Micro-cracking of tooth structure

Am J Dent. 2004 Oct;17(5):378-80.


Purpose: 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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cracked Tooth Syndrome / etiology*
  • Dental Cavity Preparation / adverse effects*
  • Dental Enamel / injuries
  • Dental High-Speed Technique / adverse effects*
  • Humans
  • Lasers / adverse effects
  • Microscopy, Electron, Scanning
  • Molar

Grants and funding