Using six kinds of Chiroptera with different food habits, the masseter and temporal muscles were observed gross anatomically and further enzymo-histochemically, light microscopically and electron microscopically. The results obtained were as follows : 1. The masseter muscle of insectivorous bats is composed of muscular tissues at almost all of its muscular layer, with vertically running muscular fibers compared with other bats that different food habits. The temporal muscle is well developed, with vertically running muscular fibers. The case is the same with carnivorous animals which there will make quick masticatory movements, with up and down dilated upper and lower jaws when capturing their prey. 2. The masseter muscle of carpophagous bats includes alternated tendon tissues and muscular tissues at the original and insertion regions of each muscular layer, and the temporal muscle includes well-developed superficial temporal muscle functioning so as to push forward the lower jaw. The case is the same with herbivorous animals which have a long time grinding down action. However, carpophagous bats, which will eat preferentially matured fruits, have improper masseter group considered to have a persistent action, which is not so well developed as herbivorous animals. 3. The masseter muscle of vampire bats is composed of muscular tissues with undeveloped tendon tissues, which seems to have for its object to injure any domestic animal as their prey, when they strongly bite at it. The deep temporal muscle, which is considered to act on the retrusion, is well developed, which seems to be due to an action strongly pulling rearward lower jaw on occlusion. 4. For proper masseter muscle of nectarphagous bats, vertically running muscular fibers at the first of the superficial masseter and tendon tissues at the second of the superficial masseter. Shallow of the masseteric fossa results in a mal-development of the deep masseter, and further the temporal muscle is also poorly developed which seems to be due to practical needlessness of opening the mouth largely. 5. The results obtained from enzymo-histochemical, light microscopic and electron microscopic examinations revealed that as with carpophagous, vampire and nectarphagous bats masticatory muscles making comparatively simple masticatory movement were composed of a single kind of muscular fibers, while as with insectivorous bats which will quickly capture their prey while flying and crush it with their large opened mouth into small pieces, which they will masticate persistently, the masseter and temporal muscles were composed of two kinds of muscular fibers with high aerobic metabolic function, and also fine structurally, contained numerous lipid droplets and mitochondria with well-developed cristae.

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The skull, dental arch, palate and teeth of beavers were measured in a morphological study made on 15 specimens. Measurements were taken studied for correlations, in particular those related to head shape, size, and the ratio of increase in various specimens. The results were as follows : 1. In the skull form, head length was long and head height was low. A significant positive correlation was found between head length, head breadth, and head height. The proportion between the measurements were invariable irrespective of head length. 2. The mandibular form was comparatively wide. A significant positive correlation was found between the measurements of the mandibular. The correlation between head length and mandibular size was higher than that of the mandibular body, dental arch, and palate. A longer head length indicated a higher increase in mandibular breadth when compared with the increase in mandibular length. 3. The mandibular head appeared like a globular form. The breadth between the mandibular angles was comparatively greater than the breadth between the mandibular heads. The height of the condylar process was less than that of the coronoid process. The mandibular notch was comparatively deep. The mandibular ramus was comparatively wide. The mandibular angle process was broad and roundish with a wide base. The mandibular body was comparatively thick. The site of mental foramen was slightly lower than the center and most posterior part of diastema. 4. Both upper and lower dental arches were widest at the third molar part. The dental arch forms were comparatively wide on both sides. The correlation between skull and dental arch length was higher than that between skull and dental arch breadth. A longer head length indicated a higher increase in dental arch length as compared to the increase in dental arch breadth on both sides. 5. Palate form was narrow and quite shallow. The lowest correlation coefficients were found in the palate. 6. In the incisors form, crown length was long, labiolingual diameter of crown was comparatively thick, and the mesiodistal diameter of crown was comparatively wide. A significant positive correlation was found between the crown parts. In the upper incisor, the lowest correlation coefficients were found in crown length. The longer the head length was, the wider labiolingual diameter of crown and the thicker mesiodistal diameter of crown were. In the proportions between the crown parts of incisor form was invariable irrespective of the head length. 7. The occlusion surface of molars was square. At the upper molars, the crown was compressed bucco-lingually, while at the lower molars, the crown was compressed mesio-distally. In the upper molars, the thickest buccolingual diameter of crown and the widest mesiodistal diameter of crown were found in premolar ; however, in the lower molars, the thickest buccolingual diameter of crown was found in premolar and the widest mesiodistal diameter of crown was found in first molar. A significant positive correlation was found between the mesiodistal and buccolingual diameters of all the upper and lower molars. In the upper first and second molars, the longer the head length was, the narrower the buccolingual diameter was. In the lower second and third molars, the longer the mandibular length was, the narrower the mesiodistal diameter of crown was. In the other molars, the buccolingual diameter of crown and the mesiodistal diameter of crown were invariablle irrespective of head length and mandibular length. 8. The above forms of each part were well adapted to the food habit of and the environment for beavers.

