Pulpotomy with calcium hydroxide was performed on teeth with incomplete root of young dogs, and growth of root and apical closure thereafter, or changes in pulpal nerve fibers at what is called Apexogenesis were investigated neurohistologically. The results were as follows : 1. On 7th day postoperatively, regenerated nerve fibers extended to the matrix formed directly under the boundary zone of the plane of pulp cross section. On 14th day, degenerated nerve fibers remaining in the living pulp were nearly nil. This stage corresponded to non-apposition stage of cellular cementum of root apex in normal growth of root, and medium and small nerve bundles, single nerve fibers, and minute nerve fibers with Schwann cells were seen ascending straight mainly in the region between the tips of Hertwig's epithelial sheath in the pulp of the root. 2. On 35th day, the dentin barrier was formed about evenly. Regenerated nerve fibers and their branches extended toward the periphery, branched out further on reaching the periphery, and formed relatively sparse nerve plexuses. This stage corresponded to apposition stage of cellular cementum of root apex in normal growth of root, and was characterized by degenerative findings of tortuous courses and moniliform in the nerve fibers penetrating between cementoblasts and in the nerve fibers penetrating through gaps where future side branches would be. 3. On 95th day, formation of dentin barrier and root dentin was stabilized. At the same time, nerve plexuses at the periphery of dentin barrier were dense and nerve endings were abundant. Many individual nerve fibers had about the same width as the contrast. This stage corresponded to terminal stage of root formation, and was characterized by arrangement into bundles of nerve fibers penetrating into the pulp, penetration together with blood vessels of mainly large, medium, and small nerve bundles through apical branches, and by absence of minute nerve fibers with Schwann's cells, and reduction in single nerve fibers.

View full abstract

In order to study the change of pulp nerve fibers in various pulp diseases, continuous sections of 227 extracted human teeth were made, stained by nerve staining method, and observed. The results were as follows : 1. In pulp hyperemia, those in the early stages did not show marked difference in nerve fibers. However, in the case with continuous hyperemia, findings of slight swelling, hypochromatosis and beading were observed. 2. In acute serous pulpitis, findings of slight swelling, hypochromatosis, and meandering of the nerve fibers in the inflammation focus and around the focus were observed. These changes however were observed mostly in thick nerve fibers ; most thin nerve fibers showed healthy findings. 3. In acute suppurative pulpitis in which inflammation was limited to a part, most of the nerve fibers in the inflammatory tissue surrounding the localized suppurative focus were degenerated. However, healthy nerve fibers were observed in thin nerve fibers. When suppurative inflammation extended to the whole pulp, most nerve fibers showed degenerative findings. 4. In the case of acute gangrenous pulpitis, whole nerve fibers were degenerated markedly or in decomposition process. 5. In the ulcerative membrane of chronic ulcerative pulpitis and in the abscess membrane of chronic closed pulpitis, reticular distribution of remarkably minute nerve fibers was observed. 6. A considerable number of regenerated nerve fibers were observed in pulp polyp and some with free nerve endings extending into the leucocyte layer in the outermost surface were seen. 7. No marked changes were seen in the nerve fibers distributed in the odontoblastic layer which showed vacuolar degeneration. 8. Most of the nerve fibers in the calcareously degenerated portion underwent swelling, laceration, and granular decomposition. A number of them were about to disappear. 9. In reticular atrophy, almost no changes were observed in the early stages. However, degeneration of nerve fibers progressed as atrophy progressed. In the case where atrophy extended to the whole pulp, most nerve fibers showed marked degenerative findings. 10. The foregoing findings indicate that nerve fibers in dental pulp show strong resistance against destructive changes of various pulp diseases and that they survive considerably longer than the surrounding tissues.

