEST)
Chlorhexidine digluconate (CHX) has shown the ability to significantly reduce inflammation and marginal bone loss (MBL) at 1-year follow-up but limited data exists regarding its long-term efficacy in peri implant stability. The objective was to compare the long-term effects of a placebo gel (16 patients in Group A) or a 0.20% CHX gel (15 patients in Group B) used at each previous surgical and prosthetic stage. Follow-ups were conducted in 2022, investigating by biological, radiological, clinical, mechanical evaluation the long-term effects. Data were statistically analyzed. The research achieved a 96.7% implant success rate over five years, but 41.9% of patients didn't attend annual oral hygiene check-ups. The average MBL was 1.04 ± 0.39 mm, with no significant differences between the two groups. Notably, patients who attended regular periodontal check-ups experienced significantly less MBL than those who didn't (p <0.05). At five years, the effects of CHX were reduced, with both groups showing moderate bone loss. The results suggest early disinfection could enhance both short and long-term outcomes. In fact, patient with initial minor MBL preserve this advantage also at 5 years of follow-up. Additionally, the data underscore the importance of annual check-ups in early detection and management of biological and mechanical complications.
ARTICLE | doi:10.20944/preprints202306.1704.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: dental implant; acquired pellicle; peri-implant disease; chemical decontamination
Online: 25 June 2023 (03:23:30 CEST)
Surface chemistry evaluation plays a crucial role in assessing the efficacy of chemical decontamination products for titanium implants. This study aimed to investigate the effectiveness of chemical decontamination solutions in cleaning a contaminated dental implant surface and to evaluate the potential of combining Pluronic gel with hydrogen peroxide (NuBone®Clean) by evaluating pellicle disruption and re-formation on implant surfaces. In addition, ensuring safety with in- vitro and human testing protocols. X-ray Photoelectron Spectroscopy (XPS) was utilized for surface analysis. All the tested gels had some effect on the surface cleanness except for PrefGel®. Among the tested chemical decontamination candidates, NuBone®Clean demonstrated effectiveness in providing a cleaner titanium surface. Furthermore, none of the tested chemical agents exhibited any cytotoxic effects, and the safety assessment showed no adverse events. The results of this study highlight the significance of conducting comprehensive evaluations, encompassing safety and efficacy, before introducing new chemical agents for dental treatments. The findings suggest that NuBone®Clean shows potential as a chemical decontamination solution for implant surfaces. However, further investigation through randomized clinical trials is necessary. By adhering to rigorous testing protocols, the development of safe and efficient chemical decontamination strategies can be advanced, benefiting patients and promoting progress in the field of implant dentistry.
ARTICLE | doi:10.20944/preprints202306.1720.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Bacterial leakage; Cone-Morse connection; dental implants; equicrestal implant placement; Finite Element Analysis (FEA); implant-abutment junction; implant placement; subcrestal implant placement.
Online: 25 June 2023 (05:49:19 CEST)
Peri-implant bone resorption has been reported around some implants after loading and this could create problems for the long-term stability of peri-implant soft and hard tissues. The causes are still not completely known, but a relevant importance could be assumed by the presence of a bacterial contamination at the micro-gap level of the implant-abutment junction. In this regard, external and internal implant-abutment assemblies have been shown to be much more permeable to bacterial colonization than Cone-Morse or conical connections. A subcrestal implant placement could have aesthetic advantages allowing a better prosthetic emergence profile. In literature controversial experimental and clinical results have been reported about bone resorption around implants placed equicrestally and subcrestally. Interestingly, Finite Element Analysis (FEA) studies revealed to be extremely useful for assessing the peri-implant bone strain and stress. Thus, the aim of this study was a FEA evaluation of implants with a Cone-Morse implant-abutment assembly (Implacil De Bortoli, São Paulo, Brazil) inserted into a bone block model (width: 10 mm, vertical height: 17.5 mm, thickness of the cortical area: 1.5 mm) mimicking equicrestal and subcrestal placements (1 and 2 mm). The results demonstrated that maximum stresses were observed within the cortical bone around the equicrestally placed implants, the lowest in the implant placed 2-mm subcrestally and intermediate stresses within the implant placed 1-mm subcrestally. Cortical bone was more stressed under lateral loads than axial loads. In conclusion, this FEA study suggested that implant placement at -1 mm could be recommended.
ARTICLE | doi:10.20944/preprints202205.0348.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: zirconia; molecular precursor method; dental-implant; osseointegration; bone-to-implant contact
Online: 25 May 2022 (10:10:35 CEST)
In previous studies regarding the osseointegration of zirconia (ZrO2) implants, a lack of consistency was observed in the surface topographies of the ZrO2 and Ti samples because of the difficult processability of ZrO2 surfaces. To resolve this problem, we used the molecular precursor method (wet process), which is a surface-modifying technique that can easily change the surface chemistry without changing the surface topography. A roughened Ti surface was prepared using sandblasting (large-grit) and acid treatment. We were able to create ZrO2-coated Ti implants with the same topography as that of roughened Ti substrates using the molecular precursor method, which solution contained a Zr complex. The uniform presence of tetragonal Zr was confirmed, and the apparent zeta potential of the surface of the ZrO2-coated Ti implant was higher than that of Ti. In animal experiments, ZrO2-coated Ti implants showed an equivalent or higher bone-to-implant contact ratio compared to that of the non-coated implants inserted into the femur bone defects of the rats. ZrO2 with the same surface topography as that of roughened Ti exhibits a promotion of osteogenesis equivalent to or better than that of Ti in the early stages of bone formation.
CASE REPORT | doi:10.20944/preprints202309.1890.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Synthetic, Alloplast, Dental Implant,
Online: 27 September 2023 (11:12:30 CEST)
Abstract: With a resurgence in ITRT (Immediate Tooth Replacement Therapy) as a method of preserving both hard and thus soft tissues for improved aesthetic outcomes, this multi-centre, retrospective study will look at two novel products and their effect on these outcomes. A new synthetic particulate graft material along with a novel Implant design was utilized in the study and a 1 year follow up assessment, analysed for hard and soft tissue regeneration.
ARTICLE | doi:10.20944/preprints202310.1237.v1
Subject: Medicine And Pharmacology, Otolaryngology Keywords: objective measurement; cochlear implant; differential diagnostics
Online: 19 October 2023 (13:20:43 CEST)
Background: By using outcome prediction scores, it is possible to distinguish between good and poor performers with cochlear implants (CI) after CI implantation. The reasons for poor performance, despite good basic conditions, can be manifold. On the one hand, the postoperative fitting may be inadequate; on the other, neurophysiological disease processes may impair speech understanding with a CI. These disease processes are not yet fully understood. In acoustics, it is known that the auditory brainstem responses (ABR) and their latencies and amplitudes allow differential diagnosis based on reference values for normal-hearing individuals. The aim of this study was to provide reference values for electrically evoked brainstem responses (EABRs) in terms of rate-dependent latencies and amplitudes. Methods: 20 experienced adult CI recipients with a predicted and measured good postoperative word recognition score were recruited from the clinic’s patient pool. In the same stimulation mode and intensity we measured latencies and interpeak-latencies of EABRs and electrically evoked compound action potentials (ECAPs). With a defined supra-threshold stimulation intensity above the individual ECAP threshold, we applied stimulation at several rates between 11 and 91 stimuli per second. Results: We found rate dependences for EABR latency t3 and t5 in the order of 0.19 ms and 0.37 ms respectively, while ECAP was not affected by rate. Correspondingly, the interpeak intervalls’ rate dependences for t5-t1, t5-t3 and t3-t1 were of the order of 0.37 ms, 0.18 ms and 0.19 ms. Comparing the EABR amplitudes between the stimulation rates 11/s and 81/s, we found that at 81/s the amplitudes were significantly reduced down: to 73% for A3 and 81% for A5. These rate dependences of latency and amplitude in EABR have characteristics comparable to those of acoustic ABR. Conclusions: These data may serve to provide reference values for EABR and ECAP latencies, interpeak intervals and amplitudes with respect to stimulation rate. Altered response patterns of ECAPs and EABRs to normalised stimulation modes could be used in the future to describe and classify neuropathological processes in a better-differentiated way.
ARTICLE | doi:10.20944/preprints202304.0715.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Implantology; implant site; thermo-printed templates
Online: 21 April 2023 (10:11:48 CEST)
In implantology, among the key choices, to obtain predictable results, it is essential to establish, on the basis of radiographic examinations, the bone site where to insert the implants; these selected locations must be identified first on the mucosa and then on the cortical bone. Surgical guides represent a valid aid especially in complex cases with more than 3 or 4 implants, whereas in single implant cases they are rarely used. This study evaluates the clinical precision with which the implant sites, on the patient's mucosa, are identified in surgical procedures planned without any templates. The verification of this precision is carried out through thermo-printed templates with radiopaque references which could however help the clinician to identify these sites in a simple, rapid and economical way.
REVIEW | doi:10.20944/preprints202008.0557.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: transplantation; dental implant; marginal bone loss; implant failure rate; systematic review; periodontitis; periodontal diseases; oral health
Online: 25 August 2020 (13:45:34 CEST)
This systematic review investigates the failure rate and marginal bone loss (MBL) of dental implants placed in Solid-organ transplant (SOT) patients compared to healthy controls. Three databases (PubMed, Web of Sciences and the Cochrane Library) were searched up to June 2020 (PROSPERO CRD42019124896). Case-control and cohort studies reporting data failure rate and marginal bone loss (MBL) of dental implants placed in SOT patients were included. The risk of bias of observational studies was assessed through the Newcastle-Ottawa Scale (NOS). Four case-control studies fulfilled the inclusion criteria, all of low risk of bias. Meta-analyses revealed consistently lower implant failure rate than control populations at patient and implant levels. SOT patients had a significant difference of -18% (p-value <0.001) of MLB towards healthy patients. SOT status poses no serious threat to implant survival. Overall, this group of patients presented lower levels of dental implant failure rate and marginal bone loss compared to otherwise healthy patients. Further intervention trials with wider sample size and longer follow-ups are necessary to confirm these summary results.
REVIEW | doi:10.20944/preprints202308.0750.v1
Subject: Public Health And Healthcare, Public Health And Health Services Keywords: bone conduction implants; middle ear implant; review
Online: 9 August 2023 (10:29:01 CEST)
This review provides a comprehensive overview of two major advancements in hearing loss treatment: the middle ear implant (MEI) and bone conduction implants (BCIs). MEI, surgically inserted in the middle ear, directly stimulate the ossicles, and are primarily employed to treat sensorineural, conductive, or mixed hearing losses. BCIs work via bone conduction, bypassing the outer and middle ear to deliver sound vibrations to the inner ear, beneficial especially for conductive or mixed hearing losses and single-sided deafness. The decision to opt for these devices is a multifaceted process, considering audiological criteria, surgical feasibility, and patient expectations. The review also details the portfolio of available devices, their functioning, and audiological usage indications. While both MEI and BCIs prove beneficial for patients, the review emphasizes the need for careful preoperative planning and counselling, considering factors such as potential complications, surgical challenges, and patient suitability. Overall, the two types of implants, despite their individual complexities, provide an effective alternative to traditional hearing aids, offering a path to improved sound clarity and quality for patients with various types of hearing loss.
