Disturbance of the sense of taste is known to be caused by radiation therapy for tumors in the head and neck region. For the purpose of investigation of changes of the lingual papillae pathohistologically, X-ray irradiation to the lingual dorsal membrane of the tongue was experimented and light microscopic and scanning electron microscopic observations were made. Nineteen young dogs, 3∿5 months old, were used for this experiment. Single dose of 1, 000_R was given in three irradiations at intervals of three days. Observations were made on the 1st, 3rd, 5th, 9th, 15th, 35th, and 60th days. The main findings were as follows. 1. The dogs became slow in motion, lost appetite, and left a third of their feed beginning on the 5th day after irradiation. From the 8th to 9th days, eye mucus and secretion from the eyes increased and appearance of weakness increased. Beginning on the 15th day, signs of recovery were observed. 2. The cases on the 5th day showed marked degeneration of yellowish-brown color of the lingual mucous membrane in the region closest to the irradiation tube. 3. Microscopically, the degenerated region was coincident with the region of erosion formation in which neither the lingual papillae nor epithelial layers were observed. Lamina propria of the mucous membrane where infiltration of inflammatory cells was marked was exposed directly. 4. Scanning electron microscopic observation of this erosion region showed a mixed finding of innumerable inflammatory cell group that migrated to the surface of the lamina propria and debris of the epithelial layer. 5. In the lamina propria of the mucous membrane of this region, connective tissue fibers were disorderly arranged and most blood vessels were congested and expanded. Muscular fiber groups extending to this layer were atrophied and striated structures were unclear. 6. The filiform and fungiform papillae in the ordinary mucous membrane neighboring to the degenerated one maintained their forms. However, erosion in part of the epithelial layer and edema in places including the lamina propria were seen. Scanning electron microscopically, both papillae changed some in morphology and their surfaces were rough, and countless microorganism and parasite-like structures aggregated together densely. The taste buds of fungiform papillae decreased in number, and showed atrophy, decrease, and vacuolar degeneration of their cells (light or sustentacular cells). 7. In the cases on the 5th day and those on the 15th day, the discolored region of mucous membrane was considerably limited beginning with the cases on the 9th day. In the cases on the 15th day, limitation was brought about by restoration of epithelium. Inflammation of adjacent healthy colored region was slight. 8. The shorter the interval after irradiation, the lighter was disturbanced. In the cases of one day after irradiation, especially, any region appeared about the same as that of controls. 9. As epithelium of the mucous membrane recovered and prolifered in the cases on the 15th day and thereafter, the number of taste buds and of taste bud cells was restored. However, atrophy of cells still continued and cell arrangements were irregular. Even in the cases on the 35th day after irradiation infiltration of inflammatory cells was seen in some taste buds and complete restoration to the normal image was seen only after 60 days.

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Left mandibular fourth premolars were irradiated for 3, 000 R using 200kVp X-rays, and effect on the dental pulp and periodontal membrane was investigated histopathologically. The results were as follows : 1. One week after irradiation, the dental pulp showed normal findings except for inflammatory cellular infiltration limited to a portion of the coronal pulp. Marked changes were hardly seen in the root dentin, epithelial sheath of Hertwig, or periodontal membrane. 2. Two weeks after irradiation, findings of inflammatory cellular infiltration and reticular atrophy limited to the coronal pulp were observed. In the epithelial sheath of Hertwig, calcification of cementum was active and cementoblasts were arranged densely. In the periodontal membrane, fiber bundles of the periodontal membrane were running disorderedly in both the lingual and buccal periodontal membrane. 3. From one to two months after irradiation, inflammatory changes continued in the coronal pulp. Deposition of hyaline materials was seen around blood vessels. The apical pulp underwent hyaline degeneration, and calcareous degeneration was also observed on the blood vessel walls. The pulp chamber was still spacious and root dentin showed good growth. Collaterals of the root apex were increased in number. In the periodontal membrane, fibroblastes decreased slightly and the finding of hyalinization was beginning to be seen. In the alveolar process, inflammatory cellular infiltration extended diffusedly and the finding of resorption was seen in the bundle bone. 4. From four to six months after irradiation, reticular atrophy and hyaline degeneration were observed markedly in the dental pulp from the crown to the apex. At this period, root dentin was formed thickly and the pulp chamber was small ; however, obliteration of the apex by cemetum was still incomplete. The periodontal membrane, although healthy in part, underwent hyaline degeneration on the whole and disappeared in many portions. Tlhe bundle bone also showed the resorption image. The periodontal membrane directly under the apex in particular was replaced by fatty marrow. 5. Eight months after irradiation, the dental pulp on the whole showed marked degenerative changes. However the pulp chamber became small along with formation of root dentin. Obliteration of the apex was incomplete yet although it was tentatively obliterated with addition of cementum. The periodontal membrane underwent severe hyaline degeneration. At this period, images of new bundle bone were observed sporadically. The periodontal membrane directly under the apex were replaced extensively by fatty marrow. 6. On the basis of the foregoing findings, it was proved that although irradiation brought about marked changes in the dental pulp and periodontal membrane, formation and growth of the root progressed rather satisfactorily, but obliteration of the apex was incomplete.

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For the purpose of studying radiation injury on mandibles at growth stage, the mandibles of young adult dogs were irradiated with X-ray of 200 kVp, and the irradiated intraoral tissues such as gingival membrane, teeth and mandibles were investigated macroscopically and the teeth and mandibles radiologically. The result were as follows : 1. As the injury on irradiated skin, partial epilation began two days after irradiation and ulceration (4 out of 16 cases) formed at 79 days and worsened further, and necrosis was seen in all subjects at 195 days. From one to three weeks was the acute phase when partial epilation, wet erosion, swelling, total epilation, pseudomembraneous formation were seen. After two months was the critical phase when ulceration and necrosis were observed. Between these two phases, a recovery phase with crust formation and desquamation was observed. 2. As the injury on the intraoral tissue, pigment loss in the gingival membrane began four days after irradiation. Ulceration of gingiva (2 out of 16) formed at 30 days and worsened, and exposure of the alveolar bone was observed at 208 days. At 220 days, bone fracture (6 out of 16) was observed. From one to three weeks after irradiation was the acute phase when pigment loss in the gingival membrane, reddening of the gingiva, and easy bleeding were observed. The third months was the critical phase when ulcerated gingiva, necrosis, exposure of the alveolar bone, and loose teeth were observed. The eighth months was the terminal phase when loose teeth, bone exposure, and gingival necrosis besides bone fracture were observed in all subjects. 3. Formation of necrosis in the gingiva leading to necrosis of the skin corresponding to the third premolar was found in four cases. Formation of necrosis in the skin corresponding to the third premolar leading to necrosis of the gingival membrane was found in 12 cases. 4. In radiological findings, enlargement of periodontal membrane space, disappearance of lamina dura (6 out of 16), and resorption of the alveolar crest (6 out of 16) began in the subjects at 1 month. Worsening began with bone destruction (10 out of 16), bone destruction accompanied by osteosclerosis, and erosion of inferior border of the cortical bone (8 out of 16) in the subjects at 3 months. Formation of sequestrum (4 out of 16) at 6 months and bone fracture (6 out of 16) at 8 months were observed. From one to four months was the critical phase when enlargement of periodontal membrane space, disappearance of lamina dura and of periodontal membrane space, bone destruction, and erosion of the cortical bone were observed. Thereafter, formation of sequestrum and bone fracture were seen. 5. In radiological findings for the subjects with formation of ulceration, enlargement of periodontal membrane space, and resorption of the alveolar crest were the early findings and lamina dura image around the bone destruction image followed. In radiographic findings for the subjects with formation of ulceration of the skin corresponding to the third premolar, the early findings were resorption of the alveolar crest, lamina dura, disappearance of periodontal membrane space, and disorder in trabeculae. Bone destruction image accompanied by osteosclerosis was observed thereafter.

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Left mandibular third deciduous molars of young dogs were irradiated for 3, 000R with 200kVp X-ray and the effect on the dental pulp and periodontal membrane was investigated histopathologically. The results were as follows : 1. From 3rd to 7th days after irradiation, localized inflammatory cell infiltration was observed in part in the dental pulp tissue. In the fiber bundles and blood vessel walls, deposition of hyalin stained lightly with eosin was beginning to be observed. No abnormal findings were observed in the periodontal membrane. 2. On 14th day after irradiation in the coronal dental pulp, cells decreased ; karyopycnosis occurred ; cells were connected only by cellular processes, and large and small reticular networks were formed. In the periodontal membrane, fibers ran irregularly although in part and findings of atrophy were seen. Fibroblasts showed a decreasing tendency. 3. In the cases from 1 to 2 months after irradiation, the pulp tissue showed marked atrophy of odontoblasts and the dental pulp showed hyalinization-like changes. Calcareous degeneration stained densely with hematoxylin was found scattered around the blood vessels. Although the pulp cells dicreased extensively but normal pulp cells were still found. In the periodontal membrane, Sharpey's fibers ran irregularly or became indistinct, and fibroblasts decreased extensively. The periodontal membrane in general showed hyalinization. 4. In the cases of 4 months after irradiation, the pulp tissue on the whole showed marked atrophy and disappearance of odontoblast layers. From the coronal dental pulp to the root pulp, reticular atrophy and hyalinization were seen. In the periodontal membrane, inflammatory cell infiltration was seen in part and membrane fibers, as those in 2nd month, showed marked atrophy, became enlarged, and presented findings of hyalinization. 5. At 8th month, the nucleoli nearly disappeared in the pulp tissue from the crown to the root and the cells were connected like filaments by cellular processes. Nearly all the blood vessels and fibers disappeared. At this stage, Korff's fibers from the pulp to predentin were no longer observed. In the periodontal membrane, most of Sharpey's fibers disappeared. Fibroblasts showed marked atrophy and disappearance, and few normal fibloblasts could be found. In the cementum and alveolar bone, marked resorption was seen. In the resorbed region of the cementum, apposition of cementum-like hard tissue was observed and the hard tissue adhered to the alveolar bone, and findings of bony ankylosis were observed.

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In order to make a radiological and histopathological investigation of radiation injury to jaw bones at growth stage, the region of left mandibular third deciduous tooth of young dogs were irradiated for 3, 000R with 200kVp X-ray. The results were as follows : 1. In the periodontal tissue of deciduous teeth, inflammatory cell infiltration was observed in the periodontal membrane on 12th day after irradiation. Thereafter, with progress in bone resorption, proliferation of cementum and alveolar bone was seen at 4th month. At 8th month, prolifered alveolar bone filled the periodontal membrane space and infiltrated into the region where root dentin was resorbed. Radiologically, this finding was shown as narrowing of the periodontal membrane space of deciduous teeth. 2. Resorption of deciduous teeth from the root apex, although slight, was seen at 4th month. At 8th month, resorption due to proliferation of the alveolar bone was seen markedly on the mesio-distal side of the root apex. Ankylosis of the proliferated alveolar bone and the deciduous tooth root was observed. This finding was thought to cause persistence of deciduous teeth. 3. As injury to the cortical bone, resorption in moth-eaten pattern and vacuolation or enlargement of bone lacunae were observed at 2nd month. At 4th month, however, resorption and vacuolated bone lacunae decreased and new Haversian system was also seen at 8th month. Radiological findings of coarsening and resorption were observed delayed when resorption in moth-eaten pattern appeared. When new Haversian system appeared, cortical bones appeared normal in radiograms. 4. As injury to the alveolar bone, radiological finding of irregular trabeculae was seen on 9th day and spotty bone resorption was seen at 2nd month. Irregular trabeculae was due to resorption of the alveolar bone. Spotty bone resorption image was the finding seen at the time bone resorption and new bone were observed concurrently. When new Haversian system was seen in the alveolar bone at 8th month, spotty bone resorption image became more marked. 5. Formation of fatty marrow began on 12th day after irradiation of bone marrow. About at 2nd month, fibrous marrow was observed and inflammatory cell infiltration was seen there. Resorption of bone trabeculae was due to appearance of osteoclasts and the appearance of osteoclasts was closely related with inflammatory cell infiltration. 6. As changes in the inferior alveolar artery, extension of elastic fibers and looseness of circular tunica media were seen between 1st and 4th month. At 8th month findings were nearly normal. 7. As injury to tooth germ of permanent teeth, hyper-calcification image resulting from early completion of calcification of dentin at the crown portion was observed. Root formation stopped at 2nd month. The root region was obstructed by osteodentin and root formation was no longer observed thereafter. On the basis of the foregoing findings, it was made clear that radiation injury to the jaw bones at growing stage was closely related with development of the jaw bones and teeth.

