The Journal of Osaka University Dental School最新文献

Mechanisms of cathepsin B activation involved in methionine-enkephalin (ME) production induced by bradykinin (BK), des-Arg9-BK or L-arginine (L-Arg) were studied using cultured fibroblasts of the rat dental pulp, especially from a viewpoint of intracellular signal transduction. BK, des-Arg9-BK, L-Arg or cysteine enhanced the release of ME-like peptides from the cells, and the release of ME-like peptides induced by des-Arg9-BK was inhibited by des-Arg9-[Leu8]-BK (BK B1-receptor antagonist) and E-64 (a specific inhibitor of cysteine proteinases). The activation of cathepsin B by BK or des-Arg9-BK was inhibited by des-Arg9-[Leu8]-BK or islet-activating protein (IAP), and the activation of cathepsin B by L-Arg was inhibited by Leu-Arg (kyotorphin-receptor antagonist) or Botulinum C3-enzyme. The activation of cathepsin B by those stimulants was dependent on calcium ion. These results suggest that the ME production by BK or des-Arg9-BK may be mediated by Ca(2+)-dependent cathepsin B activation through B1-receptors and IAP-sensitive G-proteins, whereas the production by L-Arg may be mediated by Ca(2+)-dependent cathepsin B activation through kyotorphin-receptor and Botulinum C3-enzyme-sensitive G-proteins. On the other hand, the activation of cathepsin B was inhibited by neomycin B (phospholipase C inhibitor) and various serine/threonine kinase inhibitors. These results indicate that phospholipase C and serine/threonine kinases are involved in the activation of cathepsin B by BK, des-Arg9-BK or L-Arg. Genistein inhibited the activation of cathepsin B by des-Arg9-BK or L-Arg in a different fashion, suggesting that tyrosine kinase(s) is also involved in the activation. Cathepsin B activation by BK or L-Arg but not des-Arg9-BK was inhibited by L-NMMA (inhibitor of NO synthesis), and the activation by L-Arg was enhanced by beta-glycerophosphate (beta-GP: inhibitor of phosphatases), while the activation by BK or des-Arg9-BK was inhibited by beta-GP. These results suggest that BK-induced cathepsin B activation in the fibroblasts may be due to a combined effect of des-Arg9-BK and L-Arg.

In order to investigate the relationship between condylar atrophy and tooth loss in craniomandibular disorders, we examined 37 patients with condylar atrophy (atrophy (+) group) and 109 patients without condylar atrophy (atrophy (-) group). No significant difference in the number of missing teeth between the atrophy (+) group and atrophy (-) group was observed. However, a significant relationship between condylar atrophy and loss of the lower first molars was found. And individuals in the atrophy (+) group had a tendency to lose one or both lower first molars and left them without any prosthetic restorations in the growth period of the TMJ components.

The purpose of this study was to develop a prototype handy mandibular tracking device with six degrees of freedom using the optoelectronic kinematic data acquisition system and to evaluate its accuracy. The system consisted of the light-weight sensor part mounted on the mandibular incisor portion and two 2-D PSD cameras positioned in front of the patient. On the sensor part, three light emitting diodes (LEDs) were attached in triangular form. Displacements of the sensor part were detected by two cameras, transformed into electric signals, and sampled by A/D converter in a desktop computer. Since the overall accuracy of this system was about 0.03 mm in the displacement and 0.06 degrees in the rotation angles, this system was proven to be capable for the wide range of clinical application.

The response of chondrocytes from the craniofacial complex to vitamin D3 has been investigated in vitro. Chondrocytes were isolated from nasal septal cartilage (NSC), sphenooccipital synchondrosis (SOS) and mandibular condylar cartilage (MCC) of New Zealand rabbits weighing from 250-350 g. Treatment of NSC-chondrocytes with 1,25-(OH)2D3 or 24,25-(OH)2D3 for 6 days from days 4 to 10 in medium containing charcoal-treated FBS increased DNA synthesis dose-dependently at the concentrations of 10(-9) M to 10(-8) M, or 10(-11) M to 10(-9) M, respectively. 1,25-(OH)2D3 inhibited GAG synthesis dose dependently at the concentrations of 10(-11) M to 10(-8) M. 24,25-(OH)2D3 had no effect on GAG synthesis in NSC-chondrocytes. 1,25-(OH)2D3 increased DNA synthesis in SOS-chondrocytes at a concentration of 10(-10) M and inhibited GAG synthesis. 24,25-(OH)2D3 had no significant effect on DNA and GAG syntheses of SOS-chondrocytes. 1,25-(OH)2D3 slightly increased GAG synthesis at a concentration of 10(-10) M in MCC-chondrocytes but had no effect on DNA synthesis. 24,25-(OH)2D3 had no effect on DNA and GAG synthesis in MCC-chondrocytes at concentrations of 10(-11) M to 10(-9) M. These finding suggest that vitamin D3 metabolites, 1,25-(OH)2D3 and 24,25-(OH)2D3 play an important role in the growth of craniofacial cartilage by differently stimulating proliferation and expression of the differentiated phenotype of chondrocytes from NSC, SOS and MCC.

