Wide-range absorption spectra(200nm-10μm) of human atheromatous and normal aorta from cadvars were investigated. The absorption spectra were measured by the transmitting method with crushed sample of aorta. The absorption spectrum of atheromatous aorta was similar as that of normal aorta. Moreover, these spectra were strongly affected by water spectrum, so that high absorption existed <300nm and >2.7μm. In laser angioplasty, thermal damage of artery wall could be reduced by selecting therapy laser to these wave-ranges.

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Transmission through the skin was investigated in CW and pulse semiconductor laser using rat's skin flap which is about 2mm in thickness. Transmitted lights were both scattered and those transmission rates in straight direction were both about 3%, but CW was scattered more diffusely of the two.

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Recently, the number of surgery for ischemic heart disease has been widely increased and good results have been obtained.
However, there were a few patients for whom A-C bypass could not be carried out, because of diffuse multiple stenoses or small caliber coronary arteries.
For the purpose to rescue those severely ill patients high energy CO₂ laser was employed experimentally. Subsequently, it was finally clarified that laser output more than 80W and irradiation time of approximately 0.2 sec were necessary to make a laser puncture in the ischemic myocardium.
In the long-term observation of microscopic findings of the newly created laser channels it was surely recognized that laser channels surrounded by the endothelial cells were patent even 3 years after creation.
On the basis of our excellent experimental results laser method was successfully carried out for a 55 year-old male patient with severe chest pain and constrictive pericarditis. Coronary angiogram showed 90% of stenosis of the left anterior descending artery (LAD). But in this case A-C bypass could not be done, because of severe adhesion of the epicardium. Therefore, six laser punctures were created in the anterior wall of the left ventricle on 12th November 1985.
Postoperative course was uneventful without any complications.

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The purpose of laser angioplasty is the recanalization of obstructed vessels by laser. Laser reactions in the contact irradiation laser angioplasty were evaluated using female rabbit's atherosclerosing aorta made by high cholesterol diet and hard thrombus made in goat by Gore-Tex bypass graft at the carotid artery. The ablating area of atheroma was covered by small thrombus after 1 hour, which changed to fibrin like substance after 48 hours, and healed after 2 weeks since the contact irradiation of argon laser. In the hard thrombus ablation, round hole of about 2mm in diameter was made by YAG laser through contact ceramic tip.

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Marked stenoses or occlusion of pelvic or lower extremity arteries in seven patients were treated with laser irradiation and supplementary balloon dilatation with satisfactory results.
The methods of irradiation of laser consisted of non-contact and contact methods. Contact method consisted of the use of either a new ceramic tip or polished bare tip of laser quartz fiber.
In a case of occlusion of the popliteal artery a polished bare tip of quartz fiber was applied to three points in the occluded artery.
A new laser vascular endoscope was used to irradiate an atherosclerotic lesion under direct vision with a TV monitor.
In all seven cases recanalization of stenosed or occluded artery was successful, and intermittent claudication was cured.

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The temperature at the anastomotic site during Nd-YAG laser irradiation was measured. Histological specimen of the anastomosed vessel was examined photomicroseopically.
The mechanism of vascular welding by laser beaming is postulated based on the results obtained from the experiment.
A transient dissolution of the tissue protein first takes place owing mainly to the thermal effect rendered by the laser beam in the localized minute adjacency of the vessel ends to be anastomosed, and prompt and firm fusion of the tissue protein then ensued as the temperature around the anastomosis is lowered.
The advantages of Nd-YAG laser anastomosis is briefly discussed.

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The effects of Nd-YAG laser irradiation are discussed using four normal dog's tracheal ring with an oblique irradiating probe after submucosal injection of India ink, applying that Nd-YAG laser has color dependency.
Laser irradiation was applied 14 days after the injection of India ink, on a half circle of one to three rings in the direction of major axis at 20w×0.5 seconds for 12 places in total until the mucosa turned to white. The mean dose was 100 joules per cm². Each irradiated area of those 12 places had changed to ulceration and was repaired with flat granulation afterwards. The slight deformity of cartilage ring was observed in two places out of 12 (17%). The oblique irradiating probe handles easily and it is very useful to irradiate side wall of trachea.
For irradiation to submucosa of tracheal wall, this new method was safe, definite and besides it could be performed with quite low energy of Nd-YAG laser.

