Microbiological evaluation of the antibacterial Vicryl suture in the mandibular third molar surgery

: Purpose: Selection and application of suture materials, has gained more importance especially with the increasing number of patients seeking oral surgeries. Since lying in a bacterial-filled environment, sutures make the tissue prone to infection. Suture material plays an important role in the reduction of the risk of infection. This study aimed to assess the success rate of an antibacterial suture named Vicryl Plus in preventing bacterial growth in the surgical site of the mandibular third molar. Materials and Methods: 27 patients were included in this double-blinded randomized clinical trial study. Surgical Extraction of the mandibular wisdom tooth was done and the incision was managed by randomly using Vicryl Plus and Vicryl sutures. After 7 days, sutures were removed and assessed microbiologically. Predominant species of Streptococcus mutans and Lactobacillus were assessed as well as the total number of colonies on each suture. Results: There was a significant difference between two suture materials in colony number-length ratio of lactobacillus 2 bacterial colonies (p-value=0.016); but not for S. mutans species (p-value=0.201). Conclusion: Antibacterial Vicryl suture can be a useful tool for the reduction in the rate of surgical site infection in high-risk cases and situations. and associates 17 meta-analysis which was done in 2016 on 5268 patients; which do confirm outcomes of our work.

cytoplasmic and membrane receptors; makes changes in bacterial RNA synthesis and macromolecule production, which interferes with bacterial growth and causes cellular death [11].
Cruz et al. [10] assessed the effect of manipulation of sutures coated with antiseptic ointment (iodoform + calendula) in the reduction of bacterial colonization in a clinical trial study on 40 volunteer patients. The patients had randomly divided into two case and intervention groups.
Two millimeters (mm) of the suture were removed on the first and 15 th day after the surgery and they evaluated the colony units per milliliters (CFU/ml) in each group. There was a significant decrease in bacterial growth in the case group (p=0.002). So, they concluded that the antiseptic ointment is effective in bacterial growth decline on silk sutures.
In 2011, Galal et al. [12] evaluated the effect of coating the suture materials with triclosan, as an antibacterial agent, on the incidence of infection in the surgical sites. In this prospective randomized double-blinded study, the total number of 450 patients had divided into two groups: 230 patients in the control group and 220 patients in the intervention group. The comparison was made according to the risk factors of infection in the surgical sites. The incidence of infection was 7% in the case group and 15% in the control one (p=0.011). They concluded from this study that using antimicrobial polyglactin-910 suture material can lead to saving health care resources as much as 1.5 million USD per year. studies evaluating the effectiveness of Vicryl Plus suture against Vicryl suture material in which Meta-analysis showed a significant difference in surgical site infection; but based on low graded RCTs with a high risk of bias and imprecision [14].
Despite the extensive advertisement for Vicryl Plus suture materials; limited research has evaluated the effectiveness of this new product in surgeries involving mucosa. Besides, the different microbiological characteristics of the skin and mucosa and rinsing effect of saliva; can probably have an ablative effect on Vicryl Plus sutures leading to the nonsignificant clinical and microbiological difference between coated and non-coated sutures. Due to the all abovementioned factors, we decided to assess the efficacy of these suture materials in bacterial growth reduction in the oral cavity.
This study aimed to compare the efficiency of the Vicryl (non-coated) and Vicryl Plus (triclosan-coated) sutures in the reduction of the number and variety of bacterial species related to the manipulation of these suture materials in the oral cavity during the third molar surgery.

Materials and Methods
Calculation of the sample size (27 patients and 52 samples respectively) was done using the formula for Comparison of Two Means and a difference of 1.3 × 10 4 (CFU/ml) was considered statistically significant with α-error= 0.05 and 1-β=0.80. This study was performed as a double-blinded study in which none of the patient, surgeon, and microbiological technicians were aware of the exact location of Vicryl and antibacterial Vicryl sutures.
This study followed the Declaration of Helsinki on medical protocol and ethics and the Regional Ethical Review Board of Isfahan University of Medical Sciences approved the study on 7 th May 2019. All patients who participated in this study signed informed consent.
The unwillingness of the patient to continue participation in the study came into consideration. All patients' information was kept confidential in this study. This study has been registered in the Iranian clinical trial registry (IRCT20131205015665N3).
Samples were selected among patients referred to the specialty section of the oral and maxillofacial department of the dentistry faculty of Isfahan University of Medical Sciences from May to July 2019. To be included in this study, patients should have had at least one mandibular third molar indicated for surgical extraction with the same degree of difficulty (type A mesioangular impaction) which was diagnosed through clinical and radiographic examination. Biographic data was taken (age, gender, address, and telephone number); and then, medical and dental history including pregnancy and breastfeeding, overall systemic condition, history of using medications in the last month, history of pulpitis or any malignant lesion in the site of surgery, were evaluated and recorded through clinical and radiographic examination. Patients with underlying systemic diseases, using systemic or oral medication affecting normal oral flora and colonization, smoking and drug addiction, alcohol addiction, presence of intraoral inflammation before the surgery, pregnancy, and lactation, known or suspected allergy to suture material or other materials used in this study, loss of sutures before 1 week, presence of removable prosthesis in the oral cavity, and presence of infection after surgery or any other condition indicated for antibiotic therapy were excluded from this study.
Considering an identification number (ID number) for each patient from 1 to 27, similar sterile sets were used for all patients. The site of the surgery was prepared with betadine and draping was performed for all patients in the same manner. Local anesthesia was obtained for all patients with lidocaine 2% and epinephrine 1:80000. After reflecting a standard mucoperiosteal flap, bone removal and extraction of the tooth was performed and suturing was done with randomly placed Vicryl suture (Ethicon Inc., Johnson and Johnson Company, Somerville, New Jersey, United States) and Vicryl Plus suture (Ethicon Inc., Johnson, and Johnson Company, Somerville, New Jersey, United States) in the mesial and distal part of the surgical site.
For randomization purposes, in patients with an odd ID number, Vicryl suture was placed in the mesial part and Vicryl Plus sutures in the distal part of the flap. In patients with an even ID number, the Vicryl Plus suture was placed in the mesial part of the flap, while the Vicryl suture was placed in the distal part. All the instruments including the injection needle, blade, elevator, and suture were sterile at the beginning. All procedures were performed by a single surgeon and, for blinding purposes; sutures were peeled open out of the surgeon's sight and then given to him. Cutting was done in a manner to permit 3mm of the suture to be held out of the tissue. after considering a code for each type of suture material, the exact location of the suture at the surgical site was documented (i.e. "1M" means Vicryl suture in mesial and "2D" means Vicryl Plus suture in distal). Ibuprofen (soft gel capsule/400mg) was prescribed as a pain control medicament and extra gauze was given to the patient for application on the surgical site for 1 hour. Post-surgical patient instruction for oral hygiene was done. Patients were also instructed not to use any antiseptic mouth rinse for the first week after surgery before they were discharged. After seven days, recalling the patient and removing the sutures, placing each in a 5cc saline-filled test tube which had a code number on it as had been recorded at the date of the surgery. The tube tests were transported to the microbiological laboratory of Amin hospital in less than 1 hour. Patients were carefully evaluated for wound complications including bleeding and wound dehiscence and clinical examination was done assessing signs and symptoms of SSI post-surgically.
In the laboratory, after measuring the length of the removed sutures; they were transferred separately to the thioglycolate culture media and processed within 1 hour. For each sample, a one-tenth diluted solution with 0.9% NaCl was made and 100µL of it was used on blood agar culture medium, and then Incubation was done in 37 degrees of temperature for 2 days. Gram coloring was done and cellular morphology was assessed under an optical microscope. S. mutans and Lactobacillus were considered as predominant bacterial species regarding the outcomes of similar studies evaluating the bacterial load following oral surgeries, which had reported these two species as predominant ones [15]. Counting the number of S. mutans and   Table 1). The decrease in the colonyforming unit-length (CFU-length) ratio in each patient can be seen in (Figure 3-5).

