ABSTRACT
INTRODUCTION: Gap-free/continuous cement margins have been considered important for the longevity of indirect dental restorations. Bacterial species have demonstrated esterase-like activity that can cause biodegradation of resin composites. AIM: The aim of this study was to evaluate the effect of the esterase-like activity of E. faecalis and L. casei on three resin luting cements. SETTINGS AND DESIGN: In-vitro study materials and three resin luting cements tested were: Variolink N, Rely X U200 and Panavia F2.0. E. faecalis and L. casei suspensions and supernatants were assessed for enzymatic activity by bacterial esterase activity assay. Circular samples of resin luting cements were exposed to suspensions of E. faecalis and L. casei for 7 and 28 days followed by testing for solubility, microhardness and bishydroxy propoxy phenyl propane (BisHPPP) release. RESULTS: E. faecalis and L. casei both demonstrated esterase-like activity. Bacterial suspensions had significantly increased enzymatic activity than supernatant solutions (P < 0.05). There was no significant reduction in microhardness or increased weight loss in all three cements after incubation in E. faecalis and L. casei for 7 and 28 days. BisHPPP release signifying resin degradation was seen after 7 and 28 days of incubation in E. faecalis and L. casei. CONCLUSION: Within the limitations of this in vitro study, E. faecalis and L. casei demonstrated esterase-like activity. BisHPPP release was evident in all three cements after 7 and 28 days. However, the bacterial strains did not significantly reduce the microhardness or cause weight loss of the tested resin luting cements (Variolink N, Panavia F2.0 and Rely X U200) after 7 and 28 days of incubation.
