Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: hyaluronic acid; biphasic bone substitute; biocompatibility; tissue reaction; inflammation; macrophage; M1; M2; multinucleated giant cells
Online: 28 March 2019 (06:54:57 CET)
Biphasic bone substitutes (BBS) are nowadays established biomaterials. Through their constant development even natural components like hyaluronic acid (HY) are added to improve both their handling and also their regenerative properties. However, low knowledge exists regarding the consequences of the HY addition for their biocompatibility and the inflammatory tissue reactions. Thus, the present study was conducted aiming to analyze the influence of two different amounts of high molecular weight HY (HMWHY) combined with a BBS on the in vitro biocompatibility and the in vivo tissue reaction. Established in vitro procedures using L929 cells were used for cytocompatibility analyses under the test conditions of DIN EN:ISO 10993-5. For the in vivo study part, calvarial defects were created in 20 Wistar rats and subsequently filled with the BBS and the BBS combined with two different HMWHY amounts, i.e., BBS+HY(L) and BBS+HY(H). As controls empty defects were used. Established histological, immunohistochemical and histomorphometrical methods were applied to analyze the tissue reactions to the three different materials, including the induction of pro- and anti-inflammatory macrophages and multinucleated giant cells (BMGCs). The in vitro results showed that none of the materials or compositions caused biological damages to the L929 cells and can considered to be non-toxic. The in vivo results showed that only the addition of high doses of HY to a biphasic bone substitute significantly decreases the occurrence of proinflammatory macrophages (* p < 0.05) comparable to the numbers found in the control group, while no significant differences within the three study groups for M2-macrophages nor BMGCs were detected. In conclusion, the addition of different amounts of HMWHY does not seem to affect the inflammation response to the BBS while improving the material handling properties.
REVIEW | doi:10.20944/preprints201802.0051.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: metals; dental regeneration; bioactivity; tissue regeneration; bone
Online: 6 February 2018 (05:25:46 CET)
The regeneration of bone tissue is a main purpose of most therapies in dental medicine. For bone regeneration, calcium phosphate (CaP)-based substitute materials based on natural (allo- and xenografts) and synthetic origins (alloplastic materials) are applied for guiding the regeneration processes. The optimal bone substitute has to act as a substrate for bone ingrowth into a defect, while it should be resorbed even in the time frame needed for complete regeneration up to the condition of restitution ad integrum. In this context, the modes of action of CaP-based substitute materials have been frequently investigated and it has been shown that such materials strongly influence regenerative processes such as osteoblast growth or differentiation and also on osteoclastic resorption due to different physicochemical properties of the materials. However, the material characteristics needed for the required ratio between the formation of new bone tissue and material degradation has not been found until now. The addition of different substances such as collagen or growth factors and also of different cell types have already been tested but did not allow for sufficient or prompt application. Moreover, metals or metal ions are differently used as basis or as supplement for different materials in the field of bone regeneration. Moreover, it has already been shown that different metal ions are integral components of bone tissue playing functional roles in the physiological cellular environment as well as in the course of bone healing. The present review focuses on frequently used metals as integral parts of materials designated for bone regeneration with the aim to give an overview of currently existing knowledge about the effects of metals in the field of bone regeneration.
