Influence of resin cements and ceramic systems on translucency and color stability of laminate veneers

• Grant number: 14/07478-6
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2015
• End date: February 28, 2017
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Rossana Pereira de Almeida
• Grantee: Rossana Pereira de Almeida
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The aim of this study is evaluate the conversion degree, color stability and translucency of resin cements for luting ceramic veneers with different thickness submitted to different aging protocols. Two hundred and seventy bovine incisors will be used, which root portions will be cut and the coronal portions will be embedded in acrylic resin inside PVC rings (25mm diameter) and the buccal surface will be flattened until dentin. Two hundred and forty pressed ceramic veneers (IPS e-max Press and IPS e-max ZirPress, IvoclarVivadent) will be obtained, in two thicknesses (0.5 mm and 1.0 mm), which will be randomly separated in two groups according to the type of resin cement used for lutting: photoactivated (Variolink II, Ivoclar / Vivadent) or self-adhesive (Rely U 200, 3M ESPE). After the cementation, all samples will be maintained at 37 °C for 24 h, after which initial color and translucency readings (Vita EasyShade, VITA) will be made. Next, the samples will be separated in 3 groups (n=10) according to the aging that will be submitted: control - without aging, immersion on distilled water for one year and thermomechanical fatigue (1.200.000 cycles, frequency of 1,3Hz and thermal cycling of 5°C/37°C/55°C). As control group, 30 samples will be obtained of each resin cement (0.5 mm) and 30 flattened teeth will be submitted to the same aging protocols, after which the final color and translucency readings will be taken. The conversion degree of resin cements through veneer restoration will be also analyzed (FTIR) and the cement film thickness will be measure (n=3) for each group, before and after aging. For this, the samples will be randomly selected, sectioned longitudinally and analyzed by a stereomicroscope (Nikon Measurescope). The results will be statistically analyzed according to the normal distribution found in samples. (AU)