title: Effect of chlorhexidine varnish application on mutans streptococci counts in orthodontic patients.
abstract: BACKGROUND
  Enamel demineralization occurs frequently around orthodontic brackets. High levels of mutans streptococci (MS) increase the risk of caries. The hypotheses tested in this study were that high-frequency application of 40% chlorhexidine varnish (40%CHX) results in lower levels of MS in plaque of orthodontic patients compared with low-frequency application, and that bimonthly application of 40%CHX results in lower levels of MS in plaque compared with 1% chlorhexidine/1% thymol varnish (1%CHX).
  
  
  METHODS
  Eighty adolescent patients were randomly allocated to 4 treatment groups: monthly, bimonthly, and quarterly 40%CHX application, and bimonthly application of 1%CHX. Plaque samples were collected monthly and processed for MS counts. Twenty patients dropped out before the evaluation time at 1 month. Data from the remaining 60 adolescents were analyzed by using linear regression models with the plaque bacterial ratio (PBRx) as the dependent variable. The trial was ended after 5 months because of a high number of dropouts.
  
  
  RESULTS
  High-frequency application of 40%CHX did not provide lower mean PBRx than low-frequency application. Mean PBRx after 40%CHX application was lower than 1%CHX after 1 month (P = .002). This reduction was undiscernible 2 months after the application.
  
  
  CONCLUSIONS
  40%CHX application results in greater reduction of MS in plaque than 1%CHX a month after application. A follow-up study with a larger study population is warranted to test the first hypothesis.
authors.affiliation: Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
authors.forename: Aniek
authors.initials: A
authors.lastname: Derks
authors.forename: Jo
authors.initials: J
authors.lastname: Frencken
authors.forename: Ewald
authors.initials: E
authors.lastname: Bronkhorst
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Kuijpers-Jagtman
authors.forename: Christos
authors.initials: C
authors.lastname: Katsaros
mesh_terms: D000293:Adolescent; D000891:Anti-Infective Agents, Local / Q000009:adverse effects*; D002648:Child; D002710:Chlorhexidine / Q000008:administration & dosage*; D015169:Colony Count, Microbial; D003731:Dental Caries / Q000209:etiology / Q000382:microbiology / Q000517:prevention & control*; D003773:Dental Plaque / Q000382:microbiology; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004338:Drug Combinations; D006801:Humans; D016014:Linear Models; D016910:Orthodontic Brackets / Q000009:adverse effects; D010865:Pilot Projects; D013295:Streptococcus mutans / Q000187:drug effects*; D013943:Thymol / Q000008:administration & dosage
chemical_list: D000891:Anti-Infective Agents, Local; D004338:Drug Combinations; C477721:EC40 dental varnish; C079161:chlorhexidine, thymol drug combination; D013943:Thymol; D002710:Chlorhexidine