[Anatomical study on the root apex in the maxillary anterior teeth].
This study was undertaken to anatomically investigate the apical portion of root canal. Teeth used in this study were thirty maxillary central incisors, thirty maxillary lateral incisors and thirty maxillary cuspids extracted from patients between the ages of 11 and 73. All of the teeth had periodontal disease, but none had periapical disease. Resorption of the root surface could not be seen with the naked eye. The results obtained were as follows: 1. Deviations of the root apex and the apical foramen. Both of the root apex and apical foramen of the central incisors and cuspids were displaced distolabially from the tooth axis. Those of the lateral incisors were displaced distolingually from the tooth axis. The coincidence between the root apex and apical foramen was found in 16.7 per cent of both the central incisors and the cuspids, and in 6.7 per cent of the lateral incisors. 2. Diameters of the apical foramen and perpendicular distances between the root apex and apical foramen. The labiolingual diameters in the apical foramen of the central incisors, the lateral incisors and the cuspids were 0.504 mm, 0.452 mm and 0.425 mm respectively. Those diameters were larger than the mesiodistal diameters in the maxillary anterior teeth. Both the labiolingual and mesiodistal diameters in the central incisors were the largest. The perpendicular distances between the root apex and the apical foramen of the central incisors, lateral incisors and cuspids were 0.450 mm, 0.440 mm and 0.510 mm respectively. Those in the cuspids were the largest. The apical foramen in the cuspids was located slightly closer to the cervical side. 3. Diameters of the apical constriction and perpendicular distances between the root apex and apical constriction. The apical constriction of the root canal was located in either cementum or dentin. The labiolingual diameters of the root canal in the apical constriction of the central incisors, the lateral incisors and the cuspids were 0.425 mm, 0.369 mm and 0.425 mm respectively. The root canal labiolingual diameters in the maxillary anterior teeth was approximately 0.050 mm larger than mesiodistal diameters. The shapes of the root canal in the apical constriction were mostly the circular, oval and ovoid, while a few irregular shapes were observed. The perpendicular distances between the root apex and the apical constriction of the root canal in the central incisors, the lateral incisors and the cuspids were 0.863 mm, 0.825 mm and 1.010 mm respectively. 4. The stricture ratio of diameter between the apical foramen and the apical constriction of the root canal.(ABSTRACT TRUNCATED AT 400 WORDS)