Root complex and root canal system: a correlation analysis using one-rooted mandibular second molars

The principal aim of this investigation was to verify an expected, probable correlation between certain variables, which are initially represented in the macrostructure of the root complex corresponding to the cemento-dentin junction, and certain variables that subsequently manifest themselves in the root canal system. A material consisting of 76 one-rooted, permanent mandibular second molars (M2 inf) was used. The specimens were cut at the mid-root level and all observations were made on the coronal root segment using a stereomicroscope. Relevant variables of the root complex were observed. The total macromorphologic variation of the root complex could be subdivided and classified in well-defined, distinguishable types. In accordance with the single root complex type an expected, logically deduced configuration of the root canal system was established. The relevant variables of the canal system were then recorded. Finally, the root complex morphology, as well as the expected and actually observed canal configuration, were compared type by type. In 76.3% of the teeth a good concordance could be shown between the expected and the actual canal configuration, whereas in 23.7% of the specimens there was a divergence. In 42.1% of the investigated teeth, 1 centrally localized main canal with varying cross section images, among them a C-shaped image, was found. In 30.3%, 2 main canals were found, which were often localized mesially and distally. In 23.7%, 3 main canals were observed: 1 mesiofacial, 1 mesiolingual and 1 distal. In the remaining 3.9%, 1 non-independent supernumerary canal was seen in a distolingual position.