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The pathological changes in the tracheal membrane produced by MC; laser irradiation, were studied in 18 mongrel dogs. Two types of probes, anterior and lateral irradiation probe, were used in this study.
The temperature of the membrane was monitored with a thermospot sensor throughout this procedure. The irradiated tissues were examined pathologically with reference to the specific temperature of the membranes. The membranous portion of the trachea showed a higher temperature than the cartilaginous portion with the same laser energy density. The histological grade of destruction was divided into five grades ranging from desquamation to perforation.

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53 advanced lung cancer patients with stenosis or obstruction of the tracheobronchial tree were treated by photodynamic therapy (PDT) with hematoporphyrin derivative (HpD) and an argon dye laser.
Clinically 8 case were Stage 1,5 were stage 11,30 were stage III and 10 were Stage IV.
Histologically, 35 were squamous cell carcinoma, 7 were adenocarcinoma, 4 were small cell carcinoma and 7 were large cell carcinoma. In terms of the location of the tumor, one was in trachea, 10 were in main bronchi, 33 were in lober bronchi, 8 were in segmental bronchi and one was in a subsegmental bronchus. PDT was performed 48-72 hours after intravenous administration of 2.5-5.0mg/kg HpD.
Opening tracheobronchial tree was obtained in 35 lesions among 53 lesions 66%

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Photocynamic therapy (PDT) by light stimulation of hematoporphyrin derivative (HpD) for early lung cancer have been performed and good results have been obtained.
136 patients with lung cancer were treated by PDT using HpD and argon dye laser.
19 patients with lung cancer were treated by PDT for the purpose of either reduction of extent of resection or to render inoperable cases operable.
9 cases were clinical stage I, 1 was stage II, 8 were stage III, 1 was stage IV.
2 cases of them had tracheal invasion. Intrabronchial polypoid tumor or invasion to the carina were seen in 3 cases. In 11 cases polypoid tumor or invasion to mein bronchus were seen. 4 cases had double primary foci.
60-600 Joules/cm² laser beam was irradiated for areas of superficial invasion ana 300-800 mW, 10-20 minutes for intratumoral PDT for polypoid tumors.
1-9 weeks after PDT, surgery was performed. Effective result were obtained in 15 of 19 cases by PDT. In 5 of 6 cases which were inoperable cases, operable condition were achieved.
This study suggested that PLT is effective method in combination with surgery in non-early stage lung cancer.

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The incidence of recurrence after Trans Urethral Laser Destruction of bladder cancer (TULD) is discussed. Patient studies: This study was carried out in all patients with primary superficial bladder cancer who had undergone TULD for 3 years. The TULD was performed 23 times for the 20 patients. The recurrence rate was 33.3% in 12 new patients, and 66.7% in 8 recurrent patients. It was 38.5% for patients with solitary cancer, 40.0% for patients with number of cancer less than 5 and 100% for patients with more than 5 Conclusion: A conclusion cannot be drawn due to the small number of patients and the short followup period, though it seems to suggest that TULD is an appropriate surgery for bladder cancer of new patients with a solitary cancer or less than 5 cancers in number.

