Quantitative analysis of changes in salivary mutans streptococci after orthodontic treatment.
BACKGROUND
The purpose of this study was to analyze the initial changes in salivary mutans streptococci levels after orthodontic treatment with fixed appliances.


METHODS
Our subjects consisted of 58 adults. Whole saliva and simplified oral hygiene index values were obtained at 4 time points: at debonding (T1), 1 week after debonding (T2), 5 weeks after debonding (T3), and 13 weeks after debonding (T4). Repeated measures analysis of variance was used to determine the time-related differences in salivary bacterial levels and the simplified oral hygiene index values among the 4 time points after quantifying the salivary levels of Streptococcus mutans, Streptococcus sobrinus, and total bacteria with real-time polymerase chain reaction.


RESULTS
Simplified oral hygiene index values and total bacteria significantly decreased, but salivary mutans streptococci levels significantly increased after orthodontic treatment. The amounts of total bacteria in saliva significantly decreased at T3 (T1, T2 > T3, T4), and the simplified oral hygiene index values decreased at T2 (T1 > T2, T3, T4). However, salivary S mutans and S sobrinus significantly increased at T3 and T4, respectively (T1, T2 < T3 < T4). Furthermore, the proportion of mutans streptococci to total bacteria significantly increased at T4 (T1, T2, T3 < T4).


CONCLUSIONS
This study suggests that careful hygienic procedures are needed to reduce the risk for dental caries after orthodontic treatment, despite overall improved oral hygiene status.
Graduate student, Dental Research Institute and Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea.
Woo-Sun
WS
Jung
Professor, Department of Biostatistics, Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Korea.
Ho
H
Kim
Research associate, Dental Research Institute and Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea.
So-Yoon
SY
Park
Research associate, Dental Research Institute and Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea.
Eun-Jung
EJ
Cho
Associate professor, Dental Research Institute and Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea. Electronic address: titoo@snu.ac.kr.
Sug-Joon
SJ
Ahn
D000328:Adult; D058491:Bacterial Load; D004269:DNA, Bacterial / Q000032:analysis; D017005:Dental Debonding / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009911:Oral Hygiene Index; D016910:Orthodontic Brackets / Q000382:microbiology*; D018704:Orthodontic Retainers / Q000382:microbiology; D009971:Orthodontics, Corrective; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012463:Saliva / Q000382:microbiology*; D013295:Streptococcus mutans / Q000145:classification / Q000302:isolation & purification*; D016986:Streptococcus sobrinus / Q000145:classification / Q000302:isolation & purification; D055815:Young Adult
D004269:DNA, Bacterial