Fontes fotoativadoras de diferentes tecnologias e seus efeitos na fotoativação de materiais odontológicos

Abstract

Photoactivation is a fundamental step in the restorative process. Using the correct technique and appropriate light-curing unit (LCU) will ensure long-lasting, high-quality restorations, as this step directly influences properties such as depth of cure, microhardness, and mechanical strength. Factors such as LCU technology, exposure time, and light intensity play an important role in polymerization efficiency. In addition, the choice of LCU must consider clinical performance, cost-effectiveness, and accessibility. With new technologies such as laser diodes and multi-wavelength LEDs, it is increasingly important to understand their impact on restoration quality to ensure optimized and safe patient clinical protocols. This study has four objectives: Specific Objective 1: This study evaluated the depth of cure of eight photoactivated resin-based composites (RBCs) using a multi-peak LCU with a standard output set to the exposure time recommended by the RBC manufacturer and a higher irradiance for 3 seconds. Specific objective 2: To evaluate and characterize low and high cost LCU and their effect on the microhardness of bulk-fill RBC. Specific objective 3: To evaluate the fracture resistance, energy absorption and microhardness of RBCs photoactivated with new photoactivation unit technologies: a laser diode (Monet Laser - AMD Lasers), a Polywave™ LED (PowerCure - Ivoclar) and a Quadwave™ LED (PinkWave - Apex). Specific objective 4: To evaluate the LCUs available on the local market in terms of tip diameter (mm), radiant power (mW), irradiance (mW/cm2), emission spectrum (mW/cm2/nm), effect of design on access to the posterior region, irradiance profile of the light beam, increase in pulp temperature and correlate with their market cost. Therefore, the use of LCUs providing high irradiance for a short time may not provide sufficient energy to photoactivate some RBCs. The use of short exposures (3 seconds) of high irradiance should be limited to RBCs formulated for this purpose. The microhardness at the top surface of the RBC photoactivated with different irradiance levels was not significantly different but was significantly reduced at depth. In the third study, the physico-mechanical properties of the RBCs studied were negatively affected when photoactivated at short exposure times of 1 to 3 seconds, so clinicians are advised to select a LCU that is suitable for the specific materials used in their regular practice and to try to balance the recommendations of the LCU manufacturers and the materials they use. Finally, the characterized four LCUs available on the local market, demonstrating the ability of the domestic market to produce LCU of a quality equal to or better than those produced by international manufacturers.