ARTICLE | doi:10.20944/preprints202307.1333.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: tytanium implant; mitochondrial redox balance; antioxidants; fibroblasts
Online: 20 July 2023 (02:50:11 CEST)
Despite the high biocompatibility of titanium and its alloys, the need to remove titanium implants is increasingly being debated due to the potential for adverse effects associated with long-term retention. Therefore, new solutions are being sought to enhance the biocompatibility of titanium implants. One of them is to increase the thickness of the passive layer of the implant made of titanium dioxide. We were the first to evaluate the effect of hard-anodized (type II) Ti-6Al-4V alloy discs on the cytotoxicity, mitochondrial function and redox balance of mitochondrial fibroblasts compared to standard-anodized (type III) and non-anodized discs. The study used fibroblasts obtained from human gingival tissue. The test discs were applied to the bottom of 12-well plates. Cells were cultured for 24h and 7; 14 and 21 days and mitochondria were isolated. We demonstrated the occurrence of oxidative stress in the mitochondria of fibroblasts of all tested groups, regardless of the presence and type of anodization. Type II anodization prevented changes in complex II activity (vs. control). The lowest degree of citrate synthase inhibition occurs in mitochondria exposed to titanium discs with type II anodization. In the last phase of culture, the presence of type II anodization reduces the degree of cytochrome c oxidase inhibition compared to the other tests groups and the control group, and prevents apoptosis. Throughout the experiment, the release of titanium, aluminium and vanadium ions from titanium discs with a hard-anodized passive layer was higher than from the other titanium discs, but decreased with time. The obtained results prove the existence of dysfunction and redox balance in the mitochondria of fibroblasts exposed to hard-anodized titanium discs, suggesting the need to search for new materials perhaps biodegradable in tissues of the human body.
ARTICLE | doi:10.20944/preprints202307.0665.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: surface treatment; titanium; hierarchical structures; dental implant
Online: 11 July 2023 (05:25:10 CEST)
Titanium (Ti) and Ti-based alloys are commonly used in dental implants, and surface modifications of dental implants are important for achieving osseointegration (i.e., direct connection between the implant surface and bone). This study investigated the effect of an eco-friendly etching solution—a hydrogen peroxide–sodium bicarbonate mixture—on the surface properties and contact angles of and osteoblast adhesion and proliferation on Ti surfaces. Disk-shaped Ti specimens were prepared using different surface treatments (machining, sandblasting, and sandblasting/acid-etching), and they were immersed in the etching solution and then ultrasonically cleaned. Surface characterization was performed using scanning electron microscopy, digital microscopy, contact angle analysis, and X-ray photoelectron spectroscopy. MG-63 osteoblasts were cultured on the specimens, and their adhesion to the specimen surface and their proliferation were examined using staining and the MTT assay, respectively. Additional etching with the etching solution caused the formation of nano/micro hierarchical structures, increased the surface roughness, and enhanced the hydrophilicity. Osteoblast adhesion and proliferation were found to improve on the modified surfaces. The eco-friendly etching method has the potential to enhance the biological properties of Ti implant surfaces and to thereby improve the dental implant performance.
ARTICLE | doi:10.20944/preprints202310.1060.v1
Subject: Medicine And Pharmacology, Otolaryngology Keywords: cochlear implant, computer tomography , cochlea width, cochlea length
Online: 17 October 2023 (09:36:46 CEST)
Backround Cochlear implant is the first approved cranial nerve stimulator that works by directly stimulating the cochlear nerve. Various attempts have been made to evaluate the dimensions of the cochlea related to cochlear implantationThe preoperative computed tomographic examination is essential in assessing the anatomical aspect of the cochlea, but also in determining its dimensions, in order to choose an appropriate electrode, in order to obtain the best possible audiological performance. Method In the present paper, we aimed to carry out an observational study, regarding the role of cochlear measurements in the preoperative evaluation of patients proposed for cochlear implant. The purpose of the study was to measure the cochlea and to establish the existence of a correlation between the size of the cochlea and the age and gender of the patients. Results From the group of 35 examined patients, 54% (n= 19) were male and 46% (n=16) female. The average length of the cochlea in the age group 0-4 years is 7.82 mm in the left ear and 7.86 in the right ear, in the age group 4-7 years it is 7.82 mm and 7.94 mm respectively, for the age group 7-14 years the dimensions increase to 8.48 and 8.77 mm respectively, and after 14 years these dimensions reach 9.12, respectively 9.18 mm. Comparative measurements of the length of the cochlea by age groups show an increase in length with the patient's age, but this increase does not exceed 1.5 mm for both the right and left ears. The measurements of the width of the cochlea, by age group, start from 6.84 mm left ear and 6.81 mm right ear at 0-4 years, 6.94 mm and respective 6.97 mm at the group 4-7 years, 7.71 mm and respective 7.55 mm at 7-14 years , and reaching 8.19 mmm and 8.12 mm at the age of over 14 years. Conclusions From the study carried out it can be concluded that the evaluation of the dimensions of the cochlea is important for cochlear implantation, the size variables, although small, are still an element to be considered in correlation with the age of the patient and the implanted ear. This increase is statistically insignificant, but it still exists, even if from a theoretical point of view, it is considered that the dimensions of the cochlea remain constant.
ARTICLE | doi:10.20944/preprints202307.1668.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: porcine bone grafts; horizontal ridge augmentation; dental implant
Online: 25 July 2023 (08:29:55 CEST)
The purpose of this study was to evaluate the outcomes of implants placed in horizontally augmented alveolar ridges using porcine bone grafts and to investigate the long-term stability of the porcine bone grafts. A retrospective analysis was conducted on 55 sites that underwent horizontal ridge augmentation using porcine bone grafts and implant placement with a follow-up period longer than 5 years. Furthermore, additional analysis was conducted on 24 sites where porcine bone grafts were used exclusively and implants were placed simultaneously with horizontal ridge augmentation. The mean follow-up period after prosthesis loading was 67.3 months, with a mean marginal bone loss of 0.18 mm at 1 year and a cumulative mean marginal bone loss of 0.37 mm over the entire follow-up period. Of the 55 implants, 2 were lost and 4 did not meet the success criteria, resulting in a survival rate of 96.4% and a success rate of 89.1%. In 24 sites, the mean marginal bone loss was 0.22 mm at 1 year and 0.40 mm at 65.8 months, with 100% survival and success rates. Porcine bone grafts can be successfully used in horizontal ridge augmentation for implant placement in cases of ridges with insufficient horizontal width.
ARTICLE | doi:10.20944/preprints202211.0047.v1
Subject: Medicine And Pharmacology, Otolaryngology Keywords: hearing therpy; speech therapy; cochlea implant; digital application
Online: 2 November 2022 (06:10:30 CET)
Background: In order to achieve the best possible hearing and understanding with a cochlear implant (CI), regular hearing speech therapy treatment is necessary after implantation. This treatment should also be accessible to the growing proportion of hearing-impaired people with a migration background. This requires an alternative to therapy in the therapist's native language. The aim of this study was to evaluate six multilingual conversation applications with regard to their usefulness for therapy. Material and Methods: The six most commonly used applications were reviewed in terms of accuracy of content and grammatical translation, as well as pronunciation for English, Spanish, Arabic, Turkish, and Russian by native speakers. The number of available languages, availability, cost, and additional features were also analyzed. The accuracy of the content and grammatical translation as well as the pronunciation were statistically evaluated, and the differences were highlighted. The results of the different applications were compared with the performance of a native speaker. Results: All applications tested differed significantly from the native speaker level, with Google Translator showing the closest approximation to the native speaker level. All apps offer translations for multiple languages and, with exceptions, are available in both app stores. Furthermore, all apps have additional therapist-facilitating features. Conclusion: Multilingual conversation apps can make speech therapy in a foreign language much easier when used with patients. An adaptation of the software to the specific requirements of a hearing speech therapy is necessary to achieve a linguistic level that corresponds to the native language of the therapist and to enable an easy use in the therapy.
REVIEW | doi:10.20944/preprints202012.0455.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Prognosis; prosthodontics; dental implant; clinical performance; risk factor.
Online: 18 December 2020 (11:34:49 CET)
Background: The treatment plan of prosthetic restorations supported by dental implants require comprehensive scientific knowledge to deliver prostheses with good prognosis, even before the implant insertion. This review aims to analyze the main prosthetic determinants of the prognosis of implant-supported prostheses. Methods: A systematic review of the literature was conducted with a PICO question: "For partially or complete edentulous subjects treated with implant-supported prostheses, which prosthetic factors could affect clinical outcomes?". A literature search was performed electronically in PubMed (MEDLINE), Scopus and Cochrane Library with the following equation [PROGNOS* OR RISK] FACTOR IMPLANT DENTAL, and by hand search in relevant journals and throughout the selected papers. Results: This revision was carried out based on 50 papers focused on several prosthodontics-related risk factors that were grouped as follows: implant-connection, loading protocol, transmucosal abutments, prosthetic fit, provisionalization, type of retention, impression technique, fabrication technique, and occlusion. More than a half of the studies were systematic reviews (30%), meta-analysis (16%) or prospective evaluations of prosthesis with various kinds of events (18%). But also narrative reviews of literature (14%) and in vitro/animal studies (16%) were found. Conclusions: The current literature provides insufficient evidence for most of the investigated topics. However, based on the accumulated data, it seems reasonable to defend that the best treatment approach is the use of morse taper implants with transmucosal abutments, recorded by means of rigidly splinted copings through the pick-up technique, and screwed by milled prosthesis occlusally adjusted to minimize functional overloading.
ARTICLE | doi:10.20944/preprints202010.0573.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: implant; bacterial cellulose; patch; myocardial infarction; cell; delivery
Online: 28 October 2020 (08:59:09 CET)
Biologic scaffolds have become an attractive approach for repairing the infarcted myocardium and have been shown to facilitate constructive remodeling in injured tissues. This study aimed to investigate the possible utilization of bacterial cellulose membrane patch containing cocultured cells to limit the myocardium's post-infarction pathology. Myocardial infarction was induced by ligating the left anterior descending coronary artery in 45 Wistar rats, and patches with or without cells were attached to the hearts. After one week, the animals underwent echocardiography for assessing ejection fraction and left ventricular end-diastolic and end-systolic volumes. Following the patch formation, cocultured cells retained viability of >90% over 14 days in culture. The patch was applied to the myocardial surface of the infarcted area after staying 14 days in culture. Interestingly, the bacterial cellulose membrane without cellular treatment showed higher preservation of cardiac dimensions; however, we did not observe improvement in the left ventricular ejection fraction of this group compared to coculture treated membranes. Our results demonstrated an important role for bacterial cellulose in supporting cells known to produce cardioprotective soluble factors and may thus provide effective future therapeutic outcomes for patients suffering from ischemic heart disease.
