Effects of Orthodontic Bonding Steps on Adhesion of Mutans Streptococci

Objective: The purpose of this study was to investigate the effects of orthodontic bonding steps on the initial adhesion of mutans streptococci (MS) in the presence of saliva. Materials and Methods: Hydroxyapatite (HA) and orthodontic adhesive (AD) disks were prepared to a uniform size. HA disks were etched with 37% phosphoric acid gel for 20 seconds in etched group (HE). In primed group (HP), Transbond XT primer was applied to the etched HA surface and light-cured. Adhesion assays were performed using 2 strains of MS with each specimen (HA, HE, HP or AD) in the presence of fluid-phase or adsorbed unstimulated whole saliva (UWS) for 3 hours. MS adhesion to each surface was examined by scanning electron microscopy. Results: The results showed that MS adhesion was significantly influenced by the bonding steps and the presence of UWS. There was a difference in the effects of saliva on bacterial adhesion between fluid-phase and surface-adsorbed UWS. Adsorbed UWS significantly decreased bacterial adhesion, while fluid-phase UWS did not significantly decrease bacterial adhesion compared to control. Generally, MS adhesion was significantly higher for HA and HE than for HP and AD and the adhesion pattern was not influenced by the presence of UWS phases. Conclusion: This study suggests that MS adhesion was significantly influenced by the bonding procedure and application of primer and adhesive for the bracket bonding can decrease MS adhesion irrespective of the presence of UWS. This study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare and Family Affairs, Republic of Korea (A091074).