Quantification of masseter muscle deformation during palpation using MRI and image-analysis procedure.

PURPOSE: The aim of this study was to quantify masseter muscle deformation during palpation and to discuss the clinical significance of muscle palpation using magnetic resonance imaging (MRI) and the image-analysis procedure. MATERIALS AND METHODS: Subjects were 10 male volunteers with a mean age of 26.8 years. MRIs were taken under two muscle conditions: compressed and noncompressed (control). By superimposing a compressed image on a noncompressed image, muscle deformation (the cross-sectional area, length of the surrounding area, thickness, circular convolution, compressed point, and anterior and posterior extension) was measured. RESULTS: The cross-sectional area of the masseter muscle was diminished by 14%, circular convolution of the muscle was reduced by 31%, the length of the surrounding area was enlarged by 11%, and the thickness of the muscle was reduced by 6.7 mm because of compressing. Thus, the masseter muscle was compressed. An uneven stretch of the muscle caused by compression was observed at the same time. The anterior portion of the masseter muscles extended on average 10%, with great individual differences. On the other hand, posterior extension (3%) and its individual differences were small. CONCLUSION: The method used made it possible to quantify masseter muscle deformation. By compressing, the masseter muscles were deformed especially in the anterior direction but with great individual differences.

[An investigation of X-ray examinations classified according to cases of dental diseases at Fukuoka Dental College Hospital].

This paper reports the results of an investigation on the types and frequencies of X-ray examinations given to patients with various types of their dental diseases from their first visit to the hospital to the end of treatment. The subjects were 337 patients (not including orthodontic patients and in-patients) randomly sampled out of all those who visited the Fukuoka Dental College Hospital in 1986. Out of these 337, the number of those who were given X-ray examinations was 284. 1. The Cases of dental diseases for which X-ray examinations were given were classified into the following seven: diseases caused by dental caries, trauma, inflammation, diseases of temporomandibular joint, diseases of salivary gland and other diseases, and other examinations. Out of these X-ray examinations, those given to the patients of diseases caused by dental caries and marginal periodontitis amounted to the 60% of the total X-ray examinations. 2. On the average, 3.3 radiographs were taken per patient. 3. In the examination of luxation, a case of trauma, 7.8 radiographs were taken per patient, the largest number of all diseases on this report. In the examination of marginal periodontitis, a case of inflammation, 5.4 dental radiographs and 0.5 panoramic radiograph were taken per patient. It is necessary to make the most of panoramic examination effective for this disease to decrease radiation exposure. 4. The diseases that have more difficulty of diagnosis and more necessity of observing the prognosis had a greater tendency to depend on X-ray examinations. 5. The percentage of the patients who did not receive X-ray examination was 15.7%. Out of these patients, the patients in pedodontics accounted for 34.5%.