Effect of sodium bicarbonate air abrasive polishing on attrition and surface micromorphology of ceramic and stainless steel brackets.

OBJECTIVES: To evaluate the frictional resistance of ceramic and metal brackets using rectangular stainless steel orthodontic wires before and after using sodium bicarbonate air abrasive polishing and to evaluate the surface micromorphology of these brackets by means of scanning electron microscopy. MATERIALS AND METHODS: Two commercial brands of metal brackets and two commercial brands of ceramic brackets were evaluated. The specimens were divided into eight groups (n  =  10) according to brackets and the application or not of sodium bicarbonate airborne particle abrasion for 10 seconds. A device adapted to a universal testing machine was used to simulate the movement of retraction in sliding mechanics, measuring the traction force needed to slide 10 mm of the wire over the test specimen brackets. The test speed was 5 mm/min. The data were analyzed by two-way analysis of variance (ANOVA) and Tukey test. RESULTS: There was higher frictional resistance after airborne particle abrasion irrespective of the type of bracket (P < .05). One of the ceramic brackets showed higher frictional resistance before and after airborne application than the other metal and ceramic brackets. The micromorphologic analysis showed that airborne particle abrasion caused alterations on the metal bracket surfaces. CONCLUSIONS: It may be concluded that it is not recommended to apply airborne particle abrasion on the slots of ceramic or metal brackets.