title: Pattern of transmission of laser light through carious molar teeth.
abstract: OBJECTIVE
  The aims of this study were to investigate the pattern of transmission of laser light through carious human molar teeth, and to examine the effect on light transmission of reactions to caries in the dentine.
  
  
  METHODS
  Sectioned carious human molars were examined whilst illuminated from their external surfaces by a helium-neon laser probe of 0.5 mm diameter. The pattern of light transmission was observed and selected specimens were photographed. The passage of light through the surrounding dentine toward the pulp space was investigated by confocal microscopy. Further carious and restored teeth were illuminated from three buccal and three lingual sites to establish the probability of light being able to reach the coronal pulp space.
  
  
  RESULTS
  For all 31 teeth examined, it was possible to illuminate the pulp space from a position on the buccal side. The presence of intracoronal restorations did not necessarily prevent light transmission to the pulp. Confocal microscopy demonstrated conduction of light within dystrophic deposits of irregular secondary dentine.
  
  
  CONCLUSIONS
  The presence of carious lesions or restorations in molar teeth does not necessarily interfere with transmission of laser light to the pulp space. Light is conducted within irregular secondary dentine. With appropriate probe placement, assessments of pulp health in diseased posterior teeth may be possible using laser Doppler flowmetry.
authors.affiliation: Department of Oral Rehabilitation, School of Dentistry, University of Otago, Dunedin, New Zealand. nick.chandler@stonebow.otago.ac.nz
authors.forename: N P
authors.initials: NP
authors.lastname: Chandler
authors.forename: T R
authors.initials: TR
authors.lastname: Pitt Ford
authors.forename: T F
authors.initials: TF
authors.lastname: Watson
mesh_terms: D000328:Adult; D003731:Dental Caries / Q000473:pathology*; D003782:Dental Pulp / Q000473:pathology; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000473:pathology; D003809:Dentin, Secondary / Q000473:pathology; D006371:Helium; D006801:Humans; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D018613:Microscopy, Confocal; D008875:Middle Aged; D008963:Molar / Q000473:pathology*; D009356:Neon; D010781:Photography; D014172:Transillumination
chemical_list: D006371:Helium; D009356:Neon