Panoramic radiography was originally devised to obtain a panoramic view of the jaws using a single film. At that time panoramic radiography was entirely used for examination of lesions of the jaws. However, due to the fact that the maxillary sinus is clearly observable using panoramic radiography, it has been used for the detection of maxillary sinus pathosis. There are only a few experimental studies on the detection of maxillary sinus pathosis, such as a globular radiopacity or bony defect, using panoramic radiography, Waters' projection or posteroanterior projection. However, there have been few studies comparing the detection of maxillary sinus pathosis between panoramic, occlusal, and periapical radiographies. In this study the detection of a globular radiopaque mass in the maxillary sinus of a dry skull was compared experimentally using panoramic, occlusal, and periapical radiographies. Oil-clay mass with diameters of 2mm, 3mm, 5mm, and 7mm were used as globular radiopaque masses, and they were always placed on the internal surface of the left maxillary sinus. The results obtained were as follows : 1. Globular radiopaque masses with diameters of 3mm, 5mm, and 7mm were put on the anterior wall of the maxillary sinus. The 3mm, 5mm, and 7mm masses were all detected by panoramic radiography, but only the 5mm and 7mm masses were detected by maxillary oblique occlusal radiography. In both radiographies the correct positions of the masses in the sinus were not clear. 2. Globular radiopaque masses with diameters of 2mm, 3mm, 5mm, and 7mm on the posterior wall of the maxillary sinus were better shown by panoramic radiography. In panoramic radiography it was possible not only to detect the masses, but also to determine their correct positions in the sinus. However, a 7mm mass was not detected by either maxillary oblique or hemi-maxillary occlusal radiographies. 3. Globular radiopaque masses with diameters of 2mm, 3mm, 5mm, and 7mm were put on the medial wall of the maxillary sinus. The 2mm, 3mm, 5mm, and 7mm were detected by panoramic radiography, but only the 5mm and 7mm masses were detected by maxillary oblique occlusal radiography. In both radiographies the correct positions of the masses in the sinus were not clear. 4. Globular radiopaque masses with diameters of 3mm, 5mm, and 7mm on the anterior region of the floor of the maxillary sinus were better shown by panoramic and maxillary oblique occlusal radiographies. In both radiographies it was possible not only to detect the masses, but also to determine their correct positions in the sinus. 5. Globular radiopaque masses with diameters of 3mm, 5mm, and 7mm on the middle and posterior regions of the floor of the maxillary sinus were better shown by panoramic, maxillary oblique occlusal, and periapical radiographies. In these radiographies it was possible to determine their correct positions in the sinus. 6. A globular radiopaque mass with a diameter of 2mm on the floor of the maxillary sinus was not detected by panoramic, maxillary oblique occlusal, or periapical radiographies.

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In order to minimize the damage to the periodontal tissues of the abutment tooth, numerous studies on the abutment tooth behavior with partial prostheses have been undertaken in various ways using strain gauge, photoelastic and finite element methods. However, it was difficult by these methods to detect the three-dimensional dynamic movement of the abutment tooth. The present study examined three-diminsionally the effects of the partial denture clasp assembly and its component parts on the abutment tooth movement utilizing the mandibular kinesiograph (MKG). The mandibular distal-extension removable partial denture was constructed on a simulation model of Kennedy Class II Modification 1. The gingival and alveolar ridge areas and the roots of the abutment teeth were covered with silicone material for simulating the resilient natural mucosa and membrane. Starting from the original denture consisting of denture bases on both sides of the arch and five retainers connected by a lingual plate, the experimental design was altered by reducing the components one after another. The lateral loading to the tooth on the denture caused significantly larger movement of the abutment tooth than the vertical loading. Especially, the inclination of the abutment tooth in the distal direction, which might be the principal factor causing damages to the tooth, was induced by the mesial or buccal loading to the denture tooth. It was also found that the tooth movement was smaller when the load was applied to the second molar of the denture than to the second premolar. The original design of the denture showed the smallest tooth movement in general. There was a tendency that the tooth movement became easy to occur by a smaller load as the components were reduced one after another. However, the design leaving the indirect retainers on the first premolar of the other side of the arch connected by a lingual bar showed smaller tooth movement in the distal direction rather than the original denture. In the unilateral denture with the indirect retainers being removed, on the other hand, extremely larger tooth movement was found to occur. Further reduction in the basal area of the denture base made the denture more unstable, resulting in significantly increased tooth movement. When the applied load was removed, the abutment tooth returned to its original position taking a different route from its inclination pass, occasionally rotating.

