Pattern of transmission of laser light through carious molar teeth

Aims The aims of this study were to investigate the pattern of transmission of laser light through carious human molar teeth, and to examine the effec t on light transmission of reactions to caries in the dentine. Methodology Sectioned carious human molars were examined whilst illuminated from their external surfaces by a helium-neon laser probe of 0.5 mm diamet er. The pattern of light transmission was observed and selected specimens w ere photographed. The passage of light through the surrounding dentine towa rd the pulp space was investigated by confocal microscopy. Further carious and restored teeth were illuminated from three buccal and three lingual sit es to establish the probability of light being able to reach the coronal pu lp space. Results For all 31 teeth examined. it wits possible to illuminate the pulp space from a position on the buccal side. The presence of intracoronal rest orations did not necessarily prevent light transmission to the pulp. Confoc al microscopy demonstrated conduction of light within dystrophic deposits o f 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 appropr iate probe placement, assessments of pulp health in diseased posterior teet h may be possible using laser Doppler flowmetry.