TEA-CO 2 laser inhibition of artificial carieslike lesion progression in primary and permanent tooth enamel

Abstract

Several studies during the last 30 years have demonstrated the potential of laser pre-treatment of enamel to inhibit subsequent acid-induced dissolution or artificial caries-like challenge in the laboratory. The aim of the present study was to examine the difference between primary and permanent teeth enamel in the prevention of caries-like lesion progression by long pulsed TEA-carbon dioxide (CO2) laser irradiation in vitro by means of a pH-cycling model. Thirty caries-free permanent tooth crowns and forty caries-free primary tooth crowns were cleaned and varnished with acid-resistant varnish, leaving one exposed window of enamel. Five groups of 10 enamel samples were irradiated in their individual windows by a TEA- CO2 laser at 9.6 micrometer wavelength, 25 pulses per spot, 5 microsecond pulse duration, 0.5,10,15 Hz repetition rates, 1774 micrometer beam diameter and 1.0, 1.5 J/cm2 per pulse fluence. All teeth, including 2 non-irradiated control groups, were subjected to pH-cycling to produce artificial caries-like lesions. Results were assessed by cross-sectional microhardness testing. Inhibition of caries progression of from 29% to 57% was achieved over the range of laser conditions tested. At the same irradiation conditions (repetition rate: 10 Hz, fluence: 1.5 J/cm2), the inhibition rate in primary teeth enamel was 54% compared with 49% in the permanent teeth enamel (significant at p less than 0.05). Safety and efficacy studies will be required before these promising laboratory results can be applied in clinical practice.