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 gro ups. Group I were non-lased controls, while groups II, III, and IV wer e lased with the same power (4 watts, 1 second), but at 3 different la ser-target distances (1, 3, and 5 mm), thus delivering 3 different ene rgy levels. Following lasing, 20 areas (5 per group) were examined und er SEM for detection of any structural changes. Human gingival fibrobl asts were cultured on both experimental and control samples of the rem aining 40 areas. Photomicrographs at x500 were obtained and the number : of attached fibroblasts were counted. Results showed that lased ceme ntal surfaces exhibited changes in surface topography which ranged fro m what appeared to be an apparent fusion of the surface of the coverin g smear layer (lowest energy level), to cracking and fissuring of the lased surface (highest energy level). When fibroblasts were cultured o n the specimens, the results demonstrated the presence of a monolayer of cells on the control surfaces and on the surfaces lased with the lo west energy level (5 mm distance). Specimens lased at the mid-energy l evel (3 mm) showed decreased numbers of attached cells, but not signif icantly different from the controls. On the other hand lasing the ceme ntum surface at the highest energy level (1 mm distance) caused a sign ificant decrease in the number of the attached cells as compared to th e controls. The results of the present study suggests that modificatio n of the cemental surface by the laser was dependent on the energy lev el. Furthermore, the energy level used (4 watts, 1 second) at 3 and 5 mm distance supported cell growth comparable to the controls.