ARTICLE | doi:10.20944/preprints202007.0457.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: resonance frequency analysis; implant stability quotient; reliability; validity
Online: 20 July 2020 (08:05:06 CEST)
Background: Actually, resonance frequency analysis (RFA) is the most extended method for measuring implant stability. The implant stability quotient (ISQ) is the measure obtained by the different RFA devices, however, inter- and intra- rater reliability and validity of some devices remains unknown. Methods: Thirty implants were placed in 3 different pig mandibles. ISQ was measured axial and parallel with Osstell® Beacon, Penguin® and MegaISQ® by 2 different operators and one operator performed a test-retest. Intraclass correlation coefficient was calculated to assess the intra- and inter-rater reliability. Pearson correlation coefficient was used to assess the validity. Results: The higher inter- and intra- rater reliability was obtained by Penguin® when measuring axial. The highest ISQ values were obtained using Penguin® in an axial measurement; the lowest, using the MegaISQ® in an axial measurement. The highest correlation values with the other devices were obtained by MegaISQ® measuring axially. Conclusion: Penguin® had a good reliability for measuring ISQ both inter- and intra- rater. Osstell® had good validity for measuring ISQ both axial and parallel and MegaISQ® had the best validity for measuring ISQ axial.
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Insertion torque; Pullout strength; Gripping volume; Micro-implant
Online: 10 February 2020 (11:32:53 CET)
This study evaluated the mechanical strengths of three types of orthodontic micro-implants by analyzing their structural configurations. Thirty micro-implants of three types (diameter 1.5 mm, Types A, B, C) were assessed. All micro-implants were manually driven into artificial bones at an 8-mm depth. The insertion torque (IT), pullout strength (PS), and gripping volume (GV) of each type were measured. Intergroup comparisons and intragroup correlation were investigated by statistical analysis. Type B had the greatest inner–outer diameter ratio (0.67), and Type A had the smallest (0.53). The IT of Type A (5.26 Ncm) was significantly (p = 0.038) lower than that of Type C (8.8 Ncm). There was no significant difference in the pullout strength (p = 0.868). The GV of Type A (9.7 mm3) was significant (p < 0.01) greater than Type C (8.4 mm3). Type C was significant (p < 0.01) greater than Type B (7.2 mm3). Spearman’s rho rank correlation test showed that PS of Type B was correlated significantly with GV. In conclusion, the design of thread and its GV were the important factors on the mechanical strengths of micro-implant.
ARTICLE | doi:10.20944/preprints202311.1635.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: FEM analysis, stress distribution, Ti6Al4V alloy, dental implant, design
Online: 27 November 2023 (11:05:24 CET)
Dental implant fracture is closely connected to the stress buildup surrounding the implant system during static loading. In areas where the cross section of the implant rapidly changes or where the geometry of the implant system has discontinuities, stress concentrations arise. Therefore, the implant's design is crucial in preventing early failure of the implant system, including fracture, screw loosening, and increased leakage, in addition to reducing stresses at the implant-abutment interface. In the current work, three-dimensional (3D) models of mechanically connected Ti6Al4V implant systems in various dimensions were constructed. Finite Element Analysis (FEA) was used to conduct a stress study of the created implants under actual acting forces static loading conditions in accordance with ISO 14801. In the created models, design elements including implant screw type, thickness, and taper angle of abutment were modified in order to increase the longevity of the implants. The results show that the equivalent stress level is dramatically reduced from 596.22 MPa to 212.72 MPa in the implant model, which exhibit more homogeneous stress pattern under static loading conditions. Furthermore, the relatively smoother stress transmission observed in this model holds promise for the development of new implants capable of withstanding the forces encountered in the oral environment.
ARTICLE | doi:10.20944/preprints202306.0997.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: Guided Bone Regeneration; dental implant; PLACL; resorbable bilayer membrane
Online: 14 June 2023 (07:10:22 CEST)
Insufficient oral ridge tissue presents a challenge in the treatment of dental implants. One method to enhance alveolar crest dimensions is guided bone regeneration (GBR); however, existing membranes have certain limitations. To address this issue, we aimed to compare the effectiveness of a resorbable bilayer membrane composed of poly(l-lactic acid) and poly(-caprolactone) （PLACL）with that of a collagen membrane（COL） in a rat GBR model. The rat calvaria was used as an experimental model by placing a plastic cylinder. Forty male Fisher rats underwent surgery, and micro-computed tomography and histomorphometric analyses were performed to assess bone regeneration. The results showed that bone regeneration was similar across all the groups. However, after 24 weeks, the PLACL membrane demonstrated significant resilience, occasional partial degradation, and intermittent air bubble formation. This extended preservation of the barrier effect has great potential to facilitate optimal bone regeneration. In conclusion, this study shows that the PLACL membrane is a promising alternative to GBR. By providing a durable barrier and supporting bone regeneration over an extended period, this resorbable bilayer membrane may address the limitations of the current membranes. Further studies and clinical trials are warranted to validate the efficacy and safety of this drug in humans.
ARTICLE | doi:10.20944/preprints202306.0766.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: FEA; implant-supported overdenture; locator attachments; bar-retained overdenture
Online: 12 June 2023 (05:06:58 CEST)
The objective of this study was to compare the distribution of stress in the maxillary bone, dental implants, and prosthetic components supporting implant-supported maxillary overdentures with partial palatal coverage, in both splinted and unsplinted designs. Two models of maxillary overdentures were designed using the Exocad Dental CAD program, which included cancellous and cortical bone. The complete denture design and abutments (locator abutments in the unsplinted and Hader bar with Vertix attachments placed distally in the splinted variant) were also designed. The denture material was PEEK (Polyetheretherketone), and the method used to analyze patient-specific 3D X-ray scans was 3D QCT/FEA (Three-dimensional Quantitative Computed Tomography-Based Finite Element Analysis). Loading was divided into three load cases: frontal region (both incisors of the denture) and distal region (both molars and first premolar of the denture). The forces applied were 150 N with an oblique component with a buccal inclination of 35° in the frontal region, and 600 N with a buccal inclination of 5° (molars) or solely vertical (premolar) in the distal region. The model with locator abutments showed higher stresses in all load cases in both analyzed implant variants and in the maxilla. The differences in stress distribution between the splinted and unsplinted variants were more significant in the distal region. According to the results of the present study, the amount of stress in bone tissue and dental implant parts was smaller in the splinted, bar-retained variant. The findings of this study can be useful in selecting the appropriate prosthetic design for implant-supported maxillary overdentures with partial palatal coverage.
ARTICLE | doi:10.20944/preprints202211.0533.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: Nano surfaces; Early bone formation; Implant surface; histomorphometry; osseointegration.
Online: 29 November 2022 (03:57:25 CET)
Background: Implant surface topography is a key element in achieving osseointegration. Nanostructured surfaces have shown promising results in accelerating and improving bone healing around dental implants. The main objective of the present clinical and histological study is to compare, at 4 and 6 weeks, (w) bone-to-implant contact in implants having either machined surface (MAC), SLA medium roughness surface or a Nanostructured Calcium-Incorporated sur-face (XPEED®). Methods: 35 mini-implants with 3 different surface treatments (XPEED® (n=16) – SLA (n=13) – Machined (n=6), were placed in the posterior maxilla of 11 patients then, retrieved at either 4 or 6w in a randomized split-mouth study design. Results: The BIC rate measured at 4 and 6w respectively, was: 16.8 % (±5.0) and 29.0 % (±3.1) for MAC surface; 18.5 % (±2.3) and 33.7 % (±3.3) for SLA surface; 22.4 % (±1.3) and 38.6 % (±3.2) for XPEED® surface. In all types of in-vestigated surfaces, the time factor appeared to significantly increase the BIC rate (p < .05). XPEED® surface showed a significantly higher values when compared to both SLA and MAC values at 4w (p < .05). Also, at 6w, both roughened surfaces (SLA and XPEED® ) showed signifi-cantly higher values (p < .05) than turned surface (MAC). Conclusion: Nanostructured Calcium titanate coating is able to enhance bone deposition around implants at early healing stages.
REVIEW | doi:10.20944/preprints202201.0318.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Bilateral vestibular dysfunction; saccular; posture; gait; vestibular implant; otolith
Online: 21 January 2022 (10:43:36 CET)
An ongoing EU Horizon 2020 Project called BionicVEST is investigating the effect of constant electrical stimulation (ES) of the inferior vestibular nerve in patients with bilateral vestibular dysfunction (BVD). The evidence is that constant ES results in improved postural stability and gait performance and so the question of central importance is how could constant ES of mainly saccular afferents in these BVD patients cause this improved performance? We suggest that the constant ES is substituting for the absent saccular neural input to the vestibular nuclei and the cerebellum in these BVD patients and indirectly via these structures to other structures which have been of great recent interest in motor control. One target area, the anterior midline cerebellum (the uvula) has recently been targeted as a location for deep brain stimulation in human patients to improve postural stability and gait. There are projections from midline cerebellum to basal ganglia including the striatum, structures involved in the initiation of gait. It may be that the effect of this activation of peripheral saccular afferent neurons is analogous to the effect of deep brain stimulation (DBS) by electrodes in basal ganglia acting to help alleviate the symptoms of patients with Parkinson's disease.
ARTICLE | doi:10.20944/preprints201810.0300.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: allograft, xenograft, inflammation, sclerotic bone, implant failure, antigenic ossification
Online: 15 October 2018 (10:39:43 CEST)
Cadaver bone is possibly the most common transplant material used today. Common types of cadaver bone transplants are freeze dried bone allografts and xenografts. In the case of freeze dried bone allograft transplants, it was theorized that these materials mineralize by way of osteoinduction and stimulating osteogenesis. However, these theories have been proven false. It has been proposed that these materials mineralize via osteoconduction however, there are no studies to support this hypothesis. This study was undertaken to determine how these transplants mineralize and what type of bone they produce. Materials and Methods: This study is a histological analysis of human cadaver bone graft healing from the incipient stages of mineralization through completed mineralization. All cadaver bone grafts used for evaluation in this study were particulate bone graft materials in the maxilla or mandible. No block grafts were evaluated. Results: The mineralization of cadaver bone transplants was produced by an inflammatory response to the transplanted tissue. The histologic findings of the mineralized bone produced by this process was sclerotic bone. No resorption of cadaver bone graft particles was found. When loaded the sclerotic bone was found to fail through an accumulation of microfractures.Conclusions: Particulate freeze-dried bone allografts and xenografts do not heal via the normal processes of mineralization. Cadaver bone grafts produce significant inflammation and are hypothesized to mineralize by a process termed antigenic ossification. The process of antigenic ossification produces sclerotic bone that is not capable of self-repair which can ultimately lead to bone failure.
