CO2 laser and the diagnosis of occlusal caries: in vitro study

The diagnosis of small lesions in pit and fissure sites is becoming increasingly problematical. This study was designed to evaluate, in vitro, the potential use of a carbon dioxide (CO2) laser technique as an aid to the diagnosis of incipient pit and fissure caries. Vaporization of the organic material in the 'early' carious lesion should lead to its carbonization and thus make it more conspicuous. Pilot studies were carried out to identify lasing parameters which produced no visible effect on sound enamel but which caused charring (carbonization) of white spot fissure lesions. Fifty extracted human molars and premolars were air-polished on the occlusal surfaces and independently scored clinically for caries, both before and after lasing. The teeth were subsequently sectioned and examined histologically. Of the 37 sites histologically scored as sound or exhibiting precavitation lesions, eight were correctly scored as sound both prelasing and postlasing. Of the 29 precavitation lesions detected histologically, five were detected clinically prelasing and 11 were detected postlasing. This 21% difference in the sensitivity of caries diagnosis between the prelasing and postlasing examinations was statistically significant (at the 95% level). There were no false-positive caries diagnoses. Further research, in particular the refining of lasing parameters employed, is indicated.