Light-Curing Influences Biofilm Susceptibility of Universal Resin Composite Cements

Purpose: To investigate the influence of polymerization protocol (light-curing [LC] vs. self-curing [SC]) on Streptococcus mutans (S.mutans) biofilm formation on universal resin composite cements (UCs). Methods and materials: Three commercially available UCs (RelyX Universal, 3M Oral Care - RXU; Panavia SA Cement Universal, Kuraray Noritake - PSAU; SoloCem, Coltene - SCM) and one ‘reference’ multi-step resin composite cement (Panavia V5, Kuraray Noritake - PV5) were used following two polymerization protocols (LC: Elipar Deep cure, 3M Oral Care, operating at 1470 mW/cm2 for 40 s; SC: 90 min in a dark chamber at 37 °C). S. mutans biofilms were grown on UCs samples in a bioreactor for 24 h, then adherent viable biomass was assessed using a modification of MTT assay. Half of UCs samples underwent accelerated artificial aging. Three-way ANOVA was performed considering the cement type, polymerization protocol, and aging as fixed factors (=0.05). Results: Cement type, polymerization protocol, and aging had a significant influence on microbiological behavior (p<0.0001). Considering the non-aged samples, the observed colonization was as follows: RXU >> PSAU = PV5 > SCM. Light-curing significantly decreased the viable biomass by ca. 33% for PSAU, PV5 and SCM (p<0.05). Accelerated aging caused a significant decrease in the viable biomass values of RXU and increased the values of all the other tested cements, ultimately leveling out the differences in the microbiological behavior of the tested cements. Conclusion: When clinically possible, it is advisable to always properly light-cure UCs since it can considerably decrease biofilm formation, as compared to self-curing protocol.