Biofilm Formation On Composites Differing In Resin And Filler Properties

Objective: The aim of this study was to evaluate the influence of experimental resin-based composites (RBCs) differing in resin matrix chemistry and filler properties on in vitro biofilm formation by oral microorganisms. Methods : Twenty-eight standardized specimens were prepared from each of 8 experimental RBCs (cf. table). After light-curing, specimens were polished to high gloss with grinding paper and a single-level polishing system tailored for RBCs. Surface roughness (SR), surface free energy (SFE) and chemical surface composition (EDX) of the different RBC surfaces were determined. Biofilms were developed in a Drip-Flow Reactor for a 48-h incubation period using either a Streptococcus mutans monospecific model or an oral microcosm model. Adherent viable biomass was assessed using a MTT assay. Statistical analysis was performed using two-way ANOVA and Student’s t-test (α<.05). Results : R4 showed significantly higher SR than the other groups (P<.01). Significantly higher SFE was demonstrated for R1pho than for the other RBCs (P<.05). EDX analyses indicated that the incorporation of filler particles caused a decrease in the carbon/silicon surface ratio. Less viable Streptococcus mutans biomass was identified for R2 than for R3 and R4 (P<.01), regardless of the properties of the matrix blend. Regarding the oral microcosm model, significantly more viable biomass was developed on RBCs with hydrophobic resin matrix blends than on RBCs with hydrophilic matrix blends (P<.001) with the exception of R2pho. Conclusion: Both resin matrix chemistry and dimensions of the filler particles impact biofilm formation on RBCs surfaces. These results may help to tailor novel RBC formulations that feature reduced biofilm formation properties.

Experimental RBC label	Resin matrix	Filler dimensions
R1phi	Hydrophilic	Neat resin
R2phi	Hydrophilic	Nano-scaled
R3phi	Hydrophilic	Fine
R4phi	Hydrophilic	Coarse
R1pho	Hydrophobic	Neat resin
R2pho	Hydrophobic	Nano-scaled
R3pho	Hydrophobic	Fine
R4pho	Hydrophobic	Coarse