Effect of low-level CO 2 laser radiation on the inhibition of smooth-surface caries (in-vitro study)

Abstract

The application of lasers in dentistry is not a new concept. Lasers have been used in various areas of dental research over the last two decades. However, recent technological development and research findings indicate that widespread clinical application of lasers will occur shortly. Many of the early studies discovered that high levels of laser radiation were detrimental to the vitality of the dental pulp. This has led researchers to investigate whether low level laser radiation would have positive effects on the various components of the dental hard tissues. This study examined the anti-carious effect of low level C02 laser radiation on smooth surface enamel. Fifty extracted third molars were selected and covered in acid resistant varnish except for two windows on the buccal surface just above the CEJ. The windows measured 1.5 x 1.5 mm with one window designated as the control and the other experimental. In each experiment the Pfizer Model 10-C laser system was used. The teeth were divided into two groups. In group I, the experimental window was lased with 1.2 watts at 0.1 seconds with a 1.5 mm focal spot. In Group II, the experimental window was lased with 2.4 watts at 0. 1 seconds with a 1.5 mm focal spot. Both groups were exposed for 12 days in a demineralizing solution (2.2 mM Ca, 2.2 mM P0 ,50 mM acetic acid, 5 ppmF-@ constant pH -4.3). The resulting lesions were sectioned to approximately 80 im thickness using a hard tissue microtome. Each section was examined by taking polarized light photomicrographs after imbibition in H20 medium. Results of the study suggested a significant reduction in the lesion size in both experiments, all exposures being within the biological safe zone of temperature elevation to the surrounding vital tissues, e.g. the dental pulp and periodontal tissue. Further research will be required to determine the level of CO2 laser radiation which will provide the maximum anti-carious effect.