View full abstract

A comparative anatomical study on morphology was made of the skull, mandible, dental arch, palate, and teeth of bobcats of the cat family, carnivore order. The results were as follows : 1. In tooth form, the most characteristic was that the cuspids were markedly large and strong, the upper cuspids in particular. Also, the carnassial teeth showed marked development. In contrast, the molars other than the carnassial teeth were extremely small. The degree of reduction of the upper M_1 in particular was extensive. 2. The crown width of the incisal teeth as compared with the thickness was small. This finding was different from that of the dog family. On the other hand, the thickness of the crowns of the molars as against the width was extremely small and buccolingual compression of the crown was greater. The molars of the upper jaw in particular were far more compressed than those of the animals in the dog family. 3. Appearance of the marginal tubercules on the lingual surface of the incisors was lower than that of the animals in the dog family. Especially the rate for the upper jaw was markedly low. The appearance of distal tubercules of the upper P_3 was comparatively better than the mesial ones. For the lower P_3 and P_4, the mesial tubercules were better developed than the distal ones. The development was better for P_4 than for P_3. 4. The crown of the upper carnassial tooth P_4 was elongated mesiodistally and the paracone with a sharply pointed peak stood about the center. The protocone was observed on the mesiolingual side and small tubercles on the mesiobuccal and mesial sides. Well developed metaconus was observed on the distal side of the paracone with a deep sulcus interposing and small tubercules were observed on the metaconus. 5. The lower carnassial tooth M_1 was elongated mesiodistally and the protoconid stood high about the center. The paraconid was observed on its mesial side and the hypoconid on its distal side. 6. The cephalic length-width index was 70.03, and the cephalic length-heigth index 43.14. These values, as compared with other animals in the dog family, are brachycephalic and indicated a trend toward hypsicephalic. 7. The dental arch index was 68.89 for the upper jaw and 40.46 for the lower jaw, which indicates that the dental arch length is greater than the width, in contrast with man. 8. The palatal length-width index was 87.88, which is significantly higher than those of other mammals and indicates that the palatal width is relatively greater than the length. The palatal length-height index was 16.55, and the palatal width-height index 18.82, which suggests that the palatal height was significantly low as against the width and length. 9. The mental foramens numbered four : two anterior foramens, one middle foramen, and one posterior foramen. The middle foramen was the largest and was located between and below C and P_3. 10. The difference height between the articular process and coronoid process was marked. Consequently, the mandibular notch was shallow, which is characteristic of the carnivore. 11. The mandibular head index was 28.14 and the head was extremely elongated in the right and left directions. As compared with those of animals in the dog family, the head was much more elongated. 12. The mandibular foramen was small, 2.6mm in diameter. The mandibular foramen index was 19.09, which indicates the site of the foramen is near the inferior border of the mandibular ramus. 13. Thomson's mandibular index was 104. 10. This indicates that there is not much difference between the mandibular length and width, and this finding is in contrast with animals in the dog family whose mandibular length is comparatively longer than width. 14. The mandibular width index was 80.37, which indicates that the intermandibularhead width is relatively large as against the inter-mandibularangle width. This finding is the same as for the animals in the dog family.

(View PDF for the rest of the abstract.)

