The Influence of Surface Polish and Beverages on the Roughness of Nanohybrid and Microhybri Resin Composite

AbstractStatement of the Problem: Surface roughness is a key factor in the aestheticsof restorative dentistry as it can determine the clinical quality and success ofrestorative materials. The chemical process of dissolution in the presence ofmechanical forces can accelerate the surface roughness of tooth-colouredrestorative materials.Objectives: To determine the degree of surface roughness of a microhybridand a nanohybrid resin composite after polishing and immersion in varioussolutions.Materials and Methods: Two resin composites were used : a microhybrid(Gradia direct, GC), and a nanohybrid (Ice, SDI). A total of 54 disc-shapedspecimens were prepared for each composite and immersed in distilledwater incubated at 37 °C for 24 hours. After 24 h, the baseline measurementfor surface roughness (Ra) was performed and the specimens were divided into3 groups of 18 and tested with unpolished or after polishing with Sof-Lex discand Enhance point systems. Specimens in each group were subdivided into 3subgroups(n = 6) and immersed in 3 solutions (distilled water, coffee, and cola) for 7 daysincubated at 37 °C. After 7 days, the specimens were rinsed with tap water for10 seconds, dried with paper towel and Ra was measured again. Two randomlyselected specimens of each group were sputter coated with gold and examinedusing a Field-Emission Scanning Electron Microscope (SEM).Results: Gradia direct showed a greater Ra than ice in all solutions for allpolishing systems (p < 0.001). Specimens polished with Enhance pointrevealed a significantly greater roughness than Sof-Lex discs and both showedgreater Ra than unpolished specimens. Specimens immersed in coffee exhibitedsignificantly greater surface roughness than that of distilled water (p < 0.05)and cola (p < 0.001).Conclusions: Nano-hybrid composite showed a significantly smoother surfacethan microhybrid. Coffee exhibited the highest Ra compared to distilled waterand cola. Enhance point revealed significantly greater Ra than Sof-Lex discsand unpolished group.