Avaliação da influência de aparelhos fotoativadores e fotoiniciadores nas propriedades físicas e químicas da resina composta

Abstract

Several factors can influence the longevity of composite resin restorations: composite resin composition, techniques and materials used at the time of restoration. The general objective of this work was to evaluate the factors that can interfere in the longevity of composite resin restorations. This study was divided into 4 chapters according to each specific objective: Chapter 1) The aim of this study was to evaluate the influence of different light-curing units (LCUs) with distinct tip diameters and light spectra for activating bulk-fill resins. Chapter 2) The aim of this study was to evaluate different polishing protocols and light cure units (LCU) on the surface roughness, gloss, and sorption and solubility of a composite resin. Chapter 3) this study aimed to analyze the influence of the composition of experimental nanohybrid composite resins produced with distinct photoinitiators/concentrations and the light spectrum of different LED units on the degree of conversion, hardness and diametral tensile strength of the resulting restoratives. The experimental methods used were: degree of conversion (chapters 1 and 3); Knoop hardness (chapters 1 and 3); roughness (chapter 2); gloss (chapter 2); sorption and solubility (chapter 2); diametral tensile strength (chapter 3). The results found show that: 1) LCUs and specimen diameter significantly affected the degree conversion. The center of the specimen exhibited superior KHN than the periphery. 2) No significant differences were detected on the surface roughness or gloss for the different LEDs units. Comparing the polishing systems, Sof-Lex and Opti1Step specimens presented similar surface roughness, which was significantly superior to Jiffy. 3) The experimental resins with the presence of at least 50% of BAPO showed better degree conversion and diametral tensile strength results. It can be concluded that the size of the LED tip, and the emitted light spectrum can influence the mechanical and optical properties of the composite resin, as well as the different initiators and their concentrations present in their constitution.