View full abstract

There are various studies in which malocclusion was experimentally induced and its influence on the temporomandibular joint was histopathologically examined. The mandibular condyle, especially the cartilaginous layer undergoes main changes, which are greatly varied and on which there has been no uniform view yet. Therefore, in order to make a more minute examination of the influence of malocclusion on the temporomandibular joint, malocclusion was experimentally induced in rats by upper, right and left, total molar extraction (A group, forty animals) and by periodic grinding of upper, right and left incisors plus the foregoing total extraction (B group, forty animals), and histopathological and scanning electron microscopic examinations were made of the changes in the mandibular condyle. The results were as follows : 1. Both experimental A and B groups showed the same weight gain tendency as control group. 2. Specific changes were observed early at the embryonic zone ranging from the central to internal area in experimental A group. a. Light microscopic observations revealed that from the first post-operative week, cells in the area adjacent to the articular zone presented roundness. These cells covered the entire embryonic zone at the sixth week, and thereafter the cellular arrangement became irregular with an increase in cartilage matrix. b. SEM observations revealed that from the first post-operative week, cells near the articular zone presented many processes, which continued to grow up remarkably up to the second week, and the cells presented roundness morphologically. Thereafter these processes decreased and from the ninth week the collagenous fibrils of the matrix traveled irregularly in part. 3. Greater specific changes were observed early at the embryonic zone of the internal area in experimental B group than in experimental A group. a. Light microscopic observations revealed that the cartilage matrix increased by the week, and that cellular morphology presented roundness and cellular arrangement became irregular to the most remarkable extent at the fourth week. Thereafter cellular arrangement became a little regular, but cellular morphology presented more roundness and was no longer distinguishable from the transitional zone. b. SEM observations revealed that changes of the collagenous fibrils of the matrix began as their disturbed traveling, leading to their small fasciculation to the most remarkable extent at the fourth week. Thereafter their traveling became regular and showed a tendency toward compactification. 4. The cartilaginous layer of the mandibular condyle was already thin, especially at the hypertrophic zone, at the third post-operative day in both experimental A and B groups. However, by the third week the layer became hypertrophic inversely, and from the fourth week it was re-thinned. 5. In neither A nor B group any great change was observed at the external area of the mandibular condyle. 6. Bone resorption of the lateral pterygoid attached bone margin of the mandibular internal neck stopped almost completely at the ninth week in control group, while in experimental groups there still remained bone resorption picture even then. 7. Ossification of the mandibular condyle proceeded in the order of control group, experimental A group, and experimental B group. The above results suggested that difference in malocclusion was correlated with the extent of abnormality of the temporomandibular joint.

View full abstract

Recently, prevalence of deciduous teeth caries is decreasing in Japan. This tendency, however, is restricted to urban communities ; dental caries are still highly prevalent in rural communities. We have surveyed the eating habits of elementary school children in a high caries prevalence region, Ikema island, in Okinawa. To summarize the results : on frequency of intake of twenty different foods, elementary school children in Ikema island consumed much more sweet drinks and sugar containing foods than the control group of Kitakyushu children. On the other hand, they consumed less vegetables and milk. There was no diffence in preference for eleven foods between Ikema island and Kitakyushu children.

View full abstract

Formaldehyde and glutaraldehyde were tested for their cytotoxic effect on a HeLa cell tissue culture system. Serial dilutions of the medicament were made in concentrations of 1 : 100, 1 : 10, 000 and 1 : 1, 000, 000. The tissue cells were exposed to the various dilutions of the medicaments for 24 and 48 hours. Their effects on the cells were observed by phase contrast microscopy. Both of the medicaments were extremely toxic to the tissue culture cells even when their concentration was in a dilution of 1 : 10, 000, and were insignificantly toxic when in a 1 : 1, 000, 000. The cells were conspicuously destructed at 1 : 10, 000 dilutions, whereas they were kept less transformed at 1 : 100.

View full abstract

Recently, incidence of dental caries of Japanese children has shown no regional difference with development of mass media and traffic facilities. This time, incidence of dental caries of primary school children living at an isolated island in Nagasaki was investigated once a year from 1977 to 1982. A total of 130 subjects, 57 males and 73 females, were studied on their DMF index. The results were as follows : 1. The mean number of DMF teeth was 0.74±0.12 on the males and 0.58±0.11 on the females at the 1st grade and showed increasing tendency with progressive grade and 5.11±0.35 on the males and 5.85±0.37 on the females was observed for the 6th grade. No significant difference was shown between males and females for each school grade. High range of increased DMF tooth rate was observed from 2nd to 3rd grade on the males, and from 2nd to 3rd grade and from 4th to 5th grade on the females. 2. The DMF tooth rate on the upper first molars was 0∿7.88% and that on the lower ones 29.03∿42.86% at the 1st grade, and 90% or more on both males and females was observed for the 6th grade. High range of increased DMF tooth rate on the upper first molars was observed from 2nd to 4th grade and that on the lowers was observed from 1st to 3rd grade on both males and females. 3. Significant correlation was shown between the number of DMF teeth on the first molars at the 1st grade and that on the permanent teeth without first molars at each 4th, 5th or 6th grade, and it showed increasing tendency with progressive grade.

