Immature permanent teeth of young dogs were given apexification with use of preparation of calcium hydroxide iodoform and healing of wound of periodontal membrane was investigated radiologically, photographically, histopathologically, and scanning electron microscopically. The results were as follows : 1. From 7th to 14th day after operation, Hertwig epithelial sheaths were observed in the apical portion in the control group. In the experimental group, Hertwig epithelial sheaths were directed toward outer periodontium, detached and necrosed. On the periodontium side of the Hertwig epithelial sheaths, large cementoblasts appeared and calcification of lightly eosin-stained cementum began. 2. From 1 to 2 months, findings of formation of cellular cementum were observed in the control group. In the experimental group, large and tall cementoblasts amassed densely on the periodontium where Hertwig epithelial sheaths necrosed. Between cells, collagen fibers were abundant and periodontium fibers directly below the apical portion ran monotonously and were begining to be compact. 3. At 4th month, bundles of Sharpey fibers connecting cellular cementum and the alveolar bone were observed in the control group. In the experimental group at this stage, early stage of formation of cementum-like hard tissue stained well with Hema-toxylin was observed in the periodontal membrane directly below the central apical portion and continuous cementum-like hard tissue was observed at the apical portion. 4. At 6th month, radiologically and photographically, cementum at the apical portion showed high densitometric curves in microphotograms in the control group. In the experimental group, radioopaque images were seen scattered as if they were to from closure and very irregular densitometric curves were shown in microphotograms. In photographic density also, the values were lower than those of the control group. Histopathologically, the control group showed several branches in the cementum at the apical portion. The experimental group showed coarse cementum-like hard tissue in the whole apical portion, and necrosed tissue, drug, and fibers were found scattered inside the tissue. Electron microscopically, cementum was formed extensively and presented many even surfaces in the control group. In the experimental group, cementum lacunae of various sizes were seen and the border of margins were indistinguishable. However, even cementum surfaces were formed in places. Globular structures evidencing calcification were also observed and matrix fibers were seen among them. 5. At 7th and 8th month, the control group showed about the same findings as those seen at 6th month radiologically and photographically. In the experimental group, photographic density also approached that of the control group. Histopathologically, formation of cementum of the apical portion progressed in the control group and cementum lacunae and branch-like structures were observed inside the apical portion in the experimental group. Electron microscopically, calcified cementum globules amassed and formed smooth even surfaces in the control group and the border of the margins became clearer than those at 6th month and cement canaliculi were also observed in the experimental group.

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The effect of hypervitamin A on the development of rat tooth germ was investigated in this study. Pregnant rats were treated with intraperitoneal injection of 100, 000 units or 150, 000 units of vitamin A on the 12th day of pregnancy. After macroscopic observation of rat embryos and young rats from 14 days of fetal life to 4 days after birth, a histological observation was made of the maxillary first molars. I. The general findings 1) In the macroscopic findings, the malformations in the vitamin A treated group were microstomia, micromelia, oligodactylia, etc. The degree of malformation was more intense in the group administered 150, 000 units than in the 100, 000 unit group. In the oral cavity, cleft palates were frequently observed and the degree of the defect was greater in the group administered 150, 000 units than in the 100, 000 unit group. 2) Hypervitamin A induced retardation of development and growth of dental anlage. The group administered 150, 000 units was more retarded than the 100, 000 unit group. 3) Hypervitamin A induced proliferation of blood vessels at the outer enamel epithelium and extreme hemorrhage at the enamel pulp of the developing enamel organ. Additionally, it induced retardations of the differentiation of the inner enamel epithelium and formation of the enamel matrix. Furthermore, it induced retardation of the differentiation of odontoblast and formation of dentin. 4) An increase in blood vessels by hypervitamin A was observed in the dental papilla. II. The neural findings 1) The innervation to the basement of the dental primordin was delayed by hyper-vitamin A. In addition, the nerve fibers were finer in comparison to those of the control groups and the nerve fiber bundles were diffusedly organized. 2) The small nerve fiber bundles which were observed in the mesenchymal tissues of the basement of the dental papilla were frequently seen in the areas near the epithelium diaphragm of the periphery of tooth germ, but they were scarce in the center of tooth germ. 3) In the control groups of 4-day-old rats, the fine nerve fibers entering the dental papilla were first seen in company with blood vessels. Conversely the nerve fibers entering the dental papilla were not recognized in the experimental groups.

