External and internal root morphology of second permanent molars of a Kenyan population.

Abstract

Success of endodontic treatment depends on the knowledge of the normal, and variations from the normal, of root canal configurations of teeth. There exists a racial difference of these features and the significance of these cannot be ignored when planning and carrying out root canal treatment. Second permanent molars have been widely studied among Mongoloids and Caucasians. Since minimal data of their morphology in an African population exists, it is important to establish the root canal anatomy of these teeth in an African population. Objective: To determine the external and internal root morphology of second permanent molars of a Kenyan population. Design: This was an in vitro descriptive cross-sectional study. Setting: 121 maxillary and 189 mandibular second permanent molars were collected from male and female participants aged between 16 and 40 years, who had their teeth extracted for various reasons at major hospitals and dental clinics in Nairobi. Methodology: Extracted maxillary and mandibular second permanent molars were collected from participants who had extractions done at the following facilities’ minor oral surgery clinics; School of Dental Sciences, University of Nairobi, Kenyatta National Hospital, Forces Memorial Hospital, St Mary’s Hospital Moi air Base, Mbagathi District Hospital and Social League. A total of 310 teeth were collected into two well labeled containers (one for male and another for female). The collected teeth were sorted into mandibular and maxillary second permanent molars using the defined inclusion and exclusion criteria. Determination of the tooth length in millimeters, number of roots, direction of root curvature and number of canals and canal configuration was done on each. The standard clearing technique was used to study internal morphology of teeth included in the study. The findings were recorded according to Vertucci’s classification (1984)1, into a data collection form for each tooth examined. The Statistical Package for Social Sciences SPSS version 12.0 was used for data analysis. Descriptive analytical tests were carried out to explain the frequency of various variables. Results: 96.7% of maxillary second permanent molars had three roots, 2.5% had two roots, 0.8% had five roots while for the mandibular second permanent molars, 93.12%, 5.29% and 1.59% had two, three and four roots respectively. There was no root fusion in 71.9% of maxillary second permanent molars, while 0.8%-14.9 % exhibited some form of root fusion. In the mandibular second permanent molars, there was no root fusion in 87.83%, while 7.41% showed fusion of the mesial (M) and distal (D) roots with 4.76% showing fusion of mesial lingual ( ML), mesial buccal (MB), distal lingual (DL) and distal (D) roots. On root curvature, 58.68% of the MB roots of maxillary second permanent molars curved distally while 67.77% of DB and 61.99% of the palatal (P) roots had no curvature. The mandibular second permanent molars showed a distal curvature of the mesial root in 68.78% while the distal root had no curvature in 75.66%. The mean root length of the MB, DB and P of the maxillary second permanent molars were 20.65 ± 1.77mm, 21.47 ± 1.79mm and 23.18 ± 1.65mm respectively while in the mandibular second permanent molars, the mean root length was 22.19 ± 1.71mm and 23.15 ± 1.60mm with standard deviations of for mesial and distal roots respectively. Males had longer mean root lengths than females and the variation was statistically significant (F=3.30, p=0.01). Majority of second permanent maxillary molars had three canals with the MB, MD and P roots having one canal. A second canal was found in 31% of the MB roots. The mesial root of second permanent mandibular molars had two canals in 93.7% while the distal root had one canal in 85.7%. A second canal was found in the distal root in 14.3% of the roots. Vertucci type I canal configuration was more prevalent in both mandibular and maxillary second permanent molars with types II, III, IV, V and VI occurring less frequently. Conclusions: three roots and two roots occurred more frequently in second maxillary and mandibular molars respectively. Root fusion occurred more frequently in second permanent maxillary molars than in the second permanent mandibular molars. The palatal and distal root of the second molars had the least incidence of curvatures. Most of the second permanent maxillary and mandibular molars had three canals and the most frequent canal configuration was Vertucci type I.