ARTICLE | doi:10.20944/preprints202309.1811.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: OSA; HGNS; ECG; CNN,; WPT; Rectifier; Power management; BPSK; Stimulator; Implant
Online: 27 September 2023 (10:33:52 CEST)
Hypoglossal nerve stimulator (HGNS) is a minimally invasive device used for treating obstructive sleep apnea (OSA). The conventional implantable HGNS is a device that consists of a stimuli generator, a breathing sensor, and electrodes connected to the hypoglossal nerve via leads. However, this implant is bulky and causes significant trauma. In this paper, we propose a minimally invasive HGNS based on an electrocardiogram (ECG) sensor and a wireless power transfer (WPT), consisting of a wearable breathing monitor and an implantable stimulator. The breathing external monitor utilizes an ECG sensor to identify abnormal breathing patterns associated with OSA with 88.68$\%$ accuracy, achieved through the utilization of a Convolutional Neural Network (CNN) algorithm. With a skin thickness of 5mm and a receiving coil diameter of 9mm, the power conversion efficiency was measured at 31.8$\%$. The implantable device, on the other hand, is composed of a front-end CMOS Power Management Module (PMM), a Binary Phase Shift Keying (BPSK)-based data demodulator, and a bipolar biphasic current stimuli generator. The PMM, with a silicon area of 0.06 $mm^2$ (excluding pads), demonstrates a power conversion efficiency of 77.5$\%$ when operating at a receiving frequency of 2 MHz. Furthermore, it offers three-voltage options (1.2V, 1.8V, and 3.1V). Within the data receiver component, a low-power BPSK demodulator has been ingeniously incorporated, consuming only 42 $\mu$W when supplied with a voltage of 0.7V. The performance is achieved through the implementation of the self-biased phase-locked loop (PLL) technique. The stimuli generator delivers biphasic constant currents, providing a 5-bit programmable range spanning from 0 to 2.4 mA. The functionality of proposed ECG and WPT-based HGNS was validated, representing a highly promising solution for the effective management of OSA, all while minimizing trauma and space requirements.
ARTICLE | doi:10.20944/preprints202309.1785.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: breast cancer; postmastectomy radiation therapy; implant-based reconstruction; target volume; dosimetry
Online: 26 September 2023 (10:27:56 CEST)
Background: The target volume for post-mastectomy radiation therapy (PMRT) in breast cancer patients with reconstruction has been a subject of debate. This study aimed to assess the radiation dose distribution and treatment outcomes associated with different chest wall (CW) delineation according to ESTRO ACROP guideline for patients underwent implant-based reconstruction. Methods: We conducted a retrospective review of breast cancer patients who underwent mastectomy followed by two-stage implant-based breast reconstruction and adjuvant radiation therapy (RT) between 2007 and 2022. The expanders/implants were positioned retropectorally. The chest wall target volumes were categorized into two groups: the prepectoral group, which excluded the deep lymphatic plexus, and the whole expander group. Results: The study included 26 patients, 15 in prepectoral group and 11 in whole expander group. No significant differences were observed in normal organs exposure between the two groups. There was a trend toward a lower ipsilateral lung mean dose in the prepectoral group (10.2 vs. 11.1 Gy, p=0.06). Both groups exhibited limited instances of reconstruction failure and local recurrence. Conclusions: For patients undergoing two-stage expander-implant retropectoral breast reconstruction and PMRT, our data have provided comparable outcomes and normal organs exposure for those omitting the deep lymphatic plexus.
ARTICLE | doi:10.20944/preprints202309.1042.v1
Subject: Medicine And Pharmacology, Surgery Keywords: biofilm; stainless implant; in vitro model; antiseptic solutions; irrigation; Bactisure™
Online: 15 September 2023 (04:56:56 CEST)
Irrigation and debridement using an irrigation solution is a fundamental step during the surgi-cal treatment of both acute and chronic periprosthetic joint infection (PJI). However, there is no consensus on the optimal solution, nor is there sufficient evidence on optimal irrigation time and combination of solutions. Therefore, it is necessary to determine which solution or combi-nation of solutions is most efficacious against biofilm, as well as the optimal irrigation time. We conducted an experimental in vitro model by inoculating stainless steel discs with ATCC strains of methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus, Pseudomonas aeru-ginosa, and a clinical strain of Staphylococcus epidermidis. The discs were all irrigated with com-monly used antiseptic solutions (10% and 3% povidone iodine, hydrogen peroxide, 3% acetic ac-id, and Bactisure™) for 1 min, 3 min, and 5 min and their combinations for 9 min (3 min each) vs. sterile saline as a positive control. We evaluated the reduction in biofilm based on colony form-ing unit (cfu) counts and, in combination assays, also based on cell viability and scanning elec-tron microscopy. All antiseptics alone reduced more than 90% of cfu counts after 1 min of irriga-tion; the worst results were for hydrogen peroxide and 3% acetic acid. When solutions were combined, the best results were observed for all those starting with acetic acid, in terms of both reduction of log cfu/ml counts and viable cells. We consider that a combination of antiseptic so-lutions, particularly that comprising the sequence acetic acid+povidone iodine+hydrogen per-oxide, would be the best option for chemical debridement during PJI surgery.
REVIEW | doi:10.20944/preprints202307.0945.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: mandibular flexure; mandibular deformation; fixed oral rehabilitation; implant-supported full-arch
Online: 14 July 2023 (09:51:56 CEST)
Background - Mandibular flexion (MF) is a complex biomechanical phenomenon, which involves a deformation of the mandible, due mainly to the contraction of the masticatory muscles, and can have numerous clinical effects. The main aim of the current systematic review is to highlight the different factors that can increase MF, to help clinicians, identify patients to whom they should pay more attention. As a secondary outcome, we wanted to analyze the preventive measures and suitable techniques to be adopted to minimize the negative effects of this phenomenon on oral fixed rehabilitations. Methods - The review, which was carried out in accordance with the “Preferred Reporting Items for Systematic reviews and Meta-Analyses” (PRISMA) flowchart, was recorded in the “International Prospective Register of Systematic Reviews” (PROSPERO). As research questions, “Patient/Population, Intervention, Comparison and Outcomes” (PICO) questions were employed. Using the ROBINS-I technique, the risk of bias in non-randomized clinical studies was evaluated. Results - The initial electronic search identified over 1300 potential articles, of which 54 studies were included in this systematic review. Information regarding the relationship between MF and individual factors, mandibular movements, impression-taking and fixed rehabilitations were obtained. Conclusions – The studies included in this systematic review showed that MF is greater during protrusive movements, in the posterior areas of the lower jaw, and in patients with brachial facial type, greater jaw length, small gonial angle and less density, length and bone surface of the symphysis. The biomechanical effects of mandibular flexion on fixed restorations are debated. Prospective clinical and radiological observational studies should be conducted to evaluate the potential short-, medium- and long-term consequences of MF.
ARTICLE | doi:10.20944/preprints202306.0963.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Dental implants; Dental Implant-Abutment Design; keyword 1; X-Ray Microtomography
Online: 14 June 2023 (03:15:05 CEST)
Background and Objectives: Mechanical and biological complications can lead to system fracture or screw loss on dental implants. Narrow and regular platforms have been used without a consensus about the effect of distance the abutment from the prosthetic platform margin. The aim of this study is to evaluate different insertion torques in the deformation of tri-channel platform connections through two- and three-dimensional measurements with micro-CT. Materials and Methods: 164 implants were divided into groups (platform diameter and type): 3.5, 3.75, and 4.3 mm NP (Narrow Platform), and 4.3 mm RP (Regular Platform). Each implant-platform group was then divided into four subgroups (n = 10) with different torques: T45 (45 Ncm), T80 (80 Ncm), T120 (120 Ncm) and T150 (150 Ncm). The implant-abutment-screw assemblies were scanned and the images obtained were analyzed. Results: A significant difference was observed for the linear and volume measures between the different platforms (p <0.01) and the different implant insertion torques (p <0.01). Qualitative analysis suggested higher deformation resistance for the 3.75 NP compared to the 3.5 NP, and RP was more resistant compared to the NP. Conclusions: The 0.25-mm increment in the implant platform did not increase the resistance to the applied insertion torques; the 4.3-mm implant was significantly stronger compared to the 3.5-mm implant and the proposed micro-CT analysis was considered valid for both 2D and 3D analyses of micro gaps, qualitatively and quantitatively.
Subject: Chemistry And Materials Science, Electrochemistry Keywords: titanium dental implant; vitamin D3; bioactive coating; anticorrosion protection; EIS; DFT
Online: 10 September 2019 (11:35:26 CEST)
In recent years extensive studies have been continuously undertaken on the design of bioactive and biomimetic dental implant surfaces due to the need for improvement of the implant-bone interface properties. In this paper, the titanium dental implant surface was modified by a bioactive vitamin D3 coating prepared by self-assembly process. Surface characterization of the modified implant was performed by field emission scanning electron microscopy (FE-SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and contact angle measurements (CA). Implant’s electrochemical stability during exposure to an artificial saliva solution was monitored in situ by electrochemical impedance spectroscopy (EIS). Experimental results obtained were corroborated by means of quantum chemical calculations at the density functional theory level (DFT). The formation mechanism of the coating onto the titanium implant surface was proposed. During a prolonged immersion period, the bioactive vitamin D3 coating effectively prevented the underlying titanium from corrosive attack (polarization resistance in order of 107 Ω cm2) with ~95% protection effectiveness.
ARTICLE | doi:10.20944/preprints201801.0152.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: sinus lift; graft bone; finite element analysis; 3D modeling; dental implant
Online: 17 January 2018 (11:15:00 CET)
Purpose: The aim of the present experimental 3D-finite element study was to evaluate the influence of an augmented sinus lift with an additional inserted bone graft block. The bone graft block stabilizes the implant in addition to conventional augmented bone. We placed the block in three different positions. The implants were loaded with axial force and forces secondary to laterotrusion and protrusion. Material and Methods: A simplified U-shaped 3D finite element model of the upper jaw and a more complex anatomical model of the left maxilla were created. The bone graft block was placed in three positions: in the lower third in contact with the sinus floor, the middle, and the upper third of the implant. Van Mises’ stress distribution was calculated and analyzed for the different models. We also compared the complex anatomical model with the simplified one. Results: The position of the bone graft block significantly influences the magnitude of stress distribution. A bone graft block positioned in the upper third or middle of the implant reduces the quantity of stress compared to the reference model without a bone graft block. The low bone graft block position is clearly associated with lower stress distribution in compact bone. We registered no significant differences in stress in compact bone with regard to laterotrusion or protrusion. Conclusions: Maximum values of von Mises stresses in compact bone can be reduced significantly by using a bone graft block. The reduction of stress is nearly the same for positions in the upper third and the middle of the implant. It is much more pronounced when the bone graft block is in the lower third of the implant near the sinus floor, which appeared to be the best position in the present study.
