title: Use of the checkerboard DNA-DNA hybridisation technique for in vivo detection of cariogenic microorganisms on metallic brackets, with or without use of an antimicrobial agent.
abstract: OBJECTIVE
  Using checkerboard DNA-DNA hybridisation (CDDH) assay, this randomised clinical study evaluated the contamination of metallic brackets by four cariogenic bacterial strains (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei and Lactobacillus acidophilus) and the efficacy of 0.12% chlorhexidine gluconate (CHX) mouthwashes in reducing bacterial contamination.
  
  
  METHODS
  Thirty-nine 11-33-year-old patients under treatment with fixed orthodontic appliances were enrolled in the study and had 2 new metallic brackets bonded to premolars. Nineteen patients used a 0.12% CHX mouthwash (Periogard) and 20 patients used a placebo mouthwash (control) twice a week. After 30 days, the brackets were removed and samples were obtained for analysis by CDDH. Data were analysed statistically by the Kruskal-Wallis test (α=0.05) using the SAS software.
  
  
  RESULTS
  S. mutans, S. sobrinus, L. casei and L. acidophilus were detected in 100% of the samples from both groups. However, brackets of the control group were more heavily contaminated by S. mutans and S. sobrinus (P<0.01). In the experimental group, although all counts decreased after rinsing with the chlorhexidine solution, there was significant difference only for S. mutans (P=0.03).
  
  
  CONCLUSIONS
  The use of 0.12% chlorhexidine gluconate mouthwashes can be useful in clinical practice to reduce the levels of cariogenic microorganisms in patients under treatment with fixed orthodontic appliances.
authors.affiliation: Department of Pediatric Clinic, Preventive and Community Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Brazil. nelson@forp.usp.br
authors.forename: Paulo
authors.initials: P
authors.lastname: Nelson-Filho
authors.forename: Lourdes Yanissely García
authors.initials: LY
authors.lastname: Olmedo
authors.forename: Marcela Cristina Damião
authors.initials: MC
authors.lastname: Andrucioli
authors.forename: Maria da Conceição Pereira
authors.initials: Mda C
authors.lastname: Saraiva
authors.forename: Mírian Aiko Nakane
authors.initials: MA
authors.lastname: Matsumoto
authors.forename: Alexandra Mussolino
authors.initials: AM
authors.lastname: de Queiroz
authors.forename: Raquel Assed Bezerra
authors.initials: RA
authors.lastname: da Silva
authors.forename: Lea Assed Bezerra
authors.initials: LA
authors.lastname: da Silva
mesh_terms: D000293:Adolescent; D000328:Adult; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002648:Child; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis; D003722:Dental Alloys; D005260:Female; D006801:Humans; D007779:Lactobacillus acidophilus / Q000187:drug effects / Q000302:isolation & purification; D007780:Lacticaseibacillus casei / Q000187:drug effects / Q000302:isolation & purification; D008297:Male; D009067:Mouthwashes / Q000494:pharmacology*; D009693:Nucleic Acid Hybridization / Q000379:methods; D016910:Orthodontic Brackets / Q000382:microbiology*; D018709:Statistics, Nonparametric; D013295:Streptococcus mutans / Q000187:drug effects* / Q000302:isolation & purification; D016986:Streptococcus sobrinus / Q000187:drug effects / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000891:Anti-Infective Agents, Local; D004269:DNA, Bacterial; D003722:Dental Alloys; D009067:Mouthwashes; C010882:chlorhexidine gluconate; D002710:Chlorhexidine