|Year : 2022 | Volume
| Issue : 1 | Page : 17-24
Evaluation of the root canal cross-sectional morphology in maxillary and mandibular premolars in Saudi subpopulation
Nezar Mohammed Boreak1, Mohammed Nasir Kamaluddin Inamdar2, Sheeba Khan3, Khalid A Merdad4, Ahmad Jabali1, Nassreen Albar1, Hamed Alshawkani1
1 Department of Restorative Dental Science, College of Dentistry, Jazan University, Jizan, Kingdom of Saudi Arabia
2 Preventive Dental Sciences, College of Dentistry and Pharmacy, Buraidah Private Colleges, Buraydah, Kingdom of Saudi Arabia
3 Restorative Dental Science, College of Dentistry and Pharmacy, Buraidah Private Colleges, Buraydah, Kingdom of Saudi Arabia
4 Department of Endodontic, Faculty of Dentistry, King Abdul-Aziz University, Jeddah, Kingdom of Saudi Arabia
|Date of Submission||21-Jun-2021|
|Date of Decision||15-Jul-2021|
|Date of Acceptance||19-Jul-2021|
|Date of Web Publication||8-Jan-2022|
Nezar Mohammed Boreak
Department of Restorative Dental Science, College of Dentistry, Jazan University, Jizan
Kingdom of Saudi Arabia
Source of Support: None, Conflict of Interest: None
Introduction: Cone-beam computed tomography (CBCT) is a recent advancement in diagnostic radiology in dentistry which allows the clinician to have a clear 3D view of the root canals before starting the endodontic treatment. The goal of the present research was to assess the root canal cross-sectional shape (RCCSS) in maxillary and mandibular premolars in the Saudi Arabian subpopulation.
Materials and Methods: In the present study, radiographs of 330 patients who had teeth with complete root development and closed apices were selected. Root canal shapes were assessed at the coronal and middle thirds, and in the apical third, 1 mm above the apical foramen using CBCT. Categorical variables were explained as frequencies and percentages and evaluated using the Chi-square test.
Results: 1666 premolars were evaluated in the study. Maxillary first and second premolars were found to have a maximum circular cross-sectional shape at the coronal, middle, and apical sections in most of them followed by flattened and oval cross-sectional shapes except the maxillary right second premolars where the most frequent RCCSS was flattened in the coronal section (71%), circular in the middle (14%), and apical (10%) section. The most recurring coronal RCCSS in mandibular first and second premolars was oval followed by flattened and circular, while the most frequent cross-sectional shape in the middle and apical sections was found to be circular followed by oval and flattened RCCSS.
Conclusion: Marked variations were observed in the coronal and middle RCCSS of maxillary and mandibular premolars though the most prominent RCCSS in the apical section was the circular shape.
Keywords: Cone-beam computed tomography, mandibular premolars, maxillary premolars, root canal cross-sectional shape
|How to cite this article:|
Boreak NM, Inamdar MN, Khan S, Merdad KA, Jabali A, Albar N, Alshawkani H. Evaluation of the root canal cross-sectional morphology in maxillary and mandibular premolars in Saudi subpopulation. Saudi Endod J 2022;12:17-24
|How to cite this URL:|
Boreak NM, Inamdar MN, Khan S, Merdad KA, Jabali A, Albar N, Alshawkani H. Evaluation of the root canal cross-sectional morphology in maxillary and mandibular premolars in Saudi subpopulation. Saudi Endod J [serial online] 2022 [cited 2023 Feb 1];12:17-24. Available from: https://www.saudiendodj.com/text.asp?2022/12/1/17/335235
| Introduction|| |
Endodontic treatment planning comprises a clinical examination of the patient and diagnostic radiography which are indispensable components for a good prognosis. Precise radiographs help in accurate diagnosis of the ailment and allow the dentist to get a clear view of the tooth under question and surrounding area. Although conventional intraoral periapical radiographs (IOPARs) are more economic with high-resolution imaging paradigms, they have drawbacks, for example, there is difficulty in the elucidation of radiograph predominantly when the anatomic structures and background pattern are complicated. Moreover, the 2D image of IOPAR makes it difficult for the clinician to arrive at a conclusive diagnosis.,
In dentistry, three-dimensional (3D) images of anatomical structures are obtained by computed tomography (CT), magnetic resonance imaging (MRI), and cone-beam CT (CBCT) devices.
