Gifu Shika Gakkai zasshi = The Journal of Gifu Dental Society最新文献

In a patient with a long face, skeletal open bite and excessive mandibular body length, it was found that the sagittal split ramus osteotomy to close the open bite was unstable, when the lower jaw alone was a moved surgically to correct the open bite and progenie. There was a slight relapse of the open bite and lingual compensation of the upper incisors, which may have been due to tissue rebound during the retention period.

The patient is a 10-year-old girl (Hellman's developmental stage IIIB) with a deficiency of upper second premolar (right side) erupting space caused by on upper first molar (right side) mesial shift). The treatment was proceeded with the looped lingual arch in the first place, the sectional arch and the open coil spring with the soldered lingual arch for reinforced anchorage in the second place. Consequently, the upper first molar (right side) was moved bodily without curve of the root in a short period, and upper second premolar (right side) erupted in a normal position.

In orthodontic diagnosis, one of the most important factors is to decide whether to extract or not to extract the permanent tooth. There are many so-called borderline cases. This difficulty is caused by his growth which can not be foreseen perfectly. We treated a borderline case without extraction, and established good occlusion.

A 20-year-old Japanese woman was referred to the hospital for examination and treatment of an asymptomatic swelling of the left dorsum of the tongue. Intraoral examination revealed that the tumor was covered with normal mucosa and oval, firm on palpation and measured 1.5 cm in diameter. The lesion was movable suggesting benignity in nature. No cervical lymph node was palpated. The cut surface of the extirpated tumor after fixation showed a chalky white "core region" surrounded with a yellowish white adipose tissue. Histopathological examination revealed the lesion to be a benign cartilaginous tumor. We report this case of chondroma which arose from the tongue because of its rarity, and reviewed related literature.

Researching the actual condition of tooth fractures, clinical records and X-ray photographs of 2717 patients, visited P.D.I. Dental Clinic from November, 1986 to September, 1988 were investigated statistically. 174 cases were tooth fractures in 2717 patients. The frequency rate of tooth fractures at an early age was low, increased from the latter half of the 30s and was highest at the latter half of the 50s accounted for over 10%, and decreased from the 60s. In the upper anterior teeth, the crown fractures caused by traumatic factors, at an early age showed a high proportion, and in the lower anterior the tooth fractures were rare. In the posterior the root fractures of non-vital teeth attributed to dental treatment at the middle and advanced age indicated a high proportion. In the case of tooth restored with metalcore and bridge, the proportion of the root fractures were high, the metalcore, was used in 63%, and in the bridge in 27% of the root fractures.

The effects of temperature, concentrations of activator (N, N-dimethyl-p-toluidine) and inhibitor (hydroquinone), atmosphere, liquid powder ratio and mixing time on polymerization process of self-curing resin for rebasing were studied by electron spin resonance. When powder and liquid were mixed at a ratio commercially recommended at a physiologic temperature of 37 degrees C, the propagating radical was first detected 5.5 minutes later, of which time interval corresponds to induction time for polymerization. After the induction time, the concentration of propagating radicals increased rapidly with time and reached the maximum level at 27 minutes. The radicals thus formed remained stable for more than 2.5 days when stored in air at 37 degrees C, though their concentration diminished gradually. With increasing temperature for curing, the maximum level of the radical concentration decreased and the propagating radicals disappeared more rapidly, indicating recombination reactions to be perferentially occurring at higher temperatures. Increase in the amount of activator of N,N-dimethyl-p-toluidine resulted in increase in the radical concentration. When powder was mixed with a liquid containing less inhibitor of hydroquinone, the radicals were found to remain stable longer. In air, propagating radical was detected faster and free radical was concentrated more rapidly than in the water and nitrogen gas. The fluidity of self-cured resin for rebasing as measured by use of spin probe TEMPO disappeared rapidly with increasing temperature for curing, decreasing the amount of liquid and shortening the mixing time. When curing temperature was raised to 37 degrees C from 22 degrees C at minutes after mixing, the fluidity disappeared 2.5 minutes later, i.e., at 5.5 minutes after mixing. To investigate the effects of the MMA-derivative radicals on growth of HeLa cells, HeLa cells were cultured on resins containing MMA-derivative radicals. The number of HeLa cells on resins containing MMA-derivative radicals was 7/10 of that of HeLa cells on resins containing no radicals.

