An Analysis of Accessory Canals in the Furcation Areas of Human Mandibular Molar Teeth Using the Microfocus X-ray CT System

Abstract

The objectives of this study were to perform 3-D reconstruction and analysis of accessory canal anatomy in the bifurcation area of the multirooted molar with respect to occurrence, location, frequency, running forms and terminus (opening) structure. The bifurcation area of a total of 47 extracted human mandibular molar teeth (23 first molars, 6 second molars, and 18 third molars involving 4 immature root teeth) was investigated with microfocus X-ray CT. These teeth had been stored in 10% formalin solution. The following results were obtained: 1. The crista interradicularis with presence of a distinct ridge (protuberance) in which there was an interconnection between the mesial root and the distal root was identified in the early development of the interradicular bifurcation of the formed molar tooth on 3-D reconstruction. In such areas small holes were seen extending from the dental sac of the tooth germ to the coronal pulp. Therefore, it must be true that accessory canals are present at the region where the promontory develops in the intermediate bifurcation. 2. Although these canals were observed in all 4 immature root teeth, they appeared to be absent in 32.6% of mature adult molars. In the immature teeth these canals appeared to run toward the region of the mesial canal orifice communication between the pulp and bifurcation region. In mature teeth, a multitute of these canals were present from the bifurcation region into near the dentinocementum junction. 3. As one of type IV, we indicated that numerous canaliculi might develop leading from pulp into the pulpal floor dentin and the root canal resulting from elaboration of so-called secondary dentin deposit. 4. Near the dentinocementum junction of bifurcation areas, one or a few accessory canals were sometimes seen as slit-shaped or small hole tissues. In many teeth an enamel dropletlike substance seemed to be present within these tissues.