title: Surface roughness of tooth shoulder preparations created by rotary instrumentation, hand planing, and ultrasonic oscillation.
abstract: A dentinal shoulder with a smooth surface is necessary to ensure accurate adaptation of a porcelain crown. The surface roughness of dentinal shoulders prepared with different instruments was investigated in this in vitro study. Sixty shoulders, 1 mm wide, were prepared with coarse grit diamonds in extracted formalin-stored teeth. Of these 60 shoulders 20 were further refined with fine grit, and 20 more shoulders were refined with super-fine grit diamonds. The surface roughness (Ra) of the dentinal shoulders was recorded after each procedure. Thirty surfaces were further finished and refined with a hand chisel, and the other 30 surfaces were finished with a flat-ended diamond tip held in an ultrasonic generating device; the Ra was then recorded. These shoulder preparations were examined under a scanning electron microscope. The Ra of the dentinal shoulders prepared by the ends of the different grit diamonds was not significantly different (p > 0.05). Hand planing did not improve the Ra, and ultrasonic planing significantly increased the Ra (p < 0.05). Scanning electron micrographs revealed no apparent qualitative differences between surface roughness of the shoulders prepared by the diamonds or by the hand-planed surface. However, deeper scratches were evident at ultrasonically planed surfaces.
authors.affiliation: Department of Oral Rehabilitation, Tel Aviv University, Israel.
authors.forename: B Z
authors.initials: BZ
authors.lastname: Laufer
authors.forename: R
authors.initials: R
authors.lastname: Pilo
authors.forename: H S
authors.initials: HS
authors.lastname: Cardash
mesh_terms: D003442:Crowns; D003737:Dental Cavity Preparation / Q000295:instrumentation* / Q000379:methods; D003754:Dental High-Speed Equipment; D018772:Dental Marginal Adaptation; D003775:Dental Polishing / Q000295:instrumentation; D003776:Dental Porcelain; D003804:Dentin / Q000648:ultrastructure*; D018130:Diamond; D006801:Humans; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D014464:Ultrasonic Therapy / Q000295:instrumentation*
chemical_list: D003776:Dental Porcelain; D018130:Diamond