In vitro evaluation of microleakage under orthodontic brackets bonded with different adhesive systems

OBJECTIVE: Adhesives systems have a drawback when utilized for bonding orthodontic brackets: they shrink during photopolymerization creating microleakage. The aim of this study was to assess the stability of different orthodontic adhesives around brackets and enamel. MATERIALS AND METHODS: Sixty noncarious mandibular premolars extracted for orthodontic reasons were randomly divided into six groups of adhesives used for bonding brackets to dental enamel: NeoBond(®) Light Cure Adhesive Kit, Transbond™ Plus Self-Etching, Victory V-Slot APC PLUS(®) + Transbond™ MIP, Rely-A-Bond(®) Kit, Light Cure Orthodontic Adhesive Kit (OptiBond(®)), and Transbond™ MIP. Following bonding, all teeth underwent 2500 cycles of thermal cycling in baths ranging from 5°C to 55°C before being immersed in 2% methylene blue for 24 h. All samples were examined under a binocular microscope to assess the degree of microleakage at the “bracket-adhesive” and “adhesive-enamel” interfaces in the gingival and occlusal regions of the bracket. RESULTS: A significant difference was found at the “occlusal bracket-adhesive” interface. The highest microleakage values were found in the occlusal region, although no significant. Microleakage was observed in all groups. CONCLUSION: Group 2 had the highest microleakage values whereas Group 6 had the lowest values.