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In daily clinical practice, dysqeusia patients having lingual abnormal findings are frequently encounted. However, most of studies were aimed at the taste buds and that controlling nerve. Therefore, with a purpose to investigate roles of the lingual body mucosa, especially the form of the lingual papillae and their functional maintenance, the author transected the unilateral lingual nerve of rats, and scanning electron microscopic and histopathological examinations were made of the changes in the anterior region of the tongue. The results were as follows : 1. Bending of the lingual tip region to the non-transected side was noted in a rat 24 hours after the transection of the lingual nerve, and since then bending accompanied by atrophy of the tongue musculature was very frequently observed until the 21st day after the transection. 2. From 3rd day after the transection, the filiform papillar arrangement became irregular and ulcerous changes accompanied by the defective lingual papillae were noted in the lingual tip or marginal region. The changes were continued until the 14th day after the transection were no longer noted on the days thereafter. 3. From 3rd day after the transection, the taste buds of the fungiform papillae began to show degenerative findings and the taste bud-composing cells decreased markedly in number. 4. On 7th day after the transection, all the taste buds were completely degenerated and disappeared and were displaced by surrounding epithelial cells. Observation by SEM revealed strong atrophy in the fungiform papillae and difficulty in discriminating the fungiform papillae. 5. On 21st day after the transection, regenerated taste buds were observed in the epithelial layer of the fungiform papillae. The taste pores were insufficiently developed and their communication with outside was not yet observed. All the cases showed opening of the taste pores since the 35th day after transection of the lingual nerve. 6. Degeneration and regeneration, caused by transection of the lingual nerve, of the fungiform papillae and their taste buds distributed the lingual tip and around medial groove in the lingual body were not necessarily limited to the transected side but extended to some of the non-transected side as well. Also, in the transected side, papillae presenting normal findings without being affected were observed. The above results suggest that the lingual nerve was very importantly associated not only with sense, regeneration and differentiation of the taste buds but also with functional maintenance of the lingual body mucosa, and that it was involved somehow in movement of musculature of the lingual tip region.

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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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At one month after two implants of single crystal alminum oxide were implanted in the mandible of adult monkeys, a superstructure was cemented connecting the two implants without connection with the natural teeth. Adaptation of the surrounding tissue of the implants under occlusal function were observed for 12 months from one month after cementing, and clinical, roentogenographic, light microscopic investigations were made. The results were as follows : 1. Clinically, the gingiva surrounding the implants healed favorably and showed findings similar to those of the adjacent natural teeth one month after cementing of the superprosthesis and thereafter. The implants were immobile by finger. The depth of pockets of the surrounding gingiva was within the range of 0.5-1.0mm for both S and T types 12 months after cementing. No deep pockets were formed and no marked difference in depth was seen from that of the gingival sulcus of the adjacent natural teeth. 2. Roentogenographically, no marked changes were seen between one month after and immediately after insertion of the superprosthesis. At three months and thereafter, however, lamina dura indicative of newly generated bone formation was observed around the implants for both S and T types. Lamina dura widened with time at 6 and 12 months. In one of the three monkeys of 3-month cases, a thin radiolucent area was seen between the implant and the bone. 3. In the gingival epithelium, down-growth of epithelium bordering the implant reached as far as infrabone in one of T type of 1-month cases, two each of S and T types of 3-month, one each of S and T types of 6-month, and one of S type of 12-month. In the others, the extent was slight. 4. At the lamina propria of the gingiva, inflammation was slight and the connective fibers were arranged densely surrounding the implants. In the surface facing the implant, however, they were running parallel to the axis. 5. In the cases of one month after insertion, the implant was surrounded by young new bone for both S and T types and bone trabeculae grew dense with time at 3, 6, and 12 months. Haversian canals were formed after 3 months. 6. In one of the three monkeys of 3-month cases, a layer of fibrous connective tissue interposed between the implant and the bone for both S and T types. Its width was within the range of 150-250μm for S type and 50-100μm for T type. In one of the three monkeys of 6-month cases, the screw of S type was in direct contact with the bone in some parts, and in other parts fibrous connective tissue interposed between the screw and the bone. The tissue width was within the range of 100-200μm. Except for these cases and 1-month cases, all the implants were in direct contact with the bone for both S and T types. 7. Scanning electron microscopically, in both 6-month and 12-month cases, epithelial cells and fibroblasts were attached at the post on the surface of the implant for S and T types. Where the implant was in direct contact with the bone, only many amorphous materials of different sizes were observed and cell-like structures were not seen. On the basis of the foregoing, it was confirmed that : (1) the surrounding tissue healed favorably even under functional conditions after insertion of implants of single crystal alminum oxide, (2) abnormal findings such as foreign-body reaction were not seen, (3) histo-compatibility was excellent, and (4) connecting two implants without connecting them with natural teeth enabled them to withstand biting pressure sufficiently, provided that load was not excessive physiologically. For use for longer duration, however, it was thought that oral hygiene and harmonious occlusion were important. For clinical application, it was thought the use of implants with discrestion would bring favorable results.

