[Study of structural changes in canine maxillary trabecular bone after tooth extraction]

All teeth on the right side of the upper and lower jaws were extracted from canine specimens; and changes in maxillary trabecular-bone structure caused by the resultant reduction in functional pressure were studied by means of image analysis of trabecular-bone density, width, specific length (which indicates bone length to unit area), and trabecular-bone orientations. Results 1. Trabecular-bone density Over the 13-month period, in comparison with the normal side, trabecular-bone density on the experimental side dropped to 69.4% in the incisor region, 82.2% in the premolar region, and from 60.0 to 68.0% in the molar region. The greatest reduction occurred in the molar region. 2. Trabecular-bone width Over the 13-month period, in comparison with the normal side, trabecular-bone width on the experimental side dropped to 86.9% in the incisor region, 86.1% in the premolar region, and from 66.4 to 71.4% in the molar region. The greatest reduction occurred in the molar region. 3. Specific length Over the 13-month period, in comparison with the normal side, specific length on the experimental side dropped to 81.9% in the incisor region, 82.9% in the premolar region, and from 65.6 to 70.5% in the molar region. The greatest reduction occurred in the molar region. 4. Orientation No regular trabecular-bone orientation was observed in the tooth-extraction sockets. In the incisor region, trabecular bone was often distributed at from 100 degrees to 120 degrees in relation to the dental roots. As time passed after extraction, the amount of bone with this orientation gradually decreased. At 13 months, amounts with bone orientation of from 40 degrees to 60 degrees had increased. In the premolar region, a great deal of trabecular bone was oriented at from 140 degrees to 150 degrees in relation to the dental roots. As time passed after extraction, the amount of bone with this orientation gradually decreased. At 13 months, amounts with bone orientation of from 110 degrees to 130 degrees had increased. In the molar buccal region, trabecular bone was often distributed at from 20 degrees to 40 degrees, and 90 degrees in relation to the dental roots. In the molar palatal region, trabecular bone was often distributed at from 120 degrees to 140 degrees in relation to the dental roots. At 13 months, the amount of trabecular bone oriented at about 90 degrees had increased.