|Year : 2021 | Volume
| Issue : 2 | Page : 62-67
Evaluation of the sealing ability of antibacterial sealing gel versus chlorhexidine varnish at the implant-abutment interface: An in vitro study
Soja Raju, K Harshakumar, R Ravichandran, Vivek V Nair, Kavitha Janardanan, Litty Francis
Department of Prosthodontics, Government Dental College, Thiruvananthapuram, Kerala, India
|Date of Submission||23-May-2021|
|Date of Acceptance||28-Jun-2021|
|Date of Web Publication||31-Aug-2021|
Dr. Soja Raju
Department of Prosthodontics, Government Dental College, Thiruvananthapuram - 695 011, Kerala
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Lack of complete wall-to-wall adaptation between implant and abutment of two-piece implants results in microgap at the implant-abutment interface (IAI). Leakage of bacteria and the endotoxins produced by them at the IAI play a major role in inflammatory reactions of surrounding soft tissues, which in turn lead to crestal bone loss. Objectives: The objective of the study is to compare the sealing ability of antibacterial sealing gel and chlorhexidine (CHX) varnish at the IAI by assessing the growth of Escherichia coli on agar plates. Materials and Methods: A total of 36 implants and abutments were selected for the study and divided into three groups. Sealing agents were applied at the IAI of implant groups and a control group without any sealing agent. Abutments were connected to the implants, and bacteria were inoculated. Bacterial percolation was evaluated by culturing the specimen from the internal aspect of implants on agar plates after incubation. Efficacy was evaluated by counting the colonies (colony-forming units) on the agar plates. The results were analyzed by using Kruskal–Wallis analysis of variance followed by pairwise comparison using Dunn-Bonferroni test. Results: Mean of colony-forming units for control was calculated to be 178.38 cfu, for antibacterial sealing gel was 4.75 cfu, and for CHX varnish was 18.63 cfu. In the present study, least value of colony-forming units of bacteria was exhibited by IAIs sealed with antibacterial sealing gel, and the maximum value was given by the control group with no sealing agent at IAI. Conclusion: Application of CHX varnish and antibacterial sealing gel can reduce the bacterial leakage through IAI, whereas complete seal was not attained with either of the materials.
Keywords: Antibacterial sealing gel, chlorhexidine varnish, implant-abutment interface, microleakage
|How to cite this article:|
Raju S, Harshakumar K, Ravichandran R, Nair VV, Janardanan K, Francis L. Evaluation of the sealing ability of antibacterial sealing gel versus chlorhexidine varnish at the implant-abutment interface: An in vitro study. J Interdiscip Dentistry 2021;11:62-7
|How to cite this URL:|
Raju S, Harshakumar K, Ravichandran R, Nair VV, Janardanan K, Francis L. Evaluation of the sealing ability of antibacterial sealing gel versus chlorhexidine varnish at the implant-abutment interface: An in vitro study. J Interdiscip Dentistry [serial online] 2021 [cited 2021 Dec 5];11:62-7. Available from: https://www.jidonline.com/text.asp?2021/11/2/62/325104
| Clinical Relevance to Interdisciplinary Dentistry|| |
- In this study, sealing ability of chlorhexidine varnish at implant-abutment interface (IAI) for the prevention of bacterial percolation was tested against antibacterial sealing gel and found that application can significantly reduce the bacterial leakage
- Since implant treatment is an interdisciplinary approach, the use of sealing agents by practitioners of different disciplines at the IAI during the first and second-stage surgery, beginning of prosthetic phase, maintenance phase as well as while managing complications improve success rate of implants.