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For the purpose of clarifying the effect on the alveolar bone and tibia at growth stage of administration of 1α-OH-D_3, an analogue of active type vitamin D (0.05μg/kg 3 times a week and 0.1μg/kg 3 times a week), sixty male rats of Wistar strain, 5 weeks old, were examined for weight, and radiologically, optically, photo-densitically, histopathologically and hemologically. The results were as follows : 1. From one week after the start of the experiment, the rats in the control group, 0.05-group, and 0.1-group all gained weight with time in the experiment. However, the 0.05-group and 0.1-group were slightly behind in gain. 2. Radiologically, flunctuations with time in bone density of the alveolar bone was seen in the control group, 0.05-group, and 0.1-group. The two experimental groups showed higher bone density than the control group. In the tibia, the interosseous cortex and medial cortex of 0.05-group and 0.1-group showed higher bone density than those of the control group. 3. Optically, densitic curves for the alveolar bone of the 0.05-group and 0.1-group rose showing undulations from the second week. In the tibia, the densitic curves representing the interosseous cortex and medial cortex of the 0.05-group and 0.1-group were higher than those of the control group from the second week and changed from acute to obtuse in curvature. 4. Photo-densitically, density for the alveolar bone of the 0.05-group and 0.1-group was always higher than that of the control group. Density for the alveolar bone of the 0.1-group was higher than that of the 0.05-group except for the third week. In the tibia, density for the interosseous cortex of the 0.05-group and 0.1-group was higher than that of the control group and density increased gradually with experiment time. Density of medial cortex however showed variations. 5. Histopathologically, the alveolar bone of the 0.05-group and 0.1-group prolifered toward the periodontal membrane and the crest of alveolar ridge was thicker than that of the control group. The interosseous cortex of the 0.05-group and 0.1-group showed bone proliferation toward the periosteum and bone marrow. The medial cortex showed bone proliferation of periosteum and was thicker than that of the control group. 6. Hemologically, the 0.05-group showed lower AL-P values than the control group at the second week. The 0.1-group had higher AL-P values than the control group. At the fourth week, the 0.05-group and 0.1-group showed higher serum C1 and 0.05-group showed higher SLDH than the control group. Administration of 1α-OH-D_3 causes bone proliferation in the alveolar bone and tibia. The alveolar bone showed more complicated changes in bone proliferation process than the tibia depending on administration dosage of 1α-OH-D_3. Administration of 1α-OH-D_3 is expected to improve bone debility of the alveolar bone.

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With a view to clarifying the effect of calcium-deficient diet on the alveolar bone and tibia at growth stage, sixty male rats of Wistar strain, 3 weeks old, were examined for weight and photographic density and also radiologically, photographically, histopathologically and hemologically. The results were as follows : 1. The weight of those in experimental group decreased slightly at second week. Thereafter the weight increased with time as that of control group. However, the difference in weight between the two groups was great. 2. Radiologically, bone density of the alveolar bone decreased and was low until 5th week in experimental group. However the trabecula coarsened and the alveolar bone thickened. In the tibia, interosseous cortex and medial cortex showed a decrease in width and had about the same width until 5th week. Coarsening and fracture of the bone trabecula were also observed. 3. Photographically, the densitometric curve for the alveolar bone was different for the upper part and for the lower part in experimental group. The curve for the lower part of the alveolar bone declined with time but that for the upper part rose. In the tibia, the densitometric curve for interosseous cortex and for the medial cortex appeared as acute angles at 3rd week, but gradually declined with time and approximated those of cntrol group. 4. In photographic density, bone density of the alveolar bone for experimental group was always lower than that for control group and the difference increased with time. In the latter part of the experiment, bone density of the upper part of the alveolar bone decreased and that of the lower part increased, resembling the density at 3rd week. Bone density of the tibia was low until 4th week but showed little changes. Thereafter, the bone density of interosseous cortex was higher than that of medial cortex and was increasing. Difference was observed as compared with control group. 5. Histopathologically, resorption was observed in the whole of the alveolar bone for experimental group. Almost all of the inner walls of the alveolar bone were resorbed at 5th week and a hypocalcification layer replaced them. In the tibia, a hypocalcification layer appeared on the marrow side of medial cortex at 3rd week, were located at the outer basic lamellae of interosseous cortex at 4th week, and were seen at the outer basic lamellae of the two cortices at 5th week. Harversian canals increased markedly in number in the alveolar bone and tibia. 6. Hemologically, electrolytic serum Ca and the ratio of serum Ca, and serum Ip were low in value and serum Cl was high. Biochemical Al-P, CPK, GOT, and GPT were high.

