Root and canal morphology of maxillary first premolar teeth in a Ugandan populatio
Aim : To determine the variations in the root and canal morphology of the maxillary first premolar teeth in a Ugandan population. Methodology : Extracted maxillary first premolar teeth (n = 202) were evaluated in this study. The specimens had their pulp chambers de-roofed. They were decalcified in nitric acid and made transparent with methyl salicylate. Indian ink was injected into the root canals to display their configuration. Results : One hundred and forty eight (73.3%) of the specimens had two roots, of which 16.9% (n = 25) had fused roots. About 26.7% (n = 54) of the specimens were single rooted. Eleven (20.4%) of the single rooted specimens had one canal of either Vertucci type I, III, V or VII configuration while 79.6% (n = 43) of the specimens had two canals of either Vertucci type II, IV or VI configuration. The two-rooted specimens exhibited Vertucci type IV and VIII canal configuration: 96.6% and 3.4%, respectively. The single rooted teeth had a higher prevalence of lateral canals, canal intercommunications and multiple apical foramina as compared to the two-rooted specimens. Conclusion : The maxillary first premolar teeth in this Ugandan population showed a higher prevalence of two-root morphology with majority of the roots having Vertucci type IV canal configuration. There was no three-root anomaly recorded in the present materi.
Keywords: clearing technique, maxillary premolars, root cana,dental laser tips
Anatomical variations of teeth need to be considered in clinical and radiographic evaluations during endodontic treatment . Clinical management involving maxillary first premolar teeth with unpredictable root and canal morphology may pose some challenges [2,3]. Some of the challenges include: the difficulty in extraction and orthodontic movement requiring excessive force, and frequent failures of endodontic treatment resulting from missed canals or because of difficulty to radiographically visualise the apical limit of the multi-rooted premolars.
In previous studies [2-11], the prevalence of one root varied from 15.5% to 60%; two roots, 40% to 80.9%; and three roots, 0 to 9.2% (Table 1). The canal morphology of the maxillary first premolar teeth has been reported with varying prevalence rates: one canal, 0% to 26.2%; two canals, 73.3% to 97% and three canals, 0.5% to 9.2% [3-5,8-14] (Table 2). The majority of these studies were carried out in teeth from populations of Caucasian [4-6,8,9,12,14] and Asian origins [2,7,10]. It is evident that the anatomy of these teeth tends to have racial variations [6,7,13]. Information on the root and canal morphology of maxillary first premolar teeth from populations of indigenous Africans is scarce. The purpose of this study was to assess the root and canal morphology of maxillary first premolar teeth from a Ugandan population using the clearing.
Material and methods
The material consisted of 210 extracted maxillary first premolar teeth. They were collected from Ugandan patients of African descent attending dental clinics in Kampala. Fifteen dental clinics were randomly selected from all the five divisions of Kampala metropolitan where each clinic was provided with a 500 ml plastic container having 10% formalin (Akron Healthcare Pvt. Ltd. Delhi, India). The dentists were instructed to put extracted maxillary first premolar teeth into the plastic containers. The teeth were collected with the verbal consent of the patients. However, the age and sex of the patients who donated the teeth were not recorded. The teeth were collected from the clinics and taken to the Department of Dentistry, Makerere University College of Health Sciences, for processing as previously described [15,16]. Hard and soft deposits were removed from the tooth surfaces using hand scaling instruments, and the teeth were scrubbed in running cold tap water. The teeth (n = 8) with less than two-thirds of the crown present, which could not easily be differentiated based on crown morphology as described by Scott and Symons  were excluded. The remaining 202 specimens were made transparent following the method of Yang, et al.  with modifications. An endodontic access cavity was prepared in each specimen using a high-speed handpiece and diamond fissure bur. The specimens were placed in a 5% sodium hypochlorite solution (Ameya Chemicals, Mumbai, India) and periodically agitated for 24 h to dissolve the organic tissue from the root surface and the root canal system. They were then washed in running water for 2 h, dried on a wire mesh, and decalcified in 10% nitric acid (MJ Patterson, Dunstable, UK) for 6 days. The nitric acid solution was changed daily and manually agitated once a day during the first 3 days. However, during the last 3 days the acid solution was not changed. The teeth were rinsed in running cold tap water for 4 h and dried on a wire mesh. They were dehydrated in successive solutions of 75% and 95% alcohol; each for 12 h. Transparency was induced by placing the specimens in 99% methyl salicylate (Merck, Poole, UK). To clearly view the system, India ink (Calder Colours, Ashby-de-la-Zouch, Leicester, UK) was coronally injected into the pulp chambers using a 5 ml plastic disposable syringe with a 23 gauge needle (Sherwood Medical, St. Louis, MO, USA). The ink was withdrawn through the root apical foramen/foramina using a rubber tube with one end inserted up to the cervical third of the root and the other end connected to a suction machine (Ramvac, Spear-fish, SD, USA). The specimens were then viewed in natural light through a lens at 3x magnification, and the number of root canals and their configurations according to Vertucci  classification (Table 3), lateral canals, inter-canal communications, and multiple apical foramina (deltas) were recorded. The number of roots and their morphology was also recorded. Although there is no universally accepted system for classifying root morphology , in the present study, roots were considered fused if the union occurred in the apical, middle, or cervical one-third of the roots . Data were entered in a computer and analysed using Statistical Package for Social Sciences Inc. (version 15.0 for windows, Illinois, USA). Frequency distributions were used to describe the material. The Chi-square statistics was used to test any significant differences in the canal configuration based on root morphology.
One hundred and forty eight (73.3%) of the specimens had two roots (Table 1) of which 16.9% (n = 25) had fused roots. About 26.7% (n = 54) of the specimens were single rooted (Table 1). Eleven (20.4%) of the single rooted specimens had one canal of either Vertucci type I, III, V or VII configuration while 79.6% (n = 43) of the specimens had two canals of either type II, IV or VI configuration (Table 4). On the other hand, the two-rooted specimens exhibited Vertucci type IV and VIII canal configurations: 96.6% and 3.4%, respectively (Table 4). The lateral canals were more frequently observed in the apical and cervical thirds as compared to mid third of the roots. The single rooted specimens had a significantly higher frequency of lateral canals as compared to two-rooted teeth (p<0.05, Table 4). Multiple apical foramina were the most prevalent in this material (Table 4). Canal intercommunications were more commonly recorded in the single as compared to the two-rooted specimens: 7.4% versus 0.7%.