A thorough knowledge of the root canal morphology and its variations is an indispensable prerequisite for the success of the root canal treatment. Many roots have additional canals and a variety of canal configurations. Occasionally during the formation of a root, a break develops in Hertwig’s epithelial root sheath producing a small gap. This results in “accessory canals” and can be formed anywhere in the root, leading to periodontal-endodontic communication [
Canines are universally referred to as the “cornerstone” of the dental arches. Both maxillary and mandibular canines have canine eminence on their labial portion of the teeth which has a cosmetic value. Aesthetically, they help in normal facial expressions at the “corners” of the mouth. Functionally, the shape and position of the canines play a major role in intercuspal positioning by “canine guidance” [
Root canal morphology varies according to race. For example, in the Caucasian population [
Root canal patterns in maxillary canines in % (
Authors | Population | Technique | Number of teeth | Type I | Type II | Type III | Type IV | Type V | Additional type |
---|---|---|---|---|---|---|---|---|---|
Vertucci [ |
USA | Clearing and staining | 100 | 100 | — | — | — | — | — |
Pineda and Kuttler [ |
Mexico | Radiographs | 260 | 100 | — | — | — | — | — |
Çali |
Turkey | Clearing and staining | 100 | 93.48 | — | 4.35 | — | 2.17 | — |
Sert and Bayirli [ |
|||||||||
(Men) | Turkey | Clearing and staining | 100 | 91 | 3 | 4 | 2 | — | 1 |
(Women) | 100 | 96 | — | — | 4 | — | — | ||
Present study | India | CBCT | 250 | 81.6 | 2.8 | 11.6 | 0.8 | 2 | 1.2 |
CBCT: cone beam computed tomography.
Cone beam computed tomography (CBCT) has become a successful tool to explore the root canal anatomy. Based on an in vitro study, Neelakantan et al. [
A total of 250 freshly extracted human permanent maxillary single-rooted canines and 250 permanent mandibular single-rooted canines were collected from an Indian population. The teeth were collected from various parts of India. The teeth that were restored, root canal treated, and attrited were excluded. All the teeth that were noncarious and showed complete root formation were included in the study. The age, gender, and systemic conditions of the patient were unknown. The teeth were stored in formalin. Any attached soft tissue and calculus were removed by ultrasonic scaling. The storage and handling of the teeth were performed as per the Centers for Disease Control and Prevention guidelines and regulations [
The teeth were dried and mounted on a modeling wax sheet vertically. The teeth were scanned by a CBCT scanner (Sirona Dental System) and the software used was SICAT Galileo Implant version 1.8. The three-dimensional resolution or isotropic voxel size was 0.3 mm, the spherical imaging volume was 15 cm, the magnification was 1 : 1, and the reconstruction time was 2.5 to 4.5 seconds. The scan setting was 85 Kvp 42 mAs. The exposure time was 14 seconds. The software was also used for volumetric rendering of the three-dimensional images through selective integration and measurement of adjacent voxels (all voxels are isotropic) in the display. Objects within the volume were accurately measured in different directions [
The images generated by CBCT system were processed and analyzed for the following parameters. Pattern of the root canals was evaluated and classified according to Vertucci’s [
According to the present study the various canal configurations in maxillary canines were Type I (81.6%), Type II (2.8%), Type III (11.6%), Type IV (0.8%), and Type V (2%) based on Vertucci’s classification. In mandibular canines the various canal patterns were Type I (79.6%), Type II (3.2%), Type III (13.6%), and Type V (2%) based on Vertucci’s [
Root canal patterns in mandibular canines in % (
Authors | Population | Technique | Number of teeth | Type I | Type II | Type III | Type IV | Type V | Additional type |
---|---|---|---|---|---|---|---|---|---|
Vertucci [ |
USA | Clearing and staining | 100 | 78 | 14 | 2 | 6 | — | — |
Pineda and Kuttler [ |
Mexico | Radiographs | 187 | 81.5 | 13.5 | — | 5 | — | — |
Çali |
Turkey | Clearing and staining | 100 | 80.39 | 3.92 | 13.73 | — | 1.96 | — |
Sert and Bayirli [ |
|||||||||
(Men) | Turkey | Clearing and staining | 100 | 90 | 9 | — | — | — | — |
(Women) | 100 | 62 | 22 | 13 | 3 | — | — | ||
Pécora et al. [ |
Brazil | Clearing and staining | 830 | 92.2 | 4.9 | — | 1.2 | — | — |
Present study | India | CBCT | 250 | 79.6 | 3.2 | 13.6 | — | 2 | 1.6 |
CBCT: cone beam computed tomography.
Longitudinal sections of cone beam computed tomography scans showing various root canal patterns in maxillary canines: (a) Type I
The average anatomical length of the crown and root of maxillary canines was 9.61 mm and 16.82 mm. In mandibular canines, the average anatomical length of the crown and root was 8.70 mm and 15.51 mm, respectively.
In maxillary canines, the position of the apical foramina was centrally located in 29.6% of the teeth and laterally located in 70.4% of the teeth. In mandibular canines, the apical foramina were centrally located in 34.4% of the samples and laterally located in 65.6% of the samples.
Other parameters such as accessory canals, the shape of the access cavity at CEJ (Figure
Position of the accessory canals from the root apex.
Distance from the apex | Maxillary canine ( |
Mandibular canine ( |
---|---|---|
|
4 | 11 |
0.5 mm to 1 mm | 16 | 17 |
1 mm to 1.5 mm | 6 | 2 |
1.5 mm to 2 mm | 4 | 2 |
Total number of teeth with accessory canals |
|
|
Total number of teeth without accessory canals | 220 (88%) | 218 (87.2%) |
Shape of the access cavity at cementoenamel junction in cross-sectional view.
