title: Comparative analysis of long-term biofilm formation on metal and ceramic brackets.
abstract: OBJECTIVE
  To test the null hypothesis that stainless steel and ceramic brackets show no differences in biofilm adhesion.
  
  
  METHODS
  Twenty adolescents (6 boys, 14 girls) who had received fixed orthodontic therapy for 18.9 ± 3.2 months were divided into a metal and a ceramic bracket group. Thirty brackets per group were taken from central incisors, canines, and second premolars and quantitatively analyzed for biofilm coverage with the Rutherford backscattering detection method. Five micrographs were obtained per bracket with views from the buccal, mesial, distal, gingival, and occlusal aspects, resulting in a total of 300 images. Biofilm formation between groups was compared using the Mann-Whitney U-test (α = .05).
  
  
  RESULTS
  Total biofilm formation was 12.5% ± 5.7% (3.3 ± 1.6 mm(2)) of the surface on metal and 5.6% ± 2.4% (1.5 ± 0.6 mm(2)) on ceramic brackets. Differences between groups were statistically significant (P < .05). A pairwise comparison of biofilm formation revealed significantly lower biofilm formation on ceramic brackets with respect to intraoral location (central incisor, canine, second premolar) and bracket surface (buccal, mesial, distal).
  
  
  CONCLUSIONS
  The hypothesis was rejected. The results indicate that ceramic brackets exhibit less long-term biofilm accumulation than metal brackets.
authors.affiliation: Department of Orthodontics, Hannover Medical School, Hannover, Germany.
authors.forename: Ira Dewi
authors.initials: ID
authors.lastname: Lindel
authors.forename: Cornelius
authors.initials: C
authors.lastname: Elter
authors.forename: Wieland
authors.initials: W
authors.lastname: Heuer
authors.forename: Torsten
authors.initials: T
authors.lastname: Heidenblut
authors.forename: Meike
authors.initials: M
authors.lastname: Stiesch
authors.forename: Rainer
authors.initials: R
authors.lastname: Schwestka-Polly
authors.forename: Anton Phillip
authors.initials: AP
authors.lastname: Demling
mesh_terms: D000293:Adolescent; D001422:Bacterial Adhesion; D001641:Bicuspid / Q000382:microbiology; D018441:Biofilms / Q000254:growth & development*; D002516:Ceramics / Q000737:chemistry*; D003481:Cuspid / Q000382:microbiology; D003722:Dental Alloys / Q000737:chemistry*; D003774:Dental Plaque Index; D005260:Female; D005500:Follow-Up Studies; D005884:Gingival Hemorrhage / Q000145:classification; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007180:Incisor / Q000382:microbiology; D008137:Longitudinal Studies; D008297:Male; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets / Q000382:microbiology*; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000145:classification; D013052:Spectrometry, X-Ray Emission; D013193:Stainless Steel / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D003722:Dental Alloys; D013193:Stainless Steel