ARTICLE | doi:10.20944/preprints202307.1681.v1
Subject: Medicine And Pharmacology, Surgery Keywords: orbital reconstruction, enophthalmos, CAD-CAM technique, titanium mesh, HDPE implant, personalized surgery.
Online: 25 July 2023 (11:44:52 CEST)
Enophthalmos is a severe complication of primary reconstruction following orbital floor frac-tures, oncological resections or maxillo-facial syndromes. The goal of secondary reconstruction is to re-store symmetrical globe positions to recover function and aesthetics. In this article we pre-sent a method of computer-assisted orbital floor reconstruction using a mirroring technique and a customized titanium or high-density polyethylene mesh, printed using computer aided manufac-turing techniques. This reconstructive protocol involves 4 steps: mirroring of the healthy orbit at the affected site, vir-tual design of a patient specific orbital floor mesh, computer-assisted manufacturing (CAD) of the implant, and surgical insertion of the device. Using a computed tomography data set, the un-injured side of the craniofacial skeleton was reflected onto the contralateral injured side, and a reconstructive orbital floor prosthesis was virtually designed on the mirrored orbital bone sur-face. The solid-to-layer (.STL) files of the prosthesis were then manufactured using Direct Metal Laser Sintering (DMLS) or Computer Numerical Control (CNC) methods, leading to the produc-tion of 10 titanium meshes and 2 high density polyethylene (HDPE) implants. Clinical outcomes were assessed using 3dMD photogrammetry and computed tomography measures in 14 treated patients. The technique described here appears to be a viable method to correct complex orbital floor de-fects needing delayed reconstruction. This article represents the prosecution of a previous study, which is part of a wider experimental protocol for orbital floor reconstruction using comput-er-assisted design-computer-assisted manufacturing (CAD-CAM) technology
REVIEW | doi:10.20944/preprints202305.0832.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: biomaterials; coatings; calcium phosphates; hydroxyapatite; bone implant; biocompatibility; bioactivity; hard tissue repair
Online: 11 May 2023 (09:03:34 CEST)
This review article deals with the design of bioactive calcium phosphate coatings deposited on metallic substrates to produce bone implants. The bioceramic coating properties are used to create a strong bonding between the bone implants and the surrounding bone tissue. They provide a fast response after implantation and increase the lifespan of the implant in the body environment. The first part of the article describes the different compounds belonging to the calcium phosphate family and their main properties for applications in biomaterials science. The calcium to phosphorus atomic ratio (Ca/P)at. and the solubility (Ks) of these compounds define their behavior in a physiological environment. Hydroxyapatite is the gold standard among calcium phosphate materials, but other chemical compositions/stoichiometries have also been studied for their interesting properties. The second part reviews the most usual deposition processes to produce bioactive calcium phosphate coatings for bone implant applications. Plasma spraying is the main industrial process, but magnetron sputtering, pulsed laser deposition, electrospray deposition, electrophoretic deposition, and electrodeposition are also widely studied in academic and industrial research. The last part describes the main physicochemical properties of calcium phosphate coatings and their impact on the bioactivity of bone implants in a physiological environment.
ARTICLE | doi:10.20944/preprints202108.0379.v1
Subject: Engineering, Mechanical Engineering Keywords: Fatigue; oblique loading; axial loading; finite element analysis; 3D-printed dental implant
Online: 18 August 2021 (13:54:49 CEST)
Fatigue analysis plays a vital role in determining the structural integrity and life of a dental implant. With the use of such implants on the rise, there is a corresponding increase in the number of implant failures. As such, the aim of this research paper is to investigate the life of 3D-printed dental implants. The dental implants considered in this study were 3D printed according to the direct metal laser sintering (DMLS) method. Additionally, a finite element model was developed to study their performance, while fatigue life was predicted using Fe-Safe software®. The model was validated experimentally by performing fatigue tests. The life of the dental implants was analysed based on Normal strain and the Brown-Miller with Morrow mean correction factor algorithm. The model revealed that there was a strong correlation between the FEA and the experimental results. The clinical success of 3D-printed dental implant experimentally is 20.51 years and computationally under Normal strain is 19.89 years and Brown-Miller with Morrow mean correction factor is 26.82 years.
ARTICLE | doi:10.20944/preprints202212.0042.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: nipple-sparing mastectomy; prophylactic implant-based breast reconstruction; SMI (silicone mammary implants); SMI surface topography; surface roughness; fibrosis; capsular contracture; aesthetic outcome; intra-individual comparison; titanised mesh implant pocket
Online: 2 December 2022 (07:40:06 CET)
The most common long-term complication of silicone breast implants (SMI) remains capsular fibrosis. The etiology of this exaggerated implant encapsulation is multifactorial but primarily induced by the host response towards the foreign material silicone. Identified risk factors included specific implant topographies. Of note, breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), has only been observed in response to textured surface implants. We hypothesize that reduction of SMI surface roughness causes less host response hence better cosmetic outcome with fewer complications for the patient. A total of 7 patients received the routinely used CPX®4 breast expander (~60 µM Ra) and the novel SmoothSilk® (~ 4 µM Ra), fixed prepectoral with a titanised mesh pocket and randomized to the left or right breast after bilateral prophylactic NSME (nipple-sparing mastectomy). We aimed to compare the postoperative outcome regarding capsule thickness, seroma formation, rippling, implant dislocation as well as comfortability and practicability. Our analysis shows that surface roughness is an influential parameter in controlling fibrotic implant encapsulation. First time intra-individually compared in patients, our data confirm an improved biocompatibility with minor capsule formation around SmoothSilk® implants with an average shell roughness of 4 µM and in addition an amplification of host response by titanised implant pockets.
ARTICLE | doi:10.20944/preprints202310.1935.v1
Subject: Engineering, Bioengineering Keywords: External-hexagon implants; implant-abutment connections; electrolytic deposition; micro-gap; SEM; bacterial leakage
Online: 31 October 2023 (02:39:02 CET)
Purpose: The objective of the study was to qualitatively assess micro-gap dimensions, connecting fitting surface profile and bacterial leakage of machined and cast high gold alloy UCLA abutments, with or without electrodeposited gold coatings attached to external hexagon implants. Materials and methods: 16 plastic UCLA (PUCLA) and 5 machined cast-to UCLA (GUCLA) abutments were cast with a high gold content alloy. 10 were electrolytically gold plated (8 - PUCLA, 2 - GUCLA). All abutments were attached to implants giving 21 implant-abutment combinations (IACs). External perimeter micro-gaps measured with SEM under different illumination and magnification conditions were averaged over three regions. The IACs were examined for E.coli leakage following an initial sterility test. Disassembled combinations were examined with SEM and surface profiles qualitatively assessed. Results: External micro-gap measurements did not reflect the variable connecting surface profiles but average values < 3.5 μm were observed for all IACs. Bacterial transfer was observed in 3 of 5 PUCLA plated and 2 of 5 PUCLA non-plated IACs. No transfer occurred in the 3 GUCLA non-plated or 2 GUCLA plated IACs. Abutment connecting surfaces, both Au plated and not Au plated, showed plastic deformation (smearing) in variable mosaic patterns across the micro-gap. External micro-gap dimensions although not truly reflective of surface connecting profiles averaged < 3.5 μm measured under shadow eliminating silhouette illumination for both cast and pre-machined external hexagon abutments with and without Au plating. Conclusions: Micro-gap dimensions < 5 μm were obtained with both high noble metal cast and pre-machined external hexagon abutments with and without Au electrodeposited on the abutment connecting surface. Regions of intimate contact due to plastic deformation (smearing) of these surfaces was observed. A continuous smeared region around the circumference of the surfaces can provide an effective barrier to egress of E.coli bacteria from the internal regions of the implant under static loading.
REVIEW | doi:10.20944/preprints202309.0505.v1
Subject: Medicine And Pharmacology, Otolaryngology Keywords: cochlear implant; patient-reported outcomes; pure tone average; speech in noise; music perception
Online: 7 September 2023 (11:22:04 CEST)
Electric stimulation via a Cochlear Implant (CI) enables people with severe to profound sensorineural hearing loss to regain speech understanding and music appreciation and thus allowing them to actively engage in social life. Three main manufacturers (Cochlear, MED-EL and Advanced Bionics “AB”) have been offering CI systems, thus challenging CI recipients and Otolaryngologists with a difficult decision, as currently no comprehensive overview or meta-analyses on performance outcome following CI implantation is available. The main goal of this scoping review is to provide evidence that data and standardized speech and music performance tests are available for performing such comparisons. To this end, a literature search was conducted to find studies that address speech and music outcomes in CI recipients. From a total of 1592 papers, 188 paper abstracts were analyzed and 147 articles were found suitable for examination of full text. From which, 42 studies were included for synthesis. A total of 16 studies used the consonant-nucleus-consonant (CNC) word recognition test in quiet at 60db SPL. We found that aside from technical comparisons, only very few publications compare speech outcomes across manufacturers of CI systems. Evidence suggests though, that these data are available in large CI centers in Germany and US. Future studies should therefore leverage large data cohorts to perform such comparisons that could provide critical evaluation criteria and assist both CI recipients and Otolaryngologists to make informed performance-based decisions.
ARTICLE | doi:10.20944/preprints202305.0361.v1
Subject: Medicine And Pharmacology, Orthopedics And Sports Medicine Keywords: arthroscopy; sports medicine; anterior cruciate ligament reconstruction; implant-associated infection; biofilm; septic arthritis.
Online: 5 May 2023 (11:26:50 CEST)
Background: The objective of the present study was to evaluate the formation of biofilm in bone patellar tendon bone grafts (BPTB grafts) and to compare it to the formation of biofilm formation in quadrupled hamstring anterior cruciate ligament grafts (4xHt graft). Methods: A descriptive in vitro study was conducted. One 4xHt graft and one BPTB graft were prepared. They were then contaminated with a strain of S. epidermidis. Later, a quantitative analysis was carried out by means of microcalorimetry and sonication with plating. Additionally, a qualitative analysis was carried out by means of electron microscopy. Results: No significant differences were found between the bacterial growth profiles of 4xHt graft and BPTB graft in microcalorimetry and colony counting. In the samples analyzed with electron microscopy, no specific biofilm growth pattern was identified upon comparing BPTB graft to 4xHt graft. Conclusions: There were no significant differences at either the quantitative or qualitative level when comparing bacterial growth in BPTB graft to that in 4xHt graft. Therefore, the presence of sutures in 4xHt graft cannot be established as a predisposing factor for increased biofilm growth in this in vitro study.
