title: Decontamination of viable Streptococcus mutans from orthodontic tungsten carbide debonding burs. An in vitro microbiological study.
abstract: OBJECTIVE
  To investigate the effectiveness of currently recommended decontamination procedures on tungsten carbide debonding burs (TCDBs).
  
  
  METHODS
  In vitro microbiological study.
  
  
  METHODS
  St George's Hospital NHS Trust, UK.
  
  
  METHODS
  A total of 240 extracted tooth surfaces were bonded with orthodontic brackets, debonded to leave residual composite and artificially contaminated with Streptococcus mutans.
  
  
  METHODS
  Sterilized TCDBs in a slow handpiece were used to remove this composite before random allocation into one of six different decontamination groups of 40 burs each. These included a control group that was not decontaminated and a further five that underwent different methods of presterilization cleaning within the decontamination process (none, manual, ultrasonic, washer disinfector and enzyme soak) followed by sterilization in a vacuum phase autoclave at 134 degrees C for 3 min.
  
  
  METHODS
  The burs were placed in brain heart infusion (BHI) broths, incubated for 48 h. Following this the broths were inspected for turbidity and microbiological analysis was carried out to detect viable bacterial growth. Data were analysed using the Kruskal-Wallis test for single ordered data.
  
  
  RESULTS
  S. mutans was recovered from 39 out of 40 burs in the control group and no burs from the decontamination groups, which was statistically significant (P = 0.001). No differences were found between decontamination groups (P = 0.271). However, skin flora contamination was noted in 17 broths.
  
  
  CONCLUSIONS
  The five methods of decontaminating TCDBs investigated in this study were effective in removing viable S. mutans. Other investigations are required to determine if TCDBs can be successfully cleaned of blood and protein residue prior reuse.
authors.affiliation: King's College London, UK. zahrat@gmail.com
authors.forename: Zahra
authors.initials: Z
authors.lastname: Sheriteh
authors.forename: Tasnim
authors.initials: T
authors.lastname: Hassan
authors.forename: Martyn
authors.initials: M
authors.lastname: Sherriff
authors.forename: Martyn
authors.initials: M
authors.lastname: Cobourne
authors.forename: Martin
authors.initials: M
authors.lastname: Cobourne
authors.forename: Peter
authors.initials: P
authors.lastname: Riley
mesh_terms: D015169:Colony Count, Microbial; D003666:Decontamination / Q000379:methods*; D017005:Dental Debonding / Q000295:instrumentation*; D003762:Dental Instruments / Q000382:microbiology*; D006801:Humans; D016910:Orthodontic Brackets; D018709:Statistics, Nonparametric; D013242:Sterilization / Q000379:methods; D013295:Streptococcus mutans; D017973:Tungsten Compounds
chemical_list: D017973:Tungsten Compounds; C002802:tungsten carbide