Avaliação in vitro da resistência de união ao cisalhamento na colagem de bráquetes por duas fontes de luz

• Ano de defesa: 2007
• Autor(a) principal: Mezzomo, Claudia Santos
• Orientador(a): Marchioro, Ernani Menezes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ODONTOLOGIA; ORTODONTIA; RESISTÊNCIA DOS MATERIAIS (ODONTOLOGIA); COLAGENS ORTODÔNTICAS
• Link de acesso: http://hdl.handle.net/10923/365

The aim of this study was to compare, in vitro, the shear bond strength values of brackets bonded with LED and convencional halogen (QTH) light curing units with a different exposure times. One hundred and twenty six premolar teeth were equally divided into six groups according to the curing light and exposure times used. As for LED curing light, the specimens were submitted to photoactivation for 5s, 10s end 15s, whereas the exposure times to QTH curing light was 10s, 20s and 30s. The light curing units LED (Ortholux LED Curing Light, 3M-Unitek –EUA) and QTH (XL 3000, 3M Unitek – EUA) were evaluated in the beginning, right before the first bonding, and after ten brackets bonding, using specific radiometers for each light curing, registered irradiance mean values of 581 mW/cm² and 420mW/cm², respectively. The specimens were stored in water at 37°C for 24h and then subjected to a shear force with a universal testing machine, in a gingivoocclusal direction at crosshead speed of 1mm/min. According to ANOVA and Tukey, a significant difference in mean shear bond strength was detected (p<0,01).As for the LED – photoactivaded groups 5s (17,20MPa) and 10s (20,54MPa) shear bond strength values was comparable, showing statistical difference among the LED 15s (25,24MPa) group. Considering the QTH exposures, the 10s (16,97MPa) group registered differences when related to the 20s (23,61MPa) and 30s (21,33MPa), whereas these showed none between them. The LED 15s group demonstrated the higher mean shear bond strength, but showed no statistically significant differences between the QTH 20s and 30s groups. Even the lowest mean bond strength, recorded for QTH 10s and LED 5s groups, respectively, were considered to be clinically acceptable. Kruskal-Wallis analysis of ARI scores indicated that there was statistical difference (p< 0,01) among the studied groups. In LED 15s group the majority of specimens had an ARI score 0, being observed a enamel fracture in two specimens. Instead of the LED 5s and QTH 10s groups demonstrated higher frequencies of ARI score 1 and 2, respectively, in both groups, the score 3 appear frequently (QTH 10s – 10,5%; LED 5s – 9,5%). Opposing behavior was observed in groups LED 10s and 15s, where he was not registered frequency of score 3 (0%). The findings of the present study suggest that technology LED (Free Light Ortholux, 3M - Unitek) can be used, in the brackets bonding, with lesser times of cure in relation halogen light for the resin Transbond XT, being that, the minimum time of 5s with LED presented bond strength values clinically acceptable.