A study of the internal structure of the mandibular ramus in Japanese.

To clarify the internal structure of the mandibular ramus in Japanese adults, we performed bone morphometry. Specimens were obtained from four areas: the mid-area between the mandibular foramen and the lowest point of the mandibular notch, areas immediately above and below the mandibular foramen, and the mid-area between the mandibular foramen and the mandibular angle. The mandibular ramus was divided into the anterior and posterior parts, and morphometric analysis was performed on the four areas in each part. The percentage of the trabecular bone area in spongy bone was higher in the anterior part than in the posterior part. In both the anterior and posterior parts, the percentage of trabecular bone was the highest in the most inferior area. Trabecular bone was thicker in the anterior part than in the posterior part. Both in the anterior and posterior parts, trabecular bone was the thickest in the most inferior area. The arrangement of trabecular bone was more complicated in the anterior part than in the posterior part. Trabecular bone was most frequently arranged in the anteroposterior direction. In the superior area of the posterior part, much trabecular bone ran from the posterior buccal side toward the anterior lingual side. Compact bone was thicker in the anterior part than in the posterior part and on the buccal side than on the lingual side. No age-related changes were observed in any element of trabecular bone structure.