title: Tooth structure loss apical to preparations for fixed partial dentures when using self-limiting burs.
abstract: BACKGROUND
  Burs with guide pins may be used to limit the depth of tooth preparation for fixed partial dentures. The effects of guide pins on tooth structure apical to the finish line after tooth preparation for fixed partial dentures has not been recorded.
  
  
  OBJECTIVE
  This in vitro study recorded loss of tooth structure within 1.0 mm apical to the finish line of teeth prepared with straight cylinder and tapered cylinder self-limiting burs and one conventional bur.
  
  
  METHODS
  Forty-five extracted human teeth were randomly divided into three groups. The facial surface of each tooth was prepared with two types of diamond burs with guide pins and a conventional diamond for the control. The surface was profiled before and after tooth preparation. Profiled surfaces were analyzed and the groups were compared using analysis of variance and the Tukey-Kramer HSD test (alpha = 0.05).
  
  
  RESULTS
  No significant difference was recorded between the control group and the group prepared with a round-ended tapered cylinder self-limiting pin. However, there was a statistically significant difference between the control and cylindrical pin groups, and between the two groups prepared with self-limiting diamonds.
  
  
  CONCLUSIONS
  This study revealed abrasion apical to the finish line of the preparation in all groups. The cylindrical guide pin group exhibited the greatest loss of tooth surface.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Alabama at Birmingham 35294-0007, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Ramp
authors.forename: M S
authors.initials: MS
authors.lastname: McCracken
authors.forename: R B
authors.initials: RB
authors.lastname: Mazer
mesh_terms: D000704:Analysis of Variance; D003754:Dental High-Speed Equipment / Q000009:adverse effects*; D003772:Dental Pins; D003830:Denture, Partial, Fixed; D018130:Diamond; D006801:Humans; D018709:Statistics, Nonparametric; D014072:Tooth Abrasion / Q000209:etiology*; D019231:Tooth Preparation, Prosthodontic / Q000009:adverse effects* / Q000295:instrumentation*; D014092:Tooth Root / Q000293:injuries*
chemical_list: D018130:Diamond