In cases of mandibular distal-extension edentulous ridge, it is considered that the anteroposterior and buccolingual inclinations of the edentulous ridge affect the stress of the abutment teeth transmitted from the removable partial denture.
However, few studies have examined this effect, and ridge inclinations of these areas are usually assessed and diagnosed by visual examination of mounted diagnostic casts.
A shape analyzing system for the mandibular distal-extension edentulous area was developed using a semi-conductor laser, and this system was applied to three cases. In this system, the ridge contour was divided into small triangles and normal lines were drawn at the centers of gravity of the respective triangles. The ridge inclinations were evaluated on the angles between each normal line and the tentative plane of occlusion. The results were shown on a personal computer as the occlusal, lateral, and frontal views, and the distribution on the anteroposterior and buccolingual inclinations of the edentulous ridges was shown by a histogram.
It was considered that this system is more accurate for evaluating the ridge shape on the distribution and degrees of anteroposterior and buccolingual inclinations of the mandibular distal-extension edentulous ridges than visual examination.
