We conducted an experiment in curing traumas on 6-week old balb/c mice by He-Ne laser scanning. Square traumas were prepared in 20 mice at bilateral sites 5mm from the dosal median line. The right traumas in 12 animals were radiated by a He-Ne laser with an energy density of 4 Jules/cm²/2days from a day after trauma preparation, The left traumas served as a radiation control group. A slit of light 9mm×1mm was scan-radiated at a velocity of 2 sec./cycle for a width of 10mm using newly-developed He-Ne laser scanning apparatus. The remaining 8 animales (16 wounds) served as a non-radiation control group.
The mean length of the shorter sides of the square traumas were 5.5mm in the non-radiated and radiated traumas in the radiated group was 5.8mm and 5.7mm respectively, showing no significant diference at the t-testing. The average time required for the traumas to heal was 10.5 days for The non-radiated group and 10.8 days for the non-radiated traumas in the radiated group. The period required for the radiated traumas to heal was significantly shorter, 6.3 days (p<0.01). We thus confirmed that He-Ne laser scanning radiation is effective for treating traumas.

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The effect of acceleration wound healing by irradiating low energy and polarized light was studied using near infra-red Light Emission Diodes (LED) which is maximal at 840nm and half width of 20nm. The polarized light were linear polarized light and right and left hand circular polarized light. Two circular wounds were made on the back of a Wister strain male rat. Of the two wounds, the right side was irradiated while the left side not irradiated. The condition of irradiation was as follows: power density; 2J/cm, energy density; 8mW/cm irradiation interval; 24hr. The initial wound area had been defind as 100% and the rate of contraction of the wound has been measured during 48hr interval. The rate of contraction irradiated wound was larger than that of non-irradiated one. But we have not found significantly difference between the healing of irradiated and non-irradiated sides. And there were no difference in the acceleration effect of wound healing among the kinds of polarized light. In the case of the irradiation was done in the other condition of irradiation (power density; 2J/cm, energy density; 17mW/cm, irradiation interval; 48hr), linear and right hand circular polarized light were more effective than the other polarized light. We think that the threshold of the biostimulation effect changes with the kinds of polarized light. In other words, it is suspected that the optimal condition of irradiation for the acceleration wound healing is different among the kinds of polarized light.

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低出力レーザーの創傷治癒促進効果について実験的, 臨床的に検討した。
基礎的実験としてラット背部に円形の感染創を作成, 創傷作成後4日から7日間He-Neレーザー照射を行い, 創の面積の推移と肉眼的, 光顕的変化を比較検討した。創治癒が遅延していた群で, 照射により創縮小の速度が速まり, 照射側の創には照射開始後第11日に重層編平上皮様の構造が出現した。
臨床的経験として, 腹会陰式直腸切断術術後の会陰創4例, 血行不全による難治性皮膚潰瘍1例, 仙骨部褥創1例にHe-Neレーザー照射を短期間行ない, 有効性が確認された。
以上により, 創傷治癒課程の1時期, 特に肉芽の形成期に低出力He-Neレーザー照射を行なうことで, 創治癒機転が早められることが示唆された。

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In our previous study, we found that Pseudomonas aeruginosa is more sensitive to Ar-laser than Esherichia coil and Staphylococcus aureus. In present report we applied Ar-laser to various kinds of bacteria. 1ml (10⁶-10⁷ celis/ml) bacteria solution was mixed into Muller-hinton medium. And after 30min laser irradiation of 20, 40, 60mw, they were incubated at 37°C for 48hours.
The result was that P. aeruginosa, P, fluorescens, E. coli, S. enterotidis, P. mirabiris, M. morganii, are sensitive to Ar-laser photoirradiation, but the others are not sensitive at that power.