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Ga-Al-As diode laser was used for relieving pain in 34 patients with urinary stone. They were treated by point stimulation with the laser acupuncture. These irradiation points (Tsubo) were 'Jinyu', 'Boukouyu', and 'Saninkou'. The efficacy of laser acupuncture was analyzed in accordance with a degree of relief from pain by the patient's statement. However, because of the subjective analysis, objective result will be necessary for the evaluation of the definite alleviatory effect. Thus, control study was tried with a use of non irradiated probe prior to actual irradiation. Before the clinical study, fundamental experiments were carried out for the influence of diode laser to skin and kidney. No appreciable changes could be observed to the tissue as long as laser irradiation was within 9 minutes. As to the control study, 22 of 24 patients (92%) showed no effect of laser irradiation. Even in small number of two cases, placebo effect was shown by the either the utilization of a sophisticated instrument or the maneuver of acupuncture. The total effective rate of laser acupuncture was noted in 31 of 32 (96.9%) and complete remission occurred in 12 of 32 patients (37.5). Therefore, from the present clinical study, laser acupuncture with Ga-Al-As diode demonstrated valuable method for the treatment of colicky pain by the urinary stone.

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The experience of laser hyperthermia in our urological clinic is reported. The treatment was performed in 3 cases of urethral tumor, one of urethral caruncle, one of bladder carcinoma specimen after total cystectomy and one of penile carcinoma.
A new type of ceramic tip was inserted into the tumor and Nd-YAG laser beam was irradiated with one watt of energy for 20 minutes The area 7mm distant from the tip was adjusted to the temperature of 42 to 43°C.
Macroscopic and histological examination showed an excellent antitumor effect in 2 cases of urethral tumor and one of penile carcinoma. This new modality of treatment seems to be applicable for multidisciplinary treatment of urogenital carcinoma.

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Whole bladder wall photodynamic therapy, using hematoporphyrin derivative as a sensitizer, the red light (wavelength 630nm) and a newly designed light-scattering device was carried out in a total of 12 patients with superficial multicentric bladder tumors with/without carcinoma in situ of the bladder. The total light dose was 10 Joules/cm2 to 30 Joules/cm2 except 216 Joules/cm2 in one patient. Clinical responses were evaluated by selected-site mucosal biopsies and cystoscopy 4 weeks after the treatment. The anticancer effect of photodynamic therapy was followed by urinary cytology and cystoscopic examination for 14 months. Out of the 12 patients, complete response defined as no malignant cells in all biopsies was attained in 8 patients. Out of the 12 patients no recurrence of bladder tumors developed in 6 patients with a mean tumor free time of 6 months.

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Photodynarnic effects of photoprotoporphyr in (Photo Pp) on cultured hepatocellular carcinoma cells (JTC-16) were studied, compared with those of protoporphyrin (Pp) and HpD, using an argon and dye laser. The photodynamic effects on the cells were evaluated by a phase contrast microscope at 24 hours after laser irradiation. An order of cell degeneration was obtained for Pp > Photo Pp and HpD. The cytotoxicity without laser irradiation of Photo Pp was less than Pp and HpD.

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HpD concentration in normal tissue of dogs and transplanated tumors of rabbits was examined after 5mg/kg administration by continuous intra-arterial infusion (c.i.a), one-shot intra-arterial injection (o.i.a), and one-shout intra-venous injection (i.v) for purpose the of increasing HpD accumulation in tumor. The following results for HpD concentration were obtained.
1. In tumor and non-tumor target organs it was statistically higher in c.i.a group and o.i.a than i.v group.
2. In the non-target organ it was statistically not significant among the three groups.
3. It was statistically not significant between c.i.a group and o.i.a.
4. Concentration of HpD polymer was higher than that of HpD monomer in tumor and liver.

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Recently the photodynamic therapy (PDT) for the malignant tumor has been advanced. We evaluated the efficacy of the.PDT for the malignant tumor of the parenchymal organs, especially hepatoma.
In WKA rat with tumor implanted in the subcutaneous tissue on the back, 5.0mg/Kg of Hematoporphyrin derivative (HpD) was administered via vein in the tail.
Forty-eight hours after administered, Argon Laser was irradiated the tumor under the dark condition and the fluorescence was observed only the tumor tissue which uptaked the HpD.
In experiment in vitro, in the medium containing DAB hepatis cells HpD was added and Argon Dye Laser irradiation was done.
Cytocydal effect of the irradiation with H D was evaluated by release assay. Cytocydal effect was noted in this experimental group compared with the control without irradiation and HpD adding.
As a result of this, potency of the PDT for hepatoma was supported.