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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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The tissues covering the bony surfaces and the articular disc of the temporomandibular joint differ from those of most other joints in being not hyaline cartilage but dense fibrous connective tissue. The author investigated elastic system fibers (ESF) in those tissues of the rat. The results were as follows : 1. The temporomandibular joint of the rat showed an appearance of the oxytalan fiber from 17-day-insemination age. 2. The growth of ESF in the temporomandibular joint revealed intensive correlation with increasing functional stress to the joint. 3. ESF in the mandibular condyle had especially a large number of oxytalan type fibers, and many elastase-resistant fibers in it were still noted 150 days after birth. 4. The elastase-resistant fibers were scarcely noted in the articular disc and mandibular fossa since the 25th day after birth. 5. The inferior layer of the articular disc exhibited close network structure of relatively matured elastic fibers. 6. The mandibular fossa and superior layer of the articular disc facing the superior joint cavity had mainly premature ESF and they were few in number. The above results suggested that ESF in the temporomandibular joint appeared in correlation with functional stress imposed on the dense connective tissues and that the greater functional stress at the joint movement was placed on the inferior joint cavity.

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Apexification with use of calcium hydroxide preparation was performed on immature teeth of young adult dogs and the apical bridges at the apex region were investigated radiologically and electron microscopically. The results were as follows : 1. Radiograms showed apical closure by a radioopaque apical bridge in the experimental group of 6 months. Microphotograms were also in agreement in the finding. 2. In measurements of photographic density, the apical bridge of the experimental group at 8 months showed similar values to those of apical cementum of the control. 3. Scanning electron microscopic findings showed the apical bridge to be cementum. The apical bridge was clearly separated from dentin on the root canal side by a crack line containing preparation residue. 4. Scanning electron microscopically, the lateral apical surface of the apical bridge at 6 months was rich in fibers and contained globuli, and the margin of cementum lacunae was surrounded by matrix fibrils. At 8 months, Sharpey fibers penetrated into the apical bridge, the margin of cementum lacunae was distinct, and cementum canaliculi also were observed. These findings were about the same as those of the cementum structure in the control. Accessory branch-like structures were observed in the section of the apical bridge. 5. Transmission electron microscopic findings for the control at both 6 and 8 months indicated many areas clearly showing lining cell layer of cementoblasts. Most of these cementoblasts presented the appearance of resting cells. In the experimental group, lining cell layers were indistinct and there were large cells with many cell processes. These active cementoblasts containing many mitochondria and r-ER were seen sporadically. These findings were remarkable at 6 months. 6. In the experimental group, it was suggested that active cementoblasts secreted vesicle-like structures, produced collagen fibrils, and possessed resorptive function of collagen fibrils. 7. Findings on cementocytes in the apical bridge were in good agreement with those reported by predecessors. Also, gap junction was observed between cell processes of cementocytes.

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In the oral cavity, malignant neoplasms including cancer in the early stage have been known to invade the surrounding soft tissue and jaw bones. However, the mode of invasion varies because of histological structural difference among the gingiva, tongue, cheeks and jaw bones in addition to anatomical complexity of the oral cavity. When the mandible is or is suspected to be invaded by a gingival cancer, wide mandiblectomy is desirable. However, post-operative functional and cosmetic impairment will be great. Therefore, it is most important to have a sufficient knowledge of extent and degree of the invasion by gingival cancers in order to plan optimum surgical limits which at the same time check the foregoing impairment at minimum. A histopathological investigation therefore was made of the extent and degree of mandibular invasion by transplanting VX2 carcinoma into the mandibular gingiva of normal domestic rabbits. The results were as follows : 1. VX2 carcinoma transplanted into the mandibular gingiva of the domestic rabbits prolifered first of all in the gingiva and then destroyed the periosteum of the underlying cortical bone. As invasion progressed, the cortical bone surface showed lacunar resorption and bone destruction in moth-eaten types in part. These findings increased in extent and degree with time as the tumor mass enlarged. 2. In radiological observation of resorption and destruction of the mandible invaded by VX2 carcinoma, the cortical bone was compressed evenly and resorbed and then destroyed in moth-eaten types. While the cortical bone did not show any abnormal findings radiologically, resorption and destruction histologically were already underway. 3. Along with resorption and destruction of the cortical bone by VX2 carcinoma, resorption of inner wall surface and enlargement of canals were observed in the surrounding Harversian and Volkmann canals. In some of the enlarged Harversian and Volkmann canals, VX2 carcinoma invaded and prolifered, and gradually prolifered into the mandible from the cortical bone. 4. Along with invasion and proliferation of VX2 carcinoma into the mandible, periosteal proliferation and periosteal new bone formation were beginning to be observed in the inferior margin of the mandible. 5. With invasion and proliferation of VX2 carcinoma, periosteal new bone formation was observed in the cases of 15-day after transplantation. However, no specific association with enlargement of the tumor mass was found. The formation was presumed to be reactive bone repair.

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The effects of nitrous oxide (30, 50, 70%) inhalation on the catecholamine release from adrenal medulla were investigated. Mongrel dogs were used as the experimental subjects and were intubated and ventilated mechanically. Blood samples were taken out directly from the adrenal vein. The epinephrine (EP) and norepinephrine (NE) contents were measured with high performance liquid chromatography-electrochemical detector (HPLC-ECD). The results were as follows : 1. The EP and NE releases into the adrenal vein were decreased significantly when dogs inhaled under 30% or 50% nitrous oxide. 2. The EP and NE releases under 30% nitrous oxide inhalation were decreased in all the subjects, and those under 50% nitrous oxide inhalation were increased in 3 of the 14 subjects. 3. No signigicant changes in the EP and NE releases were observed under 70% nitrous oxide inhalation. These results show that both 30% and 50% nitrous oxide decrease the catecholamine release from adrenal medulla into blood, while 70% nitrous oxide doesn't. The changing point of the gas concentration to effect on the catecholamine release can be postulated to exist between 50 and 70%.

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Many authors have studied the gingival respiration with slice and homogenate to measure the respiration in Warburg respirometer flask. However, no study on the ability to respiratory control of gingiva has been reported. The author prepared the several mitochondrial fractions from gingiva and measured the mitochondrial respiration to obtain the fractions with ability to respiratory control. The gingiva was excised from dogs during anesthesia and minced in cold. The minced gingiva was homogenized with Polytron for 0.5 min., 1 min., 1.5 min., 2 min., 5 min. and 10 min. separately. And then, the nucleus, mitochondrial and supernatant fractions were prepared by differential centrifugation method. On the other hand, the minced gingiva was treated with 0.04%, 0.2%, 1% and 5% collagenase respectively and homogenized with Polytron for 1 min.. Then, the nucleus, mitochondrial and supernatant fractions were prepared by centrifugation. Relative specific activity of the succinate dehydrogenase was measured on each fraction. Furthermore, the respiration of the mitochondrial preparation was measured by using the oxygen electrode. Results are : 1. In the mitochondrial fractions treated with Polytron for 0.5 min. to 10 min., the highest relative specific activity of the succinate dehydrogenase was observed in the treatment for 2 min.. 2. The highest activity was present in the mitochondrial fraction treated with 1% collagenase in the course of digestions with 0.04%, 0.2%, 1% and 5% collagenase. 3. The respiratory control was observed in the mitochondrial preparations treated with 1% and 5% collagenase when the endogenous, succinate-stimulated and ADP-stimulated respirations were measured. 4. The mitochondrial preparation treated with 1% collagenase had the highest ADP/O ratio and respiratory control rate in the present study.

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Two distinct forms of alkaline phosphatase (ALP) are known in most mammalian species, a liver/kidney/bone/placental/dental pulp form (universal form) and an intestinal form. They are clearly discriminated one another by quantitative inhibition with L-homoarginine and levamisole, and by their immunological properties. The artificial orthodontic movement of tooth has been reported to induce a change in ALP activity of the periodontium. There are few detailed reports on enzymatic and immunological properties of periodontal ligament ALP. In the present study, properties of ALP in the periodontal ligament were compared with those in other tissues. 1. In both domestic rabbits and monkeys (Macaca fasicularis), activity of ALP was the highest in the periodontal ligament out of various tissues. The activity in rabbits was 3-fold higher than that in monkeys in the periodontal ligament. 2. A SDS-electrophoretic mobility of periodontal ligament ALP was identical with those of ALP from the pulp and alveolar bone of both rabbits and monkeys. All of ALP from these three tissues were markedly inhibited by L-homoarginine and levamisole. Monkey kidney contained only ALP with a shorter mobility than periodontal ligament ALP. In contrast, rabbit kidney contained two forms of ALP with different mobilities from periodontal ligament ALP : one with a shorter mobility is designated ALP 1 and the other with a longer mobility ALP 2. Monkey kidney ALP and rabbit kidney ALP 1 were markedly inhibited by these two inhibitors but ALP 2 was not. 3. Upon Ouchterlony double diffusion analysis, the anti-human universal ALP serum produced a single connecting band of precipitin between periodontal ligament ALP and kidney ALP 1, but did not cross-react with kidney ALP 2 in rabbits. 4. Upon Ouchterlony double diffusion analysis, rabbit kidney ALP 2 cross-reacted with the anti-intestinal ALP serum but did not with the anti-human universal ALP serum. 5. On the basis of inhibition studies and immunological properties described above, it is concluded that in rabbits, periodontal ligament ALP and kidney ALP 1 are an universal form and kidney ALP 2 is an intestinal form. 6. ALP of the periodontal ligament differed from kidney ALP 1 only in the carbohydrate structure. 7. Mammalian kidneys (monkey, bovine, pig, dog, rat and guinea-pig) other than the rabbit seemed to contain only an universal form but not to contain an intestinal form, on the basis of inhibition studies.

