Root canal morphology of permanent maxillary teeth in the Han nationality in Chinese Guanzhong area: a new modified root canal staining technique.

INTRODUCTION: The purpose of this study was to investigate the canal morphology of 504 maxillary permanent teeth of subjects of Han nationality in Chinese Guanzhong area. METHODS: Maxillary permanent teeth were randomly collected in Guanzhong area. After regular preparation, the teeth were immersed into ink without preparing access cavities and then put into hyperbaric oxygen chamber (0.6 Mpa) for 2 hours to let the ink penetrate into root canal from apical foramen, apical deltas and foramen of lateral canals under stable positive pressure. After demineralization and clearing, the following observations were made: (1) number of root canals, (2) root canal configuration by using Vertucci's classification, (3) presence of lateral canals, and (4) frequency of apical deltas. RESULTS: All the teeth were well-stained, and the fine details were well-revealed. Apical deltas (12.2%-83.3%) and lateral canals (13.7%-68.8%) could be frequently found in all types of maxillary teeth. Most of central incisors (95.8%), lateral incisors (91.4%), and canines (75.4%) displayed type I canal configuration, whereas most of first premolars (87.3%) and second premolars (72.3%) possessed 2 canals with type II, IV, or VI canal configuration. The majority of distobuccal roots and palatal roots of first molars (88.9%, 97.8%), second molars (92.0%, 94.0%), and third molars (87.5%, 91.6%) possessed type I canal configuration. The prevalence of mesiobuccal roots with type I configuration was 66.7% in maxillary first molars, 82% in second molars, and 62.5% in third molars. CONCLUSIONS: The modified technique of canal staining can effectively reveal detailed root canal system. The canal configuration of maxillary teeth in subjects of Han nationality in Chinese Guanzhong area is consistent with previous reports in other races.

[Effects of nimodipine on human dentinogenesis].

OBJECTIVE: Studies have showed that L type calcium channel plays an important role in dentin calcification and affects tooth development and tooth reparation after injury. The objective of this article is to study the effects of nimodipine, blocking agent of L type calcium channel, on human dentinogenesis using human tooth slice organ culture in vitro. METHODS: Young healthy human premolars were collected, and cut into 2 mm-thick transverse slices by low speed diamond saw. Agarose beads dipped in nimodipine solution and PBS weresy minetrically placed on tooth slices, and the slices were then embedded in a semisolid agarose-based medium and cultured with organ culture method for 1 week. Fluorescent band of tetracycline, Von-Kossa staining, immunohistochemical staining of the slices and transmission electron microscopy (TEM) of odontoblasts were observed to evaluate dentinogenesis changes of the slices. RESULTS: Tooth slices were successfully cultured in vitro for 1 week and the odontoblasts could maintain their original morphology. After treatment with nimodipine, the fluorescent band of tetracycline was narrow and weak, and globular calcification in predentine was decreased compared with the control. TEM showed that secretory vesicles in odontoblast were somewhat increased, hut iminunohistochemical staining for collagen I showed no difference between the two groups. CONCLUSION: Nimodipine can influence the calcification of dentine, but has no obvious influence on the synthesis and secretion of dentine matrix. The results show that L type calcium channel is important in dentin calcification.