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The present studies were performed to examine the feasibility and effectiveness of intra-abdominal PDT at the paraaortic area. Vessel walls except endotheliums, striated muscles and nerves were left intact in the irradiated rats with HPD. Endotheliums at irradiated region disappeared at early stage after PDT, but regeneration of endotheliums completed by 5 days. For implanted retroperitoneal tumor models, the group with PDT obtained a significantly longer survival rate than the group without treatment. These results suggest that intra-abdominal PDT is effective as an adjuvant cancer therapy without damaging normal tissues.

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Argon dye laser (628nm) irradiation for lymph nodes of rats was performed with light doses of 75 J/cm at 80mW at 48 hours after administration of 5mg hematoporphyrin derivative/Kg. Histological changes of irradiated lymph nodes were observed at 6,24 hours, 2, 3, 5, 7, 10 and 14 days after laser irradiation. Lymph nodes were highly reactive to photodynamic therapy (PDT) with HPD. Necrosis of lymph nodes occurred maximally at 24 hours after PDT. However, structure of the lymph nodes was completely restored to the former condition by 7 days after light exposure.

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In this study we have attempted to assess the therapeutic application of PDT by argon and dye lasers on gliomas. Brain tumor in rats was developed by implanting 1 × 10⁵ of 9L-gliosarcoma cells into the left frontal lobe through a burr hole craniotomy. Interstitial PDT was studied as a method in which a fiber-tip was inserted into the tumor tissue 2 days after intravenous injection of 10 mg/kg of HPD and 514.5 nm and 630 nm of wavelength laser were used. The radiant exposures were 50mw and 100mw at 5 and 10 minutes. Furthermore, the combined therapy of the interstitial PDT and the microwave (2.45 GHz) hyperthermia was studied. The antitumor effect of reducing the tumor size to 19 to 13% was obtained in all tumors by the combined therapies of the interstitial PDT by dye laser at 50mw for 5 minutes and hyperthermia at 44°C for 5 minutes. But they developed necrosis of surrounding tissues in 20%. It was proposed that further studies were necessary for the establishment of PDT as a new therapeutic modality for malignant glioma.

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Malignant brain tumors are characterized by a pleomorphic appearance and respond poorly to therapy. Several factors may influence the therapeutic resistance of malignant brain tumors, including metabolic heterogeneity.
In this paper, changes in brain tumor metabolism related to tumor growth are described and compared with the histological findings of tumor neovascularization. The topographic changes in energy metabolism (NAD/NADH redox state and cytochrome aa₃) in rat brain tumors (9L-gliosarcoma) were examined using the laser photospectroanalysis techniques developed in our laboratory.
The following results were obtained. (1) anerobic metabolism without function of NADH and cytochrome aa₃ was the main energy metabolism for maintaining tumor growth at the initial stage (5 clays transplanted brain tumors). (2) neovascularization from the surrounding tissue and increased tumor vascular permeability were observed in the brain tumor with tumor growth. As a result, a heterogeneous metabolic pattern including both oxidative and anerobic metabolisms appeared in 7 to 10 days transplanted brain tumors. (3) at the final stage (15 clays transplanted brain tumors), anerobic metabolism anti tumor-originated intratumoral neovascularization were observed.
The tumors thus had a special metabolic pattern in which the tumor was able to grow up independently with or without adequate oxygen supply.
This results also show that only using a free radical reaction of laser photodynamic therapy is incomplete because of the lack of the complete electron transport systems in tumors.

