Effects of Third-generation LED LCU on Nanomechanical Properties of Orthodontic Adhesives

The aim of this study was to compare the hardness and elastic modulus of orthodontic adhesives cured with different light-curing units, based on light-emitting diodes. Standardized samples of orthodontic adhesives, Transbond™ XT, Opal® Bond™ and Light Bond™ were prepared in cylinder blocks and cured for three seconds with Valo Ortho LED (Ultradent Products, South Jordan, Utah) and Valo LED High-Power Mode. After grinding and polishing, specimens were stored in distilled water at 37°C for one day. Specimens were investigated using nanoindenter. Employment of Valo Ortho unit has resulted in significantly higher elastic modules for Transbond™ XT (p=0.041). The highest nanohardness and elastic modules were measured for Transbond™ XT cured with Valo Ortho (9.47 GPa; 81.85 GPa, respectively) and lowest for Opal® Bond™ for both Valo Ortho (0.44 GPa; 14.52 GPa, respectively) and Valo High-Power groups (0.44 GPa; 11.84 GPa, respectively).