Effect of dentifrice with high concentration of fluoride under remineralization and bond strength of glass ionomer cement on dental substrates with artificial caries

• Grant number: 19/13326-8
• Support type: Scholarships in Brazil - Master
• Effective date (Start): October 01, 2019
• Effective date (End): April 30, 2021
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Ticiane Cestari Fagundes
• Grantee: Diego Felipe Mardegan Gonçalves
• Home Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

The purpose of this study will be evaluate the influence of different dentifrices on the superficial, internal hardness and enamel wear, as well as on the bond strength of high-viscosity glass ionomer cement (GIC-HV) to dentin, after artificial caries lesion, pH cycling and brushing. Twenty bovine teeth will be used and divided in enamel and dentin. The enamel blocks (4x4mm) will be polished and selected according to Knoop microhardness. The dentin specimens will be sectioned transversely and longitudinally, obtaining 4 fragments per root; then, they will be embedded in acrylic resin and planned to expose the flat dentin surface. Both substrates will have a hemiface protected with acid resistant varnish to create a reference area that is not subject to artificial caries lesion and pH cycling/brushing. Demineralization cycles will be used in enamel and dentin to induce artificial caries lesions. The specimens will be subjected to pH cycling and brushing for 16 days, according to each dentifrice (n=10 enamel and n=40 dentin): sodium fluoride 1450 and sodium fluoride 5000 + TCP. After pH cycling and brushing, the enamel specimens will be submitted to the following analyses: superficial, internal hardness and profilometry to evaluate the remineralization, as well as the wear. The dentin specimens will be subdivided into groups according to each GIC-HV (n=20): Ketac Molar and Equia Forte. After restorations, the specimens will be stored under relative humidity during 7 days and prepared for bond strength analysis through microtensile test. Scanning electron microscopy will be performed on three representative specimens of each group, with the aim of illustrating the surfaces of the sound enamel and after cycles, as well as the pattern of fracture more frequent between dentin and GIC-HV. The data obtained will be analyzed for normality and, in case of normal distribution they will be submitted to ANOVA two-way repeated measures, with a significance level of 5%. (AU)