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The difficulty of identification of correct tumor localization is the most important problem during the surgery. For the over came of this problem.
We have established the photo-biophysiological diagnostic technique which is consisted by two apparatus system (1) the source of variable wave lengths excitation light, and, (2) super sensitive digital mapping analysis system of variable wave lengths emission lights of fluorescence and absorption lights. On the basic experimental studies, using these technique, the digital analysis of reduced cytochrome aa₃ and ATP. Na-fluorescein tumor marker, have been clarified the tumor localization correctly. This study opened the soficicated new surgical technique for the management of brain tumor.

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Chronic effects on the microvasculature of the rabbit brain were examined following one second exposure of Nd: YAG, CO₂, and the combination of both lasers, using soft X-ray microangiography and HE staining. Nd: YAG laser exposure showed that the edematous layer with tapered vessels was enlarged and the number of vessels in edematous tissue was decreased 2 days after exposure. 2 days after CO₂ laser exposure, however, the range of edematous layer was not so enlarged as Nd: YAG laser and the structure of vessels was well preserved. Combined exposure resulted similar effects on vasculature as Nd: YAG laser preserving cutting effect.

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To achieve laser angioplasty, blood between a laser catheter and a atheromatous plaque should be replaced by transparency material to a therapy laser. CO lasers which are suitable to eliminate thermal damage under laser angioplasty can not penetrate water involving material, such as pathological saline or blood. In this paper, the occasional formation of a gas pocket in artery for laser angioplasty is demonstrated. The gas pocket was produced by occlusion of proximal blood flow and injection of CO₂ gas in femoral artery of dog. The soluble CO₂ gas was selected to prevent air embolism. Continuous injection of CO₂ gas was necessary to conserve the gas pocket.

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In the medical laser apparatus, it is necessary to develop the suitable laser power light guide system. We have developed a nontoxic flexible CO₂ laser beam guide with metal-polymer compound structure hollow tube. The narrow tube and enough flexibility are required in endoscopic laser therapy and oral surgery, etc. In order to improvement of flexibility, we produce the trial narrow tube. The width of guide aperture was reduced from 8mm (previous product) to 4mm wide.
The present experimental results show that the transmission of bending state was above 70% at bending radius above 5cm. The emitted power of straight state was obtained ca. 15W at 30cm tube length.

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In the surgical treatment for the narrow nasal cavity and the larynx, little bleeding disturb the field of view.
We developed new probe and contact type tips of Nd-YAG Laser, which are easy to use in the narrow space, and use Nd-YAG Laser for various otorhinolaryngological treatments without bleeding.

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The contact Nd-YAG laser surgery was applied to the turbinotomy in severe patients with hypertrophic rhinitis and 10 cases with nasal allergy. This technique has a remarkable high controllability and causes less bleeding with minimal damage as well as good wound healing comparing with other conventional operations. It was also clinically revealed that there were marked improvement of the symptom of the nasal obstruction in both nasal disease groups, in addition to the impairment of the other typical symptoms of nasal allergy such as sneezing, watery nasal discharge.

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Using the Nd-YAG laser with ceramics-tip which was newly developed by us, clinical evaluation of the treatment in head and neck diseases was reported.
Contact Nd-YAG laser surgery was applied on 142 patients with head and neck diseases during the past 2 years. They were composed from 66 cases with head and neck malignancies, 20 cases with benigh tumor, 13 cases with tonsillitis, 16 cases with nasal allergy and other 27 cases. This laser technique is much more superior in head and neck surgery, especially maxillectomy and hemiglossectomy with less bleeding, time saving and wound healing as compared with the conventional laser surgery and electric scalpel.

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Based upon the 79 clinical cases treated with Nd-YAG laser surgery, the indication of Nd-YAG laser surgery for otolaryngology and head and neck were discussed. From our experience with laser therapy, the following conclusions could be drawn.
1. The use of Nd-YAG laser has proved to be good effects of mass reduction or necrotomy for carcinoma of the maxillary sinus.
2. Nd-YAG laser has been confirmed to be particularly of effective in surgery of hemangiomas and other readily bleeding tumors.
3. Endoscopic Nd-YAG laser surgery of tracheal stenosis is one of the most useful means in otolaryngological application which can not be substituted by any other alternatives.

