Efetividade de fotoativação – efeito da fonte de luz, da interposição de diferentes materiais indiretos CAD-CAM e brackets cerâmicos ; Light curing effectiveness – effect of the light source, the interposition of different indirect CAD-CAM materials and ceramic brackets

The light activation process is one of the most important procedures to ensure the success and longevity of resin materials. The polymerization activated by light can be affected by several factors, such as the composition, thickness, and color of the ceramic, indirect composite, or bracket interposed. The general objective of this study was to evaluate the influence of the interposition of different materials on the light transmission through when emitted by mono and multi-peak LED LCUs. This study was divided into 3 chapters according to each specific objective. Chapter 1) To evaluate the effect of lithium disilicate ceramic thickness on ceramic light transmission and the degree of conversion, Knoop Hardness, and modulus of elasticity of 4 resin cementation materials with different photoinitiators. Chapter 2) Evaluate the radiant power (mW), irradiance (mW/cm2), emission spectrum (mW/cm²/nm) and the beam profile of different LEDs in the passage of light through different thicknesses and shades of CAD-CAM glass-ceramic composites. Chapter 3) Evaluate the light scattering by 5 different ceramic mono and policristaline brackets with 3 light sources, two mono-peak, and one multi-peak. The experimental methods used were microhardness, degree of conversion, elasticity modulus, radiant power, emission spectrum, irradiance and light beam profile. The results found showed that: 1) Increasing the ceramic thickness greatly and exponentially reduced the irradiance. This reduction was most pronounced at the shorter (violet) wavelengths of light, with an 82% decrease when the ceramic was 1 mm thick. The increase in ceramic thickness did not affect the degree of conversion, regardless of the photoinitiators used in the cementing materials tested. The position of the violet and blue LEDs within the LCU body did not influence the Knoop hardness or modulus of elasticity in any of the tested resins. 2) The thickness of the composite had a significant effect on the radiant power and irradiance for all LEDs tested; The A3.5 shade ...