OBJECTIVES: The influence of minimum values possible for energy, frequency and pulse duration on the effectiveness of dentin ablation, by calculating the depth and the area of the laser-drilled craters.
METHODS: Thirty human molars were embedded in resin and were abraded to the dentin level with water-cooled silicon-carbide discs . The laser handpiece was placed at a fixed distance from each specimen. Irradiations were performed using a pulsed Er:YAG laser (DEKA,2940D) , at a wavelength of 2,94 µm. Three groups were randomly formed. The settings examined were 50, 100, 150 mJ for energy; 10, 15, 20 Hz for frequency; and 230, 450, 700 ìsec for pulse duration. For each parameter, 20 ablation spots were created resulting in a total number of 180 craters . The dentin surfaces were examined under a light and a Scanning Electron microscope. The diameter and the depth of the lesions produced were determined by digital ocular micrometry. One-way ANOVA and Kruskal-Wallis tests were utilized for the data analysis.
RESULTS: The mean ablation depth at energies of 50, 100, 150mJ was 133, 277, 214 µm respectively. An increase in the crater depth and area was observed with the increase of the laser parameter values.
CONCLUSIONS: Even the smallest possible values of the irradiation parameters for the tested device do have an effect on dentin ablation, with the energy appearing as the most influencing one.