Comportamento óptico e morfológico superficial de resinas compostas: influência de imersões e escovação

Abstract

This study aimed to evaluate the optical and surface behaviors of composite resin, when submitted to brushing and immersion in different medium. There were fabricated 60 specimens (cps) of a microhybrid resin (Filtek Z250) and of a nanoparticulate resin (Filtek Z350XT), using a metalized matrix (8 mm diameter x 2 mm thickness). The cps were photo activated with a LED (800mW/cm2) for 40s, then, they were polished with sandpaper disks and felt disks with diamond paste, washed with water and dried with absorbent paper. After 24 hours of hydration in deionized water at 37ºC, they divided into six experimental groups (n=10) according to the storage medium and type of treatment (stored in deionized water or red wine: not brushed, brushed with water and brushed with toothpaste). The initial reading (after 24h of hydration in water) about the surface roughness (Ra) was done with the surface roughness gauge (Mitutoyo Surftest SJ-201P) and the CIE L* a* b* parameter with the spectrophotometer (SP60 EX-Rite). Only the top surface was exposed to the staining process, the other faces were isolated with white acrylic resin, after that, they were immersed into the storage medium. Three immersion cycles were done (5, 10 and 15 days) with 5 days of duration. After the immersion periods, the resin was removed, the cp was again evaluated according to the CIE L* a* b* parameters and the surface roughness. The top surface was submitted to 585 brushing cycles in each 5 days. Successive readings were done after 5th and 15th days of immersion and after the first and third brushings. The data were submitted to Variance Analysis and Tukey test. The red wine had more impact than the deionized water on the color change of composite resins. The simulated brushing did not totally remove the pigments and its accumulation was dependent on the material composition, being the nanoparticulate resin more susceptible to this action. The composite resin showed similar behavior in relation to the surface roughness, and the toothpaste brushing promoted more abrasion than the water brushing.