Tooth movement in orthodontic treatment often causes pain in the patient. Low-power laser irradiation has been known to have a pain-alleviating effect in various general clinical cases. We applied low-power laser irradiation to volunteers with teeth separating in orthodontic treatments and examined the pain-alleviating effect with double blind test. We used 28 examinees who had teeth symmetrized between left and right side of jaws and contacted in normal range(50μm-110μm). Elastic separator were inserted beside both left and right first molar teeth. Immediately after the insertion of separators, the low-power Ga-Al-As laser (wave length 830nm, output power 20mW) was irradiated for two minutes on the buccal gingiva close to either left or right root of the first molar tooth. Decisions of the side to be irradiated were made at random and neither examiner nor examinee was aware of the side for double blind test. At the next visit (more than two weeks after the separator-insertions), the examinees stated their pain on each side of the jow in number using Visual Analog Scale (VAS). Seventeen examinees out of 28 stated that the pain on the irradiated sides was lighter than that on the another sides, and significant difference in average value of the pain was observed between irradiated sides and non-irradiated sides(p<0.02). These results sugested that the low-power Ga-Al-As laser irradiation was effective on the pain that caused by teeth the movement in orthodintic treatment.

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A wide variety of new laser devices which could be available for laser therapy via gastro-endoscope are reviewed. High power semiconductor lasers and new infrared solid-state lasers which can be pumped by the semiconductor lasers are the promising candidates for new type of therapies. The fiber delivery technologies for these lasers as well as applicability for medical equipment are also mentioned.

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Recently in UK a high power diode laser was developed. This system has the max power of 25W and can be used as a surgical laser. Since the laser can be delivered through flexible fiber, this system can be applied to minimum invasive treatment such as endoscopic application, laparoscopic application. We had a chance to visit UK and observed some clinical trials there, also we have started our clinical evaluation in Japan, the summary of which we want to introduce in this article.

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A new system of Nd: Y AG/Dye laser is reported.
A variety of lasers has been utilized in many field these days, but it is difficult to install every laser for each purpose.
The system we developed can be used not only as Nd: YAG laser coagulator but also for photodynamic therapy, in which the second harmony of Nd: YAG laser generates dye laser.
The cost of the new system is equivalent to a system of high power Nd: YAG laser.

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Recently, a remarkable progress in endoscopic diagnosis of gastrointestinal tract diseases has been achieved with the use of lasers. Observation of laser-stimulated fluorescence, spectrum analysis of fluorescence, the use of photosensitizers, laser-speckle image mapping and diode laser angiography have been tried in clinical studies.
In the near future, continuous technical improvement will provide us with new information on the diagnostic application of lasers.

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Since 1988, we evaluated the autofluorescence of cancer induced by argon dye laser at 514. 5nm for the endoscopic diagnosis on gastric and esophageal cancer patients. the fluorescent spectrum was measured with TS200 remodeled.
At first, for fundamental study, we obserbed the autofluorescence of gastric and esophageal cancer on dissected specimen by surgery. The autofluorescence of cancer was obserbed through a cut filter as color of red. The fluorescent spectrum had two peaks of 630nm and 690nm.
In order to examine the source of fluorescent material we extracted the solution from the tissue of cancer, and measured by HPLC. The result suggested that some kinds of porphyrins should accumulate in the tissue of cancer, We tried to use the autofluorescence for clinical endoscopic diagnosis. But the fluorescence was not obserbed clearly through endoscopy, because the fluorescence was very weak. therefore, we are evaluating the study using ultra-violet light which induces the fluorescence more strongly than Argon dye laser.

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In order to improve the therapeutic effectiveness, we newly investigated an excimer dye laser (EDL) instead of an argon dye laser (ATM) as the excitation light source for photodynamic therapy (PDT). Between 1981 and 1990, we treated 7 superficial esophageal cancer (SEC) and 44 early gastric cancer (EGC) lesions (41 cases) by PDT with an AEDL. Depending on the depth of cancer invasion, the rate of cure of submucosal carcinomas was only 33%(1/3) and 55%(11/20), while that of mucosal carcinomas was 100%(4/4) and 88%(21/24) in SEC and EGC, respectively. In 1990, therefore, we investigated an EDL. In this study, six cases of SEC, which consisted of 3 mucosal and 3 submucosal, and seventeen cases of EGC, which consisted of 12 mucosal and 5 submucosal, were treated by PDT with EDL. Local cure was obtained in all cases.

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We developed a new method of hyperthermia with Nd:YAG laser, designated balloon laserthermia, to irradiate wider area than the conventional method.
Balloon laserthermia systems were classified into two types as follows:1)“Intralipid type” and 2)“hybrid type”.
The former consisted of a balloon filled with a light scattering substance, Intralipid solution, attached to the end of the quartz fiber.
In the latter a light scattering system of “hybrid type” developed by SLT Japan was used to diffuse the laser light.
A compararive study between the Intralipid type of balloon laserthermia and the interstitial method, and that between the Intralipid type and the microwave were carried out on the hyperthermia effect to the tumor cells.
The findings sfowed that the Intralipid type was more useful than the interstitial method or the microwave in the treatment of malignant tumor.
The hybrid type balloon laserthermia proved stable and safe irradiation to pig liver with 10 watts for 10 minutes at 42.5-43.5°C. And then we tried to irradiate a section of an early gastric cancer type II a for 15 minutes under the same conditions as the pig liver.
After two days, the lesion was completely resected by endoscopic mucosal resection. Histological findings of the irradiated tissue showed degeneration and necrosis of the cancer cells.
These balloon laserthermia systems appeared to be adaptable to clinical use because of its effects of degeneration and its safety.

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Laparoscopic cholecystectomy using Hook shaped transparent Ceramic Probe with Nd-YAG laser (Contact Laser CL 50. SLT Japan) had been performed in 23 cases in our Department. In this paper, this laser system was introduced and experience with this instrument for laparoscopic cholecystectomy was evaluated.
Hook-shaped tip of dissector has an excellent hemostatic and cutting abilities with minimal tissue damage. A hard metaric shaft without heat conduction covering the part of light guide makes it easier to manipulate for sharp as well as blunt dissection of tissue around the gallbladder.
Although the problem to be solved still existes in remained heat at the tip of probe, the authors believe that this instrument is a useful tool for laparoscopic cholecystectomy in term of similarity to cautery probe for its practical use.

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