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.
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.
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.
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.