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The present study was made to investigate the reparative process in an extraction wound and to clarify the difference between normal and infected conditions. The right and left 2nd molars of rats were extracted. As an experimental group, endotoxin (LPS of E. coli) was inoculated into the extraction sockets and the rats were sacrificed at intervals from 0 day to 2 weeks after extraction. The rats in control group were sacrificed at the same intervals. The submandibular lymph nodes and the extraction wounds were examined histologically and immunologically. In addition, quantitative studies of the macrophages and osteoclasts were also performed. The results obtained were as follows : 1. In the histological examination of the extraction wounds, intense round cell infiltration was observed in the alveolar bone marrow at 9 hours after extraction both of experimental groupand control group. In the alveolar crest and bone marrow of control group, a large number of osteoclasts appeared at 3 days after extraction. In experimental group, the osteoclasts appeared not only in the alveolar crest and bone marrows but in the base and middle walls of the extraction socket. 2. In the histological examination of the submandibular lymph nodes of the experimental group, numerous lymph nodules were observed at 1 day after extraction. The germinal centers were seen at the same time also. 3. In the immunological examination of the submandibular lymph nodes numerous IgG positive cells appeared in the inner cortex and medullary sinuses in experimental group at 3 days after extraction. Also the titers of serum antibody to LPS increased gradually to a maximum level in this period. 4. In the submandibular lymph nodes of control group, the number of macrophages reached a maximum level at 9 hours after extraction and decreased to a minimum between 9 and 12 hours. The results of experimental group were the same as those of control group except the number of macrophages were more numerous. 5. In the extraction wounds of control group, a large number of macrophages appeared at 9 hours and then increased rapidly. At 12 hours, the largest amount were shown and then decreased rapidly. The results of experimental group were also the same as those of control group except the cell number were more numerous. 6. In the extraction wounds of control group, the osteoclasts increased rapidly from 12 hours to 3 days, while in the experimental group the osteoclasts were more numerous and increased more rapidly as compared to the control group.

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Osteoclasts were isolated from femura of 2-4 days old rat, settled on cover glasses, maintained in the culture medium, and morphologically studied using a phase contrast microscope and a scanning electron microscope. Results obtained are as follows. 1. Osteoclasts in culture were classified into five types (Type I-Type V). Type I : The hemispherical cell or the disk-like one rised at the centre. Sometimes the cells have a lot of pseudopodia at the small part of the edge. Type II : The semicircular cell with many lamellipodia at the portion of arc and with a lot of pseudopodia at the portion of cord. Type III : Highly irregular flat cell, which are surrounded by lamellipodia. Sometimes a lamellipodia grew up to a trunk which is about 40μm in length. Pseudopodia are often seen between the lamellipodia. Type IV : The turned dish-like cell without any lamellipodia and pseudopodia. Type V : The round flat cell, which have numerous particles and nuclear in the cytoplasm. 2. The number of osteoclast in each type increased at first and then decreased in the course of culture time. The peaks of the cell number appeared the following order ; Type I, (Type II), Type III and IV, and Type V. In short, cultured osteoclasts which are obtained from rat femura were classified into five morphological distinct types, and changed rapidly and morphologically during 2 days of the culture period. The cells of Type III are resemble to the resorbing osteoclast, which were seen on the endosteum surface in vivo, and on the tooth in vitro.

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Occurrence of the marginal failure of composite resins was clinically compared between the bevelless (butt-joint) cavity margin and straight-bevel margin. The margins of the filled composite resins were observed in three to five years after filling. Although the straight-bevel was prepared for the purpose of enhancing the marginal sealing effect, the marginal failures readily appeared in several cases after three years. On the other hand, some of the cases in the butt-joint group showed no marginal failures even after five years. These results indicate that the marginal region of the composite resin may be more stable as it is thicker. Thus, it is recommended to prepare a round or chamfered-bevel margin to the cavity in order to secure a long-term sound composite resin restoration.

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For the patient currently presented, the obtulator and denture are constructed as one unit. Consequentry, effective undercutting cannot be utilized fully. Therefore, a sectional denture in which the obtulator and the denture part are connected by magnet was prepared. Reduction in weight of the obtulator was achieved by making its inside hollow. By reducing the weight of the maxillary denture and improving its retentivity with effective use of undercutting, insertion and removal of the denture was made easier and wearer's mental irritation was lessened.

