In vitro studies on laser scaling of subgingival calculus with an Erbium:YAG laser
The study consisted of four experiments to see if a newly developed Er:YAG laser with a fiber delivery system is effective in removing the subgingival calculus from extracted teeth. The first experiment tried to examine the effectiveness of the laser scaling on a straight line. For this, five teeth with a band of subgingival calculus were used. The laser scaling was performed using irrigation and moving the probe on a straight line at five different energy levels (20, 30, 50, 80,120 mJ/pulse).The teeth were photographed before and after the scaling. The teeth were examined under the scanning electron microscope (SEM), and the ablation depth of the tooth substance was determined. The purpose of the second experiment was to examine the effectiveness and the efficiency of laser scaling on a broad area. For this, 30 teeth with a band of subgingival calculus were used. Laser scaling with irrigation was performed at different energy levels as in the first experiment. The teeth were divided into six groups on a random basis. All the teeth were photographed, and the time required for scaling was measured. The teeth were examined under SEM. The purpose of the third experiment was to examine the effects of water irrigation on the features on the scaled sites and to compare the efficiency of the two types of scaling. In this part, eight teeth with subgingival calculus were USEd. The calculus was divided axially in each tooth. Half was scaled with water and the other half was scaled without water, both at 30 mJ/pulse. The teeth were examined under the SEM. In the last experiment the purpose was to examine the cooling effect of water irrigation and to estimate the thermal influence on the pulp during laser scaling. Five mandibular incisors with calculus were used. Laser scaling was performed with and without water for 20 seconds. The temperature changes of the root surface during laser scaling were observed using a thermal video system. The teeth were cut in half buccolingually, and the thermocamera was used to score temperature changes during scaling on the pulpal wall.
The laser was effective in removing calculus in vitro. Very little or no charring of the cementum was observed. The laser used on a straight line revealed a groove-like appearance, regardless of the energy level used. No cracks were observed. The scaling with the Er:YAG laser was not efficient under 10 mJ/pulse, but it was very efficient at 30 mJ/pulse and higher energy levels. Irregular and chalky surfaces were observed at sites scaled without water irrigation, and in some cases the calculus was carbonized. Water irrigation did not affect the efficiency of the laser significantly. The temperature of the root surface during scaling with irrigation was from 26.2€ to 28.6 C; without irrigation it increased to 63.56-66.5 C. The temperature of the pulpal wall ranged from 28.6. to 29.48 C without irrigation and gradually increased to 47.4 C at the completion of the scaling. Heat generation was markedly reduced by water irrigation.
In conclusion, the laser was able to remove subgingival calculus effectively at the energy level of 30 mJ/PulSe. The ablation of the tooth substance was observed within the cementum, and an increase of temperature was scarcely observed during laser scaling with irrigation. [c.c.]
Aoki, A.,Y. Ando, H. Watanabe, and I. Ishikawa, J Periodont, 65:1097,1994