title: Influence of orthodontic treatment on oral streptococci.
abstract: Objective of this study is to evaluate the changes of the oral microbial flora, concentrating on the oral streptococci, after the first 3 and 6 months of orthodontic treatment.
  
  
  METHODS
  40 patients, aged 7-17, that presented for orthodontic treatment between April and September 2010 in the Department of Orthodontics and Dento-Facial Orthopedics of "Carol Davila" University of Medicine and Pharmacy, Bucharest have been selected. According to the protocol, coronary and subgingival plaque was collected from the dental surface before starting any orthodontic treatment (T0), 3 months after wearing orthodontic appliances (T1) and 6 months after wearing orthodontic appliances (T2). The samples were studied in Cantacuzino National Institute of Research-Development for Microbiology and Immunology [isolation on Columbia agar with 5% sheep blood, identification on morphotinctorial, growth and biochemical characteristics using API 20 STREP (BioMerieux)]. Bacterial concentration (colony-forming units/sample = CFU/sample) for the aerobic and anaerobic flora was calculated by the serial dilution method of counting bacteria.
  
  
  RESULTS
  106 strains of oral streptococci were isolated from dental plaque, belonging to 6 species (Streptococcus mitis, Streptococcus oralis, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis and Streptococcus acidominimus), 37 strains of oral streptococci in patients from group I (T0), 40 strains from group II (T1) and 29 strains of oral streptococci from group III (T2). After 3 months (T1) the aerobic bacteria percentage, detected at a concentration between 10(5) and 10(6), increased from 30 to 38.2%. The percentage of patients with a bacterial concentration higher than 10(6) CFU/sample increased from 5% to 8.8%. The samples colected at T2 (patients examined after 6 months of orthodonic treatment) presented a lower bacterial concentration, as compared to group II (T1). The most common isolated species of streptococci were S. salivarius, S. oralis and S. mutans (37.5%, 22.5% and 10%), whose frequency increased after 3 months of treatment to 41.14%, 32.3% and respectively 14.4%, returning after 6 months of treatment at values similar to those recorded before beginning the orthodontic treatment.
  
  
  CONCLUSIONS
  Presence of orthodontic appliances may produce a transitory increase of bacterial concentration (CFU/sample) and isolation rate of oral streptococci, returning to the level prior to the application of these devices after a time interval of several months.
authors.affiliation: Department of Orthodontics and Dento-Facial Orthopedics, Faculty of Dental Medicine, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania. theodorvizitiu@yahoo.com
authors.forename: Theodor-Cristian
authors.initials: TC
authors.lastname: Vizitiu
authors.forename: Mihaela Cristina
authors.initials: MC
authors.lastname: Giuca
authors.forename: Ecaterina
authors.initials: E
authors.lastname: Ionescu
mesh_terms: D000293:Adolescent; D058491:Bacterial Load; D002648:Child; D003773:Dental Plaque / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D009055:Mouth / Q000382:microbiology*; D009967:Orthodontic Appliances; D013291:Streptococcus / Q000302:isolation & purification*