3-dimensional Analysis and Literature Review of the Root Canal Morphology and Physiological Foramen Geometry of 125 Mandibular Incisors by Means of Micro-Computed Tomography in a German Population.

INTRODUCTION: The aim of this study was to examine the root canal system morphology of mandibular incisors by means of micro-computed tomographic imaging. METHODS: The root canal configuration, physiological foramina, frequency of accessory and connecting canals, and the size and shape of the physiological foramina of 125 mandibular incisors were investigated by means of micro-CT and 3-dimensional imaging software. Root canal configuration of the coronal, middle, and apical thirds and the physiological foramina number are described by a 4-digit system code. RESULTS: The most frequent root canal configurations were 1-1-1/1 (56%), 1-2-1/1 (17.6%), and 1-1-1/2 (10.4%); 9 additional different root canal configurations were observed. Single-rooted incisors showed in 80% 1, in 16% 2, and in 4% 3 physiological foramina, respectively. Accessory canals were found in only 13.6% of the investigated teeth. Connecting canals were observed in 36% of the sample, most often in root canal configurations 1-2-1/1 (12.8%) and 2-2-1/1 (7.2%). The morphologic dimensions of a total of 146 physiological foramina were measured. Their mean wide and narrow diameters were 0.24 mm (standard deviation = 0.1 mm) and 0.23 mm (standard deviation = 0.08 mm) when only 1 physiological foramen was present. The physiological foramen shapes observed were oval (56%), round (28.8%), and irregular (15.2%). CONCLUSIONS: The study provides detailed information about the root canal morphology of anterior teeth in a German population. Within the limitations of the study, the authors recommend according to results obtained in this investigation a final physiological foramen preparation size of ISO 30-35; yet, such a decision should be carefully considered on an individual basis.