Surface properties and biofilm formation of a manufacturer-reinforced, nanographene-modified pre-polymerized CAD-CAM polymethylmethacrylate denture base material: An in vitro study.

PURPOSE: To evaluate the surface roughness, hydrophobicity, and Candida albicans biofilm formation of three denture base materials, including two computer-aided design and computer-aided manufacturing (CAD-CAM) polymethylmethacrylate (PMMA) resins and one conventional heat-polymerized PMMA, before and after thermocycling (TC).

MATERIALS AND

METHODS

Thirty disk-shaped specimens (Ø10 × 1.5 mm) were fabricated and assigned to three groups (n = 10 each): (1) nanographene-reinforced CAD-CAM PMMA (GDM, trace graphene content <0.05 wt%), (2) pre-polymerized CAD-CAM PMMA (MDM; nanoparticle-free control), and (3) conventional heat-polymerized PMMA (CDM; nanoparticle-free control). Specimens underwent 10,000 thermal cycles in artificial saliva, followed by repeated measurements. Surface roughness was measured before polishing, before TC (after polishing), and after TC using a noncontact optical profilometer to establish baseline surface conditions and quantify finishing- and aging-related changes. Hydrophobicity was assessed before TC (after polishing) and after TC via water contact angle analysis. C. albicans biofilm formation was evaluated before TC (after polishing) and after TC using a 48-h incubation model followed by colony-forming unit quantification. The data were analyzed using a one-way ANOVA followed by Tukey's post hoc test for multiple comparisons. Additionally, paired t-tests were conducted to evaluate changes before and after TC (α = 0.05).

RESULTS

Surface roughness differed significantly before polishing and after TC (p < 0.001), but not before TC (after polishing) (p = 0.129). CDM had the highest roughness; GDM showed the lowest after TC (p < 0.001). Water contact angle did not differ significantly among materials (p ≥ 0.136). GDM initially showed higher C. albicans biofilm than CDM (p = 0.009), but levels decreased after TC (p < 0.001), with no differences thereafter. Biofilm formation after TC correlated positively with contact angle (r = 0.478) and negatively with roughness (r = -0.401).

CONCLUSION

Surface polishing reduced the roughness of all tested materials, with GDM exhibiting the lowest roughness. The incorporation of nanographene in a pre-polymerized PMMA denture base reduced roughness and C. albicans biofilm formation.