Fatores relacionados à variação de cor em restaurações totalmente cerâmicas

Abstract

Ceramic restorations associate the optical properties of natural teeth with adequate long-term clinical outcomes. However, the final esthetic appearance is affected by several factors, such as the color and thickness of the ceramic, the luting agent and the dental substrate, which act synergistically on the final esthetic result. This study was divided into three papers involving all ceramc restotations. At first, an in vitro study was conducted to evaluate the influence of different shades of flowable resin composite used as luting agent on the final shade of porcelain veneers of different opacities over high value simulated dental substrates. Afterward, it was conducted a clinical report in which the patient was treated with two different indications of all ceramic restoration. Further, the clinical study evaluated the influence of color-related factors on the color variation of ceramic restorations based on spectrophotometric analysis. In the in vitro study porcelain discs were paired with flowable resin composite disks of different shades (A1, A2, B1, WO – white opaque or IL – translucent). The translucency parameters and color variation (?E*00) of all specimens were evaluated over the simulated dental substrates (A2 and B1) and calculated by CIEDE2000 methods. The clinical report described the confection of a laminate veneer and a fixed single crown to restore superior central incisors that showed unsatisfactory resin composite restorations. In the clinical study, the ?E*00 values were obtained from eleven patients who received thirty-eight lithium disilicate ceramic restorations. The CIEL*a*b* color coordinates were measured with a spectrophotometer for ceramic restorations, initial tooth shade (baseline), prepared tooth (background), and luted ceramics. Color variation and translucency parameters were calculated by CIEDE2000 method. The in vitro study showed that opacity of the porcelain veneer paired with luting agents of different shades affected the final appearance of the restorations over distinct simulated tooth substrates. The case report showed that the ceramic restorations reestablished the esthetic condition of the patient. The clinical study indicated that natural tooth color reproduction is a complex process since all conditions evaluated presented clinically visible color differences for luted ceramic. The lithium disilicate ceramic showed lower masking ability over darker background, while L*, a*, and b* coordinates were cementation dependent.