View full abstract

The oblique lateral transcranial projection (OLTP) of the temporomandibular joint (TMJ) is widely used for the diagnosis of TMJ disease. The OLTP is a simple and valuable technique for the lateral projection of the TMJ, but is sometimes reveals a complex radiographic findings due to the overlapping of the pars petrosa and the mastoid process to the TMJ. We have recently applied a photographic subtraction technique to the OLTP for reduction of the complex radiographic findings in the OLTP. The purpose of this study is to know the value of the photographic subtraction technique in the OLTP fundamentally. The results obtained are as follows : 1) The shape of the condyle was clearly demonstrated by the subtraction technique. 2) Diagnostic ability on disease of the condyle was increased by applying the subtraction technique. 3) Location of the condyle in the fossa was easily detected by the subtraction technique.

View full abstract

Studies were carried out on the age changes of the nerve fibers, innervation to the periodontium of the rat molars from the stage of the root formation, one month after birth, to the aged stage, two and a half years after birth, through the stage of the completed root formation. The following results were obtained. 1. At the stage of root formation, the periodontal space was vast and the periodontal membrane was cellular with enormous collagen fibers, but undeveloped periodontal fiber bundles. The nerve fibers supplying the periodontal membrane penetrated through the vasoneural channel straight underneath the root apex and the interdental channel opening on the alveolar wall. At this stage the innervation was totally scanty, and the scantiness rates were in the order as follows : at the middle portion of the root and bifurcation, at the alveolar crest, and the root apex. The nerve fiber bundles mainly passed along the vessels near the alveolar wall. 2. As the root apex formation progressed, the periodontal fiber bundles were developed and showed the functional arrangement. The nerve fibers showed a gradual distribution in the periodontal membrane at the middle lateral portion of the root and the side of the cementum. When the root apex was completed in five months after birth, the nerve fibers were the most abundant. 3. The proliferation of the secondary cementum at the root apex was marked, and the periodontal spaces were strangulated, and the periodontal fibers showed the irregular functional arrangement with aging from six months to one year after birth. The degenerative findings such as the separation between the fibers of nerve fiber bundles, the partial swelling of the nerve fibers and the lowering of staining, were observed. 4. After the first postnatal year, the degeneration of the nerve fibers increased with aging and the degeneration with the form like a string of beads was abundantly seen. The intact nerve fibers were frequently observed in the portion where the remarkable strangulated periodontal membrane and no functional arrangement of the periodontal fiber bundles were seen ; on the contrary no degenerative change was seen in the portion where the intense degeneration of the nerve fibers was observed in the periodontal membrane. Therefore no correlation between the changes of periodontal membrane and the degeneration of the nerve fibers was noted. 5. After the second postnatal year, the advanced marginal periodontitis and dental caries abundantly appeared, and the functional arrangement of the periodntal membrane almost disappeared. The degenerated nerve fibers were numerously noted. It was suggested that the effect of periodontal disease as well as the aging changes exerted a synergistic action on the remarkable appearance of the degenerated nerve fibers.