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The effect of low power He-Ne laser (632.8 nm, 8.5 mW) on hypotonic hemolysis in human red cells was investigated.
Red cell floating saline solutions (0.8% NaCl, pH7.0) were centrifuged and the sediments were irradiated for 0 (control), 1, 3, 5, 7, 10, 15 and 30 minutes. Each irradiated sample was transfered into a hypotonic solution (0.405%NaCl, pH 7.0 ). After leaving the samples at room temperature for 10 minutes, optical density of every suspension was measured spectrophotomechanically at 545 nm of wave length to determine hemoglobin content.
Percent hemolysis of the control samples was 51.7±10.3% (mean±SD, n=18). Relative hemolysis at 10 and 15-minute irradiation significantly declined in comparison to the control value.
These results suggest that low power laser beams have a protective effect on red cells from hypotonic hemolysis.

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218 cases involving the application of dye laser treatment to portwine stain (PWS) using Candela model SPTL-1 tunable dye laser have been studied for a 16-months period. In the 166 cases having deeply located type (DLT) of PWS. there were many cases (78%) which have incomplete blanching result of coloring. To improve the blanchig result of the DLT cases, we have studied on additional irradiation effect and early treatment in infants using SPTL-ldye laser.
1. Two or more additional irradiations of dye laser on the same lesion were made on the 23 cases of DLT-PWS, and the effect was evaluated using a halfsided comparative method on the same lesion. The 19 cases (82%) of this study improved the blanching result without any scarring.
2. The reasonable minimum intervals of the additional irradiation was a 4months period, because the pigmentation after the previous irradiation had been disappeared within 4months.
3. Early treatment of PWS in infants was made on the 9 cases of infants under two years of age. The blanching effect was recognized on every cases without any side-effects. The early treatment was efficient, because the size of widely spreading PWS, such as Klippel Weber syndrome, were relatively small in infants.

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Treatment of hemangioma simplex using dye laser is recently accepted generally for the excellent effect.
Since september 1988, we have been treating hemangioma simplex using dye laser (Candela Model SPTL-1) and the results are so far satisfactory.
Though the results are usually evaluated subjectively by patient or physician or both, we applied the Chroma-meter (Minolta CR200) to evaluate the effects of dye laser by the color differences between normal skin (control) and treated site measured before and after the irradiation.
The Chroma-meter revealed very useful in objective evaluation of this treatment.

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The therapeutic effect of lasers on abnormal colored lesions of skin or mucosa is to apply the difference of the absorption process of lasers on abnormal colored tissue from that on normal colored tissue depending on the colors, which is one of the most usuful clinical applications of lasers. In the therapeutic application of lasers to colored lesions, some high powered lasers such as argon laser or ruby laser have usually been used. The authors have proved the useful the-rapeutic effect that a mW level low power He-Ne laser has the discoloration effect on vasculogenic red lesions such as subcutaneous hemorrahage, capillary disorder, hemangioma and so on.
The authors designed to examin the variation of skin surface temperature after exposure to He-Ne laser and obtained the interesting results that in some cases, the skin surface temperature actually fall slightly. The results in this experiment coincide with the results in the experiment on the morphologic changes of the vessels and the circulatin of rat skin induced by the exposure to He-Ne laser. Based on these results, the mechanism on the discoloration effect of He-Ne laser on vasclogenic red lesions is discussed in this paper.

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Eighty-five children, two months to 12 years of age, with port-wine stains were treated with the flashlamp dye laser (Candela, SPTL-1P, SPTL-1).
The children who did not have significant lightening at the first treatment would receive 2 or more treatments at intervals of more than one month.
At least six months after the final irradiation, evaluation of its effects were made as follows: Excellent; Identical to uninvolved skin, Good; Marked improvement, Fair; Slight improvement, Poor; No improvement.
Satisfactory results (excellent or good) were achieved in 80% of the children, and less satisfactory results (fair or poor) were achieved in 20% of the children. Seventeen children who were judged to have less satisfactory results, received only one or two treatments. All the children who received three or more treatments were judged to have satisfactory results.
All children were treated without hypertrophic scarring.
It appears that the flashlamp dye laser is capable of favorably treating port-wine stains in children with the advantage of avoiding side effects. It seems that increases in number of treatment times are positive factors for obtaining satisfactory results.

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For the treatment of nevus spilus, we have used carbon dioxide laser and dye laser. The results have been better than those of the conventional methods such as dermabrasion and dry ice therapy. To control the effective depth and enable an even irradiation for a significant area, micro-manipulator is successfully combined with the carbon dioxide laser, preventing hypertrophic scar. Although the mechanism of dye laser treatment for nevus spilus is not proven, we have recognized that the dye laser irradiation is one of the most beneficial treatment for nevus spilus.

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Fundamental studies of the laser irradiation effect on skin of black-colored guinea pigs rat and ear of white Rabbits were carried out using two different lasers, Ruby (694.3nm) and Dye (585.0nm) lasers.
Deep roots of hair were destroyed by Ruby laser irradiation and shallow superficial region was damaged by Dye laser.
At ear of Rabbit, Ruby laser gave almost on damage through the tissue, While Dye laser induced agglutination around at red blood cell within blood vessels.
Selectivity of the damage region around basal layer of the epidermis was observed between with 0.5 and 2.5 msec Ruby laser pulse irradiations.

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Currently, the pain due to Dry Ice therapy for Ota's nevus, laser therapy for portwine,stain and pigmented nevus, has been intolerable, especially for children. Recently in Europe and United States of America a local anesthetic named EMLA cream has been used to reduce this kind of pain. As we have used EMLA cream for 3 years for Dry Ice therapy, or laser therapy, this drug is not easily availabel in Japan. So we have developed a new cream which has similar effects. Thus we have compounded a 7% lidocaine cream and found out that this cream has similar effects as the EMLA cream. In this report, we described the comparison of our 7% lidocaine cream and the EMLA cream.

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We performed Nd-YAG laser therapy for patients with nevus Ota via 2 different irradiation methods on each patient. Nevus Ota has been recognized that it is due to the growth of melanocyte in the intra-dermal. We irradiated lesions with low energy, non-contact, and frequent irradiation. Two different methods were apllied (A&B). In method A, we used the special probe to uniform irradiation with 80J/cm₂, in method B, we stained the lesion in black with 2J/cm₂. In both of these 2 methods, we observed the disappearence of melanocyte to the depth of 450-550μm histologically with no damage of epidermis.

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113 cases involving the application of ruby laser treatment to melanin pigmented skin lesions using Toshiba model LRT-301 A ruby laser system have been studied for a 10-months period. The results of such treatment and some of its advantages compared with the results of dermabrasion, cryosurgery, and argon laser treatment are reported.
1. Post operative inflammatory redness and pigmentation were extremely slight compared with the results of the conventional methods, and disappeared within a one-month period. Consequently,a period of post operative care and intervals of additional treatment were shortened.
2. Superficially located pigmented lesions in the basal layer of epidermis, such as nevus spilus and senile fleck, easily disappeared after only one ruby laser treatment, without any side-effects.
3. Pigmented lesions located in the upper layer of dermis, such as compound type of nevocellular nevus, incompletely disappeared after one ruby laser treatment. Two or more additional laser treatment would be required to remove these lesions completely.
4. Deeply located pigmented lesions in the lower layer of dermis, such as intradermal type of nevocellular nevus and Ota's nevus, resulted in scarring or hyperpigmentation after the minimal energy irradiation of ruby laser(20 J/cm₂). Because the ruby laser beam penetrated the deeply located lesions and coagulated the almost whole dermis.

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The transmission characteristics of OH doped quartz fiber and metal hollow tube for KrF, XeC1 lasers have been investigated. In XeC1 laser, the transmittance of 85% at lm length fiber was obtained. At high intensity transmission, the reduction of transmittance was observed and this reduction was suppressed by OH doping into core glass. In KrF laser, the transmittance of 85% in OH 800ppm fiber was reduced to 25%, but that of <2% in OH 2-5ppm fiber was elevated to 60%. The transmittances of metal hollow tube for KrF, XeC1 lasers were 35%, 50%, respectively. The transmission power in hollow tube was about ten times higher than that in fiber.

