Bond strength and colorimetric and optical changes after photoactivation of adhesive/cement through transillumination of ceramic veneers with different thicknesses

• Grant number: 25/06374-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: December 31, 2025
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: José Maurício dos Santos Nunes Reis
• Grantee: Larissa Bastos Ciolin
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The aim of this study is to investigate the bond strength and colorimetric and optical changes resulting from the photoactivation of the adhesive/cement system by transillumination of lithium disilicate ceramic veneers with different thicknesses. Discs (7.5 x 1.0 mm; N=120) of IPS e.max CAD (Ivoclar Vivadent) with medium translucency (MT) and three thicknesses (0.5, 1.0, and 1.5 mm); and enamel (N=60) and dentin (N=60) from bovine teeth will be obtained. Two resin cements will be used, one dual-cure (Variolink Esthetic DC, Ivoclar Vivadent) and one light-cure (Variolink Esthetic LC, Ivoclar Vivadent). To evaluate the colorimetric and optical properties, discs of IPS e.max CAD with different thicknesses and translucency (n=10) will be cemented onto enamel or dentin substrates with the cements Variolink Esthetic DC or Esthetic LC, which will undergo photoactivation by transillumination (Valo Cordless Grand 3200, Ultradent). Afterward, the specimens will be submitted to thermocycling (12,000 cycles, 5.0ºC -> 37ºC -> 55ºC, 30 s dwell time). The color coordinates L*, a*, and b* of each specimen will be measured with a spectrophotometer (CM-2600d, Konica Minolta) on a white and on a black background under three illuminants (A, D65, or F2). Colorimetric properties (lightness and color difference) and optical properties (opalescence, translucency, and contrast ratio Y) will be calculated between data obtained immediately after cementation and after hydrothermal aging. Colorimetric data will also be evaluated based on perceptibility and acceptability thresholds. Next, the specimens will undergo shear bond strength tests until failure, being the bond strength results expressed in MPa. Quantitative data will be subjected to normality and homoscedasticity tests, followed by the most appropriate statistical analyses with a significance level of 95%. Qualitative data will be presented in a descriptive interpretative way.