STRUCTURAL AND FUNCTIONAL-CHANGES OF CEMENTUM SURFACE FOLLOWING EXPOSURE TO A MODIFIED ND-YAG LASER

A MODIFIED ND:YAG LASER WAS EVALUATED for its effect on root cementum topography and fibroblastic attachment. Fifteen extracted human teeth were curetted, sectioned, and divided into 60 areas representing 4 groups. Group I were non-lased controls, while groups II, III, and IV were lased with the same power (4 watts, 1 second), but at 3 different laser-target distances (1, 3, and 5 mm), thus delivering 3 different energy levels. Following lasing, 20 areas (5 per group) were examined under SEM for detection of any structural changes. Human gingival fibroblasts were cultured on both experimental and control samples of the remaining 40 areas. Photomicrographs at x500 were obtained and the number: of attached fibroblasts were counted. Results showed that lased cemental surfaces exhibited changes in surface topography which ranged from what appeared to be an apparent fusion of the surface of the covering smear layer (lowest energy level), to cracking and fissuring of the lased surface (highest energy level). When fibroblasts were cultured on the specimens, the results demonstrated the presence of a monolayer of cells on the control surfaces and on the surfaces lased with the lowest energy level (5 mm distance). Specimens lased at the mid-energy level (3 mm) showed decreased numbers of attached cells, but not significantly different from the controls. On the other hand lasing the cementum surface at the highest energy level (1 mm distance) caused a significant decrease in the number of the attached cells as compared to the controls. The results of the present study suggests that modification of the cemental surface by the laser was dependent on the energy level. Furthermore, the energy level used (4 watts, 1 second) at 3 and 5 mm distance supported cell growth comparable to the controls.