| Introduction|| |
Implantology has emerged as the most successful treatment modality for the replacement of missing teeth. There are mainly two established protocols for implant placement, the two-stage and the single-stage procedures. The traditional two-stage implantation procedure allows undisturbed osseointegration of the implant within the bone before occlusal loading. Implant design for two-stage, implantation procedure ought to be two pieces. The implant-abutment interface (IAI) though precisely machined results in a microgap which is liable to bacterial ingression. This microgap will act as retention site for bacteria and also allows fluid exchange between the oral cavity and internal aspect of the implant. The microgap is found to be 1–49 micrometer in width, and hence, it is wide enough for periodontopathogenic bacteria to pass through., Several studies have shown the translocation of bacteria from surrounding medium to the lumen of implant or from inner part to the external portions.,
Leakage of bacteria and the endotoxins produced by them at the IAI play a major role in inflammatory reactions of surrounding soft tissues., Thus, the gaps and hollow spaces at implant lumen and IAI contribute to inflammation of surrounding tissue by acting as an additional reservoir for periodontal pathogens or endotoxins.
To reduce implant-abutment gap, several investigators have examined the effect of mechanical sealing using, silicon, O rings, or grease at the IAI.,, However, none of these methods have resulted in complete obliteration of the microgap. Silicones containing disinfectant (GapSeal – highly viscous silicon-containing thymol) have shown marked reduction of microleakage into the implant, if it is applied immediately after implant placement. Chlorhexidine (CHX) has been considered as the gold standard oral antiseptic for plaque control for the past 2 decades with no possibility of systemic toxicity, microbial infection, or superinfection. A recent study also revealed that rinsing with CHX in saline solution was efficient to decontaminate implant surfaces following periimplantitis. The CHX in the form of varnish (Cervitec Plus – 1% CHX varnish) intended for preventing bacterial activity on the tooth surface has been proven to significantly hinder bacterial leakage into and from prefabricated screw-retained crowns on implants. However, the sealing ability of CHX varnish at the IAI has to be determined and compared with silicone-containing disinfectant for effective crestal bone preservation. In this context, the present study was conducted for evaluation of the sealing ability of silicon-based antibacterial sealing gel versus CHX varnish at internal hexagon IAI.
| Materials and Methods|| |
Preparation of specimens
Before the study, sterilization of the implants and components was accomplished by Gamma irradiation. Supplementary instruments and materials were autoclaved at 121°C for 20 min, and sterility after procedure was ensured by pretests. All further steps were carried out in a biosafety cabinet for avoiding contamination. A total of 36 implants and straight abutments were used in the study to check the efficacy of sealing at the IAI. Implants and abutments were allocated into three groups, of 12 implants and 12 abutments. In the first group, no sealing agent was applied at the IAI and served as the control. The second group comprises implants and abutments that were sealed with the antibacterial sealing gel, GapSeal at the IAI. Application of antibacterial sealing gel was accomplished with provided applicator and disposable carpules containing antibacterial sealing gel. Two complete loops of antibacterial sealing gel applied at internal hex junction of implant and abutment before insertion. Implants and abutments in the third group were sealed with CHX varnish, Cervitec at implant-abutment interface. Coating of 1 ml of varnish over the innerspace of implant, abutment, and abutment screw was attained with applicator brush. The implants and abutments of three groups were assembled using a torque wrench at a torque of 20Ncm by stabilizing them in a clamp [Figure 1]. Abutment screws were retightened 10 min after the initial torque application to reduce the settling effect.
|Figure 1: Assembling of the implants and abutments using torque wrench stabilizing them in a clamp|
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Microbiologic sampling and examination
Two assembled implants (randomly taken) from each group were incubated in peptone water (one dismantled and other without dismantling). The incubation was carried out for 24 h and absence of turbidity of peptone water ensured complete sterilization of the implant-abutment assembly. The remaining implant-abutment assemblies from each group were then immersed in the test tube containing peptone water, inoculated with Escherichia coli, which is small enough for passage through the microgap, and the dimensions are similar to periodontal pathogens. Inoculation of E. coli was done with inoculating loop utilizing aseptic technique. Afterward, assemblies in inoculated peptone water were incubated in an incubator for 30 min at 37°C. After incubation, the assemblies were removed from the test tubes and surfaces were washed with 1% freshly prepared hypochlorite solution for 5 min and then with saline solution for 5 min under sterile conditions. To check the efficiency of the surface decontamination procedure, all implants were incubated in sterile peptone water for 24 h and ensured the absence of turbidity of peptone water. Eight implants from each group were then dismantled and again placed in sterilized peptone water and well shaken to ensure adequate contact of the broth with the interior of the implants. Then, 1 ml from each test tube was inoculated on preprepared sterile agar plates by drop method using syringe and needle of uniform size and incubated for 24 h. The colonies formed on the agar plates of three groups were counted with a digital colony counter to determine the efficacy of sealing agent [Figure 2].
