Resin composites containing S-PRG fillers: effects on pH modulation of the surrounding medium, surface roughness, and gloss following erosive/abrasive challenge

Abstract

Composite resins containing S-PRG fillers may degrade under pH fluctuations and abrasion, influenced by their composition, particle size, exposure time, and solution acidity. Objective: This study evaluated the ability of resin composites containing S-PRG fillers to modulate the pH of the surrounding medium, as well as their surface roughness and gloss following an erosive/abrasive challenge. Methodology: Resin disks (∅4mm x 2mm) (n=15) were prepared using Filtek Z350 XT (control), Beautifil II, Beautifil II Enamel, and Beautifil II LS (the latter three containing S-PRG fillers). To assess buffering capacity, disks (n=5) were immersed in a demineralizing solution, and pH was measured at baseline and after 1, 3, 7, 14, and 21 days. Separate specimens (n=10) underwent daily erosion cycles using 0.3% citric acid, combined with abrasion via toothbrushing, conducted over a 5-day period to simulate an acidic diet and twice-daily oral hygiene. Surface roughness (Ra) and gloss (GU) were assessed at baseline, after polishing, and following the challenge; surface topography was analyzed by a scanning electron microscope (SEM). Data were analyzed using a generalized linear mixed model for repeated measures over time, in addition to Tukey-Kramer, Kruskal-Wallis, Dunn, Friedman, and Nemenyi tests (α=0.05). Results: All materials showed a significant increase in the pH of the surrounding medium over time (p<0.05). After 24 hours, Beautifil II exhibited a significantly higher pH than the others (p<0.05). Filtek Z350 XT demonstrated lower surface roughness than the other materials after the erosive/abrasive challenge (p<0.0001). Following the challenge, Beautifil II and Beautifil II Enamel presented higher gloss values (p<0.05). Conclusions: Resin composites containing S-PRG fillers slightly increased the pH of the surrounding medium over time. Surface roughness increased after the erosive/abrasive challenge, although the gloss of the S-PRG-containing composites also improved.