Effect of water storage on the color stability and surface roughness of resin composites with S-PRG fillers subjected to additional polymerization for semidirect use.

Abstract

Background: Additional polymerization in the semidirect technique improves the physicochemical properties of resin composites. However, the effects of long-term water storage on the color stability and surface roughness of resin composites containing S-PRG (Surface Pre-Reacted Glass) fillers remain unclear. This study evaluated the effect of autoclave polymerization on the color stability and surface roughness of a conventional nanohybrid resin composite and one containing S-PRG fillers after one year of water storage.

Materials and methods: Disc-shaped specimens of Forma (Ultradent) and Beautifil II LS (Shofu; containing S-PRG fillers) were prepared (N = 48). Half of the specimens (n = 12) underwent additional autoclave polymerization. Color parameters (L*, a*, b*, Eab, E00) and surface roughness (Ra) were measured at baseline (24 h) and after 12 months of storage in distilled water. Scanning electron microscopy (SEM) was performed. Data were analyzed using generalized linear mixed models (=0.05).

Results: Color variation (Eab and E00) was significantly greater for the resin composite containing S-PRG than for the conventional nanohybrid resin composite (p<0.05), whereas the polymerization method did not affect color variation (p>0.05). Ra values did not differ according to resin composite type or polymerization method (>0.05); however, all groups exhibited a significant increase after storage (<0.05). SEM revealed no differences attributable to the polymerization method.

Conclusions: Additional autoclave polymerization did not influence the color stability or surface roughness of resin composites used in the semidirect technique. However, the resin composite containing S-PRG fillers exhibited lower long-term color stability, highlighting the influence of filler composition on esthetic durability.