title: Micro-cracking of tooth structure.
abstract: OBJECTIVE
  To determine if the cutting procedure utilized in producing a cavity preparation, i.e., a high speed dental handpiece or an Er:YAG laser may be a factor in initiating the formation of micro-cracks during or after preparation of the cavity and before and after placing and curing the dental composite.
  
  
  METHODS
  Class I occlusal and Class II MOD preparations were prepared in extracted third molars using a high speed dental handpiece equipped with a coarse diamond bur or with an Er:YAG laser at 260mJ and 25Hz. Composite was placed into the cavity level with the occlusal surface and bulk cured. The extreme factors of a coarse diamond bur and bulk curing of the composite were utilized to maximize the stresses at the tooth-composite interface. The teeth were vertically sectioned, facio-lingually, and examined, along with resin replicas, under a scanning electron microscope (SEM) to look for the presence of microcracks at the composite/enamel interface and composite/dentin interface.
  
  
  RESULTS
  SEM examination indicated that micro-cracking of the tooth structure was not significant or consistent in any of the specimens examined. This study was unable to confirm that micro-cracks form at the composite/tooth interface.
authors.affiliation: Department of Restorative Dentistry, College of Dentistry, University of Illinois, Chicago 60612-7212, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Sehy
authors.forename: James L
authors.initials: JL
authors.lastname: Drummond
mesh_terms: D003387:Cracked Tooth Syndrome / Q000209:etiology*; D003737:Dental Cavity Preparation / Q000009:adverse effects*; D003743:Dental Enamel / Q000293:injuries; D003755:Dental High-Speed Technique / Q000009:adverse effects*; D006801:Humans; D007834:Lasers / Q000009:adverse effects; D008855:Microscopy, Electron, Scanning; D008963:Molar