抄録
The purpose of this study was to know how the crown-root ratio affects periodontal tissue as a predisposing factor of periodontal disease.
Eight hundred and forty teeth which had been previously extracted because of periodontal disease, 549 teeth extracted as control from 65 cadavers, aged from 17 to 83, 62 males and 3 females were used.
Crown and root lenghths were measured and the anatomical crown-root ratios were calculated for incisor, canine and premolar teeth except molars.
The teeth were divided into 7 groups (1|1, 2|2, 3|3, 54|45, 21|12, 3|3, 54|45) for statistical analyses.
The following results were obtained from the statistical analyses of the data.
1. The roots of the extracted teeth because of periodontal disease were significantly shorter than those of control except lower canines.
2. The crown-root ratios of the extracted teeth because of periodontal disease were significantly larger than those of control in the following groups, 1|1, 3|3, 54|45, and 54|45.
The results of our study may indicate that the unfavorable crown-root ratio acts as a factor of occlusal trauma and contributes to periodontal bone destruction, early mobility, and subsequent teeth loss in process of periodontal disease.
