The first Japanese laser textbook was published in 1986, covering all medical and dental areas. I was responsible for clinical laser application related to conservative and periodontal treatment.
This study compares the laser treatment situation between 30 years ago and now for conservative and periodontal treatment.
It is not clear whether laser pulpotomy is available, but laser irradiation has been used to treat dentin hypersensitivity for the last three decades.
Lasers are now used to disinfect and enlarge the root canal dentin using a cone-shaped crystal fiber. Especially, Er:YAG laser and Er,Cr:YSGG laser using radial emitting tips could be valuable tools for root canal disinfection.
The irradiation conditions of laser treatment have been clearly established, but laser treatment is not used for specialized diseases.
We hope that new types of laser approved by the Japanese Ministry of Health, Labour and Welfare will be developed and used.

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Oral leukoplakia is considered to be a whitish patch or plaque that cannot be characterized either clinically or pathologically as any other disease, but various histopathological aspects are seen in the occurrence of oral leukoplakias including different aspects ranging from epithelial hyperplasia to epithelial dysplasia and this is considered to be a precancerous lesion. A general diagnosis including histopathological examinations is considered to be important, because oral leukoplakias should be distinguished from squamous cell carcinoma, which clinically shows a similar appearance to that of oral leukoplakias, and the diagnosis affects the selection of an appropriate therapeutic method. The aim of this study was to evaluate the clinical diagnosis of oral leukoplakias and investigate the rate of concordance between the clinical and histopathological diagnosis, and also to identify appropriate therapeutic methods. The present study included 301 lesions in 236 patients that were clinically diagnosed with oral leukoplakia, and histopathological examinations were performed for 195 of the 228 lesions (82.6%). One hundred and ten patients were male and 85 were female (male : female ratio = 1 : 0.77), with an age range of 27–94 years (mean age, 60.5 years). The most common location of the lesion was the tongue, followed by the gingiva, buccal mucosa, and lip. In addition, the most common clinical type was the white-spotted type, followed by the erythroleukoplakia type, hillock type, and verrucous type. The results of the histopathological examinations showed 187 cases to be oral leukoplakia, while 2 were verrucous carcinoma, 4 were carcinoma in situ, 27 were squamous cell carcinoma, and 8 were oral lichen planus. In the 178 lesions that underwent surgical treatment, 107 lesions were treated by laser using the excision technique, 63 were treated by laser using the vaporization technique, and 8 were treated by surgical excision. The rate of recurrence was 10.3% in cases undergoing laser excision, 38.1% in those undergoing laser vaporization, and 25% in the others. In conclusion, the diagnostic discordance rate in our department was 18%, which was not so low, and it included squamous cell carcinoma in the disconcordant cases, therefore histopathological examinations should be performed to confirm the presence of malignant transformation or the grade of dysplasia. Furthermore, this study suggests that laser therapy for oral leukoplakias is a safe technique compared with other treatment modalities.

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Oral lichen planus (OLP) is a chronic inflammatory disease classified as a potentially malignant disorder. As the etiology of OLP is unknown, there is no standard therapy for it. Therefore, a novel therapy for OLP which achieves early healing and is pain-free, is required. This prospective study examined the clinical efficacy of CO₂ laser vaporization therapy for OLP.
Twelve patients (with 17 lesions) in whom OLP was diagnosed clinically were included in the study. In the first step, all patients (lesions) were diagnosed with OLP pathologically by biopsy and underwent conservative treatment for 90 days. In 9 patients, 11 lesions which did not heal or remained painful even after conservative treatment underwent laser vaporization therapy with a CO₂ laser. This study evaluated the patients according to two scales, one for subjective symptoms (VAS) and the other for objective disease grade (TSS), for a period of 90 days after the laser treatment. During the 90 days, a lower score of VAS and TSS was shown in 100% and 80% of lesions, respectively. The average scores of VAS and TSS of OLP lesions at 30 days and 90 days after laser treatment were reduced significantly (p<0.01) compared with those before laser treatment. Our study suggests that CO₂ laser vaporization could be a standard therapy for OLP lesions which reduces the scale of both subjective and objective symptoms and offers early efficacy.

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Although endodontic surgery has evolved into endodontic microsurgery, several authors have found that ultrasonic root-end cavity preparation produces micro-cracks. Meanwhile, various sizes of root canals are encountered in endodontic surgery cases. An ultrasonic root-end cavity preparation for narrow canals might produce a larger strain than for wide canals. The root-end cavity preparation for wide canals only needs removal of gutta-percha, so the effect on dentin might be low. The wedge effect and ultrasonic vibration might affect narrow canals more strongly. The Er:YAG laser mechanism may not cause a large force on the dentin, because it can avoid the wedge effect and ultrasonic vibration. This case report describes the application of an Er:YAG laser to root-end cavity preparation in intentional replantation for roots with narrow canals. The extra-oral time of the case was about 12 minutes and it took 246 sec to prepare two root-end cavities. The manipulation time satisfied the criterion of completion in 15 minutes. Eight months after the surgery, the lesion was found to be healing, with continuous improvement 14 months after the surgery. The essential factors of endodontics are cleaning, shaping and filling; in endodontic surgery, the cleaning factor is often compromised. However, endodontic surgery using laser irradiation may accomplish all the three factors. The Er:YAG laser may be a useful option for preparing root-end cavities in intentional replantation for narrow canals with patients who have a high risk of root fracture.

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