title: Effects of bur abrasive particle size and abutment composition on preparation of ceramic implant abutments.
abstract: BACKGROUND
  Amid increasing use of preparable ceramic implant abutments, there is a lack of quantitative data to show which abrasive particle size of diamond bur yields the fastest reduction and provides the smoothest surface.
  
  
  OBJECTIVE
  The research aim was to determine the effects of diamond bur abrasive particle size and abutment material composition on preparation efficiency, prepared surface roughness, and surface deterioration of diamond burs.
  
  
  METHODS
  Fifteen alumina (Cera Base) and 15 zirconia (ZiReal) implant abutments were each machined using a high-speed hand piece with a diamond bur having 1 of 3 abrasive particle sizes (150, 100, or 30 microm) (n=5). Control abutments (n=5) were analyzed without machining. Abutments were weighed before starting and between machining cycles. Three profilometry measurements (root mean square surface roughness) were made for each abutment. Scanning electron micrographs were made of each bur. Lost abrasive particles were then counted on each micrograph through a randomly placed template. Two-way analysis of variance (alpha=0.05) was used to test for significant effects.
  
  
  RESULTS
  Bur abrasive particle size and ceramic type had a significant interactive effect on the amount of material removed (P<.001). Super coarse (150 microm) burs yielded the roughest surfaces for each abutment material (P<.001), and prepared alumina surfaces were rougher than zirconia surfaces (P<.001). Super coarse burs showed the highest proportion of lost particles (P<.001). Abutment composition did not significantly affect bur wear.
  
  
  CONCLUSIONS
  Super coarse burs yielded the most efficient material removal for alumina abutments. All abrasive particle sizes removed a similar amount of material from zirconia abutments. Fine-grained alumina abutments experienced greater material removal and rougher prepared surfaces compared with zirconia abutments. Material was removed by an intergranular fracture mechanism for alumina abutments, in contrast to transgranular fracture for zirconia abutments.
authors.affiliation: Baylor College of Dentistry, Dallas, TX, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Blue
authors.forename: Jason A
authors.initials: JA
authors.lastname: Griggs
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Woody
authors.forename: Barbara H
authors.initials: BH
authors.lastname: Miller
mesh_terms: D000537:Aluminum Oxide; D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry; D000044:Dental Abutments; D015921:Dental Implants; D003762:Dental Instruments; D003775:Dental Polishing / Q000295:instrumentation*; D004867:Equipment Design; D016876:Metal Ceramic Alloys; D010316:Particle Size; D013499:Surface Properties; D015040:Zirconium
chemical_list: D015921:Dental Implants; D016876:Metal Ceramic Alloys; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide