Abstract
Objectives This study assessed the incidence and variability features of root canals system (RCS) and their ramifications according to Pucci & Reig (PR) (1944) and the American Association of Endodontists (AAE) (2017) by micro-computed tomography (μCT).Methodology 500 representative extracted human teeth of each tooth group (n=50) (maxillary/mandibular central and lateral incisors, canines, first and second premolars and molars) were scanned by μCT with a resolution of 26.70 μm. The reconstructed cross-sections images and the visualization of the continuous slices in the transversal axis were performed using DataViewer software. RCS were classified according to Pucci & Reig (main canal, collateral canal, lateral canal, secondary canal, accessory canal, intercanal, recurrent canal) and AAE (main canal, accessory canal, lateral canal). The apical deltas were assessed for both classifications. The prevalence of apical deltas was evaluated using the Chi-squared test (p<0.05).Results According to PR, a higher incidence of lateral canals was observed in maxillary canines (10%), central incisors (8%) and first premolars (6%). Using AAE, the highest incidence of lateral canals was observed in the mandibular first premolars (85%), first and second molars (84%), lateral incisors (67%), canines (59%), and in maxillary first premolars (52%). Regarding accessory canals, the PR showed a frequency in 2% of the maxillary lateral incisors and maxillary and mandibular first premolars and 3% of mandibular first and second molars. On the other hand, the AAE showed the highest incidence of accessory canals in 86% of the maxillary first premolars, 71% in mandibular lateral incisors, 69% in mandibular first premolars, 65% in mandibular canines, and 56% in maxillary canines. The PR showed the lowest incidence of apical deltas for all dental groups when compared with AAE (p=0.004). Interestingly, distal canals in maxillary molars showed a significant discrepancy between classifications (p=0.027).Conclusions μCT enabled accurately describing the RC system and related ramifications, adding to the PR and AAE classifications, with some discrepancies reported for maxillary molars. Clinical Relevance This μCT study enabled a thorough description of the variability among root canals and their ramifications, including clinically relevant details on the presence and location of lateral canals and accessories in all human tooth groups, beyond the currently existing classification systems.
Highlights
After the approval by the Research Ethics Committee (CAAE n.o 0072.0.138.000-09) for the use of 500 human teeth extracted with reasons unrelated to this study from a representative Brazilian subjects, 50 subsets were selected for each tooth group (n=50), with complete rhizogenesis, root structure completely formed, and without caries or previous endodontic treatment
The assessment evidenced the presence of a main canal in 100% of the assessed dental groups, except for the second mesiobuccal canal in the maxillary first and second molars, which showed an incidence of 87% and 75%, respectively
The accessory canals were observed in 2% of the maxillary lateral incisors and maxillary and mandibular first and second premolars and between 3% and 4% of mandibular first and second molars
Summary
The success of endodontic treatment directly depends on complete cleaning, disinfection, shaping and three-dimensional (3D) filling of the root canal system (RCS). The subsequent steps should be meticulously performed to ensure the total removal of healthy or necrotic tissue and to eliminate microorganisms and related subproducts from root canals. a deepened knowledge of the 3D RCS morphology contributes to the diagnosis and establishment of the endodontic therapy protocol, supporting the prognosis and obtaining a successful treatment.4,5,8,12-17Studies on the morphology of root canals of human permanent teeth have shown that the number and classification of root canals could vary in each teeth group, according to ethnicity, sex and between populations, within the same population as well as individually, in each person.4,5,15,16,20-23The accessory (extra or additional) root canals refers to an anatomical development variation, with the presence of additional root canals compared to the original dental anatomy previously described in the literature. This anatomical variation is very common in human teeth (primary and permanent) and interconnects the main root canal or pulp chamber to the external root surface due to the trapping of periodontal blood vessels during the Hertwig root epithelial sheath formation and development. it is essential to know the internal dental anatomy and its variations for endodontic treatment, since the literature has reported the incidence of accessory canals between 40% and 80% in different dental groups.. The success of endodontic treatment directly depends on complete cleaning, disinfection, shaping and three-dimensional (3D) filling of the root canal system (RCS).. The accessory (extra or additional) root canals refers to an anatomical development variation, with the presence of additional root canals compared to the original dental anatomy previously described in the literature.. The accessory (extra or additional) root canals refers to an anatomical development variation, with the presence of additional root canals compared to the original dental anatomy previously described in the literature.4 This anatomical variation is very common in human teeth (primary and permanent) and interconnects the main root canal or pulp chamber to the external root surface due to the trapping of periodontal blood vessels during the Hertwig root epithelial sheath formation and development..
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