The relationship of the main foramen to the anatomic root apex has been the subject of several studies. Although they are anatomically close, they rarely coincide, and their distance can vary according to age or tooth type, ranging from 0.2 to 3.0 mm. The aim of this short communication was to evaluate the distance between the main foramen of independent middle mesial canals (MMCs) and the anatomical mesial root apex of mandibular first molars using the micro-computed tomography. Twenty-five mandibular first molars with MMCs were scanned (resolution of 9.9 µm), and the distance from its main foramen to the anatomical apex was evaluated. Overall, the distance ranged from 0.2 to 2.4 mm; however, in 3 specimens the distance was greater than 3 mm. This report demonstrates that the exit of the main foramen of the MMC varies considerably and could approach a substantial distance from the anatomical apex greater than previously reported in the literature.
The aim of this study was to evaluate in vitro the apical sealing ability of cold lateral and system B root filling techniques using dye penetration. Eighty-six extracted single-rooted human teeth were prepared and randomly divided into two experimental groups to be obturated by cold lateral condensation (n = 33) and system B (n = 33). The remaining 20 teeth served as positive and negative controls. The roots were embedded for 72 h in methylene blue dye solution and sectioned transversely for dye penetration evaluation using stereomicroscope. The results of this study showed that cold lateral condensation leaked significantly more (P < 0.001) than system B technique.