Comparison of linear tomography and direct ridge mapping for the determination of edentulous ridge dimensions in human cadavers

Abstract

The purpose of this study was to compare the accuracy of linear tomography (LT) and direct ridge mapping (RM) for determining alveolar ridge dimensions. One site in the posterior mandible was selected for evaluation in each of 5 cadaver heads. Vacuum-formed stents made from models of the cadaver ridges were used to identify 3 sets of measurement points for each specimen: coronal (intersection of coronal and middle third of ridge), middle (intersection of middle and apical third), and apical (base of vestibule). The imaging stent contained 2-mm metal balls at each point, while the RM stent had holes drilled at corresponding locations. Linear tomograms and periapical radiographs (PA) were taken of the selected sites. RM measurements were made with calipers. Five blinded examiners measured ridge width at the designated measurement points with both LT and RM as well as distance from the ridge crest to mandibular canal (using PAs for RM group). Mandibles were then sectioned and an independent examiner made direct measurements (DM). MANOVA was used to determine whether LT and RM differed significantly from DM. There were no significant differences between LT and RM for ridge width measurements. However, both techniques underestimated ridge dimensions compared to DM ( P < .05). Measurement of mandibular canal height was accurate when determined by periapical radiographs but not by LT. Neither LT nor RM proved to be completely accurate in determining ridge width in the posterior mandible.