|Figure 2: Counting of colony-forming units on agar plates using a digital colony counter|
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| Results|| |
Sealing ability of antibacterial sealing gel and CHX varnish was tested by assessing the growth of E. coli on agar plates, and values were obtained as colony-forming units [Table 1]. The number of colonies in control group ranged from 138 to 227 (mean, 178.38; standard deviation [SD], 32.833), in antibacterial sealing gel group ranged from 0 to 12 (mean, 4.75; SD, 4.166) and in CHX varnish group from 3 to 36 (mean, 18.63; SD, 12.950) [Table 2]. In the present study, least value of colony-forming units of bacteria was exhibited by IAIs sealed with antibacterial sealing gel and the maximum value was given by the control group, no sealing agent at IAI [Graph 1]. The basic data for all groups were subjected to statistical analysis using Kruskal–Wallis analysis of variance; a statistically significant value was seen where P value was. 000 (P value. 01, significant at a 5% level significance) [Table 3]. Application of sealing agent decreases the number of colony-forming units of E. coli in agar plates by inhibiting the percolation through microgap at IAI.
|Table 2: Mean, median, standard deviation, and interquartile range of colony-forming units formed by three groups|
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|Table 3: Comparison of colony-forming units among three groups using Kruskal–Wallis analysis of variance|
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Further pairwise comparison was done using Dunn-Bonferroni test, which showed statistical significance at the 5% level for the control group and antibacterial sealing gel group (P < 0.0001); statistical significance was also shown at the 5% level for the control group and CHX varnish group (P < 0.05). However, there was no statistically significant difference while comparing antibacterial sealing gel group and CHX varnish group (P > 0.05) [Table 4].
|Table 4: Intergroup comparison of colony-forming units among the three subgroups using Dunn-Bonferroni test|
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| Discussion|| |
Implant dentistry has overcome the various limitations of the conventional prosthetic treatment procedures. It helps in improving retention, stability, and esthetics of the prostheses. The major advantage of implant-supported prosthesis over conventional prosthesis is that it prevents the bone loss of edentulous area. Hence, it provides a perfect solution for the functional problems and psychological needs of partially and completely edentulous patients. On long-term functioning, the success of an implant-retained or implant-supported prosthesis depends primarily on biological and mechanical factors. The implant failure can be classified into early or late failures. Early failures occur immediately after implant placement due to the lack of osseointegration whereas late failures occur after prosthetic rehabilitation and a period of function. Biological and mechanical complications are the two main causes of late implant failures. Biological complication is due to the loss of supporting tissues, secondary to peri-implantitis whereas mechanical complications arise as a result of loosening and/or fracture of abutment or prosthetic screws and the wear and fracture of the prosthesis or various components in the system.,
According to Lindhe et al., the incidence of peri-implantitis ranges between 28% and 56%. Peri-implantitis is a polymicrobial anerobic infection. Microbiota involving in peri-implantitis not only include typical peridontopathogens but also bacterium like Staphylococcus aureus which have high affinity for titanium. The major complication of peri-implantitis is destruction of bone induced by bacteria and bacterial toxins.
