In Vitro Assessment of the Antibacterial Properties of Novel Chemomechanical Caries Removal Agents and Their Impact on Bonding Performance to Resin Composite Restorations

OBJECTIVES: To assess the antibacterial efficacy of novel bromelain-containing chemomechanical caries removal (CMCR) agents and their effect on the bonding strength of residual dentine to an adhesive resin composite restoration. METHODS: The antibacterial efficacy of three formulated CMCR gels, comprising 30% bromelain (F1), 30% bromelain with 0.1 wt.% chloramine-T (F2), and 30% bromelain with 1.5% chlorhexidine (F3), was evaluated in comparison to Brix 3000, specifically against Streptococcus mutans and Lactobacillus acidophilus species. A total of 120 extracted permanent molars exhibiting natural carious lesions were randomly allocated into six groups based on excavation techniques; hand excavation, rotary excavation, Brix 3000, F1, F2, and F3. The microshear bond strength (µSBS) of the residual dentine to resin composite was assessed after two-time intervals. The morphological assessment was conducted using scanning electron microscopy (SEM). RESULTS: F3 demonstrated the most pronounced statistically significant antimicrobial efficacy against both bacterial species (p < 0.001), as well as the highest statistically significant immediate µSBS to the residual dentine (p < 0.001). In contrast, F2 exhibited the highest µSBS mean value post aging (p < 0.001), along with the greatest percentage of mixed and cohesive failures. This was accompanied by the presence of a well-integrated hybrid layer and numerous elongated resin tags within the residual dentine. CONCLUSION: The novel bromelain-based CMCR gels, particularly when combined with chlorhexidine, demonstrated a remarkable antimicrobial efficiency. In contrast, the formulation containing chloramine-T exhibited superior prolonged bonding performance. CLINICAL SIGNIFICANCE: These novel formulations present a promising strategy for caries management and enhance the longevity of adhesive restorations.