title: Comparative study of the cutting efficiency and working life of carbide burs.
abstract: OBJECTIVE
  The aim of this study was to establish the wear and cutting efficiency of tungsten carbide burs from different manufacturers by performing cutting tests with machinable glass ceramic.
  
  
  METHODS
  Cutting tests were performed with 70 tungsten carbide burs from seven manufacturers: (A) Coltene/Whaledent, (B) CEI, (C) Meisinger, (D) Axis, (E) Komet, (F) Kerr, (G) Edenta. All groups were examined under scanning electron microscope (SEM) before and after the cutting efficiency test for similarities and differences. A specially designed cutting device was used. An electric handpiece was operated at 200,000 rpm with a 120 ml/min coolant water supply rate. The burs were tested under a 165 g constant load using 3 mm wide Macor ceramic as substrate. For each bur the cutting procedure involved a total of five cuts of 3 minutes on every cut, with a total cutting time for each bur of 15 minutes. Data were analyzed using one-way ANOVA at 95.0% confidence level.
  
  
  RESULTS
  Significant differences (p < 0.05) were found in the mean cutting rates of the different groups. Groups A and B showed the highest cutting rates. Higher cutting rates were associated with a longer bur lifespan. SEM photomicrographs of the burs and substrates revealed significant changes on the surfaces after the cutting process.
  
  
  CONCLUSIONS
  The morphology characteristics of tungsten carbide burs are related to their effectiveness. The group that presented the worst working life also showed substantial wear on its surface according to the results of SEM.
authors: Department of Prosthetic Dentistry, Universitat Internacional de Catalunya, Barcelona, Spain.
authors: Rebecca G Riera
authors: RG
authors: Di Cristofaro
authors: Lluis
authors: L
authors: Giner
authors: Juan Ricardo
authors: JR
authors: Mayoral
mesh_terms: D002516:Ceramics / Q000737:chemistry; D003754:Dental High-Speed Equipment; D003755:Dental High-Speed Technique / Q000295:instrumentation; D003764:Dental Materials / Q000737:chemistry*; D055615:Electrical Equipment and Supplies; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011476:Prosthodontics / Q000295:instrumentation; D013314:Stress, Mechanical; D013499:Surface Properties; D017973:Tungsten Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D003764:Dental Materials; D017973:Tungsten Compounds; D014867:Water; C002802:tungsten carbide; C023506:Glass ceramics
keywords: Carbide tungsten bur; cutting efficiency; dental burs; high-speed handpiece; machinable glass ceramic