Method: Four incisor brackets from both the maxilla and mandible were collected from 64 patients at debonding after plaque index and gingival index were measured. Adhesions of Streptococcus mutans, Streptococcus sobrinus, and total bacteria were quantitatively determined using real-time polymerase chain reaction after genomic DNA was extracted. Factorial analysis of variance was used to analyze bacterial adhesion to the brackets with respect to the bracket type and jaw position. Correlation coefficients were calculated to determine the relationships of bacterial adhesion with oral hygiene indices.
Result: Amounts of bacterial adhesion was various according to bracket type and jaw position. Adhesion of total bacteria to CSL was higher than DQ, while adhesion of S. mutans to CSL and DQ was higher than CC. Adhesion of total bacteria to the mandibular brackets was higher than the maxillary ones, while adhesion of S. mutans to the maxillary brackets were higher than the mandibular ones. In particular, the proportion of S. mutans to total bacteria to CSL was higher than CC and DQ in the maxillary anterior teeth. There were no significant differences in adhesion of S. sobrinus among the brackets and between the jaws. Interestingly, no significant relationships were found between bacterial adhesion and oral hygiene indices.
Conclusion: Orthodontist should carefully examine the maxillary anterior regions in patients with self-ligating brackets, specifically CSL, to prevent enamel demineralization, regardless of oral hygiene status.