Gram-negative periodontal pathogens and bacterial endotoxin in metallic orthodontic brackets with or without an antimicrobial agent: an in-vivo study

Abstract

Introduction: High levels of periodontal pathogens can cause periodontal alterations. The presence of endotoxin might be responsible for the occurrence and progression of tissue inflammation and bone resorption. The aims of this study were to use checkerboard DNA-DNA hybridization and limulus amebocyte lysate assay to evaluate in metallic orthodontic brackets (1) the presence of 16 gram-negative periodontal pathogenic microorganisms of the orange complex and red complex +Treponema socranskii, (2) the amount of bacterial endotoxin, and (3) the efficacy of 0.12% chlorhexidine gluconate mouthwash in reducing bacterial contamination and endotoxin amount.

Methods: Thirty-three patients (ages, 11-33 years) under orthodontic treatment with fixed appliances had 3 new metallic brackets bonded to 3 different premolars. Sixteen patients used a 0.12% chlorhexidine gluconate mouthwash (Periogard, Colgate-Palmolive, São Bernardo do Campo, São Paulo, Brazil) (experimental group), and 17 patients used a placebo mouthwash (control group) twice a week. After 30 days, the brackets were removed, and the samples were obtained. The data were analyzed statistically by Mann-Whitney, Kruskal-Wallis, and Dunn tests (α = 0.05).

Results: The 0.12% chlorhexidine gluconate group accumulated significantly lower levels of microorganisms than did the placebo group (P = 0.01). When each microbial complex was analyzed separately, a statistically significant difference between the experimental and control groups was found for the orange complex (P = 0.04). A greater amount of bacterial endotoxin was detected in the 0.12% chlorhexidine gluconate group than in the control group (P = 0.02).

Conclusions: The 0.12% chlorhexidine gluconate oral rinses can be useful to reduce the levels of gram-negative periodontal pathogenic microorganisms in patients with fixed orthodontic appliances. Considering the increased amount of bacterial endotoxin after chlorhexidine gluconate use, further research is necessary to develop clinical procedures or antimicrobial agents with action against bacterial endotoxin adhering to metallic brackets.