Model analysis in "8020" achievers using three-dimensional images.

The purpose of this study was to clarify the effect of aging on the dentition by quantifying the dimensions of the dental arches in elderly persons aged over 80 years with 20 or more remaining teeth (8020 achievers). The study included twenty 8020 achievers (10 males and 10 females, with an average age of 82.3 years and an average of 28.3 present teeth). Their dental casts were digitized with a 3-dimensional (3-D) laser scanner, reconstructed into 3-D images, and measured with IMAGEWARE. The anterior and posterior widths of the upper and lower coronal arches and their anterior and posterior lengths together with the anterior and posterior widths of the maxillary and mandibular basal arches and their anterior and posterior lengths were measured. An unpaired t-test was performed using statistical analysis software. Dental models of 31 people with normal occlusion (16 males and 15 females, with an average age of 23.3 years) were measured with digital calipers and compared with the measurements obtained from the 8020 achievers. Several common items with significant differences were observed in the mandibular measurements. Each comparison indicated a tendency toward a decrease in size in the 8020 group: Coronal Arch P-length (p<0.05 in Male group, p<0.01 in Female group), Basal Arch A-width (p<0.05 in Male group, p<0.001 in Female group), Basal Arch A-length (p<0.001 in both group), and Basal Arch P-length (p<0.001 in both group). From these results, 3-D dental model analysis in twenty 8020 achievers revealed narrowing of the mandibular intercanine width and shortening of the mandibular anterior and posterior lengths.