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CO₂ LASER has been widely used for the treatment of benign and malignant tumors in the head and neck area. The LASER provides excellent hemorrhage control by sealing the capillaries. The LASER method of treatment also results in the minimal dissemination of cancer cells improving long term outcome. Survival rate as of October 1986 is 39/43 (90.7%) and all of the living patients are tumor free histologically.
Two patients died of generalized carcinomatosis, apparently related to the original tumor. Other two patients died of early generalized metastasis after total laryngectomy.

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Application of the laser power in the field of surgery has recently begun. In this paper we discuss benefits of Nd-YAG laser using a contact laser probe in the head and neck surgery. Twenty-seven cases of radical neck dissection and sixteen cases of reconstructive surgery using a pedicle myocutaneous island flap were carried out using contact Nd-YAG laser. Contact Nd-YAG laser surgery greatly reduced the volume of blood loss. The mean volume of blood loss was 93ml during radical neck dissection, and 73ml during the preparation of a pedicle myocutaneous island flap. This loss did not require blood transfusion. The volume of blood and exudate from negative pressure drainage after surgery was significantly smaller in laser surgery than in conventional surgery. There was no major complication in our laser operations. Laser probe can be used safely in cutting the skin and mucosal wall and in dissecting subcutaneous tissues since the identification of blood vessels, nerve fibers, and other parts is very easy because the bloodless operation.

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During the period from 1978 to 1985, 532 patients have been treated by means of carbon dioxide laser surgery at otolaryngology and head and neck surgery of the Kurume University Hospital. The carbon dioxide laser operation was performed on 621 cases composed of head and neck malignancies, benign tumors, and other lesions.
The laser surgeries which employ carbon dioxide laser are very useful in treating otorhinolaryngology and head and neck surgery when correctly indicated.

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We made peripheral liver infarction in normal canine livers by simultaneous coagulation of the potal vein and hepatic artery using Nd-YAG Laser in depth radiation. Three weeks after irradiation, this infarction was surrounded by fibrous tissue. and in four weeks, it was organized instead of falling into abscess.
Our method is useful for making small selective infarctions of the liver and should become a new method of treatment for hepatoma to eliminate of TAE faults.

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We applied echo-guided radiation of YAG laser within the resected bovine liver, to compare tissue change, echographic change and temperature distribution. There existed central vaporized cavity, charcoal zone and outer coagulated zone around laser fiber tip. The peripheral temperature of charcoal zone was 80-130°C and that of outer coagulated zone was 50-60°C. Hyperechoic area corresponded to tissue change. Hyperechoic area was larger than tissue change by 3-5mm. Behind the hyperechoic area accoustic shadow was recognized. From the comparative study, the acoustic shadow existed behind the central vaporized cavity.

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The purpose of this study was to evaluate laser evaporation of liver tumors under a fiberscopic laparoscope. We inserted a cholangioscope to the air-filled canine abdominal cavity, passed the laser guide fiber through the cholangioscope and irradiated the canine liver with 900 joules of YAG laser. The visible field was wide enough to observe both lobes and we could irradiate both lobes. Comparing to the operative laser evaporation, this technique is more valid because 1) there is no harm of total anesthesia, or 2) no harm of opening the abdomen. Comparing to the liver resection and transarterial embolization, this has also advantage because loss of liver function is much less. We conclude that our method will be a useful tool for the treatment of some kind of liver tumors in the future.

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In order to apply some interfaces on stand-alone laser treatment equipments which have been introduced into hospitals, we developed general purpose laser energy delivering system based upon the technology that has been established during developing Photo Dynamic cancer therapy system. The system developed consists of a therapeutic laser, laser beam destination selector, laser beam delivering fiber, light communication devices and of computer terminal. Delivery efficiency of laser energy was proved to be 80% by testing the proto type system. The output deviations of each 8 terminal was small. We checked the deviations by changing the fiber cable and got almost all the same results before changing it. Our prototype system showed enough performances previously expected. Our next steps of study to complete the hospital laser system should be taken (1) for smaller size,(2) for beam mixing and separating of various wave length lasers (3) for improved and integrated system, and (4) for low cost.

