In recent years, lasers have been used for root canal disinfection. Root canal disinfection by CO2 laser irradiation has been shown to reduce the microbial count. When a CO2 laser irradiates the inside wall of a root canal, most of the energy is absorbed by surface dentin and transformed to heat energy, which transmits through the dentin and to the root surface. However, if the apical foramen of the root is open, the laser beam can irradiate the periapical tissues and may cause tissue damage. A study by Horiba, et al evaluated damage that might occur to viable cells after CO2 laser irradiation of root canals with apical foramen opened to various diameters. Extracted teeth were used in the study. The study found that the larger the apical foramen, the greater the decrease in the percentage of viable cells, meaning that greater damage to the periapical tissues could be expected to occur. The study indicates that if the laser irradiated a root canal system that was enlarged to within 1 mm of the root canal length, little damage to the periapical tissues would be expected to occur. Therefore, if care is taken not to enlarge the apical foramen, little damage may occur to periapical tissues following CO2 laser irradiation of a root canal system. The authors state that it would be worthwhile to investigate the usefulness of CO2 laser irradiation of root canal systems in further detail.
(Source: Oral Surgery, Oral Medicine, Oral Pathol-ogy, Oral Radiology, and Endodontology, Vol. 100, No. 6, 2005)
