Surface roughness and micromorphology of restorative materials after fluoride application

Objectives: The aim of this study was to evaluate the effect of frequent acidulated phosphate fluoride (APF) gel (Gelato) and a fluoride varnishe (CavityShield) on the surface roughness and micromorphology of tooth-colored restorative materials; a glass ionomer cement (GC Fuji IX GP), a compomer (Compoglass F), and a resin-composite (Filtek™ Z250 XT) using a profilometer and scanning electron microscope (SEM).
Methods: A total of 30-15/subgroup standardized disc-shaped specimens were prepared for each material using Teflon molds. After 24 hours, specimens were finished and polished and stored in distilled water for 48 hours. As baseline data, surface roughness (Ra) was measured with a profilometer and an impression of each specimen was made for epoxy replicas for SEM evaluation. Topical fluoride agents were applied four times. After the treatment, the Ra was determined and a new SEM replicas were made and examined. The data were statistically analyzed using two-way ANOVA and Tukey post hoc test.
Results: Both the compomer and the resin-composite showed significantly lower surface roughness when subjected to topical fluoride agents compared to controls. No statistically significant difference in Ra between Compoglass F and Filtek™ Z250 XT was found. However, GC Fuji IX GP showed significantly higher Ra than these materials after all surface treatments (P<0.05). There was a general trend of Ra increase from controls to APF (Gelato) gel and fluoride varnish (CavityShield) for all materials. APF (Gelato) gel was associated with a significantly higher roughness at the final measurement compared to controls (P < 0.05). SEM micrographs showed differing surface topographies which in many specimens confirmed Ra analysis.
Conclusions: Glass ionomer cement showed significantly higher roughness compared to the compomer and the resin-composite after four applications of topical fluoride agents compared to controls. SEM observations showed that the surface micromorphology of the compomer did not differ significantly from that of the resin-composite.