Shape | Maxillary canine ( |
Mandibular canine ( |
||
---|---|---|---|---|
Number | Percentage | Number | Percentage | |
Round | 53 | 21.2% | 44 | 17.6% |
Oval | 94 | 37.6% | 103 | 41.2% |
Long oval | 37 | 14.8% | 42 | 16.8% |
Flattened | 66 | 26.4% | 61 | 24.4% |
Root diameter in cross-sectional view in mm (mean, ±standard deviation).
Position | BP | MD | ||||
---|---|---|---|---|---|---|
Mean | ±SD | Range | Mean | ±SD | Range | |
Maxillary canine ( |
||||||
At CEJ | 7.26 |
|
5.51–8.85 | 4.79 |
|
3.45–6.64 |
Middle third | 6.56 |
|
5.17–8.52 | 3.9 |
|
2.92–5.97 |
Apical third | 5.28 |
|
2.74–6.59 | 3.2 |
|
2.10–4.36 |
Mandibular canines ( |
||||||
At CEJ | 7.08 |
|
5.32–8.22 | 4.74 |
|
3.93–5.57 |
Middle third | 6.21 |
|
3.25–6.98 | 3.79 |
|
3.10–4.83 |
Apical third | 5.51 |
|
3.24–6.11 | 3.13 |
|
2.19–3.83 |
BP: buccopalatal, MD: mesiodistal, and SD: standard deviation.
Dentine thickness in cross-sectional view in mm (mean, ±standard deviation).
Position | Surface | Maxillary canine ( |
Mandibular canine ( |
||||
---|---|---|---|---|---|---|---|
Mean |
|
Range | Mean |
|
Range | ||
At CEJ | Buccal | 2.28 |
|
1.45–2.65 | 2.02 |
|
1.31–2.42 |
Palatal/lingual | 2.51 |
|
1.66–3.46 | 2.18 |
|
1.71–2.76 | |
Mesial | 1.72 |
|
0.96–2.67 | 1.54 |
|
1.11–1.92 | |
Distal | 1.94 |
|
1.22–2.73 | 1.75 |
|
1.28–2.37 | |
|
|||||||
Middle third | Buccal | 2.09 |
|
1.07–2.99 | 2.20 |
|
1.15–2.26 |
Palatal/lingual | 2.33 |
|
0.97–3.36 | 2.61 |
|
1.16–2.59 | |
Mesial | 1.40 |
|
0.79–2.44 | 1.31 |
|
0.79–1.77 | |
Distal | 2.14 |
|
0.98–2.37 | 2.72 |
|
0.95–1.70 | |
|
|||||||
Apical third | Buccal | 1.78 |
|
1.21–2.55 | 1.50 |
|
0.72–2.11 |
Palatal/lingual | 1.97 |
|
1.25–3.02 | 2.90 |
|
0.96–2.58 | |
Mesial | 1.74 |
|
0.59–2.09 | 0.92 |
|
0.54–1.89 | |
Distal | 2.01 |
|
0.67–1.85 | 1.84 |
|
0.61–1.75 |
CEJ: cementoenamel junction; SD: standard deviation.
Cross sections of cone beam computed tomography scans showing various shapes of the access cavity at cementoenamel junction; (a) round, (b) oval, (c) long oval, and (d) flattened.
Cross-sectional view of three levels at which root diameter and root dentine thickness of canines were measured; (a) at cementoenamel junction, (b) middle third (5 mm from CEJ), (c) apical third (10 mm from CEJ); (d) longitudinal section of the teeth.
A thorough knowledge of tooth morphology, careful interpretation, adequate access, and exploration of the tooth are prerequisites for successful root canal treatment [
It is important to identify and manage root canal variations. Differences in methodologies to study the morphology of the teeth account for highly variable results. In the past, various methodologies used to study canal anatomy were histopathological studies [
In the present study, the most common root canal pattern in the maxillary canine was a Type I in 81.6% of the samples. Similar findings were reported by Vertucci [
Among the various studies on mandibular canines, Pécora et al. [
In the present study, 3 (1.2%) of the samples in the maxillary canine and 4 (1.6%) of the samples in mandibular canine had Sert and Bayirli’s [
The average length of the crown was 9.61 mm in the maxillary canine in our study. Ash and Nelson [
In the present study all the accessory canals in both maxillary and mandibular canines were found in the apical one-third region within 2 mm from the root apex (Table
The various shapes of the access cavity of maxillary and mandibular canine are tabulated (Table
The present study included identifying the position of the apical foramina. In maxillary canine 70.4% of the apical foramina were laterally positioned and 29.6% of them was centrally positioned. In mandibular canines the position of the apical foramina was 65.6% laterally and 34.4% centrally placed. Similar results were reported in the literature amongst different populations [
Based on the reports of Ash and Nelson [
In the present study, the measurement of the dentine thickness of the root in cross-sectional plane (Table
The present study reports both the normal anatomy and the variations of maxillary and mandibular canines in an Indian population, highlighting the role of CBCT as a tool to study tooth morphology. To sum up, the most common canal pattern was Type I both in maxillary and in mandibular canines; additional canal pattern Type XIX (Sert and Bayirli) was present in the maxillary (1.2%) and mandibular (1.6%) canines; all the accessory canals were found within 2 mm from root apex; mesial surfaces of both maxillary and mandibular canines had the least dentine thickness at the root.
The authors declare that there is no conflict of interests regarding the publication of this paper.