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The incision characteristics of bone were experimentally investigated in two excimer lasers; KrF (248nm) and XeC1 (308nm). The thermally affected region around the laser-irradiated area in XeC1 laser irradiation was larger than that in KrF. The drilling depth per unit pulse in XeC1 was smaller than that in KrF. Biotissue is supposed to be incised by ablation effect under high peak power laser irradiation, which depends on laser absorption characteristics of biotissue.

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Incision of biotissue by Er: YAG laser (2.94μm) and TEA-CO₂ laser (10.6μm) has been investigated. Incision ability of Er: YAG laser for biotissue (beef, bone) was experimentally confirmed to be superior to TEA-CO₂ laser. For moisture biotissue incision by Er: YAG laser is efficient. Er: YAG laser is more strongly absorbed by water (in biotissue) than CO₂ laser, so Er: YAG laser is supposed to have high incision ability.

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The thulium-holmium-chromium: YAG laser (THC: YAG) with a wavelength of 2.1μm offers tissue penetration on the intermediate order compared with other YAG lasers; Nd: YAG laser and Er: YAG laser, and has an advantage of efficient transmission through flexible quartz and floride fibers. In this paper, we report the development results of a flashlamp pumped THC: YAG laser and its delivery system consisting of quartz fibers. An output energy of 1J and an average power of 5.6W at a pulse repetition rate of 1pps and 10pps, respectivly. The maximum transmission efficiency through quartz was 92%. We also perfomed an in vitro comparison of Nd: YAG,Er: YAG and TUC: VAG lasers for tissue ablation by using meats. From these results, we conclude that THC: YAG laser has good potential for a tissue coagulator in pulse operation.

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To develop the efficient and safe laser lithotripter, suitable wavelength (WV) of pulsed dye laser was attempted to determine.
(1)Both CA-OX and CA-P had the peak ref lectance at about 1000nm and reflectance was weakened as the WV became short. This tendency was more obvious in CA-P than CA-OX. The ureter and blood had high reflectance between 460 and 530nm WV. (2)Between 480 and 504nm WV laser, there was no difference in energy to create shock wave on the surface of the CA-OX. However, the energy required to generate shock wave in CA-P at 480nm WV was about 60%of that required at 504nm WV. (3)There was no difference in the degree of tissue injury produced either by 480nm or by 504nm WV. Both 480 and 504nm WV laser were desirable for CA-OX disintegration. However, 480nm WV was more efficient than 504nm WV for CA-P disintegration and was equally safe as 504nm WV.

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A method is studied for evaluating the blood flow at the ocular fundus using laser speckle phenomena. The intensity fluctuation of time-varying speckles scattered from a 1-mm diam probe area at the fundus is detected and analyzed by the photon correlation technique which gives us the relative degree of total blood flows within the probe area. The experiments were performed to evaluate the blood flows in a glass capirally and at the ocular fundus of a rabbit. The results show the usefulness of the photon correlation technique for obtaining the blood flow information from speckle signals.

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The laser speckle method is further studied for evaluating the blood flow at the ocular fundus of normal human volunteers on the basis of the photon correlation technique. The time-correlation length τ_c of the photon correlation function varies obviously due to the change of the probe position at the human ocular fundus. This paper also studies the ways of eliminating the effect of eye movements and of estimating the shape of the photon correlation function. The experimental results show that the present method can provide favorably the blood-flow information.

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Peripheral tissue blood flow (PTBF) of the index finger was measured by laser flowmeter during extracorporeal circulation (ECC) in coronary revascularization patients (group I n=15) and in repair of ASD or VSD patients (group II n=5) respectively. Before ECC, PTBF mesured in group I was 17.3±15.5 and that in group II was 18.61±9.0. But during ECC, PTBF of group I was 17.9±8.1 and higher (p<0.01) than 1.4±0.5 which was measured in group II. And Correlations between PTBF and hematocrit, systemic vascular resistance index and urine output during ECC were not significantly different.

