Light and scanning electron microscope investigations comparing calculus removal using an Er:YAG laser and a frequency doubled Alexandrite laser

With respect to lasers emitting within the mid infrared spectral domain fiber applicators are being developed. Intented is the use of these lasers in periodontal therapy and their application inside the gingival pocket. Aim of the study presented here is to compare the effect of an Er:YAG laser (wavelength 2.94 mu m, pulse duration 250 mu s, free running, different power settings) on dental calculus with the results following irradiation with a frequency doubled Alexandrite laser (wavelength 377 nm, pulse duration 100 ns, q-switched, fluence 1 Jcm(-2)). The surface of freshly extracted wisdom teeth and of extracted teeth suffering from severe periodontitis were irradiated with both laser wavelengths (either frequency doubled Alexandrite or Er:YAG laser) using a standardized application protocol. Calculus on the enamel surface, at the enamel cementum junction and on the root surface was irradiated. For light microscope investigations undecalcified histological sections were prepared after treatment. For the Scanning Electron Microscope teeth were dried in alcohol and sputtered with gold. Investigations revealed that with both laser systems calculus can be removed. Using the frequency doubled Alexandrite laser selective removal of calculus is possible while engaging the Er:YAG laser even at lowest energies necessary for calculus removal healthy cementum is ablated without control.