Evaluation of the shear bond strength of the Orthobond composite under different conditions

Objective: Evaluate the shear bond strength of metal brackets bonded with Orthobond composite (Dental Morelli Ltda, Sorocaba, Brazil) under different enamel surface conditions. Methods: Ninety bovine mandibular permanent incisors were divided into six groups (n = 15). In Group 1 (control) and Group 2 the bonding procedures were performed by using Transbond XT (3M Unitek, Monrovia, USA) and Orthobond (Dental Morelli Ltda, Sorocaba, Brazil) composites,respectively, according to the manufacturer’s recommendations. In the other groups brackets were bonded with Orthobond composite (Dental Morelli Ltda, Sorocaba, Brazil) as follows: Group 3 – dental surface conditioned with Transbond Plus Self-Etching Primer (3M Unitek, Monrovia, USA); Group 4 – bonding procedure without application of Orthoprimer (Dental Morelli Ltda, Sorocaba, Brazil); Group 5 - Eagle Bond applied on saliva/blood-contaminated dental surface; and Group 6 – use of homogenized Orthobond (Dental Morelli Ltda, Sorocaba, Brazil). After bonding the brackets, all the samples were submitted to shear bond strength tests by means of an Emic Universal Testing Machine at a crosshead speed of 0.5 mm/min. The results obtained in mega Pascal (MPa) were submitted to the analysis of variance (ANOVA) and then to the Tukey test. Results: The results in mega Pascal showed statistically significant differences between Groups 1 and 2 (p= 0.041), 1 and 5 (p=0.000) and between 4 and 5 (p=0.016). The ARI (Adhesive Remnant Index) scores showed evidence of a higher number of fractures at the bracket/composite interface. Conclusion: In all tested situations the Orthobond (Dental Morelli Ltda, Sorocaba, Brazil) was shown to be apt for bracket bonding