A comparative in vitro efficacy of conventional rotatory and chemomechanical caries removal: Influence on cariogenic flora, microhardness, and residual composition

BACKGROUND: Chemomechanical caries removal system is part of the minimal invasive dentistry; the aim of the study was to compare the amount of bacteria after caries removal with chemomechanical system and conventional rotatory instruments and to test the Vickers microhardness and micro-RAMAN analysis of residual dentin after excavation. MATERIALS AND METHODS: Molars were induced for demineralization, confirmed with DIAGNOdent; Streptococcus mutans were inoculated into the cavities and filled. Caries removal was performed with rotatory instruments and chemomechanical system; surviving bacteria were cultured for 24 and 48 hours at 37°C. Vickers microhardness and micro-RAMAN analysis were tested after excavation. Data were analyzed with Wilcoxon, continuity correction, odds ratio, ANOVA post hoc Tukey test, and Spearman correlation. RESULTS: Demineralization was significantly detectable at 240 hours of incubation; conventional rotatory instruments and chemomechanical caries removal were effective in 19.4%-22.6% and 25.8%-32.3%, respectively. Vickers microhardness of chemomechanical system was higher (P < 0.0001) than conventional rotatory instruments and comparable to healthy dentin. Micro-RAMAN analysis showed that healthy dentin is correlated to chemomechanical system (R(2) = 0.683, P < 0.00001) and drilling with burs (R(2) = 0.139, P < 0.00001). CONCLUSION: The chemomechanical system is effective for caries elimination, comparable to conventional rotatory instruments; the remaining Vickers microhardness and composition surface tissue are similar to healthy dentin.