Noriaki Saburi

Endochondral ossification of the condyle in rats on a strontium or low-calcium diet

The mechanism of abnormal endochondral ossification induced by administration of strontium salts was studied in the mandibular condyles of rats by radiographic, histologic, and histochemical methods. It was shown by radiographic and histologic findings that ossification of the mandibular ramus was clearly inhibited in rats fed a low-calcium diet and rats fed a strontium diet. The change in appearance of the mandibular condyles of the rats fed strontium was more severe than that in those fed low amounts of calcium. From the histochemical findings, it was suggested that the metabolic dysfunction of chondroitin sulfate, periodic acid-Schiff positive materials, and collagen in the hypertrophic zone of the condylar cartilage (or in the part corresponding to trabecular bone of the mandibular ramus) was one factor inhibiting normal endochondral ossification.

Clinical studies on TMJ arthrosis in young people. An epidemiological assessment of TMJ disorder in students by a questionnaire.

In order to do an epidemiological investigation of temporomandibular joint disorder, 612 students of a junior high school and a high school in Nagoya city were investigated by a questionnaire. The results were as follows:1. Frequencies of complaints of temporomandibular joint sound were 12.1%. No significant difference was found in age and sex distributions.(P>0.1)2. 3.7% of junior high school students and 7.9% of high school students complained of more than two complex symptoms (P<0.05), which were typical symptoms of TMJ arthrosis, TMJ sound, pain and limitation.3. For the initial onset of disorder, 55.2% of the total samples indicated that the disorder was manifest in junior high school students. This result suggested the association between complaints of TMJ disorder and dental stage IVA (Hellmans classification).4. The association between complaints of TMJ disorder and feeding, bruxism and chewing on one side were P<0.05 (in girls), P<0.001 (total), P<0.05 (in boys), respectively.5. The results suggested that further extention of the sample is necessary to investigate the etiology of TMJ disorder.