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In the removable partial denture, especially in the unilateral distal-extension denture, it is very important to minimize the denture movement and to make the occlusal forces appropriately distribute to the abutment teeth and residual ridges. In this study, the characteristic movements of the Konus Krone partial denture and the abutment teeth were investigated utilizing the mandibular kinesiograph (MKG) on a Kennedy Class II simulation model. Three types of unilateral distal-extension partial dentures were constructed : Type I, having a single Konus Krone abutment tooth ; Type II, having two Konus Krone abutment teeth whose outer crowns were connected ; and Type III, having two Konus Krone abutment teeth whose inner and outer crowns were respectively connected. The results obtained were summarized as follows. 1. The movement of the distal abutment tooth was significantly larger than that of the mesial one when a load was applied to the denture. 2. Type I showed the smallest movement of the distal abutment tooth. The tooth movement was significantly increased by connecting the crowns although the movement of the outer crowns was decreased. Particularly the inclination of the tooth to the distal direction was induced in Type II. 3. The movement of the distal abutment tooth was the smallest in Type III and the largest in Type I. 4. The outer crown movement was larger than the tooth movement. The tendency was marked in the mesial abutment tooth. 5. In Type I, no significant changes in the tooth movement were caused by increasing in the applied load. 6. Type III was effective for reducing the denture movement when the applied load was smaller. However, its superiority was damped as the load was increased. 7. On vertical loading to the denture, the outer crowns and the abutment teeth inclined to the opposite directions each other. 8. The largest tooth movement was found to occur on buccal or vertical loading. 9. There were no significant differences in the abutment tooth movement between the loadings to the second premolar and to the second molar of the denture. 10. It was suggested from the foregoings that Type I might be favorable for protecting the mucous membrane against damages and Type III for ensuring the denture stability.

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Food habit and predation have some effects on the development of the muscles related to mandibular movement. It seems that comparative anatomical studies of muscles and nerves in head and neck is useful. A comparative anatomical study on suprahyoid muscles of six species of mammals was made by means of macroscopy. The mammals in the present study were selected according to the individual food habit : the carnivora (racoon dogs, dogs and cats), the omnivora (pigs) and the herbivora (guinea pigs and rabbits). In a total of 39 mammals, the digastric muscle, stylohyoid muscle, mylohyoid muscle and geniohyoid muscle were observed in gross anatomically for the shape, origin, insertion, direction and innervation. The results were as follows : 1. The digastric muscle arises from the jugular process in racoon dogs, dogs, pigs, guinea pigs and rabbits, from the posterior surface of the mastoid process and the notch between the jugular process and the mastoid process in cats. It inserts into the ventral border of the mandible in all of the species. It appears as a fusiform muscle highly developed in the carnivora. It appears as a double-bellied muscle, or the posterior belly muscle is absent, in the omnivora and the herbivora. The posterior belly is innervated by the facial nerve, and the anterior belly by the mandibular nerve in all of the species. 2. The stylohyoid muscle is absent in racoon dogs and guinea pigs. It arises from the tympanohyoid in dogs and cats, from the stylohyoid in pigs, from the notch between the jugular process and the mastoid process in rabbits. It inserts into the lateral surface of the basihyoid in all of the species. It runs inside the digastric muscle in pigs, and outside the digastric muscle in dogs, cats and rabbits. It is very degenerative in dogs and highly developed in pigs and rabbits. It is innervated by the facial nerve in dogs, cats, pigs and rabbits. 3. The mylohyoid muscle appears as a single sheet in racoon dogs, dogs, cats, pigs and guinea pigs. The anterior muscle bundles arise from the ventral border of the mandible and the posterior muscle bundles from the inner surface of the mandible in racoon dogs and dogs. The both muscle bundles arise from the inner surface of the mandible in cats, pigs and guinea pigs. It appears bilayer, and the superficial layer arises from the ventral border of the mandible, the deep layer from the medial surface of the mandible in rabbits. Almost all the muscle bundles insert into the mylohyiod raphe and other bundles in the posterior portion into the ventral surface of the basihyoid. It is innervated by the mandibular nerve in all of the species. 4. The geniohyoid muscle arises from the inner surface of the mandible adjacent to the mandibular symphysis and inserts into the central portion of the anterior surface of the basihyoid in all of the species. It is a slender and triangular pyramid muscle with the origin at the apex and the insertion at the bottom in all of the specimens. It is in close contact with its counterpart on the opposite side in racoon dogs, dogs, cats and pigs, but not in guinea pigs and rabbits. It is innervated by the hypoglossal nerve in all of the species. 5. The difference of the origin of the digastric muscle and the presence of the degeneration of the stylohyoid muscle among the carnivora seem to be due to the transition of the size or to the relative position with the phylogenetic reconstruction of the stomatognathic system. 6. It seems that the difference of the development of the digastric muscle between the carnivora and the herbivora is due to the difference of their food habits. The more developed the posterior belly muscle of the digastric is, the more degenerated the stylohyoid muscle tends to be in mammals. 7. The lamination of the mylohyoid muscle and no contact with its counterpart on the opposite side in rabbits seem to make the pivoting of the right and left mandibles united

