Three-dimensional modeling and measurements of root canal anatomy in second primary mandibular molars: a case series micro CT study

Purpose This study aimed at establishing a comprehensive specification of the root canal anatomy of second primary mandibular molars using micro computed tomography (CT). Methods 10 s primary molars from Caucasian young patients were selected for this purpose. Micro CT imaging with a high resolution of 20 microns was performed to observe the roots and canals according to specific criteria. The Vertucci canal configuration, the presence of lateral canals and their location, the presence of an isthmus and its location, were first observed. Then, the length of the canals, their diameter in the mesio-distal and vestibulo-lingual direction, the dentinal thickness and the direction of the minimal dentinal thickness were measured. Results The mean working length was not significantly different between the canals (p = 0.710). The bucco-lingual diameter was significantly higher when the tooth had a single distal canal at the coronal (p < 0.001), middle (p < 0.001) and apical (p = 0.012) levels. The root dentin thickness on the distal wall of the mesial root and the mesial wall of the distal roots were reduced, respectively, from the coronal to the apical thirds. Conclusions The results obtained in this case series report clearly show a complex, sometimes unpredictable, anatomy with dangerous areas where dentin is extremely thin. The plethoric presence of anastomoses, large bands of isthmus, lateral canals at all levels induces the need for the development of instruments specific to pulpectomies on primary teeth.