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Recently satisfactory results have been obtained with laser therapy. Lasers are expected to have wider applicability in the future.
The introduction of a new medical system to meet future demand was examined when the hospital was established. Functional and economical laser apparatus and the centralization of this system were under consideration for future laser therapy. From this point of view, a low-priced laser central supply system was developed. The laser central supply system is as follows. The laser beam produced by a YAG laser apparatus ISMS is transmitted through optical fiber cable via a fiber box to a connector box. A laser beam with equivalent output can be irradiated from the end of a secondary fiber cable joined to the connector box. The conditions for the irradiation of laser beam are indicated through interphone. There are foot switches in treatment rooms to start and stop the laser irradiation as a useful precaution.
The characteristics of this system are as follows. As the YAG laser apparatus IS101S is fixed, regulation on movement of the apparatus is not needed. It does not need large space other than a small fiber box and connector box on the wall in the treatment room. Moreover these boxes perform as well as the main machine. It does not require a large capacity power supply or water cooling apparatus in each treatment room. It is inexpensive and it is easy to set up additional YAG laser apparatuses or other laser apparatuses.

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Recently in Japan, a number of general hospitals managed by some medical associations has been built one after another. However, the systems of their medical service is not so different from that or conventional hospitals, moreover these new hospitals tend to be in conflict with local existing private clinics.
The laser system in this hospital installed YAG laser 2 unit, Argon laser 1 unit, Argon-Dye laser 1 unit in the central supply room, locating in the center of this fiber network system.
And there is a control box in each treatment room,(operation, endoscope, urology, gynecology, plastics, dermatology, etc.).
By this control box (in each room), doctor can select desired pieces of lasers among YAG, Argon, Argon-Dye and can set the condition of irradiation. Also compact, movable laser equipment like CO₂ laser apparatus can be available in any of the treatment room and operation room.

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To know the laser light distribution on and in tissues exposed to the lasers is crucial in the therapeutic application of laser technology, but there are few useful techniques to survey such a laser distribution, particularly in the case of low power diode lasers. In our practice of laser therapy the authors have found that near infra-red laser distribution can be easily detected by TVcameras provided CCD image sensor.
This experiment has been planned to evaluate the capability of CCD TVcamera to survey the laser light distribution on and in tissues and successfully performed. As a result even in such low power lasers as diode laser of mW order in out put the laser distribution can easily be detected on the TVimage. This technique must be extremely expected to clinical application of lasers.

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It is very important and desirable in laser treatment that the laser beam is irradiated to the target on a body surface keeping with the exact exposure condition throughout the treatment. The authors have devised a new laser exposure system the laser beam of which follows up the movement of the subject. This system is consisted of (1) tracer of a moving target, (2) computer output control unit for tracing signal of the moving target, (3) X-Y controller for operating X-Y table by the tracing signal and X-Y table to drive a laser handpiece to follow the moving target.

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By applying the heat effect of laser, it was attempted to fuse artificial materials to tooth enamel with laser irradiation for direct bonding tooth restoration. The fusing methods of enamel were studied and the fused enamel was analyzed. Among the pigments that were placed on the enamel surface, Fe₂O₃-particulate-dispersed agents solution was most suitable for the fusion of enamel, and the best irradiation condition was the focused beam of 20J energy (20WX1.0sec.). Three areas were observed for polarized microscopes and contact microradiograms. One of the areas is the radiopaque area, because the evaporation of water and organic components and the condensation of inorganic components resulted in the increase of its density. Second area is the radiolucent one because of the evaporation of some parts of inorganic components. Third area is the birefringence-changing area, because the enamel did not fuse but a small amount of water vaporized slightly from the enamel. X-ray diffraction pattern (Debye ring) of the fused enamel gave the facts that the orientation of axis of enamel crystal was dearranged and there were α-tricalcium phosphate which is in high temperature phases of hydroxyapatite. It is being in progress to study about fusing artificial materials to tooth enamel.

