Effects of Delayed Finishing/Polishing on Roughness, Gloss of Restorative Materials

Objectives: The aim of this study was to investigate the effect of delayed finishing/polishing on surface roughness and gloss of tooth-coloured restorative materials. Methods: Four different tooth-coloured restorative materials were used in the study: a hybrid composite resin-Venus, a nanofilled composite resin-Grandio, a flowable composite resin- Tetric Flow, and a polyacid modified resin composite-Dyract Extra. Thirty disc shaped specimens of each material (10-mm in diameter and 2-mm thick) were made according to the manufacturer's instructions; the first 10 were used as controls and the remaining 20 specimens were randomly divided into two groups. The first group was finished/polished immediately and the second group was finished/polished after 24 hours. The same operator performed all finishing and polishing procedures. The surface roughness of each specimen was recorded using a laser profilometer by a second operator who was blind to the restorative material and finishing/polishing time. Gloss measurements, expressed in gloss units (GU) were performed using small-area glossmeter. Data for surface roughness were analyzed by Kruskal Wallis test and data for gloss were subjected to one-way ANOVA and Tukey test. Results: For all materials, the smoothest surfaces were obtained under Mylar strip(control). While there were no significant differences in surface roughness of immediate and delayed finished/polished Dyract Extra samples, immediately finished/polished Venus and Grandio samples showed significantly higher roughness values than delayed finished/polished samples. In Tetric Flow samples, immediately finishing/polishing caused smoother surface than delayed finishing/polishing (p<0.05). The highest gloss values were recorded under Mylar strip for all materials. While delayed finishing/polishing resulted in a significantly higher gloss compared to immediate finishing/polishing in Venus samples (p<0.05), no difference in gloss measurements were observed between delayed or immediate finishing/polishing for the rest of the materials(p>0.05). Conclusion: The effects of delayed finishing/polishing on surface roughness and gloss appear to be material dependent.