Surface roughness assessment of selected direct cosmotic restorative materials at different pH challenges.

The ideal dental restorative material and associated techniques continue to be the goal of materi¬al scientists and clinicians alike. The "gold standard" for restoration quality is considered to be its long term performance in clinical service. However, laboratory tools are useful as indicators of the clinical performancc of restorations' An increase in surface roughness has been used as a criterion to assess and predict the clinical deterioration of restorations of different types of material. This study was conducted to assess surface roughness 0'1' four direct cosmetic restorative materials; a resin mod¬ified glass ionomer (Photac-Fil), a compomer (Dyract), a tlowable resin composite (Tetric Flow) and a packable composite (Tetric Ceram HB) at different storage media. A total of 60 disc-shaped speci¬mens (2x2 mm) were prepared, 15 for each material. Baseline surface roughness measurement (Ra value) was performed using image analysis method. Then, each group was divided into three sub¬groups (n = 5) according to the pH of the storage media used (pH 2.5, pH 4 and pH 6.8). Surface roughness assessment was performed using the same method after a storage period of three months. Data were submitted to Dunean's .Multiple Range Test to identify significant difference in Ra values among the variables analyzed (restorative materials and storage media). The results showed no sig¬nificant difference between restorative materials tested at baseline measurements. However, after the storage period all restorative materials showed a significant increase in surface roughness (Ra value) in all pH storage media compared to baseline Ra measurements. Regarding the pH storage media, a statistically significant difference was found in Ra value of a1l restorative materials. Increase in acid¬ity of the storage media, increases the surface roughness of the restorative materials. While re¬garding the restorative material interaction, at pH 4 and at pH 6.8 no significant difference in Ra val¬ues was revealed between any or the restorative materials. However, at acidic pH 2.5 packable composite showed a significantly higher mean Ra value than that of compomer and t1owable com¬posite. It was therefore concluded that, pH challenge of direct cosmetic restorative materials're¬markably increased the surface roughness of a1l restorative materials tested, especia1lY at acidic pH. Moreover, the effect of pH on the surface roughness of the materials was not material-dependent ex¬cept at highly acidic challenge.King Saud Universit