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Rat livers in-vivo were irradiated with two types of laser rays with different wavelengths under the same conditions. With the Nd-glass laser ray, various examinations showed no changes in the rat liver. The Nd-glass laser rays were less absorved and scattered in the liver tissue. With the ruby laser ray irradiation, necrotic liver cells were found in the center of the exposure site and fatty degeneration was seen in the nearby surrounding area. Moreover, increased lipid peroxidation, which could cause these phenomena and probable is secondary to radical generation, was demonstrated biochemically (TBA test). The site of this fatty degeneration coincided with the localization of GSH-Po, a scavenger for lipid peroxide, which is known to stimulate GSH-Po synthesis. This finding suggested that the fatty degeneration might be attributed to the increased lipid peroxide. The results suggested that cells exposed to laser rays strong enough to inhibit both synthesis and activity of GSH-Po might be necrotized by the direct action of radicals or the toxic action of lipid peroxides beyond the defense capability of GSH-Po.

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The effect of Er: YAG laser on living tissues was studied through the observation of coagulation and evaporation in Wister rat skins.
Pulse irradiation number and repetition frequency dependences of the evaporation cross section of the tissues were observed. Very thin coagulation layer was observed. The cross section was not increased with the pulse number according to the effect of bleeding. After irradiation over certain number of pulses, the increase of the cross section was observed,which was assumed to be come from the enhanced coagulation of the tissue.

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We have studied the effects of superpulse YAG laser by changing its peak energy and wave length when irradiated on an animal tissue, with the idea that by changing the peak energy and pulse duration the superpulse laser could be used both for cutting and for coagulation. With the irradiation of superpulse YAG laser of three different wave lengths (1064, 532, 355 nm), it was shown that the higher the peak energy and the shorter the wave length, the better the vaporization and the lesser the thermal effect of the tissue. This laser may be used for variety of conditions.

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The reaction of super pulse laser, which has very high peak power and very short pulse duration, in living cell destruction was investigated.
Pulse YAG laser with Q switch, which is able to oscillate three different wavelengths, was used for the super pulse laser. Its pulse duration is 8 nanosecond and its original wavelength is 1,064nm which is involved in infra red. The second harmonics oscillates 532nm as visible laser. The third harmonics oscillate 355nm as ultra violet laser. Rat and rabbit were anesthetized and super pulse laser was irradiated to there muscle for 10 minutes with one pulse/second and 46-1,000mJ/cm² of energy under three different wavelengths. The reaction in cell destruction was investigated with an electron microscope.
In 1,064nm, almost no reaction were observed. In 532nm, mitochondria was expanded. In 355nm, mitochondria was destructed to be. vacuous. The heat diffusion inside the cell is thought to be very small with super pulse laser irradiation, as the destructed particle inside the cell was able to be detected.

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Mono-L-aspartyl chlorin e6 (NPe6) tetrasodium salt tetrahydrate is a compound with a mol. wt of 871.75 in which the double bond porphyrin ring has been reduced and an aspartic acid is attached to the propionic group at the 17th carbon of the tetrapyrrole ring via a peptide linkage. The absorption peaks of NPe6 in PBS solution pH7.4 appeared at the 502, 530, 620 and 654nm. The fluorescence peak of NPe6 in PBS solution appeared at a 662nm with a 400nm excitation. Addition of bovine serum albumin into the phosphate buffer saline solution conteins 1.0×10^-5mol/liter NPe6, the absorption spectra of NPe6 showed a shift of about 10nm towareds longer wavelength (bathochromic shift). Each of the above solutions and mixtures were excited with a 400nm to give a fluorescence spectrum curve of NPe6. The fluorescence peak appeared at 662nm for a without BSA, BSA solution showed a peak at 672nm.
Absorption peaks of 1,0×10^-6mol/liter BSA in the phosphate buffer saline solution pH7.4 appeared at the 278 and 288nm. The fluorescence spectrum of the BSA showed a peak at 350nm with a 290nm excitation for tryptophan.
Addition of BSA into the 1.0×10^-5mol/liter NPe6, fluorescence peak of BSA showed a shift from 350nm to 320nm and the relative intensity of fluorescence decreased from 1.0 to 0.1 at 290nm excitation. Then fluorescence peak of NPe6 appeared at 672nm with a 290nm excitation. The relative intensity of fluorescence at 672nm increased proportionaly with a added concentration of BSA.
These changes were due to the energy transfer from tryptophan residues in BSA to NPe6. It is suggested that NPe6 interracted with a BSA.

