Avaliação do efeito de diferentes técnicas de fotoativação no manchamento de resinas compostas monocromáticas

Abstract

Staining on composite resins is still one of the most important causes of clinical failure in anterior and posterior teeth. Coloring substances as well as distinct lightcuring processes may influence color stability from these materials. Objective – To evaluate color change in two single-shade composite resins, Vittra UniqueÒ (FGM, Joinville – SC, Brazil) and Palfique OmnichromaÒ (Tokuyama, Yamaguchi, Japão), which were submitted to three light-curing processes and immersion in coffee for 30 days. Materials and methods – Methodological process was composed of the following articles: the first one evaluated color stability in two single-shade composite resins, Vittra Unique (FGM, Joinville – SC, Brazil) and Palfique Omnichroma (Tokuyama, Yamaguchi, Japan), which were submitted to three distinct light-curing processes. A light-curing process was performed using a LED unit that were positioned in the center of the specimen and also other two light-curing processes, in which the LED unit was positioned in the center of the two halves: upper and lower of the specimen, while the time of light application varied (20 seconds and 40 seconds, respectively); the second one evaluated specimens which were submitted to light-activation process, but using two LED units with distinct diameter lenses, Valo (9.75mm) and Valo Grand (12mm). For both articles, specimens measuring 2X8X10mm were made, which were submitted to the protocol of immersion in coffee for 30 days and color evaluation was carried out throughout the experiment (initial, 15 and 30 days) in CIEL*a*b* system standards, using a spectrophotometer (UV-2600, SHIMADZU) and a portable spectrophotometer (Easy Shade), in order to evaluate color alteration along the specimen. Results – For statistical analysis, the Analysis of Variance (ANOVA) and the Tukey test were used as a post hoc test, with a significance level of p ≤ 0.05. In Article 1, results of spectrophotometer showed higher ΔE for the 20s second group and lower ΔE for 40s first group. In Article 2, no statistically significant differences were observed for total color change (ΔE) between the two tested light-curing fixtures. In both articles, there was no significant difference in color stability between the two areas of the specimen in two tested resins. Conclusion – For both articles, the composite resins from groups that were immersed in coffee showed greater staining. In Article 1, two places light-curing process in association with long light exposure resulted in higher color stability for both tested composite resins. In Article 2, the diameter of the LED unit lens did not influence the color stability of the tested composite resins.