Many low-power laser apparatuses have been developed, and their efficiencies have been reported for treatment of dentinal hypersensitivity or temporomandibularis. In addition, several reports indicated the application of a low-power laser. The purpose of this study was to investigate the effect of low-power laser irradiation on bone remodeling using rat calvaria with an artificially formed defect. Artificial bone defects of 4 mm in diameter were prepared by a round bur with a low-speed dental engine.
Ga-Al-As laser (830nm, 30mW, or 80mW) irradiation was applied to bone defects in right calvaria, as an experimental site, for 10 minutes once a day, and this procedure was carried out up to 1, 2, 3, 4, 5 or 6 weeks. Bone defects in left calvaria, without laser irradiation, were used as a non-irradiation site. Results obtained were as follows.
New bone formation was enhanced with 30mW laser irradiation. Particularly, 4-week irradiation showed the highest amount of new bone formation, compared with the control groups.
1. New bone formation was also enhanced with 80mW laser irradiation. Particularly, from 2-week to 4-week irradiation showed a significant difference between experimental groups, and control groups in the amount of new bone.
2. Camparing 30mW and 80mW irradiation, 80mW groups showed more new bone formation than 30mW groups after 3-week laser irradiation. However, there was no significant difference between 30mW and 80mW groups after 4-week irradiation.
(J. Jpn. Soc. Laser Dent. 12: 2-9, 2001 Reprint requests to Dr. MEZAWA)

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Seventeen cases of tongue lesions treated with a KTP laser were retrospectively assessed. Out of these, the effectiveness of treatment on eight leukoplakias and five squamous cell carcinomas, which were resected with output power of 10 watts, was compared with those in a group of similar cases that had been treated with a CO₂ laser.
It was easy to cut the tongue lesions in both groups. Forty percent of squamous cell carcinoma patients in both groups had bleeding from the tongue during the operation. Consequently, silk-suturing was performed. No cases of leukoplakia of the tongue in either group resulted in bleeding during the operation. In both types of lesions, the postoperative bleeding was mostly confined to the group treated with the KTP laser. Furthermore, postoperative pain tended to continue longer in the KTP laser group, compared with the CO₂ laser group.
The period necessary for wound healing was shorter in the KTP laser group, for both types of lesions. Postoperative functional disturbance of the tongue was slight in both groups.
(J. Jpn. Soc. Laser Dent. 12: 10-15, 2001 Reprint requests to Dr. ISHII)

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Laserthermia, a kind of interstitial hyperthermia, has become available for intraoral application. This paper describes clinical use of laserthermia in our department.
Laserthermia was carried out respectively on five cases of oral cancer. It was applied for one to five days, and was repeated two to eight times/day. A total of 43 applications were given Thermal changes could be recorded by a feedback system in 28 of the 43 applications A temperature level of 42.5-43.5°C was maintained for 15.42±3.80 minutes in 19 applications by 20 minutes of laserthermia. Necrosis or shrinkage of tumor was found in four cases. There was also improvement of local swelling. The tumor failed to response in one case. The heating condition was examined ther mometrically from radiological phantoms. The tissue temperature was found to have rapidly decreased on the outside of the thermocouple heated to 42.5-43.5°C. Temperature monitoring using a thermocouple was considered important to obtain successful results.
In conclusion, laserthermia was found to be applicable to hyperthermia to the treatment of oral cancer.
(J. Jpn. Soc. Laser Dent. 12: 16-20, 2001 Reprint requests to Dr. SHIKIMORI)

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The purpose of this study was to clarify that performing the sealant procedure in the cleanest possible condition, following laser irradiation, helps to increase the probability of maintenance. This study included 45 upper first premolars that were removed for the purpose of occlusal guidance. The methods for fissure cleaning were 1) using brush cone alone, 2) using a brush cone and 3 % NaOCl, and 3) using a brush cone and laser irradiation. After each treatment, sealant was applied following acid etching treatment. Nd: YAG laser (20 pps, 100mJ, 2w, one shot mode 20sec, without using black ink) was used for the irradiation. A laser irradiation was done for fissure cleaning, and then sealant was applied. After that, the state of a dental pulp was examined. The following conclusions were obtained:
(1) The procedure using a brush cone and laser irradiation was the most effective for the cleaning debris from the fissure and less destructive to the fissure structure.
(2) When the laser irradiation was performed before acid etching, the leakage between enamel and sealant was the smallest.
(3) The harmful effect of laser irradiation without using black ink was less influential on the dental pulp tissue, in the present study.
(J. Jpn. Soc. Laser Dent. 12: 21-36, 2001 Reprint requests to Dr. NAMIOKA)

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Diagnodent, a device for dental caries diagnosis with a laser, senses fluorescence generated from dental caries in response to light irradiated by the device, providing nondestructive real time measurement of the range and degree of dental caries. To clinically use this device, we determined how measurement was influenced by differences in the state of dryness/wetness of the tooth surface, changing the probe angle at measurement, and exogenous deposits on the tooth surface. Measurements were found to have almost no errors, even in the presence of water. It was possible to estimate the expansion of dental caries through continuous measurement with the probe tip that was being moved and inclined. However, this device markedly responded to dental calculus, indicating a need for tooth scaling before operation.
(J. Jpn. Soc. Laser Dent. 12: 37-40, 2001 Reprint requests to Dr. TAKASE)

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