Comparative evaluation of the antibacterial effects of four dentine bonding systems: An in vitro study

AIM: The aim of this in vitro study was to evaluate and the compare antibacterial efficacy of four dentin bonding system against Streptococcus mutans, Streptococcus salivarius and Lactobacillus acidophilus over a period of three months using agar disk diffusion test. METHODOLOGY: All the three standard bacterial strains were inoculated into BHI broth and incubated at 37°C for 48 hours. A 100 μl of broth suspension containing aliquots of S. mutans, S. salivarius and L. acidophilus were spread onto M-H agar medium using sterile cotton swabs. The experimental groups were as follows: GROUP A: Test conducted for evaluation of antimicrobial efficacy against S. mutans MTCC 497, GROUP B: Test conducted for evaluation of antimicrobial efficacy against S. salivarius MTCC 1938, and GROUP C: Test conducted for evaluation of antimicrobial efficacy against L. acidophilus MTCC 447. For sample preparation, 20 μl bonding agent was dropped with micropipettes on paper disks, and blown dry for 10 seconds. Then it was light-cured at 2 mm for 20 sec using a QTH visible light curing unit. For first reading, the sample disks were placed over the freshly inoculated agar plates and then incubated at 37°C for 48 hours. The rest of the paper disks were stored in dark, submerged in distilled water at 37°C. They were placed on freshly inoculated spread plates after specific time intervals- 1 day, 1 week, 2 weeks, 1 month and 3 months after ageing in PBS. After incubation, the diameters of zones of inhibition around the plates were measured. The experiment was performed twice in triplicate. The data was then statistically analysed using Two way ANOVA test and post hoc. RESULTS: Results showed that Xeno III had the maximum antibacterial efficacy over a period of three months, followed by XP bond. This antibacterial activity was maximum against Streptococcus mutans, followed by Lactobacillus acidophilus and least against Streptococcus salivarius. Adper Easy One and G bond had minimal effect against the test bacteria during the test period. CONCLUSION: The antibacterial effect decreased over a period of three months for all the dentin bonding systems.