In recent years there have been many reports on studies related to the temporomandibular joint (TMJ) in orthodontic treatment, but an adequate system of diagnosis and treatment has yet to be established, and they often cause considerable difficulty clinically. The patient in this case report sustained generalized contusions, a cerebral concussion, a midline fracture of the mandibular corpus, and bilateral fractures of the condylar process of the mandible when he fell asleep while driving a car and collided with a truck. Because non-surgical reduction was impossible, mandibular condylectomy was performed, and when orthodontic treatment was attempted to improve the open bite that persisted as a sequela of the accident, the favorable results were obtained, as described below. 1. The open bite was corrected by the orthodontic treatment, and the impairment that remained as a sequela resolved. 2. The mandibular condyles were removed during surgical reduction, and the mouth opening disturbance, the TMJ pain, and the TMJ noise resolved. The patient was able to go about his everyday life unimpaired, with hardly any awareness of limitation of jaw movement, and this situation remained unchanged even after the orthodontic treatment was performed. (J. Oral Sci. 40, 1-8, 1998)
A study was conducted to examine the efficacy of carboxylic acid monomers as self-etching primers by measuring the tensile bond strengths between composite resin and dentin. Several kinds of carboxylic acid monomers, such as o- (N-methacryloyl amino) benzoic acid (o-MABA), m- (N-methacryloyl amino) benzoic acid (m-MABA), p- (N-methacryloyl amino) benzoic acid (p-MABA), 4-methacryloxy phthalic acid (4-MPA), 2- (N-methacryloyl amino) terephthalic acid (2-MATPA), and 5- (N-methacryloyl amino) isophthalic acid (5-MAIPA), were prepared. 4-methacryloxyethyl trimellitic anhydride (4-META) was also used as a component of the self-etching primer. The DMSO solutions of these monomers were used as self-etching primers. The tensile bond strengths between composite resin and dentin were measured after 24 h immersion in water at 37°C. When DMSO was used as a self-etching primer, the bond strengths were below 5 MPa. Among the monocarboxylic acid monomers, m-MABA gave the highest mean bond strength at 60 s application, and 5MAIPA gave the highest mean bond strength at 30 s application among the dicarboxylic acid monomers, although the differences among the values were not always significant. The smear layer was partially dissolved by treatment with the self-etching primer. (J. Oral Sci. 40, 9-16, 1998)
Endothelial cells in the atrioventricular (AV) segment of the developing chicken heart undergo a transition into mesenchymal cells. When the AV segment is explanted onto a hydrated collagen gel, endothelial cells grow out and reproduce in vivo cell transition regardless of the precise orientation of the explant on a gel. Our results showed that when the luminal side of an explant was placed towards a gel surface, the inverted polarity of endothelium was not adjusted by direct reorganization of polarity, but that the endothelium crawled down so as to settle on a gel surface in the correct original cell polarity. Subsequently, endothelial cells showed cytoplasmic hypertrophy, formed microvillous projections and then extended filopodial migratory appendages. These cellular changes were quite similar to those in vivo. However, the continuity of the endothelial layer was specifically disrupted in AV explant cultures. Such disruption was never observed in ventricle explant cultures in which endothelial-mesenchymal cell transition did not occur. The disintegration of AV endothelial outgrowth must be closely related to its capability to transform into mesenchymal cells and mitotic activity to keep a depository of endothelial cells. (J. Oral Sci. 40, 17-23, 1998)
The aims of this study were to investigate gender differences in frontal sinus morphology and to estimate differences between Fijian and Western Samoan populations. Cephalograms of 118 Fijians (59 male, 59 female), 80 W. Samoans (33 male, 47 female) and 89 Japanese (60 male, 29 female) were used in this study. The thickness of the frontal sinus and the convexity of glabella in males were found to be larger than those of females in each population. The angle of Sg-N-G in the Fijians was larger than that of the Western Samoans and Japanese. In order to compare the frontal sinus morphology among populations, Mahalanobis' generalized distances were calculated on the basis of the five distance diameters. The results indicate that gender is separated by the first axis which indicates the overall size. Japanese samples were separated from South Pacific samples by the second axis which indicates the shape factor. In populational discrimination, there was a higher percentage of correct discriminations of the females of the males. In conclusion, gender difference was recognized in the size of the frontal sinus, and the populational differences were shown in the shape factor between Melanesian and Polynesian populations, and also between South Pacific and Japanese populations. (J. Oral Sci. 40, 25-30, 1998)
The polymerase chain reaction (PCR) assay is a powerful tool for quick diagnosis of various infectious diseases. We applied this technique as well as conventional histopathological examination to diagnose oral tuberculosis. Ziehl-Neelsen staining of oral mucosal specimens often fails to detect Mycobacterium (M.) tuberculosis due to the low number of bacteria in the tissue. Specific primers and probes were synthesized based upon the nucleotide sequence of the 65 kDa membrane protein of M. tuberculosis. DNA extracted from the paraffinembedded tissue was amplified using tali polymerase. PCR assay detected M. tuberculosis in 5 of 6 samples. Although the gene segments from these species were quite similar, the r32P labeled noligonucleotide probes distinguished between M. tuberculosis and M. fotuitum by southern blot hybridization. In all specimens that were Ziehl-Neelsen negative, M. tuberculosis DNA was detected by PCR. These results suggest that PCR is a useful means of diagnosing mycobacterium infection. (J. Oral Sci. 40, 31-36, 1998)
The purpose of this study was to compare the degree of osseointegration between hydroxyapatite (HA) -coated and uncoated threaded titanium dental implants placed into a surgically created bone defect with or without an expanded polytetrafluoroethylene (ePTFE) membrane. A conventional implant site was prepared and either a HA-coated or an uncoated implant was placed in each tibia of 12 rabbits (conventional group). A bone defect approximately 3 mm in width was created on the distal end of the conventional site and either a HA-coated or an uncoated implant was placed there (bone defect group). For another group, the same procedure was performed as in the bone defect group, except the implant sites were covered with ePTFE membranes (ePTFE group). After 4 months, the rabbits were sacrificed. Specimens were prepared and examined histometrically. The results demonstrated that HA-coated threaded titanium dental implants consistently showed a greater amount of osseointegrated surface either in the conventional site or defect region with and without ePTFE membranes in this animal model. In conclusion, a HA-coated threaded titanium implant may be the choice of dental implants to establish greater osseointegration with the defect or conventional site. (J. Oral Sci. 40, 37-41, 1998)
The authors have devised a new attachment for a removable partial denture with a dimple-bar clasp, guiding channels, and a shoulder, named the dimple-bar telescopic system. This system has advantages over the clasp-type retention device in that it not only satisfies esthetic requirements, but also improves the handling and adjustability of the attachment denture. Furthermore, it was shown clinically that the dimple-bar telescopic system was free from food impaction when used as an intracoronal attachment, and maintained a feeling of comfort during tongue movement and speech. We present a typical case in which the dimple-bar telescopic system was used. (J. Oral Sci. 40, 43-47, 1998)
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