Oral bacteria in plaque and invading buccal cells of young orthodontic patients

Introduction: In this longitudinal study, patients with fixed orthodontic appliances served as models to determine whether Actinobacillus actinomycetemcomitans, Tannerella forsythia, and total streptococci increased after treatment, and whether treatment affected bacterial invasion into the adjacent buccal epithelial cells (BEC). Methods: Supragingival plaque, subgingival plaque, and BEC were collected from 27 patients before and at least 4 weeks after placement of orthodontic fixed appliances. Total sample DNA was determined, and bacteria were assayed by quantitative polymerase chain reaction. The BEC were also examined by confocal microscopy after fluorescent in-situ hybridization to visually detect the presence of each species bacteria in BEC. Results: Total DNA in supragingival and subgingival plaque increased after appliance placement (P = .005). There was also a significant increase in supragingival streptococci (P = .0002). By confocal microscopy, a trend toward fewer buccal cells recovered was found after appliance placement, and there was a significant increase in the percentage of buccal cells containing A. actinomycetemcomitans (P = .0058). Conclusions: Appliance placement appeared to increase buccal cell susceptibility to A. actinomycetemcomitans invasion. This might be due to physical trauma or to leaching of metals from the appliances.