ARTICLE | doi:10.20944/preprints202304.0992.v1
Subject: Medicine And Pharmacology, Other Keywords: Early onset scoliosis; Shilla technique; growth guidance; implant complications; quality of life scores
Online: 26 April 2023 (13:03:49 CEST)
Growth-preserving instrumentation techniques are utilized in early-onset scoliosis (EOS) cases requiring surgical intervention. Shilla technique corrects the deformity and may reduce the need for surgical treatment with its growth-directing effect. As with other techniques, various prob-lems can be encountered following the administration of the Shilla technique. The aim of this study was to examine the effect of complications encountered with Shilla treatment on correction and growth. Sixteen patients with a follow-up period of at least 1 year who received Shilla growth guidance for EOS were included in the study. No complications occurred in 50% cases and no unplanned surgery was required. Of the remaining 8 patients with postoperative im-plant-related complications (50%), 6 (37.5%) required unplanned surgery; this consequently caused implant failure in the proximal region in 5 cases (31.25%) and deep tissue infection around the implant in 1 case (6.25%). Deformity correction, spine length, and quality-of-life scores significantly improved in EOS through Shilla growth guidance. Although implant-related com-plications were observed and related unplanned surgeries were required with Shilla growth guidance in our patients, these complications did not have a significant negative effect on correc-tion and spine growth.
ARTICLE | doi:10.20944/preprints202109.0221.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: quasi-static load; abutment screw; dental implant; finite element method; dynamic load; mesiodistal
Online: 13 September 2021 (15:55:30 CEST)
Variations in the implant thread shape and occlusal load behavior may result in significant changes in the biological and mechanical properties of dental implants and surrounding bone tissue. Most previous studies consider a single implant thread design, an isotropic bone structure, and a static occlusal load. However, the effects of different thread designs, bone material properties, and loading conditions are important concerns in clinical practice. Accordingly, the present study performs Finite Element Analysis (FEA) simulations to investigate the static, quasi-static and dynamic response of the implant and implanted bone material under various thread designs and occlusal loading directions (buccal-lingual, mesiodistal and apical). The simulations focus specifically on the von Mises stress, displacement, shear stress, compressive stress and tensile stress within the implant and the surrounding bone. The results show that the thread design and occlusal loading rate have a significant effect on the stress distribution and deformation of the implant and bone structure during clinical applications. Overall, the results provide a useful insight into the design of enhanced dental implants for an improved load transfer efficiency and success rate.
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: refractory glaucoma; XEN implant; management; retrospective study, MIGS, glaucoma surgery, bleb, subconjunctival stent
Online: 2 March 2021 (14:25:54 CET)
The aim of this study was to analyze surgical and refractive outcomes of XEN glaucoma implant (Allergan, an Abbvie company, Irvine, CA, USA), a minimally invasive surgical device for the treatment of refractory glaucoma. A retrospective chart review of eyes that received XEN Gel Stent placement from December 2014 to October 2019 was conducted. Intraocular pressure (IOP) change, best corrected visual acuity (BCVA), change in glaucoma medications, frequency of slit lamp revision procedures, and frequency of secondary glaucoma surgeries were the primary outcomes. Seventy-two subjects were included in the study: 32 (44%) males and 40 (56%) females. The mean follow-up time was 26.87 ± 15.33 months. The mean IOP before surgery was 24.82 ± 8.03 mmHg and decreased to 17.45 ± 5.84 mmHg at the end of the study, MD = -7.48, CI95 [-10.04; -4.93], p < 0.001. The mean decrease from baseline was 23%. Before surgery BCVA was 0.38±0.30 and at the end of the follow-up period it had improved to 0.47±0.37, MD = 0.09, CI95 [0.04; 0.13], p < 0.001. Additional procedures (fluorouracil injection, Bleb needling) were performed in 11/72 patients (15%). Further glaucoma surgery was necessary for 23.9%% of the patients. Implantation of XEN Gel Stent is both safe and effective for lowering IOP in refractory glaucoma patients.
ARTICLE | doi:10.20944/preprints201709.0093.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: CAD/CAM implant abutments; zirconia; surface roughness; soft tissue adhesion; focus variation microscopy
Online: 20 September 2017 (05:28:24 CEST)
Objective: CAD/CAM generated ceramic implant abutments have recently attracted interest due to their superior customization possibilities and aesthetic advantages. Despite their widespread clinical use, little information is currently available on their surface topography, however. The transmucosal portion of the abutment shoulder is of particular interest, as it ideally supports soft tissue but minimizes mechanical plaque retention. The aim of this in vitro study was to topographically characterize the trans- and subgingival roughness of CAD/CAM zirconia abutments from different manufacturers and compare them with zirconia stock abutments. Material and Method: The surface topography of eight CAD/CAM zirconia implant abutments (tests) and two prefabricated zirconia stock abutments (controls) was determined using focus variation microscopy. Two points on the abutment shoulder were subjected to profilometric examination. 2D and 3D parameters of roughness were obtained and compared. Results: The surface roughness of all the test abutments exceeded the recommended threshold of Ra = 0.2 µm and therefore exhibited an increased risk of mechanical plaque retention. Obvious differences in surface structure were apparent, allowing conclusions to be drawn about the manufacturing method and subsequent reworking processes. Conclusion: Manually reworking the trans- and submucosal area of the investigated CAD/CAM zirconia abutments appears necessary to fulfil the conditions for optimal surface topography. The Sa value as arithmetic mean, taking the maximum height (Sz value) and surface excess (Sdr) into account, is an essential parameter for assessing the surface topography of implant abutments.
REVIEW | doi:10.20944/preprints202311.0924.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: dental implants; implant survival; biological complications; mechanical complications; yttria stabilized zirconia; marginal bone loss
Online: 14 November 2023 (15:27:29 CET)
The advent of zirconia ceramics with excellent mechanical, biomechanical and optical properties has made it an attractive metal-free substitute for titanium implants. Both animal and human studies have documented shortcomings with titanium implants. A review of the current literature on 3 iterations of zirconia implant designs has been challenging due to heterogeneous success data and limited follow-up. Zirconia implants hold promise for a new generation of dental implants, but technical developments are needed for design and material enhancements that will need to be validated by long-term rigorous studies.
TECHNICAL NOTE | doi:10.20944/preprints202308.1950.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: digital Implantology; computer-guided implant surgery; digital workflows; full-arch immediate loading; surgical template
Online: 29 August 2023 (11:57:29 CEST)
A maxillary totally edentulism was rehabilitated with one-piece implants starting from pre-existing totally removable denture. A 3D digital scan of the removable denture and upper and lower arches was performed. On this basis, a prototype with optimal esthetic and functional outcomes was re-alized and turned into a custom-made radiological stent with markers. The superimposition of STL and DICOM files allowed the virtual planning of one-piece implants ideal position. The stackable templates composed of a fixed component, namely base template, and removable components, were realized. The fixed component, once secured with anchor pins to the bone, was no longer removed. The removable components, screwed to the fixed component, were used to perform the implant surgery and the immediate prosthetic loading. A base template allowed for maintaining a fixed reference during the entire workflow, improving the transition between the digital project, the surgical procedure, and the prosthetic rehabilitation.
ARTICLE | doi:10.20944/preprints202201.0363.v1
Subject: Engineering, Mechanical Engineering Keywords: multibody simulation; multi-way sensitivity analysis; spinal implant anchor screw; stiffness and damping parameters
Online: 24 January 2022 (14:56:06 CET)
Finite element (FE) modeling is commonly used as a method to investigate the influence of medical devices, such as implants and screws and their effects on the biomechanical behavior of the spine. Another simulation method is a multi-body simulation (MBS), where the model is composed of several non-deformable bodies. MBS solvers generally require a very short computing time for dynamic tasks compared to an FE analysis. Considering this computational advantage, in this study, we examine whether parameters whose values are not known a priory can be determined with sufficient accuracy using MBS model. Therefore, we propose a Many-at-a-time sensitivity analysis method that allows approximating these a priory unknown parameters without requiring long simulation times. This method enables a high degree of MBS model optimization to be achieved in an iterative process. The sensitivity analysis method is applied to a simplified screw-vertebra model, consisting of an anterior anchor implant screw and vertebral body of C4. An experiment described in the literature is used as a basis for developing and assessing the potential of the method for sensitivity analysis and to validate the models action. The optimal model parameters for the MBS model were determined to be c=823224N/m for stiffness and d=488Ns/m for damping. The presented method of parameter identification can be used in studies including more complex MBS spine models or to set initial parameter values that are not available as initial values for FE models.
ARTICLE | doi:10.20944/preprints202112.0003.v1
Subject: Medicine And Pharmacology, Surgery Keywords: cervical spine; finite element; dynamic cervical implant; multi-level fusion; hybrid surgery; disc replacement
Online: 1 December 2021 (10:24:47 CET)
Cervical fusion has been a standard procedure for treating the abnormalities associated with the cervical spine. However, the reliability of anterior cervical discectomy and fusion (ACDF) has become arguable due to its adverse effects on the biomechanics of adjacent segments. One of the drawbacks associated with ACDF is adjacent segment degeneration (ASD) which has served as the base for the development of dynamic stabilization systems (DSS) and total disc replacement (TDR) devices for cervical spine. However, the hybrid surgical technique has also gained popularity recently but their effect on the biomechanics of cervical spine is not well researched. Thus, the objective of this FE study was to draw the comparison among single, bi-level and hybrid surgery with DCI implant with traditional fusion. Reduction in range of motion (ROM) for all the implanted models was observed for all the motions except extension, compared to intact model. The maximum increase in ROM of 42% was observed at C5-C6 level in Hybrid-DCI model. The maximum increase in adjacent segment’s ROM of 8.7% was observed in multilevel fusion model. The maximum von Mises stress in the implant was highest for the multilevel DCI model. Our study also showed that the shape of DCI implant permits flexion/extension relatively more compared to lateral bending and axial rotation.
ARTICLE | doi:10.20944/preprints202309.1732.v1
Subject: Social Sciences, Psychology Keywords: high variability phonetic training (HVPT); lexical tone; perception-production link; cochlear implant (CI); perceptual learning
Online: 26 September 2023 (05:00:33 CEST)
Purpose: This study builds upon an established effective training method to investigate the advantages of high variability phonetic identification training for enhancing lexical tone perception and production in Mandarin-speaking pediatric cochlear implant (CI) recipients, who typically face ongoing challenges in these areas. Method: Thirty two Mandarin-speaking children with CIs were quasi-randomly assigned into the training group (TG) and the control group (CG). The sixteen TG participants received five sessions of high variability phonetic training (HVPT) within a period of three weeks. The CG participants did not receive the training. Perception and production of Mandarin tones were administered before (pretest) and immediately after (posttest) the completion of HVPT via lexical tone recognition task and picture naming task. Both groups participated in the identical pretest and posttest with the same time frame between the two test sessions. Results: TG showed significant improvement from pretest to posttest in identifying Mandarin tones for both trained and untrained speech stimuli. Moreover, perceptual learning of HVPT facilitated trainees’ lexical tone production as rated by a cohort of 10 Mandarin-speaking adults with normal hearing. In contrast, CG did not exhibit significant changes in either perception or production. Conclusion: The results represent initial evidence of HVPT-induced transfer of perceptual learning to lexical tone production in CI users, which supports the application of this speech training protocol to aural rehabilitation practice.
