Abstract
The purpose of this study was to evaluate the effect of aging protocols on surface gloss of composites. Cylindrical resin composite specimens (6 mm in diameter, 1 mm thick) were fabricated and divided into three groups (N = 60): microfilled (MiFi), nanohybrid (NaHy), and nanofilled (NaFi). Specimens were distributed into four aging subgroups: thermocycling (5° to 55°C, 15,000 cycles); ethanol immersion (15 days); brushing (10,750 cycles); and light aging (216 h). Surface gloss readings (Novo-Curve, Rhopoint TM, England) were performed at baseline (R0) and after every one-third of aging protocols (R1 to R3). Data were submitted to one-way repeated measures ANOVA and Tukey's test (5%). Overall, surface gloss alterations were detected over time (p < 0.001). Thermocycling reduced surface gloss, except for NaHy. Ethanol immersion resulted in surface gloss reduction after R1 for MiFi and NaFi, while reduction after R1 and R2 was detected for NaHy. For brushing, gloss reduction was detected after R1 and R3 for all composites. For light aging, gloss was reduced after R1 and R2 for MiFi and NaFi, while a reduction only after R1 was detected for NaHy. The studied aging protocols affect surface gloss differently, being material and aging therapy dependent. In general, the surface gloss is reduced with aging.
Highlights
The demand of patients for esthetic treatments boosted the development of restorative materials simulating optical characteristics of natural teeth, allowing tooth characteristics to be mimicked with esthetically satisfactory results
For the NaFi resins, the gloss decreased in R2 in comparison to R0 and decreased in R3 in comparison to R1, with similar gloss values between R0 and R1, and R2 and R3 (Figure 2(a))
It is known that thermal cycling might create internal tensions in the resin structure due to differences in the linear thermal expansion coefficient of the organic matrix and filler components, leading to degradation [18] and possible surface microcracks [19]
Summary
The demand of patients for esthetic treatments boosted the development of restorative materials simulating optical characteristics of natural teeth, allowing tooth characteristics to be mimicked with esthetically satisfactory results. The maintenance of surface gloss is of great importance [2, 3]. This characteristic is usually related to the deterioration or wear of materials [4, 5]. This leads to unsuitable optical properties of restorations and to the necessity for repolishing, repairing, or restoration replacement [6]
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