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It is said that the fluoride-containing dental cements are effective for strengthening the dental hard tissues and preventing the occurrence of recurrent caries. This is due to the expective mechanism that the fluoride ion released from the cements will react with hydroxyapatite (HAp) to form fluorapatite (FAp) and calcium or other fluorides. Although some constituents other than fluoride ion may be also released from the cements, their behaviors have not been well defined in association with FAp formation. Therefore, the present study was scheduled to investigate the potential effects of those ions on fluoride ion uptake by HAp and on FAp formation. Synthetic HAp was stirred in the prepared fluoride solution with or without other ions for 24 hours at 37℃, and the quantitative determinations of the fluoride ion uptake and the FAp formation were made by ion meter with fluoride electrode and ESR, respectively. All the experiments were carried out under a fixed condition where the concentration of the fluoride ion was 100ppm and the pH of the solution was 6.0. Both the fluoride ion uptake and FAp formation were inhibited when Zn^<2+> or Sr^<2+> was added to the fluoride solution. It is probably because these ions might have preferentially reacted with HAp to form stable compounds. The presence of Al^<3+>, Ca^<2+> or RCOO^- in the fluoride solution significantly increased the apparent uptake of fluoride ion but decreased the FAp formation. It means that the fluoridization of HAp into FAp was inhibited by the preferential fluoride formation with these ions. If such fluorides are formed in cooperation with HAp, however, they may be effective as the long term sources of fluoride ion even though the initial FAp formation is not marked. The FAp formation was significantly decreased by adding low concentration of PO^<3->_4 in the fluoride solution, while it was increased by higher concentration of PO^<3->_4. It is well known that PO^<3->_4 will easily substitute for CO^<2->_3 in HAp and improve the crystallinity of HAp. The well-crystallized HAp would be less fluoridized. It is also known that dicalcium phosphate dihydrate (DCPD) will be formed from HAp in phosphoric solution and it will be easily fluoridized into FAp. The difference of FAp formation by the concentration of PO^<3->_4 might have come from the interaction of these inhibiting and accelerating effects, and the results showed that the former effect would be valid for the lower concentration of PO^<3->_4 and the latter for the higher concentration of PO^<3->_4. It was found, however, that once HAp was pretreated by PO^<3->_4 the transformation of HAp into FAp was inhibited by the earlier shell formation of FAp from DCPD surrounding HAp crystal. It is concluded from these results that Ca^<2+>, Al^<3+>, PO^<3->_4 and RCOO^- released from fluoride-containing dental cements may be favorable and Zn^<2+> and Sr^<2+> unfavorable for the FAp formation.

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The use of the composite resin has been rapidly increasing because of its superior esthetics as well as improved bonding systems by the introduction of the enamel etching and new formulation of the bonding agents. The conventional bonding agents are merely composed of the same monomers as the respective composite resins have. They are enough fluid to penetrate into the grooves among the etched enamel prisms and form resin tags to cause the mechanical interlocking between the resin and the enamel. On the other hand, the new bonding agents contain some adhesive to tooth structure, and they may bond the composite resin mechanically and chemically to the enamel as expected resulting in better retention and marginal sealing. However, there are very few papers on the quantitative consideration for the chemical bond between the resin and the tooth. In the present study, therefore, the chemical reactivity with hydroxyapatite and the bond strength to the enamel were examined for one conventional bonding agent and four adhesive-containing agents. It was evidenced that the adhesive-containing bonding agents were capable of reacting chemically with hydroxyapatite although the reactivity was different among the agents. It was also found that the reaction was accelerated when the hydroxyapatite was etched with acid and the pH of the agent was lower. The higher the reactivity with hydroxyapatite and the lower the polymerization shrinkage of the bonding agent were, the higher was the bond strength between the bonding agent and the unetched enamel. It indicates that the chemical adhesion of the bonding agent would be reasonably effective for tight bonding to the enamel. The chemical adhesion, however, appeared insufficient on the unetched enamel since the fractograph at the interface after tensile test showed mixed aspect of cohesional and adhesional failures even if the bonding agent having maximum chemical reactivity with hydroxyapatite was used. When the enamel was etched with acid, the bond strength was significantly increased for all the bonding agents used. The bond strength to the etched enamel was well correlated with the shear strength of the bonding agent itself together with the two factors mentioned above for the unetched enamel. As a wide variation from 0.5 to 40% was observed in the polymerization shrinkage among the bonding agents, it is advisable to apply the agent twice or more on the enamel to increase the contact area in oder to make sure the better bonding if the agent with high polymerization shrinkage is to be used.

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A study was made on the effect on condylar path of the guide plane of the clutch and of raising occlusal vertical dimension by mounting the clutch when a pantograph is used. For this purpose, an intraoral guiding devices which allowed free adjustment of the degree of raising occlusal vertical dimension and of guide inclination were used. Improvements were also made on the pantograph so that (1) the posterior recording table itself could be attached or detached at will and (2) condylar point and the stylus position would agree. Examination was made on the degree of occlusal vertical dimension raised by attaching a Denar pantograph and the inclination of protrusive condylar path obtained by using the experimental devices. The results were as follows : 1. With use of the clutch of a Denar pantograph, the occlusal vertical dimension raised was a minimum of 7mm and a maximum of 11mm with an average of 8.1±1.3mm. 2. Inclination of protrusive condylar path obtained by tooth guidance was a minimum of 26.3°and a maximum of 54.2°with an average of 37.2±7.3°. 3. When occlusal vertical dimension was kept constant, no effect was made on the guide plane which guides the mandible to 10, 30, or 50°. 4. When inclination of the guide plane was set at 10°, the inclination of protrusive condylar path at high occlusal vertical dimension was 29.5±8.2°and that at low occlusal vertical dimension was 32.7±7.9°. There was a tendency for the protrusive condylar path to be gentler with higher occlusal vertical dimension. This tendency was the same when the inclination of the guide plane was set at 30°or 50°. 5. When a comparison was made of inclination of protrusive condylar path during tooth guidance and that during the use of the clutch, the latter was gentler with statistical significance. At this time, there was a tendency for the inclination to be gentler with raising of occlusal vertical dimension. 6. In using a pantograph, care must of course be given to the setting of guide inclination. However, more important is that raising of occlusal vertical dimension must be kept to a minimum.

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Alveolar bone loss is the most striking feature of periodotitis in humans and animals. Many chemical mediators have been known to activate osteoclasts, and prostaglandins (PGs) are included in them. Since the levels of PGs increase in inflamed gingiva of humans with periodontitis, PGs would play the main role of alveolar bone destruction in periodontitis. Recently some investigators reported that indomethacin, a potent inhibitor of PG synthesis, reduced the macroscopic bone loss and the number of ostoclasts in some experimental model of periodontitis. But the bone always changes in the architecture by remodeling in which bone formation follows resorption. The inhibitor of PG synthesis may affect not only bone resorption but also formation. In order to understand the change of bone dynamics after administration of such drugs, bone histomorphometry, initiated by Frost et al, is very useful. This study was designed to determine the effect of flurbiprofen, a potent inhibitor of PG synthesis, on alveolar bone loss and the alveolar bone dynamics during experimental periodontitis in dogs by histomorphometry. In both medicated and non-medicated groups, dental floss ligature was placed around the second, third, and fourth premolars of the left jaw during a 32-day experimental period. The second, third and fourth premolars of the right jaw served as control. Evaluation of the dynamics of appositional bone growth was facilitated by subcutaneus administration of calcein and oxytetracycline. Administration began on day 10 of the experimental period with the use of a schedule of 2 days on (calcein), 8 days off, 2 days on (calcein), 8 days off and 2 days on (oxytetracycline). The dosage was about 10 mg/kg/day for calcein and 300 mg/kg/day for oxytetracycline. Medicated group was given daily administration of flurbiprofen (0.2 mg/kg/day) from days 22 to 32. At the end of this experimental period, the dogs were killed. The mandibles were removed and fixed immediately in 70% ethanol, dehydrated and embedded without demineralization in polyester resin. Sections, about 100μm thick, were prepared for histomorphometry. Frontal sections were divided into two segments, shallow side (S) and deep side (D). The alveolar bone surface on shallow and deep segments were further divided into two segments for measuring parameters of bone surface, gingival side (G) and periodontal side (P). The alveolar cortices on shallow and deep segments were further divided into two segments for measuring parameters of internal remodeling, buccal side (Bu) and lingual side (Li). The morphometric measurments were taken at these sites using a computer-based system. The following parameters were measured on alveolar bone surface : the fractional resorption surface (Lr), the active resorption surface ratio (aLr), the number of osteoclasts per 1 mm of active resorption surface (ocNo./arl), the number of osteoclasts (ocNo.), the fractional bone surface with osteoid seam (osLf), and the oxytetracycline single labeled surface ratio (tcLf). The following parameters were measured in alveolar cortex : the number of resorption cavities (Ar), the number of osteons with osteoid seam (osAf), the number of oxytetracycline single labeled osteons (tcAf), the proportion of mineral appositional rate of inflamed to control side (rMo), and the length of circumference of labeled osteon (Sl). The results were as follows : 1. Lr were significantly decreased in gingival side by flurbiprofen. 2. Neither aLr nor ocNo./arl were changed by flurbiprofen. 3. ocNo. were considerably decreased in gingival side by flurbiprofen. 4. Both osLf and tcLf were somewhat increased in gingival side by flurbiprofen. 5. Ar were somewhat decreased by flurbiprofen. 6. osAf were not changed, while tcAf were slightly increased by flurbiprofen. 7. rMo were not changed by flurbiprofen, and Sl were not different between medicated and non-medicated groups. These results

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Mouse peritoneal macrophages were induced by lipopolysaccharide (LPS), isolated and cultured for an hour. They were fixed with glutaraldehyde. Sheep erythrocytes (SRBC) and three other RBCs (mouse, rat and dog) were sensitized with LPS (LPS-RBC) and were also fixed. Each of the RBCs was added to the macrophages and incubated for 30 minutes at 37℃. Then attachment of the RBCs to the macrophages was investigated. The results obtained were as follows : 1. SRBC attached to the induced macrophages more than to the normal ones. 2. LPS-SRBC also attached to the induced macrophages more than to the normal ones. 3. LPS-SRBC attached to the normal macrophages in the same degree as SRBC. 4. SRBC and three other RBCs attached to the macrophages in the same degree. These results suggested that LPS enhanced attachment of foreigen bodies to the macrophages in vivo. And it was supposed from these results that the macrophages did not have the specific binding to SRBC.

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The calcifying odontogenic cyst was first described in 1962 by Gorlin as a cystic lesion from odontogenic epithelium. A case of calcifying odontogenic cyst was reported with some clinical and histopathological considerations. The cyst containing an odontoma and an ectopically impacted right upper canine occurred in the right maxilla of an 11-year-old girl. Histopathological findings showed interesting findings tumorous characteristics.

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An extracellular dextranase has been detected and isolated from Streptococcus mutans AHT (serotype g). Dextranase was partially purified from the culture supernatant of S. mutans AHT by precipitation with ammonium sulfate, chromatography on DEAE-cellulose. DEAE-cellulose column chromatography permitted the removal of a large proportion of the extracellular glucosyltransferases. But glucosyltransferase isozyme (pI 4.2) remained with the dextranase solution. Dextranase activity in DEAE-cellulose fraction was detected by method of agar plate containing DT2000 and newly method of polyacrylamide gel electrophoresis containing Blue dextran. The remaining glucosyltransferase isozyme (pI 4.2) in DEAE-cellulose fraction was attempted to separate from dextranase by filtration on Ultrogel AcA34, fast protein liquid chromatography (FPLC, Mono Q column). But we could not completely separate glucosyltransferase isozyme (pI 4.2) from dextranase.

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Eleven cases of odontoma occurring over a period of 10 years were investigated. The results were as follows. The cases were classified into nine compound odontomas and two complex odontomas. A predominance in males was seen. Most cases were diagnosed during or before the second decade of life. The mean age at detection was 20.5 years old. Most commonly observed symptom was an impacted permanent tooth occurring in 55 per cent of the cases. There was no difference in the rate of occurrence of odontomas in both the maxilla and mandible. However they most often occurred in the anterior jaw (64%). The size of the odotomas ranged from 3×5mm to fist size in diameter. Inspection of the histopathological specimen revealed evidence giving credence to the theory that the odontoma is hamartoma rather than true neoplasm.

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A boy and his younger sister were diagnosed as partial anodontia. The boy had other symptoms of congenital ectodermal dysplasia. The two patients' clinical correspondence was investigated. The results were as follows : 1. The two patients were diagnosed as anhidrotic ectodermal dysplasia in X-linked recessive in heredity (A.E.D.X.) because the boy presented symptoms of hypotrichosis, hypohidrosis, and anodontia, and cases of anodontia were also found in the lineage. 2. Although the patients were mild anodontia frequently experienced in clinic, there were many dental problems involved. Therefore concrete clinical correspondence was needed to be determined. 3. The girl, 5 years and 3 months old, had <B|B>___- and <21|1>___- absent congenitally. The boy, 9 years and 7 months old, had [numerical formula] and [numerical formula] absent. 4. The dental problems of these patients were missing teeth, malocclusion, lack of aethetics, retarded eruption of teeth, and anomalies in size and shape of the teeth. In this paper, a plan for treatment of these dental problems is proposed.

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