title: The effect of handpiece spray patterns on cutting efficiency.
abstract: BACKGROUND
  High-speed handpieces' spray ports direct coolant at the cutting interface. The authors evaluated the effect of the number of ports and their positions on cutting rates, or CRs.
  
  
  METHODS
  The authors performed cutting studies on a machinable ceramic block using an established testing regimen. One-port, three-port and four-port handpieces from one manufacturer were operated at maximum torque and rotation speed under a water flow of 25 milliliters per minute. The authors made 6-millimeter long edge and groove cuts in 13-mm cross-section blocks using six medium-grit diamond burs for each handpiece. Each bur cut a total of 78 mm. The authors determined CR as the time to transect the block and analyzed the data by two-way analysis of variance with post hoc Scheffé tests.
  
  
  RESULTS
  CRs varied by the type of cut and the number of spray ports. No differences were found in CRs for the three handpieces during edge cutting. The one-port handpiece cut significantly slower (P < .001) than did the three- and four-port handpieces during groove cutting.
  
  
  CONCLUSIONS
  The data indicate that the number of handpiece spray ports, and their positioning relative to the bur affect water supply to the cutting interface and, consequently, the CR under these study conditions.
  
  
  CONCLUSIONS
  Optimal cutting efficiency requires good coolant access, especially within restricted areas. A multiple-port handpiece may be advantageous when preparing the interproximal region for a crown or a proximal box, owing to the better water spray pattern. Dentists should consider the influence of the number of spray ports when selecting handpieces for cutting procedures.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Maryland, Baltimore 21201, USA. SCS001@Dental.umaryland.edu
authors.forename: Sharon C
authors.initials: SC
authors.lastname: Siegel
authors.forename: J Anthony
authors.initials: JA
authors.lastname: von Fraunhofer
mesh_terms: D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry; D003737:Dental Cavity Preparation / Q000295:instrumentation; D003754:Dental High-Speed Equipment / Q000592:standards; D003764:Dental Materials / Q000737:chemistry; D018130:Diamond / Q000737:chemistry; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D012212:Rheology; D012399:Rotation; D013223:Statistics as Topic; D013499:Surface Properties; D013997:Time Factors; D019246:Tooth Preparation / Q000295:instrumentation*; D019231:Tooth Preparation, Prosthodontic / Q000295:instrumentation; D019415:Torque; D014867:Water / Q000737:chemistry; D016474:Weight-Bearing
chemical_list: D003764:Dental Materials; D014867:Water; D018130:Diamond; C023506:Glass ceramics