REVIEW | doi:10.20944/preprints202308.1476.v1
Subject: Medicine And Pharmacology, Other Keywords: breast; autologous reconstruction; implant-based breast reconstruction; MRI of reconstructed breast; complications of reconstruction surgery; breast cancer recurrence
Online: 21 August 2023 (12:35:42 CEST)
The incidence of breast cancer and therefore need for breast reconstruction is expected to increase. The many reconstructive options available and the changing aspects of the field make this a complex area of plastic surgery, requiring knowledge and expertise. Two major types of breast reconstruction can be distinguished: Breast Implants and Autologous Flaps. Both present advantages and disadvantages. Autologous fat grafting is also commonly used. MRI is the modality of choice for evaluating breast reconstruction. Knowledge of the type of reconstruction is preferable to provide the maximum of pertinent information and avoid false positives. Early complications include seroma, hematoma, and infection. Late complications depend on the type of reconstruction. Implant rupture and implant capsular contracture are frequently encountered. Depending on the implant type, specific MRI signs can be depicted. In case of myocutaneous flap, fat necrosis, fibrosis and vascular compromise represent the most common complications. Late cancer recurrence is much less common. Rare reported late complications include breast implant associated large cell anaplastic lymphoma (BIA-ALCL) and, recently described and even rarer, Breast implant-associated squamous cell carcinoma (BIA-SCC). In this review article, the various types of breast reconstruction will be presented, with emphasis on pertinent imaging findings and complications.
ARTICLE | doi:10.20944/preprints202310.1641.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: Refractory high-entropy alloy; Biomaterial; Biomedical implant; Blend element; Mechanical alloying; Mechanical properties; Impulse excitation technique; Powder metallurgy; Casting
Online: 26 October 2023 (03:27:19 CEST)
TiNbZrTa alloys are promising for multidisciplinary applications, such as refractory and biomedical purposes due to their high thermal stability and non-toxicity. Hardness and elastic modulus are among the key features for their adequate industrial applications. The influence of porosity and Ti/Ta ratio were investigated on TiNbZrTa alloys produced by three different processing routes, i.e., (i) blend element and posterior press and sintering (BE + P&S), (ii) mechanical alloying with press and sintering (MA + P&S), and (iii) arc melting and casting. Atomic diffusion was improved during processing, resulting in lower porosity in the following order: casting < MA + P&S < BE + P&S. Ta offered limited atomic diffusion due to its high melting point compared to other constituent elements. Thus, the total porosity of alloys increased with increasing the Ta contents, i.e., by lowering the Ti/Ta ratio. However, the Ti/Ta ratio did not considerably affect the bonding energy or the elastic modulus. Hardness was increased significantly in dense alloys compared to the porous ones. However, porosity and Ti/Ta ratio did not show a clear trend in hardness among the porous alloys.
ARTICLE | doi:10.20944/preprints202306.0732.v1
Subject: Chemistry And Materials Science, Other Keywords: artificial bone; conical implants; cylindrical implants; dental implants; implant stability quotient; insertion torque; polyurethane; post-extraction sites; removal torque
Online: 9 June 2023 (16:15:15 CEST)
Keywords: artificial bone; conical implants; cylindrical implants; dental implants; implant stability quotient; insertion torque; polyurethane; post-extraction sites; removal torque.
ARTICLE | doi:10.20944/preprints202211.0007.v1
Subject: Social Sciences, Cognitive Science Keywords: high variability phonetic training (HVPT), categorical perception (CP), cochlear implant (CI), lexical tone, Mandarin-speaking kindergarteners, training-induced gains
Online: 1 November 2022 (01:41:59 CET)
Objectives: Although pitch reception poses a great challenge for individuals with cochlear implants (CIs), formal auditory training (e.g., high variability phonetic training, HVPT) has been shown to provide direct benefits in pitch-related perceptual performances such as lexical tone recognition for CI users. As lexical tones in spoken language are expressed with a multitude of distinct spectral, temporal, and intensity cues, it is important to determine the sources of training benefits for CI users. The purpose of the present study was to conduct a rigorous fine-scale evaluation with the categorical perception (CP) paradigm to control the acoustic parameters and test the efficacy and sustainability of HVPT for Mandarin-speaking pediatric CI recipients. The main hypothesis was that HVPT-induced perceptual learning would greatly enhance CI users’ ability to extract the primary pitch contours from spoken words for lexical tone identification and discrimination. Furthermore, individual differences in immediate and long-term gains from training would likely be attributable to baseline performance and duration of CI use. Design: Twenty-eight prelingually deaf Mandarin-speaking kindergarteners with CIs were tested. Half of them received five sessions of HVPT within a period of three weeks. The other half served as control who did not receive the formal training. Two classical CP tasks on a tonal continuum from Mandarin Tone 1 (high-flat in pitch) to Tone 2 (mid-rising in pitch) with fixed acoustic features of duration and intensity were administered before (pretest), immediately after (posttest), and 10 weeks post training termination (follow-up test). Participants were instructed to either label a speech stimulus along the continuum (i.e., identification task) or determine whether a pair of stimuli separated by zero or two steps from the continuum was the same or different (i.e., discrimination task). Identification function measures (i.e., boundary position and boundary width) and discrimination function scores (i.e., between-category score, within-category score, and peakedness score) were assessed for each child participant across the three test sessions.Results: Linear mixed-effects (LME) models showed significant training-induced enhancement in lexical tone categorization with significantly narrower boundary width and better between-category discrimination in the immediate posttest over pretest for the trainees. Furthermore, training-induced gains were reliably retained in the follow-up test 10 weeks after training. By contrast, no significant changes were found in the control group across sessions. Regression analysis confirmed that baseline performance (i.e., boundary width in the pretest session) and duration of CI use were significant predictors for the magnitude of training-induced benefits. Conclusions: The stringent CP tests with synthesized stimuli that excluded acoustic cues other than the pitch contour and were never used in training showed strong evidence for the efficacy of HVPT in yielding immediate and sustained improvement in lexical tone categorization for Mandarin-speaking children with CIs. The training results and individual differences have remarkable implications for developing personalized computer-based short-term HVPT protocols that may have sustainable long-term benefits for aural rehabilitation in this clinical population.
ARTICLE | doi:10.20944/preprints202012.0245.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: preload loss; conical abutment screw; Multi-Unit-Abutment; OT-Bridge; prosthetic connection; implant-supported prosthesis; loosening torque; tightening torque
Online: 10 December 2020 (10:21:40 CET)
Background: To compare the loss of preload in absence of loading and after a fixed number of ideal masticatory cycles in two different connection systems using all-on-four prosthetic model. Methods: Two equal models of an edentulous mandible rehabilitated with all-on-four technique with two types of abutment system (MUA and OT-Bridge) supporting a hybrid prosthesis, were used. Initial torque values of the prosthetic fixing screw, after ten minutes from initial screw tightening and after 400000 masticatory cycles were registered using a mechanical torque gauge. Differences between initial and final torque values were reported for each anchoring system and the two systems were finally compared. Results: No statistically significant differences regarding the loss of preload between MUA and OT-Bridge system were found after 400000 masticatory cycles; however, in MUA system it was found between anterior and posterior implant screws. A significant difference in preload loss was found only for MUA system comparing the initial screw torque to that measured after 10 minutes from the tightening in absence of cyclic loadings. Conclusions: MUA and OT-Bridge are reliable prosthetic anchoring systems able to tolerate repeated masticatory cycles also on distal cantilever in all-on-four rehabilitation model without any significant loss of preload in screw tightening
ARTICLE | doi:10.20944/preprints202107.0110.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: blow-out; biocompatible materials; computer-aided design; finite element analysis; orbit; implant; orbital fracture; patient-specific modeling; printing; three-dimensional.
Online: 5 July 2021 (15:37:53 CEST)
Pure orbital blowout fractures occur within the confines of the internal orbital wall. Restoration of orbital form and volume is paramount to prevent functional and esthetic impairment. The anatomical peculiarity of the orbit has encouraged surgeons to develop implants with customized features to restore its architecture. This has resulted in worldwide clinical demand for patient-specific implants (PSIs) designed to fit precisely in the patient's unique anatomy. Fused filament fabrication (FFF) three-dimensional (3D) printing technology has enabled the fabrication of implant-grade polymers such as Polyetheretherketone (PEEK), paving the way for a more sophisticated generation of biomaterials. This study evaluates the FFF 3D printed PEEK orbital mesh customized implants with a metric considering the relevant design, biomechanical, and morphological parameters. The performance of the implants is studied as a function of varying thicknesses and porous design constructs through a finite element (FE) based computational model and a decision matrix based statistical approach. The maximum stress values achieved in our results predict the high durability of the implants, and the maximum deformation values were under one-tenth of a millimeter (mm) domain in all the implant profile configurations. The circular patterned implant (0.9 mm) had the best performance score. The study demonstrates that compounding multi-design computational analysis with 3D printing can be beneficial for the optimal restoration of the orbital floor.
ARTICLE | doi:10.20944/preprints202309.0546.v1
Subject: Medicine And Pharmacology, Orthopedics And Sports Medicine Keywords: Sacroiliac joint dysfunction; Sacroiliac joint fusion; Minimally invasive surgery; Virtual surgical planning; Simulated fluoroscopic images; Implant placement accuracy; Patient-specific modeling
Online: 7 September 2023 (10:44:29 CEST)
Sacroiliac (SI) joint dysfunction can lead to debilitating pain but can be treated with minimally invasive sacroiliac joint fusion (SIJF). This treatment is commonly performed using 2D fluoroscopic guidance. This makes placing the implants without damaging surrounding neural structures challenging. Virtual surgical planning (VSP) using simulated fluoroscopic images may improve perioperative guidance. This article describes a workflow with VSP in SIJF using simulated fluoroscopic images and evaluates achieved implant placement accuracy. Routinely collected survey data on the added value of VSP were also evaluated. Ten interventions were performed on 10 patients by the same surgeon, comprising 30 implants; the median age was 39 years, and all patients were female. The overall mean implant placement accuracy was 4.9 ± 1.26 mm and 4.0 ± 1.44°. There were no malpositioning complications. The VSP helped the surgeon understand the anatomy and determine the optimal position and length of the implants. The average Likert scale score of the survey was 4.7, suggesting a positive role of VSP for SIJF. Planned positions of the implants could be reproduced in surgery with clinically acceptable accuracy and VSP was a valuable asset for the surgeon.