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Many denture wearers, especially full denture wearers who have atrophy of mucous membrane or sharp spicules, complain of pain in mucous membrane. For these patients the denture is usually lined with soft lining material to reduce the pain and increase the masticatory performance. At present many brands of such materials are on the market. Although they seem to be different from each other in physical and mechanical properties, there are no fundamental criteria for choosing a material and making a good use of it for increasing the masticatory performance. In the present study, therefore, characteristics of the materials were examined through static creep tests for eleven commercial soft lining materials, and the masticatory performance of duplicate dentures were clinically evaluated for three typical materials out of eleven. According to the creep properties the materials tested were classified into two types. They are : (1) Type A-The deformation stops in a very short time, as short as 10 sec ; silicone group (Neosnugger, Simpa and Mollosil) and fluoropolymer group (Kurepate) are of this type. (2) Type B-The deformation occurs rapidly for about first 30 sec and then it increases at a slow but steady rate ; the materials of this type are acrylic group (Coesuper soft, Tru-soft, Ardee, Visco-gel, Soft-liner and Coe-soft) and vinyl polymer group (Vina-soft). The Type A materials showed smaller delayed elastic deformation, and the Type B larger. The instantaneous elastic deformation did not change for any of the Type A materials after the specimen was aged for one week, and little changed for Softliner (acrylic group) and Vina-soft (vinyl polymer group) of Type B. Deformation decreased by aging for Coe-super soft, Tru-soft, Visco-gel and Coe-soft (acrylic group), while it increased only for Ardee (acrylic group). In the mastication tests, it was confirmed that all the three soft lining materials employed were significantly effective for improving the masticatory performance in the patients having pain in mucous membrane. The masticatory performance appeared to be maximum when the denture was lined with any material in thickness of about 2 mm. If the lining was thicker than 2 mm, the masticatory performance was apt to be decreased. Although the thinner lining also decreased the masticatory performance, it was found that the material showing larger elastic deformation such as Visco-gel was more effective than others when the lining was as thin as 1 mm. In the case where it is difficult to secure sufficient thickness of the lining, therefore, it may be desirable to choose a material bearing larger elastic deformation. Thus, the soft lining materials may be used under various circumstances, and it is important to make a proper choice and use of the material after due consideration of the characteristics of the materials as well as the aspects of the patient such as the condition of the mucous membrane and the thickness of the denture.

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In making a complete denture, maxillomandibular registration is very important step and various methods for registration have been reported. Of these methods, tapping movement has often been used clinically. Therefore, effectiveness of use of tapping movement was examined. For this study, tapping movement with the vertical dimension changed was recorded for 20 dentulous subjects and 13 denture-wearing subjects. Sweep recording of 50 tapping movements without overlapping was made possible by connecting a 2 pen recorder to a Mandibular Kinesiograph. On the basis of the recordings, anteroposterior displacement and lateral displacement of tapping point, tapping area, variance in tapping point, at various mandibular positions, were obtained. The results were as follows : 1. The maximum anteroposterior displacement of tapping at the centric occlusion in 20 dentulous subjects was 0.05±0.12mm anterior and 0.29±0.13mm posterior with an average of 0.09±0.10mm posterior. The maximum displacement was 0.13±0.06mm on the right and 0.21±0.10mm on the left with an average of 0.01±0.07mm on the right. The maximum tapping area was 0.06mm^2 and the minimum was 0.00mm^2 with an average of 0.02±0.02mm^2. 2. The anteroposterior displacement of the tapping point at various mandibular positions in the dentulous subjects increased as the vertical dimension was raised. However, the lateral displacement did not show any significant difference. 3. The tapping area in the dentulous subjects increased as the vertical dimension was raised. 4. In variance of tapping point at different mandibular positions in dentulous subjects, anteroposterior variance was significantly greater in 64.2% on the average and lateral variance in 12.9%. 5. The anteroposterior displacement and lateral displacement at various mandibular positions with the vertical dimension lowered in the denture-wearing subjects did not show any significant difference when compared with the displacement (0.46±0.29mm anterior and 0.16±0.30mm on the right to the centric relation) at the appropriate vertical dimension. The lateral displacement did not show significant difference even when the vertical dimension was raised. However, the anteroposterior displacement increased as the vertical dimension was increased and the displacement was 1.09±0.74mm anterior to the centric relation at the mandibular position raised by 6mm. 6. The tapping area at various mandibular positions with the vertical dimension lowered in the denture-wearing subjects did not show any significant difference in comparison with the tapping area (0.06±0.08mm^2) with the appropriate vertical dimension. However, as the vertical dimension was raised, the tapping area increased and the area was 0.39±0.46mm^2 at the mandibular position raised by 6mm. 7. When the anteroposterior variance was compared with the lateral variance of the tapping point at various mandibular positions in the denture-wearing subjects, the anteroposterior variance was significantly greater in 46.1% on the average and the lateral variance was significantly greater in 13.5% on the average.

