Effect of Two Different Concentrations of Chlorhexidine Digluconate on the Shear Bond Strength of Resin Composite to Biodentine using Self-etch and Etch-rinse Bonding Strategies: An In-vitro Study

Introduction: Chlorhexidine (CHX) has been most commonly used as an antimicrobial component as well as for disinfection before the placement of restorations. CHX has demonstrated successful inhibition of dentin Matrix Metalloproteinase (MMP) collagenolytic activity when used in concentrations of 0.2% and 2%, however this may influence the bond strength of composite resin to Biodentine when applied before adhesive procedures. The present study endeavours to evaluate a bonding strategy that would best suit the preconditioning with CHX. Aim: To evaluate the effect of two different concentration of CHX on Shear Bond Strength (SBS) between resin composite and Biodentine, using self-etch and etch-rinse bonding strategies. Materials and Methods: The present in-vitro study was carried out in the Department of Conservative Dentistry and Endodontics in Mahatma Gandhi Mission Dental College and Hospital, Navi Mumbai, Maharashtra, India, from January 2022 to May 2022 on 108 acrylic blocks. A central cavity was prepared in the acrylic block and randomly divided into six main groups. Group 1 (control) Biodentine placement; selfetch adhesive application followed by resin composite. Group 2 (control) Biodentine placement; etch and rinse adhesive application followed by resin composite. Since two different bonding strategies, self- etch and etch-and-rinse were used, two control groups were included. Each of these bonding methods has different application protocols and bonding mechanisms, which could independently affect the SBS between resin composite and Biodentine, therefore two control groups were included. Including both controls allows for a fair and unbiased comparison with the experimental groups where CHX (at 0.2% or 2%) was used. This ensures that any observed differences in bond strength can be accurately attributed to the effect of CHX, rather than differences between the bonding strategies themselves. Group 3 Biodentine placement; application of 0.2% CHX prior to application of self-etch adhesive followed by resin composite placement. Group 4 Biodentine placement; application of 2% CHX prior to application of self-etch adhesive followed by resin composite placement. Group 5 Biodentine placement; for etch and rinse adhesive system application 0.2% CHX after acid etching prior to application of adhesive followed by resin composite placement. Group 6 Biodentine placement; for etch and rinse adhesive system application 2% CHX after acid etching prior to application of adhesive followed by resin composite placement. Thereafter the samples were subjected to the shear bond testing in a universal testing machine. The obtained data was tabulated and statistically analysed for normality using Shapiro-wilk test. Further statistical analysis was done using One-way Analysis of Variance and Two-way ANOVA followed by Tukey–Kramer Test for pair-wise comparisons. Post-hoc test was done to compare control group compared with CHX treated group irrespective of bonding technique. Results: Surface treatment of Biodentine with 0.2% or 2% CHX reduced the bond strength of composite resin to Biodentine irrespective of bonding strategies. The One-way ANOVA test showed there was statistically significant difference in SBS of the resin composite bonded to Biodentine when the different bonding strategies and surface treatment are applied( p<0.001 ). Two-way ANOVA test showed statistically significant difference in SBS between etching technique and different concentrations of CHX with p<0.001. A higher SBS was observed when the Biodentine was pretreated with 0.2% CHX (Group 3 and Group 5) compared to 2% CHX (Group 4 and Group 6) (p<0.001). Posthoc test statistically significant difference found in SBS when control groups when compared to groups treated with CHX, irrespective of bonding technique (p<0.001). Conclusion: Application of 2% and 0.2% CHX on Biodentin reduced the SBS with resin composite, irrespective of the bonding strategy. Between the self-etch and etch-rinse adhesive system used in this study, etch-rinse showed higher SBS for 0.2% CHX compared to self-etch adhesive system.