title: Effect of various grit burs on marginal integrity of resin composite restorations.
abstract: The purpose of this study was to evaluate the generation of enamel cracks and gaps at the cavosurface margin of resin composite restorations using various burs. Saucer-shaped cavities with a bevel were prepared on mid-coronal buccal or lingual surfaces of extracted human molars using a regular-grit round diamond bur, a fine-grit diamond bur, a superfine-grit diamond bur or a six-bladed tungsten carbide bur with an air turbine handpiece. The enamel margin of the cavity in each group was observed by a light microscope. Cavities were restored with a self-etching adhesive and a light-cured composite resin. After thermocycling, enamel cracks and gaps at the cavosurface margins were observed and scored. Specimens were sectioned longitudinally in two halves, and the resin-cavity interface was observed by means of a light microscope. In cavity preparation, the regular-grid diamond bur and the tungsten carbide bur caused more cracks in the marginal enamel than other groups. From the surface and sectioned surface observation of restored teeth, the superfine-grit diamond bur generated fewer cracks and gaps than the other burs.
authors.affiliation: Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Japan. nishimura.ope@tmd.ac.jp
authors.forename: Kozo
authors.initials: K
authors.lastname: Nishimura
authors.forename: Masaomi
authors.initials: M
authors.lastname: Ikeda
authors.forename: Takako
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Otsuki
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D003737:Dental Cavity Preparation / Q000295:instrumentation*; D003743:Dental Enamel / Q000473:pathology; D003762:Dental Instruments / Q000009:adverse effects*; D018772:Dental Marginal Adaptation; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods; D018130:Diamond; D006801:Humans; D008689:Methacrylates; D008963:Molar; D018709:Statistics, Nonparametric
chemical_list: C112828:Clearfil AP-X; D003188:Composite Resins; D008689:Methacrylates; D018130:Diamond