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We are pursuing the new biomedical measurements using highly sensitive detecting techniques of ultraweak photon emission from subjects related to human being. Ultraweak photon emission phenomenon (Biophoton emission) is caused by biochemical reactions in living body, and closely associated with biological functions. Especially this phenomenon is known to be related to the production of excited species or radicals in the process of lipid peroxidation of living body. This detection of ultraweak photon emission should provide new information on the physiological state of the body. We have measured ultraweak photon emission characteristics of human breath, particularly the temporal change of photon emission during excessive exercise. It was then found that their characteristics reflect the physiological change in body condition during the exercise, and their measurement is valuable to provide new biomedical information.

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It is essential to understand the dynamic behavior of the excite triplet state of sensitizer in PDT (Photodynamic Therapy). Usually the Laser Flash Photolysis is used for measuring the triplet state in vitro, but the method for in vivo has not been reported. In this study we developed the system for in vivo measurement of the triplet state. The animal experiments revealed that the life time of HpD and NHpD in vivo is almost coincide with the life time of air saturated HpD and NHpD in vitro.

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The fluorescence emission spectra of hematoporphyrin derivative (HpD) from the bladder of C3H/He mice with experimentally N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) induced carcinoma in situ (CIS) were measured by an endoscopic spectroscope fluorescence detection system following intraabdominal injection of HpD. HpD contained in carcinoma in situ of the bladder was exited by an excimer laser pumpted dye laser at a wavelength of 405nm, 7.5Hz. The autofluorescence spectra from the normal bladder without HpD were subtracted as back-ground. The intensity of HpD in the bladder was determined by the excimer-dye laser at a wavelength of 630nm. The bladder with CIS and the normal bladder following HpD injection exhibited characteristic HpD fluorescence specrum having 2 peaks at 630 and 690nm.
No fluorescence spectrum was detected from the bladder bearing CIS without HpD administration. When the distance between the spectroscope and animal bladder surface was less than 10mm, the fluorescence magnitude of the bladder bearing CIS was significantly (p<0.05) higher than that of the normal bladder from 72 to 144 hours following HpD administration.
This system is effective on demonstrating the fluorescence spectrum differentiating the fluorescence magnitude of the bladder bearing CIS from that of the normal bladder. To obtain a geographical mapping picture of the CIS in human following HpD injection, a more sensitive detecting system should be used because the human bladder has a large capacity.

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The purpose of this study is to examine the effect of Nd: YAG laser irradiation on the amputated pulp of the rat developing molars.
The amputated pulp was irradiated with Nd: YAG laser (5W 0.1sec or 15W 0.1sec). The cavity was then covered with silver amalgam after coating the pulp with calcium hydroxide. Histological examination of the specimens was made postoperation to 2 weeks after amputation.
2 weeks later a large amount of dentine bridge covered the amputated pulp in the 5W lased specimens. On the other hand the 15W lased specimens showed fibrous dentine formation on the wall of the orifice of the root canal. But the continuation of normal root development was observed in all specimens.
These results suggest that the irradiation to the amputated pulp with Nd: YAG laser may be useful for the endodontic treatment of the developing teeth.

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Tooth pulp response to the irradiation of Nd: YAG laser on class five cavities was examined in this study. The cavities were prepared with a standardized diamond point so that the thickness of remaining dentin was 350 to 550μm. The experimental periods were 3, 7 and 28 days after the irradiation of continuous Nd: YAG laser wave (1w 5sec, 1w 10sec, 5w 1sec and 10w 1sec) on the cavities.
The pulp wound recovered with time. After 28 days, the tooth pulp tissue returned nearly to normal and the secondary dentin formation was found under the remaining dentin. More secondary dentin was formed in the laser-irradiated group than in the non-irradiated control group.