The clinical techniques of the students were examined by analyzing the results of some measurements on the side wall inclination as a width and height of the full formed abutment of posterior fixed bridge, and the results of full covered crown data were compared. Significant differences in the inclination degree to the axis between upper and lower were not noticed in either premolars or molars on the mesio-distal side wall and bucco-lingual side wall, and were noticed between premolars and molars of the same jaw on both side walls. Margin diameter and height of diameter of the premolars showed a closer rank correlation than molars in mesio-distal side wall, but in bucco-lingual side wall, molars showed a closer rank correlation than premolars.

Tipping movement in orthodontic therapy, which is often performed even in the absence of the adjacent tooth, is represented by the movement following tooth extraction. Such tipping movement in the absence of the adjacent tooth depends not only upon the magnitude of orthodontic force as classified into Stoner 4D, but also upon the condition of the extracted wounds. To evaluate the clinical applicability of HAp-packing used in combination with tipping movement, histopathological investigation was performed in the periodontal tissue with tipping movement toward the adjacent to HAp-packed socket. HAp packing into the extracted wound cavity produced no significant changes in quantitative tipping movement compared with non-HAp packing. HAp packing into the extracted wound cavity, followed by tipping movement, produced compressed sides not only for the moved tooth but also for the anchor tooth. Resorption and disappearance of alveolar septum were observed on the compressed sides of both these teeth for all experimental sides. HAp in an amount enough to meet the narrowing of the extracted wound cavity, associated with tipping movement was discharged from the suture surface. In the same region, fibrous connective tissue lay between the dental root and the HAp mass, which were not adjacent to each other. The fibrous connective tissue presented temporal bone regeneration so as to surround the tooth. Apart from the moving distance, the tissue change showed no essential difference either for a weak force or for a strong force. The above results revealed the usefulness of HAp packing into the extracted wound cavity for tipping movement of the adjacent tooth in the direction of the wound cavity and immediate move ability after extraction.

Early application of bodily movement of teeth at an unfinished stage of the healing of the extracted wound i.e. ossification is presumed to increase the risk of jiggling. Using adult dogs, an experimental study was made on bodily movement in the case of HAp packing into the extracted wound cavity to avoid jiggling. When tooth movement was performed immediately after extraction and HAp packing, no encapsulation of HAp with fibrous connective tissue was noted. Either for a weak force or for a strong force, the moved tooth lacked alveolar septum on its compressed side, its dental root being in direct contact with the HAp mass. Remarkable enlargement of periodontal cavity on the tension side and strong osteoclastic resorption of proper alveolar bone were noted. When tooth movement was clone one week after extraction and HAp packing, Either for a weak force or for a strong force, the extracted wound surface was sealed and the HAp mass in the extracted wound cavity got encapsulated by fibrous connective tissue. Alveolar septum has disappeared completely on the compressed side of the moved tooth. Fibrous connective tissue lay between the dental root and the HAp mass and presented its partial osteogenesis. Vigorous bone apposition was noted in the proper alveolar bone surface on tension side. When tooth movement was done one month after extraction and HAp packing, definite ossification was noted in fibrous connective tissue which encapsulated the HAp mass in the extracted wound cavity. Alveolar septum on the compressed side of the moved bone presented resorption and disappearance. For a weak force, gradual ossification was noted in fibrous connective tissue which lay in the same region, and for a strong force, osseous adhesion to the HAp mass was noted. On the tension side, bone apposition was remarkable in proper alveolar bone surface either for a weak force or for a strong force. The above findings revealed thus most suitable time to begin tooth movement was one week after extraction and HAp packing.

Bond strength of hardened plastic teeth or acrylic resin teeth to microwave-curing, conventional heat-curing and 4-META-containing denture base resins were comparatively investigated in this study. Effects of grinding and monomer coating of the tooth ridge lap were also studied. Bond strength of plastic denture teeth to microwave-curing denture base resin was slightly higher than the other two resins. With all denture base resins used, an increased bond strength was obtained with hardened plastic teeth by treatment of tooth ridge lap but not with acrylic resin teeth. However, scattering of the bond strength was reduced by treatment of tooth ridge lap in acrylic resin teeth specimens. With hardened plastic teeth specimens, fracture in the base resin was increased by monomer coating. With acrylic resin teeth specimens, no specific fracture patterns were demonstrated by treatment of tooth ridge lap. Fracture occurred mostly in the acrylic resin teeth. These results suggest that bond strength of both denture teeth to microwave-curing or 4-META-containing denture base resin was increased or solidified by grinding or monomer coating of tooth ridge lap.