Analysis of Root and Canal Morphology of Second Permanent Molars in a Selected Kenyan Population Using Cone Beam Computed Tomography

Abstract

Study background: Successful root canal treatment involves proper access, chemico-mechanical preparation and a three-dimensional hermetic obturation. To achieve this, a thorough knowledge of root and canal anatomy is essential, since undetected canals act as a bacterial reservoir leading to post-treatment disease. Therefore, determining root and canal configurations is necessary. More importantly, variations among different study populations in both internal and external root anatomy are known to exist. Broad objective: To evaluate the internal and external root morphology of second permanent molars in a Kenyan population using CBCT imaging. Study design and site: This was a retrospective cross-sectional study involving analysis of CBCT images taken at Digital Healthcare Solutions imaging centre located in Kilimani area of Nairobi. Materials and methods: Previously taken CBCT images of mandibular and maxillary second permanent molars were analysed. External root morphology specifically: number of roots, mean root length, direction of root curvature and presence of root fusion were determined. Internal root morphology was evaluated using Vertucci (1984) classification. The data was entered in a coded form and analysed using Statistical Package for Social Sciences version 24. Descriptive analytical tests, t-test and chi-square tests were carried out to determine the frequency and relationship between various variables. Ethical approval was sought and granted from KNH-UoN Ethical Research Committee (Approval No. P837/19/2019). Additionally, permission to carry out the study at Digital Healthcare Solutions imaging centre was requested from its administration and granted. Results: One hundred and forty two maxillary second permanent molars examined, out of which three (2.1%) had a single root, nine (6.3%) had two roots and 129 (90.8%) had three roots. Majority xiv (97.1%) of mandibular second permanent molars had two roots, with only 3 (1.7%) and 2 (1.1%) having one and three roots respectively. Root fusion was more common in the maxillary (29.2%) than mandibular (8%) second permanent molars with the most common fusion occurring between the mesiobuccal and distobuccal roots. Mesiobuccal root of the maxillary second permanent molar was curved in 69 (52.3%) of the images examined with a distal curvature being the commonest (50.5%), while distobuccal and palatal roots were found to be mostly straight. In the mandibular second permanent molars, about half (50.5%) of the mesial roots were curved in the distal direction, while the distal root was majorly (150, 87.2%) straight. Regarding the root length, mesiobuccal, distobuccal and palatal roots of maxillary second permanent molars were found to have a mean root length of 19.67mm (±1.57 SD), 19.29mm (±1.47 SD) and 20.84 mm (+1.69 SD) respectively. Additionally, the mesial and distal roots of mandibular second permanent molars were 21.16 mm (+1.61 SD) and 20.29 mm (+1.58 SD) respectively. Internal morphology/canal configuration was described using Vertucci classification (1984). In the maxillary second permanent molar, the mesiobuccal root presented with the most varied root canal configurations unlike the palatal and distobuccal roots which exhibited only Vertucci type I configuration in all the images examined. Specifically, most (81.8%) of the mesiobuccal roots had Vertucci type I canal configuration followed by type IV seen in 12.2% of the teeth, while type II, III and V appeared in 3%, 1.5% and 1.5% of the images respectively. In the mandibular second permanent molars, Vertucci type IV was the main (58.5%) canal configuration identified in the mesial root while in the distal root type I predominated (93.6%). Other canal configurations found in the mesial root of the mandibular tooth were type I, II, III and V at a frequency of 13.5%, 7.0%, 8.8% and 12.2% respectively. Conclusion: Maxillary second permanent molars had three roots while mandibular had two roots. Root fusion was found to be more common in the maxillary second permanent molars than in its xv mandibular counterpart. Vertucci type I was the commonest canal configuration in both maxillary and mandibular second permanent molars. The mesiobuccal root of the maxillary second permanent molars and mesial root of the mandibular second permanent molars presented with the most varied canal configurations. Cone beam computed tomography is a useful imaging modality in assessment of external and internal root and canal anatomy hence very relevant in endodontic diagnosis, treatment planning and follow-up.