title: Comparison of sectioning rates among carbide and diamond burs using three casting alloys.
abstract: OBJECTIVE
  This study compared the sectioning rates of commercially available high noble, noble, and base metal casting alloys using two new cross-cut tungsten carbides specifically manufactured for alloy sectioning and two medium grit diamond burs.
  
  
  METHODS
  Rectangular bars cast from a base metal alloy (Ni-Cr-Mo-Be), a noble alloy (Pd-Cu-Au), and a high noble alloy (Au-Ag-Cu-Pd) were sectioned under controlled conditions. Two types of cross-cut tungsten carbide and two types of medium grit diamond burs were tested using a high-speed handpiece under a coolant flow rate of 20 mL/min and an applied load at the bur tip of 0.9 N (91.5 g). Three 4-mm cuts were made through the alloy specimens using six burs of each type. The time required for Cuts 1, 2, and 3 was recorded, and sectioning rates in millimeters per minute were calculated as a relative measure of cutting efficiency. For each alloy, the total time required for the three cuts was analyzed using one-way analysis of variance (one-way ANOVA) and Scheffé tests (alpha = 0.05) to determine differences in sectioning rate among bur types.
  
  
  RESULTS
  In general, mean sectioning rate for Cut 1 through Cut 3 decreased with longer use of the bur. Regarding total sectioning times, the carbide burs sectioned the base metal alloy significantly faster (P < .001) than the diamond burs. However, diamond burs sectioned the high noble alloy significantly faster (P < .001) than the carbide burs. Diamond burs also sectioned the noble alloy more quickly than the carbide burs, but the difference was not statistically significant.
  
  
  CONCLUSIONS
  The cross-cut tungsten carbide burs should be used to section the base metal alloy but the medium grit diamond burs should be used to section the high noble alloy.
authors.affiliation: Department of Restorative Dentistry, Dental School, University of Maryland, Baltimore 21201, USA. scs001@dental.umaryland.edu
authors.forename: S C
authors.initials: SC
authors.lastname: Siegel
authors.forename: J A
authors.initials: JA
authors.lastname: von Fraunhofer
mesh_terms: D000704:Analysis of Variance; D002858:Chromium Alloys; D003442:Crowns; D003722:Dental Alloys; D003754:Dental High-Speed Equipment; D003764:Dental Materials; D020878:Device Removal / Q000295:instrumentation*; D018130:Diamond; D006047:Gold Alloys; D006244:Hardness; D008422:Materials Testing; D013674:Technology, Dental / Q000295:instrumentation; D017973:Tungsten Compounds
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D003764:Dental Materials; D006047:Gold Alloys; D017973:Tungsten Compounds; C002802:tungsten carbide; D018130:Diamond