ARTICLE | doi:10.20944/preprints202205.0286.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: bioglass; ion release; hydroxyapatite deposition; bone tissue regeneration; macrophages; vascularization; copper doping; strontium doping; 45S5; ICIE16
Online: 23 May 2022 (05:24:12 CEST)
Bioglasses are highly adoptable bone substitute materials, which can be combined with so-called therapeutic ions. These ions have shown to influence underlying molecular processes of the bone regeneration cascade. Moreover, it is known that bone substitutes induce an immune reaction within their implantation area involving macrophages and their pro- and anti-inflammatory subtypes dependent on their chemical composition. However, only poor knowledge exists regarding the influence of therapeutic ions onto the immune reactions and the associated bone healing. Thus, the aim of this work was to investigate the influence of strontium- and copper-doped bioglasses on the induction of M1- and M2-macrophages as well as the implant bed vascularization. (2) Methods: For this study, two alkali glasses were produced on basis of ICIE-16 bioglass via the melt-quench route with the addition of 5 wt% copper or strontium (ICIE16-Cu and ICIE16-Sr). Pure ICIE16 and 45S5 bioglasses were used as control materials. The bioactivity (ion release), chemical composition and the surface pattern were investigated, as well as an in vivo experiment was performed using the subcutaneous implantation model in rats. (3) Results: SEM imaging showed different formations of hydroxyapatite on the surfaces of the bioglass systems after submersion in simulated body fluid. EDX analysis confirmed the doping process by showing the release kinetics. Copper-doped bioglass exhibited a higher ion release than strontium-doped bioglass. Copper induced both a low immune cell migration and triggered a low number of M1- and M2-macrophages but also of blood vessels. The strontium-containing bioactive glass induced higher numbers of M1-macrophages after 30 days. Both copper- and strontium-doped bioglasses induced comparable numbers of M2-macrophages as found in the control groups. (4) Conclusions: Bioglass doping with copper and strontium did not exhibit significant influence on the foreign body response or the implantation bed vascularization in vivo. However, the prepared bioglass systems seemed to be biocompatible.
ARTICLE | doi:10.20944/preprints201904.0169.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: esthetic archwires; coating stability; backscattered electron microscopy
Online: 15 April 2019 (11:55:14 CEST)
Background/Aim: There is continuing interest in engineering esthetic labial archwires. The aim of this study was to coat nickel-titanium (NiTi) and beta-titanium (β-Ti), also known as titanium molybdenum (TMA), archwires by plasma electrolytic oxidation (PEO) and to analyze the characteristics of the PEO-surfaces. Materials and Methods: PEO-coatings were generated on 0.014-inch NiTi and 0.19x0.25-inch β-Ti archwires. The surfaces were analyzed by scanning electron microscopy and stereomicroscopy. Cytocombability testing was performed with ceramized and untreated samples according to EN ISO 10993-5 in XTT-, BrdU- and LDH-assays. The direct cell impact was analyzed using LIVE-/DEAD-staining. In addition, the archwires were inserted in an orthodontic model and photographs were taken before and after insertion. Results: The PEO coatings were 15 to 20 µm thick and esthetically pleasing. The cytocompatibility analysis revealed good cytocompatibility results for both ceramized NiTi and β-Ti archwires. In the direct cell tests, the ceramized samples showed improved compatibility as compared to those of uncoated samples. However, bending of the archwires resulted in loss of the PEO-surfaces. Nevertheless, it was possible to insert the β-Ti PEO-coated archwire in an orthodontic model without loss of the PEO-ceramic. Conclusion: PEO is a promising technique for the generation of esthetic orthodontic archwires. Since the PEO-coating does not resist bending, its clinical use seems to be limited so far to orthodontic techniques using straight or pre-bended archwires.
ARTICLE | doi:10.20944/preprints201812.0155.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Bone tissue engineering, magnesium implants, ISO norms, in vitro, PEO
Online: 12 December 2018 (15:43:04 CET)
Magnesium (Mg)-based biomaterials are promising candidates for bone and tissue regeneration. Alloying and surface modifications provide effective strategies for optimizing and tailoring their degradation kinetics. Nethertheless, biocompatibility analyses of Mg-based materials are challenging due to its special degradation mechanism with continous hydrogen release. In this context, the hydrogen release and the related (micro-) milieu conditions pretend to strictly follow in vitro standards based on ISO 10993-5/-12. Thus, special adaptions for the testing of Mg materials are necessary, which have been described in a previous study from our group. Based on these adaptions, further developments of a test procedure allowing rapid and effective in vitro cytocompatibility analyses of Mg-based materials based on ISO 10993-5/-12 are necessary. The following study introduces a new two-step test scheme for rapid and effective testing of Mg. Specimens with different surface characteristcis were produced by means of plasma electrolytic oxidation (PEO) using silicate-based and phosphate-based electrolytes. The test samples were evaluated for corrosion behavior, cytocompatibility and their mechanical and ostogenic properties. Thereby, two PEO ceramics could be identified for further in vivo evaluations.