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In daily clinical practice, residual occlusal teeth after a multiple dental defect often involve traumatic changes due to an abnormal biting pressure. However, no report is available of an experimental study on changes in the residual occlusal teeth and the paradentium after a multiple dental defect. Using rhesus monkeys with teeth and paradentium most similar to man, the author made a histopathological examination of the influences of a bilateral mandibular molar regional defect on the residual teeth and the paradentium in the anterior region. The results obtained were as follows : 1. On the mesial angle side from the labial side of the root upper region and on the palatal (lingual) side of the root lower region, findings on the pressure side, such as narrowing of the periodontal space, regressive changes of the periodontal fibers and bone resorption in the alveolar inside wall, were observed on and after the 5th postoperative day. 2. On the distal side from the palatal (lingual) side of the root upper region and the labial side of the root lower region, findings on the tension side, such as enlarging of the periodontal space, tension of the periodontal fibers and osteogenesis in the alveolar inside wall, were observed on and after the 5th postoperative day. 3. These changes became slight on the 30th postopeative day, and on and after the 60th postoperative day the periodontal membrane and the alveolar bone underwent a tissue reconstruction to cope with the abonrmal biting pressure. This tissue reconstruction was almost over on the 180th postoperative day. 4. With the alveolar inside wall reconstruction, there also occurred changes in both the alveolar outside wall and the alveolar marrow. 5. The cementum always had less changes than the alveolar bone, and there was observed only a persistent apposition of newly developed cementum on the labial side of the root lower region. 6. Histological changes on the upper and lower jaw sides presented some differences in degree and appearance time but were almost the same. 7. The dental drifting was considered to be in the labial direction due to a tipping with a point one-third of the footh length from the root apex as its center. 8. The above histopathological examination of a bilateral mandibular molar regional defect suggested that the anterior teeth region was strongly influenced by a lateral pressure in the labial direction rather than by a vertical pressure in the root apical direction.

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Many operative methods have been devised for surgical orthopedics of the mandibule, of which methods sagittal split osteotomy of the mandibular ramus is now in the most frequent use. The author has a preference for Obwegeser-Dal Pont method for those cases which require rotation of the mandibule in addition to its forward and backforward sliding. However any of these methods needs 6 to 8 weeks of intermaxillary fixation with wire ligatures, which gives the patient a great deal of physical and mental distress, while Spiessl devised a method in which instead of intermaxillary fixation. The fixation is made with cortex bone screws of A.O. Osteosynthesis, which need, however, to be removed about one year after operation. Then, Seto prepared single crystal alumina ceramic screws requiring no removal, which he is actively putting in clinical use. Favored with an opportunity to use such ceramic screws, the author made clinical studies of related cases and obtained the following resultes ; 1. Application of osteosynthetic screws resulted in several merits such as sufficient area of bone contact, shortening or disappearance of duration of intermaxillary fixation. 2. Application of ceramic screws permits doing without any removal of screws. 3. Application of this procedure to mandibular prognathism of the skeletal type and open bite led to neither lesional relapses nor anomalies of the temple mandibular joint.

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A variety of accidents often encountered in daily dental practice are liable to turn into a cause of lawsuits against alleged malpractice. Patients who visited the Fukuoka Dental College Hospital were reviewed in this study. Cases reviewed and reported herein are : accidental swallowing of a foreign body into the digestive tract in 5 cases (reamer in 5 cases, inlay in 2 cases, and postcrown in 1 case); residual roots straying into the maxillary sinus in 1 case ; mandibular third molar roots going astray into the jaw bone in 1 case and into lingual gum tissues in 1 case ; and an accident caused by orthodontic rubber bands in 1 case.

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For a standardization of instrumental measurements of the skull radiographs of living dogs, the mandibles of beagles at various angles were investigated as a fundamental study and compared with those of racoon dogs. 1. Almost all items showed no differences by sex. 2. Mandibular angle observed from the upper side and lower side was nearly the same for both the beagles and the racoon dogs. 3. Between the beagles and the racoon dogs, there were differences in size and direction of the mandibular angle process and in the bakward protrusive degree of the condylar process, which a significant difference in the angles of the mandibular branch region. 4. On the basis of the above results, a study will be doue on cephalometric radiography of living dogs.

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歯牙の疼痛が脳皮質部の血流(CBF)と酸素消費量(CMRO_2)にいかなる影響を与えているかを検索する目的で実験を行なった.実験には雑種成犬7匹を用いた.脳血流(CBF)は上矢状洞よりの還流血を電磁血流計を用いて計測した.また脳酸素消費量はCBFと脳動静脈酸素含量較差との積として求めた.平均動脈圧MAPは大腿動脈へのカニューレによる直接法を用いた.歯牙への刺激としては下顎犬歯歯髄内に27Gの注射針を刺入し, これに40 voltの電気刺激を加えた.以上より以下の結果を得た.・CMRO_2は刺激開始後40秒で有意に上昇した.・CBFは刺激開始後, 10秒, 40秒でそれぞれ有意に上昇した.・MAPは実験期間中, 有意の変化はなかった.

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