A Morphological Study of the Apical Third of the Root Canal in the Maxillary First Premolar using Micro-CT

Abstract

To date, measurements of root canals have been performed two-dimensionally. Thus, measuring the diameter of curved root canals was difficult. Recently, micro-computed tomography (micro-CT) has enabled the measurement of any cross-sectional subject, therefore, it has often been applied to teeth and bones. In this study, we have measured the detailed diameter of the apical foramen of buccal and lingual canals in the maxillary first premolar using micro-CT. Eight maxillary first premolars were obtained from patients (4 males, 4 females) at the age of forty. Reconstructed three-dimensional images of each root canal were sliced orthogonally at 12 μm intervals, and the major and minor axes were measured on the sliced images. Measurements were taken up to a distance of 1.68 mm from the root apex. The narrowest point of the root canal was defined as the point where the minor axis was the smallest. The flatness ratio was also determined by dividing the major axis by the minor axis. The narrowest points of the buccal and lingual canals were located at 1.20 mm and 1.08 mm from the root apex, respectively. The flatness ratios of the buccal and lingual canals were 136.7% and 150.2%, respectively. The narrowest point of both the buccal and lingual canals was located approximately 1 mm from the root apex, and the data of the flatness ratios indicated that the lingual canal was more flat than the buccal canal at the apical third of the root canal. Micro-CT has been shown to be a useful tool for performing detailed measurements of root canal structures.