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The possibility of glazing by Laser was suggested, so next we observed the porcelain surface
(1) glazed by CO₂ Laser, (2) ground by carborundum point, and (3) finished by self-glazing, with electron probe X-ray microanalyser, Consequently the surface glazed by Laser was most uniform in comparison to another.

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In dental clinical procedure, the metal fused porcelain used in metal fused crowns and bridges, after reshaping or occlusal adjustment, must be subjected to glazing procedures.
Commonly, the metal fused porcelain is glazed by self-glazing in furnace.
In our studies, the possibility of glazing by Laser is reported in observation of the porcelain surface.

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The effect on acid resistance of human enamel by laser irradiation has been researched by many investigators since Stern et al. reported in 1984. However, there are still many problems to be resolved in order to clinically for the dental caries prevention system.
In particular, dental pulp damage by laser irradiation is of great concern, and so we have been studying this problem by using the teeth of monkeys and humans. In our study, we found that laser irradiation to the tooth surface is better at an energy density of under 80 J/cm² in the case of CW. Nd: YAG laser irradiation.
Furthermore, we examined the relationship between laser irradiation alone and laser irradiation with fluoride solution. As a result of the experimental study, we confirmed that there was evidence of acid resistance in the group of Ag (NH₃)₂ F. On the other hand, we recognized a strong relationship between enamel acid resistance and laser irradiation with NaF.
At present, we are clinically applying the above method for caries prevention. In the near future, we will report the results of our clinical work.

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Recently various soft laser are developed. They are useful in treatment. But the biological mechanism of the laser is not known in details. And psychosomatic effect may be considerable in the case of pain treatment.
So we evaluated the clinical effect of the soft laser for the pain, strange feeling, muscle stiffness etc in the oral and maxillofacial region objectively by double blind method.
As a result of this study, the irradiation group was effective as compared with the control group. We suggested that soft laser is really useful clinically.

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It is necessary to consider the peculiarity of teeth and the security of vital pulp in case of laser irradiation on teeth. The degree of temperature rise in coronal pulp after Nd-YAG and CO₂ laser irradiation was determined using freshly extracted bovine teeth that preparing the standard cavities of various depths.
The result proved that the degree of temperature rise by CO₂ irradiated in coronal pulp was evidently lower than that of Nd-YAG laser in case of laser irradiated with the same energy density.

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The interesting results about the effects of the laser irradiation on the vital dental pulp of the rat molars with or without Indian ink coating were reported. A long-term histopathological examination of the rat molar pulp at successive time intervals after cw Nd: YAG laser irradiation 0.3 sec. (36.5 J/cm²) and 0.5 sec. (61.5 J/cm²) revealed that there were 2 patterns of long-term effects of a single laser irradiation. The lased tooth with Indian ink coating showed prominent formation of the secondary dentin-like tissue following cell differentiation and proliferation of odontoblasts. On the contrary, the lased tooth without Indian ink coating showed progressing degeneration of the dental pulp and little formation of the secondary dentin-like tissue. The mechanisms of these different effects of laser irradiation were discussed.

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A beam of Argon laser would be highly absorbed on tissue or cells with red color. Few reports have been published about removal of gingival melanin with Argon laser. In a present case a young female patient who had typical melanin pigmentation was treated by the laser without local anesthesia. The pigment in gingiva was significantly removed by the laser with energy density of 60 J/cm². Furthermore, there is no recurrence of melanin pigmentation for 6 months after irradiation.
The biopsy revealed that melanin located in melanogenic cell layer was removed by the laser irradiation.

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