The purpose of this study is to examine the fatigue profiles of wrought wire clasps during the clinical use. Cobalt-chromium-nickel alloy wires were bent into circular beams, which dimensions and fabrication methods were similar to the clinical cases. Deflections of 0.5 mm in a normal direction were applied 10,000 times to the tips of clasp arm and permanent deformations were measured. The following results were obtained. 1) The clasp arms with larger cross sectional diameter, shorter length and smaller radius of curvature showed larger amounts of permanent deformation. 2) The amounts of permanent deformation of the clasp arm remarkably decreased by electric resistance soldering and decreased further more by heat treatment at 500 degrees C for 10 minutes after soldering regardless of the number of deflection. From the results of this study, it was concluded that dimensional factors and heat treatment influenced the permanent deformation of the wrought wire clasps remarkably. Therefore, considering these factors, wrought wire clasps could be designed to reduce permanent deformation.

To clarify the role of vitamins D and C in chondrocyte hypertrophy of craniofacial cartilage, we have studied cultured chondrocytes from rabbit mandibular condylar cartilage (MCC), sphenooccipital synchondrosis (SOS) and nasal septal cartilage (NSC) under conditions in which these cells mature into hypertrophic chondrocytes. In cultures of MCC- and SOS-chondrocytes, alkaline phosphatase (ALPase) activity started to increase on day 9 at confluence and the cessation of cell division, and reached a maximum on day 18. The degree of the increase of ALPase activity on day 18 was higher in MCC-chondrocytes than in SOS-chondrocytes. ALPase activity was very low level in NSC- and CGC-chondrocytes. Ascorbic acid induced a marked increase in ALPase activity in MCC-, SOS-, NSC- and CGC-chondrocytes. The ALPase activities in MCC- and SOS-chondrocytes with 50 micrograms/ml ascorbic acid were 2.5-times those in its absence. Those in NSC- and CGC-chondrocytes were 10 times and 20 times, respectively. When chondrocytes were cultured with 10% charcoal-treated serum, ALPase activity decreased less than that in cultures with 10% normal serum in MCC-, SOS-, NSC- and CGC-chondrocytes. Treatment of 1,25-(OH)2D3 for 9 days from days 4 to 13 in MCC-chondrocytes and for 14 days from days 4 to 18 in SOS-, NSC- and CGC-chondrocytes inhibited ALPase activity dose-dependently at the concentrations of 10(-12) M to 10(-8) M in MCC- chondrocytes, 10(-10) M to 10(-8) M in SOS- and CGC-chondrocytes, 10(-11) M to 10(-9) M in NSC-chondrocytes. These findings suggest that 1,25-(OH)2D3 and ascorbic acid may be involved in the control of cartilage growth and terminal differentiation.

In this paper, some problems in commercially available surveying systems were discussed, and a clinical technique for designing and fabricating clasps by using an improved 'Digital Surveyor' and a computer system were presented. This system has the advantages as follows: (1) morphological factors on abutment teeth could be measured and evaluated using the improved 'Digital Surveyor' and its accessories set, (2) clasps providing with proper mechanical properties according to various conditions in the mouth could be designed and fabricated precisely and easily. It became clear that conventional surveying methods involved empirical rules should be re-examined and replaced by the more rational surveying method like this system.

The present study was designed to investigate biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions. A three-dimensional finite element model of the upper central incisor was developed to analyze tooth displacements and stress distributions in the periodontal ligament. Lingual horizontal and apical vertical forces of 100 gf were applied at a point on the labial surface of the crown and at three different points on the lingual surface of the crown. Tooth displacements and stress distributions from the forces applied at the lingual points were compared with those from the labial force loading. The following results were obtained. 1. Lingual horizontal force produced almost similar patterns of tooth displacements and stress distributions, irrespective of labial and lingual application points of the orthodontic forces. 2. Apical vertical force applied at the lingual points produced more uniform tooth displacements and stress distributions than labial application of the force, although the force applied at the lingual point close to the cervix generated different patterns from those with the remaining lingual force loadings. The present results suggest an important role of the positional relation of force application points to the center of resistance. It is shown that lingual force application may produce more optimal tooth movement in terms of more uniform patterns of tooth displacements and subsequent stress distributions in the PDL.

A laser displacement meter which equips two sensors was developed in order to measure the shape of teeth with higher efficiency and accuracy. By this displacement meter the rotational measurement to compensate the data at the shaded points became needless. The measurement of the 6 molar was carried out, and the regions such as cusps and fissures of the occlusal plane were measured precisely without errors. The time required for the measurement was about 10 min. and reduced to one third that of the previous system. While, by the measurement from one direction, the undercut portion such as toothneck is less accurate. Then, 7 molar model was tilted on the gonio stage with +/- 20 degrees and measured divisionally, and two groups of data were connected. By this method, the whole shape of tooth including the undercut portion became to be measurable. In the case of a crown abutment tooth with steeply inclined axial wall and margin, tilting method was also applied to measure more accurately. 7 abutment was tilted with +/- 30 degrees and measured and connected. The gingival and marginal line which are the characteristic spots for designing the crown were recognized. These data thus obtained will be able to give the inner and outer shape of crown for processing the prostheses by CAD/CAM technique.

A rare case of malignant melanoma of the hard palate following malignant schwannoma of the left maxilla in a 47-year-old woman is reported. Twenty-two months after surgical excision of malignant schwannoma with postoperative radiation and chemotherapy, malignant melanoma appeared with symptoms of gingival bleeding and swelling. Although the patient was treated by the partial maxillectomy with radical neck dissection and postoperative chemotherapy and adjuvant immunotherapy, she died of multiple distant metastases 9 months after the oral manifestation. A possible histological relationship of both tumors which are considered to be derived from the neural crest cells is also discussed.