Discussion
Our results showed that using Vicryl Plus sutures which are coated with TCS in comparison with Vicryl in the oral surgery significantly reduced the total number of bacterial colonies' CFU length ratio as well as Lactobacillus colonies' CFU-length ratio; although it also decreased the S. mutans colonies' CFU-length ratio, this decrease was not statistically Although many studies are in favor of our results, there is some degree of contradiction in some other studies [25][26][27] . In one study performed by Tabrizi et al. 28 , comparing the ability of TCS coated sutures to reduce the infection in 320 patients undergone implant surgery, no difference were reported between Vicryl and Vicryl Plus sutures. One probable reason may be the fact that one important requisite for patients undergoing implant surgery, is to have excellent oral hygiene. The site of the surgery may be another factor that can be considered; since the site of surgery in mandibular wisdom tooth extraction located in the most posterior aspect of the mouth, less accessibility before and after surgery, this fact can make it more prone to SSI. Thus, antibacterial suture materials including Vicryl Plus can be a useful tool for the reduction of bacterial load and subsequent surgical site infection in cases with a high risk of infection due to the patient-related factors (i.e. poor oral hygiene).
In another study with split-mouth design, after surgical extraction of both impacted mandibular wisdom teeth simultaneously, suturing was performed using Monocryl plus or silk in each side and microbiological evaluation was done 72hours and 7 days after surgery.
The most common bacterial species were gram-positive cocci, gram-positive bacillus (lactobacillus), and gram-negative bacillus (prevotella). Only one case of SSI was reported after 72h. Utmost antibacterial effect of Monocryl plus suture was after 72h, but the difference was not significant after 5-7 days which is the routine time of suture removal in everyday practice in dentistry 15 , and also our study, but the results are in contrast which may be due to the difference in suture materials between two studies; the reason may be the loss of antibacterial effect of Monocryl plus after 72h while Vicryl Plus may have a longer antibacterial effect in the similar situation. It seems that performing a similar study comparing these two suture materials can help assess this theory.
In an in vitro study by Venema et al. 25 , Vicryl Plus had no inhibitory effect on Streptococcus sanguis PK1889 or other microorganisms residing in saliva. This study is in contrast with our results. This might be due to the differences in the method of performing these two studies and in vitro nature of Venema's et al. study versus in vivo nature of our study.
Our study had certain strengths and limitations. The strength of our study is the random allocation as well as having a parallel design with two simultaneous interventions in each participant which makes the results more reliable by having control over confounding variables when compared to a design with separate case and control groups. As per the limitation of our study, since the number of female participants was noticeably greater than male participants (21 versus 6) the results of this study cannot be generalized in terms of gender. Moreover, further studies with more samples can confirm the results of this study and clarify the true usefulness of Vicryl Plus sutures in the reduction of bacterial colonies in the surgical field. Increasing the period of follow up from two to four weeks could have also increased the validity of our study and is suggested for the future studies. The longer period of follow up other antibacterial sutures and the comparison between them can also help the dentists to choose the best suture material in oral surgeries. The selection of aerobic species as well as other common anaerobic species other than those evaluated in our study can increase the accuracy of future studies. Besides, performing other culturing and coloring techniques which were not included in our study due to their complexity and high price can be a good suggestion.

Conclusion:
The results of our study have shown that Vicryl Plus suture is more beneficial than Vicryl suture in bacterial load reduction after mandibular third molar extraction surgery. This might benefit especially high-risk patients with poor oral hygiene.