Effect of finishing systems on the surface roughness of an experimental low-shrinking composite resin

Abstract

PURPOSE: This study evaluated the surface quality of a new low-shrinking experimental resin restorative material after polishing with seven different techniques. METHODS: The composite resin used in this study was the experimental material, Hermes (3M/ESPE). Seventy standardised specimens were prepared using a perspex mould. All samples were stored in distilled water for 10 days. Samples were randomly divided into 7 groups (n=10). Thereafter, the average roughness of one side of each specimen (formed against the matrix) was recorded using a surface roughness meter (Surftest SJ 301)(control). The other side of each specimen was roughened with 320grit silicone-carbide paper in a polishing machine for 45 seconds. The finishing/polishing of specimens was performed following the five different protocols according to the manufacturer’s instructions: (1) Enhance polishing cones (E), (2) Enhance followed by POGO (EPG), (3)Jiffy Polishing Cups (J), (4) consecutive use of four flexible Sof-Lex discs (S), (5) consecutive use of four flexible Sof-Lex discs followed by Sof-Lex brush(SB), (6) consecutive use of three flexible OpenDiscs (O), and (7) consecutive use of three flexible OpenDiscs followed by Openshine brushes (OB). The mean roughness of each polished surfaces was determined using the surface profilometer, collecting 5 measurements from each specimen. Data was analyzed statistically (ANOVA). Results: The mean average roughness (Ra) values obtained for specimens in Groups 2-8 that were treated with one of the polishing systems ranged from 0.63 – 1.21 μm. ANOVA analysis demonstrated a statistically significant difference between Enhance (roughest) compared to all the other groups (P <0.001). There were no statistical significant differences (p<0.001) between Groups 3(Enhance and POGO2), 4(Jiffy Polishing Cups), 5(Sof-Lex), 6(Sof-Lex and Sof-Lex Brushes), 7(OpenDiscs) and 8 (OpenDiscs and OpenShine Brushes). Clinical Significance: All the polishing techniques evaluated in this study, with the possible exception of Enhance Points, can be utilised to produce a smooth surface on Hermes composite resin material. The material Hermes can be polished to a high gloss and excellent smoothness, and will be acceptable for usage in the mouth.