Effect of light-curing units in shear bond strength of metallic brackets: An in vitro study

Objectives: to determine the influence of the light curing units on the shear bond strength of orthodontic brackets. material and methods: seventy-two premolars were divided into six groups (n=12): group i: brackets bonded with transbond and polymerization with halogen light; group ii: transbond and led; group iii: fuji ortho and halogen light; group iv: fuji ortho and led; group v: fuji ortho,without acid and halogen light; group vi: fuji ortho,without acid and led. the groups were tested to shear strength in a universal testing machine at a crosshead speed of 0.5 mm/min. data were analyzed statistically by anova and tukey's test. results: the composite resin presented higher shear bond strength than the resin-modified glass ionomer cement (p<0.05). the halogen light and led sources produced similar shear bond strength (p>0.05). conclusion: the shear bond strength was influenced by the material but not by the light-curing unit. the use of led reduced the experimental time by approximately 60%,with the same curing efficiency.