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We have already reported at the ninth meeting of this academy some opinions on radiological observations of the healing process of experimentally induced extract cavities irradiated with low energy laser. This time, we reported further opinions on radiological observations of the healing process.
(1) From the radiographic and macroscopic observations, there were no significant differences between the laser-irradiated groups and non-irradiated (control) groups at any period of the observation.
(2) On the three and four-minute irradiated groups, the new generation and expansion of the vascular system were slightly more energetic at three and seven days after irradiation on the microangiographic specimens.
(3) In microradiographic specimens of the three-minute irradiated group, the widespread generation of trabecular bone from the cavity wall as well as the cavity bottom was observed on the seventh and 14th days after tooth extraction.
(4) The vascular and bony conditions of the ten-minute irradiated groups were as energetic as the non-irradiated (controll) group for any observed specimens.

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In order to investigate the influence of local hyperthermia by non contact low power Nd-YAG laser irradiation (laserthermia) on the normal oral tissue, a fundamental study has been made in the tongue of rabbit. Laserthermia was administered directly to the dorsum of the tongue via 2W of Nd-YAG laser irradiation with a spot diameter of 4mm. During laser irradiation, the temperature of the spot was measured continuously and kept constant at 43, 47 and 51°C. Irradiation time was set as 20min at a time, twice weekly for 2 weeks at each temperature, and at every time of laserthermia, the tongue was examined histopathologically. For comparison, tungsten halogen lamp and hot water were chosen as the method with which the same temperature of laserthermia is obtainable, and a similar experimental study has also been made.
At 43°C for once through four times, no remarkable change was observed by any method macroscopically histopathologically. With laserthermia at 47°C for once, observed were edematous change in the whole region of the tongue and bulla in the sublingual portion. Such changes were seen more strongly, and ulcer formation grew as the frequency of laserthermia increased. With laserthermia at 51°C, extensive necrosis mass grew. Also at 47 and 51°C by tungsten halogen lamp, similar histological changes were observed but evidently weaker than those by laserthermia. While similar findings were seen scarcely with hot water at 47°C, but at 51°C, the severity of the edema in the whole region of the tongue was almost the same as that by laserthermia except for lacking the bulla.
It was considered that laserthermia has a sufficient potentiality of increasing the temperature of a selective local site as narrow and intricate as the oral cavity.

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In this experiment, the-authors observed the depth of tissue penetration of contact Nd: YAG laser irradiation on the circulatory structure of a rat's tongue and the following healing process using the injection replica scanning electron microscope method. The experimental animal was a 6-week-old, male Wister rat, and the irradiation power was 6W delivered for 1 second. Experimental data was collected directly after irradiation and on the 1st day, 4th, 7th, 10th 14th and 21st.
Directly after irradiation, scanning electron microscopic observation of the tongue's surface showed that the wound was large and that the blood vessels surrounding the wounded area were well-sealed by laser irradiation. There was very little fluid secretion and the blood vessels were well-fused together. On the 4th day, the healing was progressing with great activity, and numerous blood vessels were reaching out from the edge of the wound towards the center. On the 7th day, the blood vessels had joined together and the recovery of the circulatory network of the new tissue was nearly complete. On the 21st day, observations showed that capillary loops directly beneath the filiform papillae were gradually being reconstructed from the edge of the wound.

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The present study was performed to investigate the healing process of ablation wound by eximer laser irradiation. A 1×1×5 mm-sized ablation defect was made on the dorsum of the tongue of the mature male Wistar rat under the following irradiation condition: wave length; 248 nm, pulse width; 15n sec, power density; 12W/cm²; pulse repetition rate; 20 Hz, irradiation area; 1.2×5.0 mm, irradiation time; 60 seconds (experimental group ). The same sized defect was made by Nd YAG laser irradiation (10 W) with a contact probe (control 1) and by stainless steel surgical knife (control 2).
The tongues were harvested and examined histopathologically at timed sequence from 1 hour to 7 days after irradiation or excision. Severe thermal damage around the wound prolonged in control 1. In experimental group, wound showed marked hemorrhage during irradiation and slight thermal damage around the defect. Its healing process was almost the same as that of control 2, and the wound healed earlier than that of control 1.

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