Tissues adjacent to the IAI revealed a marked infiltration of inflammatory substances irrespective of the amount of plaque. Colonization of bacteria at the IAI is due to misfit between different components of implant systems. To reduce the implant-abutment gap, several investigators have examined the effect of mechanical agents as well as disinfectants at the IAI. The mechanical agents used include silicone, O ring, and grease and disinfectants include thymol and CHX.,
The present study evaluated the sealing ability of antibacterial sealing gel and CHX varnish at implant-abutment interface of titanium premachined internal hexagon implant system. Results are shown the presence of bacterial colonies on agar plates of all the three groups. This indicates that complete seal at the IAI is not possible with either of the sealing agents whereas the number of colonies on agar plates of implants with sealing agents was far less than the control group without sealing agent and the difference was statistically significant. Application of sealing agent at the interface helps to reduce microleakage. Difference between the number of colony-forming units of implant group with CHX varnish as sealing agent and implant group with antibacterial sealing gel was not statistically significant. However, the leakage of the bacteria can be reduced to a negligible number by using antibacterial sealing gel rather than CHX varnish.
This study highlights that there is leakage at the IAI and probably due to the lack of complete wall-to-wall adaptation between implant and abutment. This is in accordance with studies done by Gross et al., Jansen et al., and Quirynen and van Steenberghe.,, According to Mishra et al., microbial contamination is present in all the implant-abutment connections. Among them, internal hexagon and conical connection implants showed less leakage of bacteria at the peri-implant sulcus and inside the connection than external hexagon implants., Rismanchian M et al. found in their study that premachined Ti abutments have less microgap when compared with Cast on and Castable abutments. The use of compatible abutments leads to significant microgap when compared with the use of original ones. The reasons for the microgap on the fitting surfaces of cast on and Castable abutments may be due to lack of finishing and polishing procedures. Hence, the present study evaluated leakage at internal hexagon connection with titanium abutments, which has the popular clinical usage and lesser mechanical complications. According to the study conducted by Smith and Turkyilmaz, there is correlation between the degree of leakage and the closing torque. Therefore, the abutments were tightened to a torque of 20 Ncm, the amount recommended in the oral cavity. To avoid the effect of settling, abutment screws were retightened after 10 min of initial tightening. Sealing ability of CHX varnish at the IAI was evaluated in this study by comparing with antibacterial sealing gel (GapSeal), which has shown marked reduction of microleakage into the implant in previous studies. CHX was used in the form of varnish, as they are easy to apply and although they have an unpleasant flavor, they do not cause discoloration of the adjacent teeth. Results of the present study have shown that CHX varnish as effective as antibacterial sealing gel in preventing percolation through IAI. This is in accordance with study done by Besimo et al. They used CHX-containing varnish for the prevention of bacterial leakage into and from prefabricated screw-retained crowns on implants and found successful. Bacteria used in the study to evaluate efficacy of sealing agents were E. coli, which have dimensions similar to periodontopathogenic bacteria. Thus, sealing against the periodontopathogenic bacteria can be evaluated indirectly.
The major limitation of the study was that it was conducted in vitro, therefore, the presence of saliva and solubility of sealants could not be assessed. Further evaluation is needed to find the longevity of the sealants and the relation between the quantity of the sealant applied and its sealing ability. Efficacy in preventing percolation was assessed during unloaded conditions, therefore, the effect of masticatory load on microgap at the IAI and bacterial leakage could not be assessed in this study.
Regardless of the studies conducted, clinical relevance of sealing the microgap at the IAI with sealing agents in maintaining inflammation-free marginal mucosa and in achieving clinically successful treatment of peri-implantitis has yet to be determined.
| Conclusion|| |
The present study was conducted to evaluate the efficacy of antibacterial sealing gel and CHX varnish in preventing percolation of bacteria through the IAI. Within the limits of the study, the following conclusions were drawn:
1. Application of CHX varnish and antibacterial sealing gel can reduce the bacterial leakage through IAI, whereas complete seal was not attained with either of the materials
2. Antibacterial sealing gel (GAPSEAL) provides better sealing than CHX varnish. However, the difference was not statistically significant.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]