Effect of three different acidic beverages on surface characteristics of composite resin restorative materials

Abstract

The purpose of this study was to compare the effects of different beverages upon the surface hardness, roughness and micromorphology of light cured composite resins. One microhybrid (Artemis), one nanohybrid (Grandio), one microfil (Tescera) and Filtek Silorane composite resin materials were selected for this study. Sixty-four disc shaped specimens (8 × 2 mm) of each resin composite were prepared according to manufacturers' instructions. After light curing, the specimens were polished with flexible aluminium oxide discs (Sof-Lex; 3M ESPE) under water spray and immersed in 37°C distilled water for 24 h. Sixteen specimens (half for hardness and half for roughness) were set aside to measure the initial hardness and roughness of four different composites. Baseline surface roughness Ra (in μm) measurements were taken by a surface profilometer (Mitutoyo Surfcorder/SE-40D; Kosaka Laboratory Ltd, Japan) on the top of the specimens. Baseline Vickers hardness measurements were made on the surface of eight specimens for each composite group with a Vickers hardness testing machine (Buehler OmniMet MHT1600-4980T). The remaining specimens were exposed to a dynamic pH cyclus in three different beverages (orange juice, spring water and Coca Cola) over 7 days. After a 7-day storage, samples were taken from the beverages. Specimens were subjected to post-immersion surface roughness and microhardness testing. Samples of SEM images were recorded before and after storage. Data were analysed using two-way ANOVA and Duncan's test at a significance level of 0·05. The results of this study showed that acidic drinks did not reduce the surface hardness of composite restoratives. However, for all resin composites, surface roughness measurements showed a statistically significant increase (p<0.05) after the seven days' storage. Micromorphological changes were noticed in a situation of acid challenge. This study evaluated the effect of three acidic beverages under ph cycling conditions on four composite resins after seven days' storage protocol. Microhardness and surface roughness were measured to evaluate mechanical surface properties. Surface degradation and changes were evaluated using SEM. The one-week period of storage in different beverages presented no significant deleterious alteration or softening effect on the surface of the composites, although it did have a significant effect on the surface roughness of composites. Surface degradation was observed in specimens immersed in different beverages.