PDT (Photodynamic therapy) is a relatively new treatment modality for cancer, having the advantage of selective destruction of malignant tumor cells. It has received the approval of the Japanese government for medical insurance coverage to apply PDT to patients with early stage cancer of the lung, esophagus, stomach and uterine cervix. It is expected that patients with oral cancer also would be good candidates for the modality, and its clinical applications have been investigated. However, there were some unexpected problems when it came to practice. In this paper, some problems that occurred in practical PDT and measures learned by experience are presented.
The purpose of this study was to clarify the effect of CO2 laser irradiation in the prevention of pit and fissure caries of immature molar teeth with a covering operculum. The CO2 laser was used in clinical cases, where 22 immature molars erupting with an operculum were tested. Firstly, the operculum was cut with the CO2 laser in a 2-or 3-watt continuous mode. Secondly, the occlusal surface was irradiated spot by spot along the pits and fissures of the immature molars with the CO2 laser in a 2-watt superpulsed mode (average power: 0.3 watt, pulse width: 10msec, repetition time: 15pps), energy density of 15J/cm2. After irradiation, a Fluoride gel (2% NaF) was applied to the subjected teeth. The teeth were clinically examined for dental caries for 3 years. The cutting of the operculum took less than 2 minutes and had no bleeding. The patients did not complain of any pain after operation. The irradiation imparted acid resistance to the teeth without any discomfort to patients. Almost all subjected teeth had no dental caries during the observation period. Therefore, it was concluded that use of CO2 laser might be an effective mode of treatment in the prevention of pit and fissure caries of partially erupting permanent molars covered with an operculum.