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The surgical treatment for preventing severe atrophy of the alveolar ridge caused by extraction of a tooth or cystectomy has improved considerably because of a development of calcium phosphate implant materials, in particular hydroxyapatite (HA), which has been shown to be bioactive in hard tissues. Histological studies have demonstrated that HA directly bonds with a bone after implantation. However, there has been no accurate answer to the question why HA shows bioactivity. In addition, numerous studies show that alveolar ridge augumentation utilizing HA granules does not always produce good results. Attempts to overcome these questions and clinical disadvantage have been made by a biochemical study of initial calcification of HA surrounding tissues and by a clinical study of sintered bone (TBC)-collagen complex. 1. Matrix vesicles were isolated from the epiphysial growth plate of young rabbits. Lactate dehydrogenase (LDH) activity was detected in the isolated matrix vesicles only in the presence of detergents. The isolated matrix vesicles contained all five LDH isoenzymes but not other cytosolic enzymes. These results show that LDH is located in the matrix vesicles. 2. Non-enzymatic phosphatase activity was detected in HA. Among different types of HA, biological HA (sintered bone ; True Bone Ceramic) showed the highest activity. 3. True Bone Ceramic (TBC)-collagen complex was prepared. Collagen serves as an adherent for the HA particles, resulting in a material that is easy to handle in the augumentation of a bone. 4. In a primary culture of chicken growth chondrocytes, TBC-collagen complex promoted cell growth and cell differentiation. 5. The healing process of TBC implanted dental extraction sites in mongrel dogs was histologically evaluated with and without the use of collagen. At 4 weeks after implantation of TBC-collagen, numerous immature osteoids were observed in the central area of extraction sites. At 12 weeks, TBC-collagen showed good ossification at the extraction sites where cortical bone had existed.

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A total of 43 cases of carcinoma of the tongue treated at the Second Department of Oral Surgery, Kyushu Dental College Hospital, between 1977 and 1986, were clinically analyzed. The following results were obtained. 1) A series of 43 primary cases with carcinoma of the tongue were reported. Its incidence was seen in 33.9% of the patients with malignant tumors in oral cavity. All cases were found histopathologically to be squamous cell carcinoma. 2) The carcinoma of the tongue in the majority of 43 cases were located in the right lingual margin (95.4%). Of the 43 cases, 27 cases (62.8%) were between 50 and 60 years of age (the avarage 56.9 years). By sex, the incidence it was higher in male. 3) In TNM classification of UICC (1978), the majority of 43 cases were T1, T2, N0 cases and Stage II, Stage III cases. 4) Treatment was performed mostly by combination therapy of the surgery with chemotherapy and/or radiation therapy. 5) The 5-year-survival rate for all cases was 34.4% and that for high stage cases (Stage III, Stage IV) was lower than that of low stage ones (Stage I, Stage II). The 5-year-survival rate of low stage cases in the second 5 years (86.1%) has improved greatly compared with that of the first 5 year term (30.0%), while the improvement of the 5-year-survival rate in high stage cases was not observed.

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Demand for aesthetic prosthetic appliances in addition to restoration of such functions as mastication and pronunciation has been increasing. As a result, anterior teeth with individual tooth forms have been made available commercially. This trend indeed made the range of selection of tooth form wider. There is however a question about ratio of tooth size of these commercially available anterior teeth. Therefore, widths of commercially available anterior teeth of three basic types, tapering, ovoid, and square, were measured and compared with the measurements of natural teeth which had been examined and compiled by our department. Livdent had small ratios for its lateral incisors in the ovoid type and small widths for its canines on the whole excluding the tapering type. Endura had small ratios for its lateral incisors in the tapering type and ovoid type and small canines on the whole. Its square type showed ratios similar to those of natural teeth. Duradent showed little difference in all forms for the upper anterior teeth. Its lateral incisors were slightly small. As described above, these artificial teeth showed quite small width ratios for the lateral incisors in general and small canines in nearly all types.

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Two cases of basal cell nevus syndrome are reported. Both cases were referred for evaluation of multiple radiolucent jaw lesions. In the case of a 20-year-old female, multiple jaw cysts, a broad nasal root, ocular hypertelolism, frontal bossing, several bifid ribs, calcification of the falx cerebri and pit of palm were presented. In the other case, her younger sister, a 13-year-old female, had findings same as her sister. Both cases had many features of basal cell nevus syndrome. Histopathological diagnosis of multiple jaw cysts was odontogenic keratocyst in both cases. Both cysts were enucleated. Recurrence of cysts are not seen, but we think it necessary to have a long term follow up.

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