View full abstract

The purpose of this study was to investigate the histopathological and enzyme histochemical changes in the periodontal tissues at the bifurcation which the occlusal trauma elicited in rat molars. In addition, the cases administered with the indomethacin which was one of the inhibitors of the prostaglandin biosynthesis were investigated. The following results were obtained. 1. By the injury, the periodontal space narrowed, the periodontal membrane caused decrease and disappearance of the cell ingredients, and partial hyalinization and necrosis occurred. On the other hand, the undermining resorption became active from the bone marrow side about 3 days after operation, the periodontal space was enlarged, and fibroblasts and capillaries increased in the periodontal membrane. The repairing of the periodontal tissue became active from 1 week and in 3 weeks it resembled that in the preoperative period. 2. In the fibrous ingredients of the periodontal membrane, the occlusal trauma elicited decrease and irregular arrangement of collagen fibers, and also decrease, swelling, lowering of staining, and irregular arrangement of oxytalan fibers. As the periodontal tissue was repaired, thin argyrophilic fibers increased from the marrow side and grew up to be meshy collagen fibers, and then the collagen fibers formed bundles and adhered to the cement and the alveolar bone, and at last they were restored to the periodontal membrane in the preoperative period. As oxytalan fibers were repaired, they regenerated, thickened and showed the regular arrangement and good staining. 3. In ALP, the activity was seen totally in the periodontal membrane and specially intensely around the alveolar bone. The activity decreased in the periodontal membrane which was depressed by the occlusal trauma. But its activity became intense again as the repairing progressed. In ACP, the activity was generally weak in the periodontal membrane. It was further decreased in the periodontal membrane which was depressed by the occlusal trauma. But intense activity was shown in osteoclasts and in the periapical area of the undermining resorption area. When the periodontal membrane began to be repaired in a week after operation, the activity decreased totally. But the activity was seen in fibroblasts, osteocytes, osteoblasts and cementoblasts. In LDH, the activity was generally weak, but intense activity was shown in cementoblasts and osteoblasts. The activity decreased in the periodontal membrane which was depressed by the occlusal trauma. The osteoclasts in the undermining resorption area showed intense activity and the fibroblasts in the periapical area showed increased activity. In a week after operation, the activity increased in osteoblasts and cementoblasts. 4. As compared with the nonindomethacin treated rat group, the indomethacin treated rat group showed decrease in the number and morphologic changes in osteoclasts. This suggested that the indomethacin inhibited the biosynthesis of the prostaglandin which was related to the appearance of the osteoclasts. As the result, it was postulated that the indomethacin depressed the bone resorption which played an important role in the destruction of the periodontal tissue in the periodontal disease.

View full abstract

The canine experimental endotoxin shock was prepared by intravenous administration of lethal dose of E. coli endotoxin. Serum zinc and copper concentrations in the shock were determined using a Hitachi 180-50 model atomic absorption spectrophotometer. The results were as follows : 1. The initial increase of serum zinc consentration was observed at one hour after administration of endotoxin. 2. Thereafter, serum zinc consentration seemed to decrease in the reversible shock phase and to increase in the irreversible shock phase. 3. No significant change was recognized in serum copper concentration.

View full abstract

Progressive systemic sclerosis (PSS) is a generalized disease that is characterized by hardness and rigidity of the skin and subcutaneous tissues. This disease sometimes disturbs the digestive organs, lungs, heart, kidney, and other organs. Then, its prognosis is very poor. PSS also shows several oral manifestations, such as atrophy of the oral membrane with hardening, retraction of lips, induration of tongue and difficulity of opening mouth. Widening of the periodontal membrane space and mandibular bone resorption are also revealed radiologically. This paper describes a clinical and oral radiographic findings of a PSS patient who suffered from mandibular bone resorption.

View full abstract

The term calcifying odontogenic cyst was proposed by Gorlin and his collaborators in 1962. A follow-up report is made here on the clinical course and pathohistological findings on a case of the cyst found in the left mandibular ramus of a 7-year-old boy. The cyst was enucleated from the patient under GOP anesthesia on May 31, 1976. Thin cortex bone and periosteum of the regions suspected to be in direct contact with the cyst were removed. Only cortex bone formed in a bridge-like shape, 0.8-1.0 cm wide, was left between the mandibular head and body. As to the pathohistological findings, ghost cells were found to be present scattered individually and in groups in the epithelial basal layer assumed to be the site of odontogenic origin and some of the cells were found to have been calcified. Furthermore, dental lamina-like epithelial cords were found penetrated into the surrounding connective tissues in part and proliferating. The observation eight years and three months after the operation showed no recurrence. Bone loss by operation was restored to the anatomical morphology corresponding to his normal age.

View full abstract