Analysis of Root Canal Morphology in Maxillary Lateral Incisor Using Micro-CT

Abstract

 Purpose: The maxillary lateral incisor is regarded as a type of tooth that is difficult to treat because it has poor diagnosis after root canal filling despite the fact that it is an anterior tooth with a single root canal. Recently, μ-CT has been introduced, by which it is possible to observe a specimen from a three-dimensional viewpoint without destroying it, and it is frequently used for the study of internal structure. In the present study, by using μ-CT, we have carried out observation and analysis on a maxillary lateral incisor that has a complicated root canal morphology and is difficult to heal by treatment.
 Materials and methods: On 50 pieces of human extracted maxillary lateral incisors with no dental caries, tomography was performed continuously by using μ-CT. From the images obtained by a three-dimensional study on the curvature and oblateness of the root canal, observations and studies were carried out on accessory root canals, and morphological abnormalities were examined. Regarding the root canal oblateness, these cases were compared with the results of a study on 50 pieces of human extracted maxillary central incisor with no dental caries.
 Results: Root canal curvature in a distal direction was studied in 46 teeth, and root canal curvature in a lingual direction was seen in 35 teeth, and cases of dual or triple curving have been confirmed. The curvature of the root canal was mostly seen in 1/4 of the apical side. Dens invaginatus was found in 5 teeth, and a radicular groove was observed in 3 teeth. In one of these teeth, the root canal showed a rather complicated shape under the influence of a radicular groove. Oblateness of the root canal at a position of 2 to 6 mm from the apex in the maxillary lateral incisor was more severely compressed than the maxillary central incisor. Apical ramification was found in 26 teeth, a lateral canal was seen in 7 teeth, and the form of apical ramification was diverse.
 Conclusion: The results of the present experiment revealed anatomical complexities and difficulties in the treatment of maxillary lateral incisors. In particular, curvature, bending, and oblateness of the root canal on the apical side and branching of the root canal were the factors that make it difficult to control files, and these results suggest difficulties in the treatment of the maxillary lateral incisor. Maxillary lateral incisor root canals are full of variations. Accordingly, it seems that sufficient anatomical knowledge and experience are required to accomplish endodontic treatment in a more efficient manner.