REVIEW | doi:10.20944/preprints202309.0453.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: platelet-rich fibrin; ridge augmentation; socket augmentation; grafting; cytokines; growth factors; tissue regeneration; bio-enhancement; PRF; platelet concentrate; accelerated implant treatment
Online: 7 September 2023 (09:27:09 CEST)
Alveolar bone atrophy after tooth extraction presents significant difficulties when planning delayed-immediate implant treatment to replace a lost tooth. Socket augmentation is an effective therapy that limits the post extraction volumetric changes and facilitates implant placement whilst reducing the need for staged grafting. However, socket augmentation and osteoconductive graft conversion is a slow process that could take 4-6 months. PRF and its variants have significant bio-enhancement effect on wound healing and regeneration through release of platelet drived growth factors, bioactive substances, cytokines. Leukocytes in PRF also play a significant role in enhancing tissue regeneration as part of osteo-immune response. Use of PRF during socket augmentation is highly effective in enhancing extraction site healing and graft integration by angiogenesis, cell proliferation, recruitment, and differentiation through release of growth factors and bioactive substances mediated by platelets and leukocytes. PRF with SA is recommended as an adjunct to SA as a sole biomaterial or in combination with xenograft or allograft bone substitutes to enhance tissue regeneration and to reduce risk of infection, osteitis and postoperative pain in extraction sockets
ARTICLE | doi:10.20944/preprints202308.1727.v1
Subject: Medicine And Pharmacology, Otolaryngology Keywords: third window effect; otosclerosis; osteogenesis imperfecta; cavitating otosclerosis; cavitating osteogenesis imperfecta; pseudo-CHL; internal auditory canal diverticulum; double ring effect; cochlear implant
Online: 25 August 2023 (04:57:24 CEST)
There are several pathologies that can change the anatomy of the otic capsule and that can distort the bone density of the bony structures of the inner ear, but otosclerosis is one of the most frequent. Similar behavior has been shown in patients affected by osteogenesis imperfecta (OI), a genetic disease due to a mutation in the genes coding for type I (pro) collagen. In particular, we note that otosclerosis and OI can lead to bone resorption creating pericochlear cavitations in contact with the internal auditory canal (IAC). In this regard, in our experience we have collected 5 cases presenting this characteristic and their audiological data and clinical history were analyzed. This feature can be defined as a potential cause of a third-window effect, because it causes an energy loss during the transmission of sound waves from the OW away from the basilar membrane.
ARTICLE | doi:10.20944/preprints202304.0534.v1
Subject: Medicine And Pharmacology, Otolaryngology Keywords: micro injection molding; 3D printing; rapid tooling; digital light processing; implant; drug delivery system; dexamethasone; anti-inflammatory; TNF-α; biocompatibility; inner ear therapy
Online: 19 April 2023 (03:57:41 CEST)
A novel approach for the long-term medical treatment of the inner ear is the diffusion of drugs through the round window membrane from a patient-individualized, drug-eluting implant, which is inserted in the middle ear. In this study, drug-loaded (10 wt% Dexamethasone) guinea pig round window niche implants (GP-RNIs, ~1.30 mm x 0.95 mm x 0.60 mm) were manufactured with high precision via micro injection molding (µIM, Tmold = 160 °C, crosslinking time of 120 s). The medical grade silicone elastomer MED-4244 (NuSil Technology LLC, Radnor, PA, USA) was used. Molds for µIM were 3D printed from a commercially available resin PlasGRAY V2 (Asiga, Alexandria, Australia, TG = 84 °C) via a high-resolution DLP process (xy-resolution of 32 µm, z-resolution of 10 µm, 3D printing time of about 6 h). Drug release, biocompatibility, and bio-efficacy of the GP-RNIs were investigated in vitro. GP-RNIs could be successfully produced. Wear of the molds due to thermal stress was observed. However, the molds are suitable for single use in the µIM process. About 10% of the drug load (8.2 ± 0.6 µg) was released after 6 weeks (medium: isotonic saline). The implants showed high biocompatibility over a time of 28 days (lowest cell viability ~80%). Moreover, we found anti-inflammatory effects over a time of 28 days in a TNF-α-reduction test. These results are promising for the development of long-term drug-releasing implants for human inner ear therapy.
ARTICLE | doi:10.20944/preprints202212.0004.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: SMI (silicone mammary implants); FBR (foreign body response); wound healing; wound infection; capsular fibrosis; implant encapsulation; early-stage fibrosis; surface adsorption; immunomics; biomarkers
Online: 1 December 2022 (02:02:11 CET)
The etiology of exaggerated fibrous capsule formation around silicone mammary implants (SMI) is multifactorial but primarily induced by immune mechanisms toward the foreign material silicone. The aim of this work was to enlighten the disease progression from implant insertion and immediate tissue damage response reflected in (a) the acute wound proteome, and (b) the adsorption of chronic inflammatory wound proteins at implant surfaces. An intra-individual absolute quantitation TMT-liquid chromatography-tandem mass spectrometry approach was applied to profile wound proteome formed around SMI the first five days post-implantation. Compared to plasma, the acute wound profile resembled a more complex composition comprising plasma-derived and locally differentially expressed proteins (DEPs). DEPs were subjected to functional enrichment analysis, which revealed the dysregulation of signaling pathways mainly involved in immediate inflammation response and ECM turnover. Moreover, we found time-course variations in protein enrichment immediately post-implantation and adsorbed to SMI surfaces after 6-8 months. Characterization of the expander-adhesive proteome by label-free approach uncovered a long-term adsorbed acute wound and the fibrosis-associated proteome. Our findings propose a wound biomarker panel for the early detection and diagnosis of excessive fibrosis that could potentially broaden insights into the characteristics of fibrotic implant encapsulation.
REVIEW | doi:10.20944/preprints202308.1866.v1
Subject: Medicine And Pharmacology, Surgery Keywords: breast reconstruction; reconstruction following mastectomy; prophylactic mastectomy; chest feminization; transgender; implant reconstruction of breast; immediate reconstruction; delayed reconstruction; two-stage breast reconstruction; autologous breast reconstruction
Online: 29 August 2023 (03:19:28 CEST)
(1) Importance of problem: Breast cancer accounted for 685.000 deaths globally in 2020, and half of all cases occur in women with no specific risk factor beside gender and age-group. During last 4 decades we see a reduction by 40% of age-standardized breast cancer , which in turn means that the number of mastectomies performed for younger women increased, raising the need for adequate breast reconstructive surgery. Advances in oncological treatment have made it possible to limit the extent of what represents radical surgery for breast cancer, yet in the past decade, we see a marked trend toward mastectomy in breast conserving surgery eligible patients . Prophylactic mastectomy has also registered an upward trend [3,4]. This trend together with new indication for breast reconstruction like chest feminization in transgender patients  have increased the need for breast reconstruction surgery. (2) Purpose: The purpose of this study is to analyze the types of reconstructive procedures, their indications, their limitations, their functional results and the safety profiles when used during the integrated treatment plan of the oncologic patient; (3) Methods: We conducted an extensive literature review of the main reconstructive techniques, especially the autologous procedures, summarized the findings and presented a few cases from our own experience for exemplification of the usage of breast reconstruction in oncologic patients. (4) Conclusions: Breast reconstruction has become a necessary step in the treatment of most breast cancers and many reconstructive techniques are now routinely practiced. Microsurgical techniques are considered the "gold standard", but they are not accessible to all services, from a technical or financial point of view, so pediculated flaps remain the safe and reliable option, along with alloplastic procedures, to improve the quality of life of these patients.
ARTICLE | doi:10.20944/preprints202108.0202.v1
Subject: Medicine And Pharmacology, Surgery Keywords: congenital breast asymmetry; PROM, autologous fat injections, fat grafting, lipograft, implant augmentation, breast augmentation, 3D volumetry, three-dimensional imaging, Breast-QTM; human adipose stem cells
Online: 9 August 2021 (15:06:09 CEST)
Congenital breast asymmetry represents a particular challenge to the classical techniques of plastic surgery due to a young group of patients. This study compares traditional breast augmentation using silicone implants to the more innovative lipograft technique regarding long-term results. To achieve this, we not only captured subjective parameters like satisfaction with outcome and symmetry, but also objective parameters such as breast volume and anthropometric measurements. Objective examination was performed manually and by using the Vectra® H2 photogrammetry scanning system. Patients who underwent implant augmentation and lipograft both showed no significant differences in patient´s satisfaction with surgical outcome (p = 0.55) and symmetry (p = 0.69). Furthermore, a breast symmetry of 93 % in both groups was reported. Likewise, no statistically significant volume difference between left and right breast was observed in both groups (p<0.41). However, on average, lipograft patients needed 1.3 procedures more until the desired result was achieved. In contrast, patients treated with implant-based breast augmentation usually need several implant changes during their life. In conclusion, both methods should be considered for patients with congenital breast asymmetry.
ARTICLE | doi:10.20944/preprints202308.0446.v1
Subject: Medicine And Pharmacology, Ophthalmology Keywords: glaucoma; open-angle glaucoma; collagen implant; glaucoma surgery; bleb less glaucoma surgery; bleb independent glaucoma surgery; suprachoroidal space; uveolymphatic aqueous humor outflow; conjunctival lymphatic vessels; conjunctival lymphatics
Online: 4 August 2023 (13:18:18 CEST)
A surgical technique aimed at rerouting aqueous humor (AH) outflow from the anterior chamber to the suprachoroidal space (SCS) without performing surgical cyclodialysis was developed to decrease intraocular pressure (IOP) in glaucoma patients. The surgical outcomes of the technique were retrospectively analyzed in fifty-eight patients. At 6, 12, and 24 months, the mean IOP decreased from 27.8±8.3 to 14.95.0 mmHg, median 15.0 (25th percentile (p25 )13.0; 75th percentile (p75) 18.0), and 15.23.3 mmHg; hypotensive medication use reduced from median (p25; p75) 3 (2; 3) to 0 (0; 2), 0 (0; 2), and 0 (0; 1.5), and complete success was achieved in 62.8%, 51.2%, and 32.5% cases, with partial success in 28.4%, 44.2%, and 62.5% cases, respectively. Eight cases (13.8%) presented unsatisfactory outcomes. Intra- and postoperative complications were few and manageable. No bleb formation was observed in any of the cases. In 50% of cases, conjunctival lymphatic vessels (CLVs) developed following surgery in superior quadrants. The technique is safe and effective in providing a long-term decrease in IOP and hypotensive medication use. It was hypothesized in this study that the IOP decrease occurred as a result of enhanced AH outflow from the SCS to CLVs through intrascleral microchannels connecting the SCS to CLVs.