Influence of Polymerization Protocol on Adhesion and Proliferation of Streptococcus mutans on Three Dental Composite Resins

Background/Objectives: The aim of this in vitro study was to analyze and compare the Streptococcus mutans ability to adhere and form biofilm on the surface of light-cured VS heat-cured dental composite resins; Methods: Three composite resins with different chemical formulations were selected: GrandioSO (GR), Venus Diamond (VD) and Enamel Plus Hri Biofunction (BF). Disk-shaped specimens were manufactured by light-curing the composite resins (light-cured subgroups) and subjecting them to a further heat-curing cycle at 80° for 10 min (heat-cured subgroups). Specimens were analyzed for planktonic CFU count (CFU/mL), sessile CFU count (CFU/mL) and for biomass quantification (OD570nm); Results: The planktonic CFU count was higher in all the light-cured subgroups than in the heat-cured subgroups (light-cured: GR = 7.23 × 106, VD = 2.14 × 107, BF = 4.40 × 107; heat-cured: GR = 4.89 × 106, VD = 4.95 × 106, BF = 2.80 × 107), with a statistically significant increase for BF and VD. Focusing on the sessile CFUs, both GR (light-cured = 7.49 × 106; heat-cured = 3.97 × 106) and VD (light-cured = 2.93 × 107; heat-cured = 6.07 × 106) showed a significantly increased number of colonies in the light-cured subgroups. The OD570nm values recorded for the light-cured BF subgroup (0.4280) were significantly increased compared to the heat-cured BF subgroup (0.1931); Conclusions: A more complete polymerization protocol seems to lead to a potential reduction in the risk of secondary caries.