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Root and canal morphology of maxillary first premolar teeth in a Ugandan
Charles Mugisha Rwenyonyi1, Annet Kutesa1, Louis Muwazi1, William Buwembo2
1Department of Dentistry, 2Department of Anatomy, College of Health Sciences,
Makerere University, Kampala.
Dr. Charles Mugisha Rwenyonyi
Department of Dentistry
College of Health Sciences,
Running title: Root and canal morphology of maxillary first premolar teeth
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
Keywords: clearing technique, maxillary premolars, root canal, Ugandan
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 technique.
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 root canal
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. The
level of significance was set at 5%.
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% (Table 4).
Several methods have been employed in studying the root and canal morphology of the
different teeth. Recently, spiral computed tomography  and micro-computed
tomography  have been advocated for use in studying root and canal system. Despite
their accuracy, these methods involve expensive equipment. In the present study, a
modified clearing method was used. It enabled viewing of a three-dimensional
morphology of the roots and canals . It is relatively simple, acceptable and
The specimens used in the present study were clearly identified by instructing the dentists
to put the extracted maxillary first premolar teeth from patients of African descent in the
provided containers. The specimens were further identified before processing by
assessing the crown morphology as described by Scott and Symons . About 3.8% (n
= 8) of the specimens, which could not be identified based on their coronal structure were
excluded. It is unlikely that there was any misclassification of the specimens.
In the present study, 26.7% of the first maxillary premolar teeth had one root. This value
is higher than reported in the Polish  and Saudi populations  but, much lower than
reported from other populations [2-8] (Table 1). A prevalence of 73.3% of two-rooted
specimens was recorded in the present study, which is higher than values (41.7% to
60.8%) observed in other populations [2-8,10] (Table 1). However, Lipski, et al. 
recorded 75.3% of two-rooted specimens in the Polish population while Atieh, et al. 
recorded 80.9% in the Saudi population (Table 1).
In the present study, 16.9% (n = 25) of the specimens with two roots were fused. This
value was much lower as compared to 32.1% of the teeth in the Singaporeans , 26% in
the Polish  and 36.2% in the Saudis . In corroboration to the finding in the Chinese
 and Singaporean populations , the present study showed no three-root anomaly in
the maxillary first premolar teeth (Table 1). However, studies in other populations found
the anomaly in the range of 0.8% to 9.2% [3-6,8-11] (Table 1).
Apart from assessing the number of roots in the present study, the number of the canals,
the canal configuration and the apical foramina were also evaluated, which are more
important to the clinicians. We found 5.4% of all the specimens had one canal. This
prevalence is considerably lower when compared with those of previous studies [3-5,10-
13] but, higher than reported by other workers [8,9,14] (Table 2).
Our finding of 92.1% of the two-canalled specimens (Table 2) corroborates those of
previous studies in the Polish  and Jordanian populations . However, lower
values (73.3% - 89.8%) were previously reported in other populations [3-5,9,11-13]. On
the other hand, Chaparro, et al.  reported a higher prevalence of specimens with two
canals (Table 2). When the analysis was based on root morphology, the predominance of
two canals was still evident in the present study (Table 4).
In this Ugandan population, lateral canals were 64.8% and 14.9% in the single and two-
rooted specimens (Table 4). Pineda and Kuttler  reported a value of 41.2% in the
Mexican maxillary first premolars. Multiple apical foramina were the most prevalent in
the present study (Table 4), which corroborates a previous finding in the Mexicans .
Awawdeh  reported a lower value in the Jordanians.
The maxillary first premolar teeth in this Ugandan population showed a higher
prevalence of two-root morphology with the majority of the roots having a Vertucci type
IV canal configuration and multiple apical foramina. There was no three root anomaly
recorded in the present material.
The authors are grateful to the dentists who collected the specimens for this study.
Musoke David of the Department of Pharmacy, Makerere University College of Health
Sciences advised on the handling of chemicals. Sida/SAREC financially supported the
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Table 1. Comparison of frequency distribution of root morphology of the maxillary first
premolar teeth in the present and previous studies Frequency of roots (%) Study Population Number
of teeth One root Two roots Three
Pineda and Kuttler  Mexicans 259 43.0 54.6 2.4
Carns and Skidmore  White Americans 100 22.0 72.0 6.0
Vertucci and Gegayff  White Americans 400 39.5 56.5 4.0
Walker  Chinese 100 60.0 40.0 0
Pécora, et al.  Brazilians 240 55.8 41.7 2.5
Chaparro, et al.  Spanish 150 40.0 56.7 3.3
Loh  Singaporeans 957 49.4 50.6 0
Lipski, et al.  Polish 142 15.5 75.3 9.2
Awawdeh, et al.  Jordanians 600 30.8 68.4 0.8
Atieh  Saudis 246 17.9 80.9 1.2
Present study Ugandans 202 26.7 73.3 0
Table 2. Comparison of frequency distribution of root canal morphology of maxillary
first premolar teeth in the present and previous studies Frequency of root canals (%) Study Population Number.
of teeth One
Pineda and Kuttler  Mexicans 259 33.9 65.6 0.5
Carns and Skidmore  White Americans 100 9.0 85.0 6.0
Vertucci and Gegayff  White Americans 400 8.0 87.0 5.0
Kartal, et al.  Turkish 300 8.7 89.6 1.7
Pécora, et al.  Brazilians 240 17.1 80.4 2.5
Chaparro, et al.  Spanish 150 1.4 95.3 3.3
Lipski, et al.  Polish 142 2.1 88.6 9.2
Awawdeh, et al.  Jordanian 600 5.6 92.2 1.5
Różylo, et al.  Polish 55 0 91.0 9.0
Atieh  Saudis 246 8.9 89.8 1.2
Present study Ugandans 202 5.4 92.1 2.5
Table 3. Root canal configuration according to the Vertucci  classification
Type I One root canal extending from the pulp chamber to the apex
Type II Two separate root canals leave the pulp chamber and join short of the
apex to form one canal
Type III One root canal leaves the pulp chamber before dividing into two
within the root, which then merge to exit as a single canal
Type IV Two separate root canals extend from the pulp chamber to the apex
Type V One root canal leaves the pulp chamber and divides short of the apex
into two separate and distinct canals with separate apical foramina.
Type VI Two separate root canals leave the pulp chamber, merge in the body
of the root, and again divide short of the apex to exit as two separate
and distinct canals
Type VII One root canal leaves the pulp chamber, divides and rejoins within
the body of the root, and finally re-divides into two distinct canals
short of the apex
Type VIII Three separate and distinct root canals extend from the pulp chamber
to the apex
Table 4. Frequency distribution of root canals and their configuration according to
Vertucci  classification, lateral canals, canal intercommunication and apical foramina
in different root morphologies of the maxillary first premolar teeth (n = 202)
Variable Two-rooted teeth (n = 148) Single rooted teeth (n = 54)
Type I 0 (0.0) 7 (13.0)
Type II 0 (0.0) 16 (29.6)
Type III 0 (0.0) 1 (1.9)
Type IV* 143 (96.6) 26 (48.1)
Type V 0 (0.0) 1 (1.9)
Type VI 0 (0.0) 1 (1.9)
Type VII 0 (0.0) 2 (3.7)
Type VIII 5 (3.4) 0 (0.0)
Lateral canals* 22 (14.9) 35 (64.8)
Canal intercommunication 1 (0.7) 4 (7.4)
Single foramen 0 (0.0) 24 (44.4)
Multiple foramina 148 (100) 9 (55.6)
Percentages are in parentheses; *P-value < 0.05