The Morphological Changes of Deciduous Tooth Structure by Er: YAG Laser Irradiation

Abstract

Recently, the Er: YAG laser was invented for the hard tissue ablation. The Er: YAG was low noise, less vibration and less pain during procedure compared with conventional drilling machines. Above mentioned advantages of the Er: YAG laser was very useful in Pedodontics fields. The irradiation condition of the laser on the deciduous tooth becomes necessary for the clinical application of the laser on the pediatric patients.
The purpose of this study was to decide the most suitable laser irradiation condition in the deciduous tooth.
The extracted deciduous upper central incisors were used in this experiment. The energy of the laser was varied from 100mJ/pulse, 200mJ/pulse, 300mJ/pulse, 400mJ/pulse and 500mJ/pulse, the repetition rate was 8Hz and irradiation time was 5 seconds in each.
Then the morphological changes of the tooth structure were examined by the light microscope or the scanning electron microscope.
The conclusions from these results were as follows.
1) The laser irradiated area had clear margin with the surrounding tissues. The crater was occurred in this area. The depth of the crater was depend on the energy density of the laser.
2) Any smear layer was not seen at the laser irradiated dentin, but opening of the dentinal tubules were clearly observed.
3) This experiment showed that the optimum laser irradiation energy for cavity preparation of the deciduous tooth was 300mJ/pulse.
In this laser condition, little heat degenerative changes could be seen at the laser irradiated area and no degenerative changes were seen in surrounding tooch structures.
(J. Jpn. Soc. Laser Dent. 7: 6-11, 1996 Reprint requests to Dr. Moriya)