Evaluation of flexural strength, elastic modulus and depth of cure of experimental resin composites containing functionalized TiO2 nanostructures

• Grant number: 19/22618-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2020
• End date: January 31, 2021
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Adilson Yoshio Furuse
• Grantee: Flávio Yutaka Ikeda Ishiara
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The objective of this study is to evaluate the influence of different concentrations of functionalized TiO2 nanostructures on the mechanical properties of experimental composite resins. TiO2 nanotubes or nanoparticles at concentrations of 0.3 and 0.9% by weight functionalized with 3-aminopropyl trimethoxysilane silane (APTMS) or 3-Trimethoxysilyl Propyl Methacrylate (TMSPM) will be added to experimental composite resins, containing BisGMA/TEGDMA (75-25% weight ratio), 0.25% camphorquinone (QC) and DABE (1%). The groups will be distributed according to the type, concentration of TiO2 nanostructures and type of functionalization. Scanning electron microscopy (SEM) will be performed to characterize the experimental composite resins. For analysis of flexural strength and modulus of elasticity, 45 resin bars (n = 5) will be manipulated from a bipartite matrix, containing 8x2x2 mm in its dimensions. The specimens will be photoactivated for 20s at 1000mV/cm2 and will be subjected to the 3-point bending test on a 50N load cell universal testing machine at a speed of 0.5mm/min. To evaluate the depth of polymerization, 2mm, and 4mm specimens will be performed (n = 5) from a cylindrical polyethylene mold. The resin will be inserted into the matrix and the specimens will be photoactivated (1000 mW/cm2 for 20s). After 24h, the specimens will be evaluated to analyze the depth of cure through the degree of conversion and hardness. The results will be analyzed by one-way ANOVA and Tukey tests if there is normality and homogeneity of variances. The significance level adopted will be 5%.