Fontes de luz em odontologia - caracterização e desempenho na ativação de resinas compostas e cimentos resinosos

Abstract

Photoactivation is an important step for direct and indirect restorative procedures. The light-curing units used for this purpose present characteristics such as radiant power, emission spectrum, irradiance, and equipment design which are different among themselves, and have influenced the procedures. The general objective of this thesis was to evaluate and characterize the performance of different light-curing units in the activation of direct and indirect restorations. Three objectives integrate this study: Specific objective 1: To evaluate the effect of the sample preparation and light-curing units on the Knoop hardness and degree of conversion at different depths and regions of bulk-fill resin-based composite restorations. Specific objective 2: To evaluate the influence of thickness and surface condition on the transmission of violet and blue light through two ceramics. Specific objective 3: To evaluate the effect of delivering isolated violet, blue, or a combination of violet and blue light from a polywave® light-curing unit (LCU) through ceramic on the degree of conversion (DC) of two resin cements with different photoinitiators. Based on the results of these studies, the following conclusions can be drawn: preparation methods that embedded the samples in polystyrene resin and polished the specimens reduced the differences between the KH and DC values obtained by different preparation techniques. The use of the NotPol method was able to detect differences produced by light activation in deeper areas. According to the second study, there is a rapid logarithmic decline in light transmission as the ceramic thickness increases means that little useful light is transmitted through 1.5 mm of either ceramic. Even less of the shorter wavelengths of light are transmitted. Celtra Duo glazed ceramic had a higher surface gloss compared to IPS e.max CAD, however there is no correlation between surface gloss and light transmission. Finally, the third study demonstrated that a polywave® light is not required to cure Variolink Esthetic LC, and RelyX Veneer does not benefit from receiving violet light from the polywave® light.