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The mandible (dentition of immature permanent) young adult dogs was irradiated for 3, 000R with X-ray of 200 kVp and radiation hazard to the mandibles was investigated radiologically, photographically, pathohistologically at one week, two weeks, one, two, four, six, and eight months after irradiation. The results were as follows : 1. Radiological findings 1) Effect of irradiation on root formation was observed until 1 month after irradiation. Thereafter, apical obliteration was observed. 2) Lamina dura in the periodontal membrane space disappeared at 2 months but was observed in part at 8 months. 3) The alveolar bone (at root bifurcation region) showed resorption of the alveolar crest and bone resorption in moth-eaten appearance at 2 months, and formation of sequestrum and bone fracture at 4 months. From 6 months, osteosclerotic image was observed in the resorption image ; yet bone defect image was observed in the inferior portion of the alveolar bone. 4) Almost all cortical bone was resorbed at 6 months and a fall in radiopacity was observed on the whole. 2. Photographical findings Microphotograms showed a fall in densitometric curve of the alveolar bone at root bifurcation region at 1 month. However, the densitometric curve of the alveolar bone rose at 6 months. The curve for the inferior region of the alveolar bone was a falling type with very irregular undulations. 3. Pathohistological findings 1) Almost all buccal cementum disappeared at 4 months. However, regeneration image of cementum was observed from 6 months. 2) The buccal connective tissue in the periodontal membrane space ran irregularly at 2 weeks and the periodontal membrane space disappeared completely at 4 months. However, the lingual periodontal membrane was irregular arrangement of connective tissue. Bundle bone showed resorption image at 2 weeks and the buccal bundle bone disappeared at 2 months. At 8 months, however, new bundle bone was observed. 3) The cortical bone at 2 weeks showed empty lacunae on the buccal side. At 4 months, resorption image of Haversian canalis was seen in every cortical bone. At 8 months, Haversian canalis appeared buccolingually and resorption image such as new lacunae was observed. 4) Fatty marrow was already formed in bone marrow at 1 week. At 8 months, fatty marrow was seen on the whole. 5) In the inferior alveolar artery, irregular arrangement, extention, and proliferation of elastic fivers were seen and rupture and disappearance of ring form were observed in the mesothelium.

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Three-week-old male rats of Wistar strain were given 0.2u/kg of calcitonin (eel calcitonin) and its effect on the alveolar bone and tibia after administration was investigated. The results were as follows : 1. The control and experimental groups showed increase in weight with time from the first week, but from the third week, increase was greater in the experimental group. 2. Optically, the densitometric curves of the alveolar bone of the experimental group showed higher patterns than thoes of the control group until the fourth week. In the fifth week, however, density curves with ragged undulation were seen. For the tibia, the densitometric curves of interosseous cortex and medial cortex were higher than those for the control group until the fourth week but showed ragged irregular patterns in the fifth week. 3. On the X-ray microanalyzer, in percentages of the averages of Ca and P for the control group, Ca was the highest in the fifth week and P was the highest in the third week, and both were the lowest in the fourth week. For the experimental group, the percentages of both Ca and P were the lowest in the third week and the highest in the fifth week. In standard deviation, increase and decrease in Ca and P in the control and experimental groups occurred in linkage. For the tibia, percentages of the averages of Ca and P in the control and experimental groups showed increase and decrease in linkage and the standard deviation was always smaller for the control group than for the experimental group. The average and standard deviation of P were not linked. 4. Histopathologically, the experimental group, in comparison with the control group, showed a thicker and more compact osseous layer in the alveolar bone and increase in Haversian canals and bone lacunae until the fourth week. However, no osteoclasts were observed. In the fifth week, bone lacunae in the alveolar bone in the experimental group became fewer and many findings of bone resorption by osteoclasts were observed. In the tibia, the experimental group showed more increase in Haversian canals and bone lacunae until the fifth week, as compared with the control group. In the fifth week osteoclasts appeared and bone resorption was observed. Under the scanning electron microscope, collagen fibrils in the experimental group were arranged more compactly irrespective of increase or decrease in the bone tissue. 5. Hemologically, serum Ca in the experimental group was higher than that in the control group in the third week, In the fifth week, serums Ca and CT in the experimental group were higher than those in the control group.

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