A CT device produces fan-shaped X-ray beam, and in one rotation, it can irradiate only a thin layer of the region of interest, and thus it needs several rotations to irradiate the whole region. On the other hand, MRI is a well-established imaging method that has the advantage of being noninvasive by not using the ionizing radiations and thus preventing damage to the biological tissues. However, the main disadvantage with MRI is the high acquisition charges and long scanning time.
CBCT is an imaging technology that offers a 3D image of the teeth and surrounding structures in the maxillofacial region. It provides radiographic images at low radiation doses at peak voltage of 60–120 kV along with an acceptable spatial resolution for diagnosing the case and planning the course of treatment. These devices are more compact and appropriate for dental clinics with their narrow space availability compared to CT and MRI. CBCT incapacitates many limitations which conventional radiography happenstances such as initial detection of cervical resorption lesions and 3D valuation of the root canals and adjacent anatomical structures.
In endodontics, various studies have reported that CBCT has been used to analyze and classify root canal configurations in longitudinal sections. However, very few studies have been conducted on the analysis of the root canal cross-sectional shape (RCCSS). RCCSS is the shape of the canal when then the root and canal are viewed in the cross-section.,
It is essential to have a good understanding of the RCCSS for the reason that root canals have diverse morphology and their biomechanical preparation and obturation need to be done by different techniques that are apt for the particular root canal morphology. The majority of the root canal preparation instruments are designed for round configuration root canals. These instruments cannot be used for canals that have different cross-sectional morphology and if used it may leave a part of the root unprepared or underprepared which can cause endodontic failure. It may also lead to perforation of canals. In some cases, due to discrepancy in instrument taper, there can be excess dentin removal or overpreparation of the canals which can weaken the root. Thus, meticulous diagnosis with a complete radiographic view of the tooth is necessary for good treatment and prognosis.
In the present study, it was appraised that the root canal cross-sectional morphology and its variations in three-thirds of the roots of maxillary and mandibular premolars in Saudi subpopulation using CBCT radiographic analysis.
| Materials and Methods|| |
The database records in the College of Dentistry at Jazan University, Kingdom of Saudi Arabia were searched for CBCT radiographs available from 2018 to 2019. 330 CBCT radiographs were recovered. These retrieved radiographic records belonged to 180 males and 150 females with ages ranging from 18 to 45 years. CBCT images that were taken for other diagnostic purposes were assessed in this. Before piloting the research, ethical approval was acquired from the Institute Ethical Committee (Ref no-CODJU-2012F). The radiographs selected for this study were taken in a CBCT machine that was 3D Accuitomo 170 (MORITA, Japan) with the following configuration: 5-8 mA, 90Kv, with 17.5s exposure time, and 0.25 mm voxel size. The CBCT radiographs were processed using Morita's i-Dixel 3D software imaging program.
The teeth that were included in the study were those with complete root development and closed apices. The teeth that underwent root canal therapy, pulpotomy, teeth with fractured roots, and grossly decayed roots were excluded from the study. Other exclusion criteria were subjects with congenital syndromes, patients with cancer under radio/chemotherapy, patients with prostheses about the tooth understudy, patients with root resorption, and edentulous patients. Teeth whose images were unclear in the radiograph were also excluded from the study.
CBCT images were viewed in a software called i-Dixel 3D. The images were arranged perpendicular to the long axis to elude parallax errors. The standard locus to determine the RCCSS was the main root canal. The cross-sectional root canal shapes were assessed in the included teeth in axial segments in three-thirds of the root canal, coronal, at 2 mm level below the root canal orifice, at the middle of the root canal, and apical, 1 mm above the apical foramen. The RCCSSs were classified as follows: 1 – circular, 2 – conical/pyramidal, 3 – oval/long oval, 4 – flat/ribbon-like, 5 – eight shaped, 6 – C-shaped, 7 – calcified, 8 – trapezoidal, 9 – drop shaped, and 10 – other shapes.
| Results|| |
In the present study, a total of 1666 premolars were analyzed, of which 790 were maxillary premolars and 876 were mandibular premolars [Figure 1].
Maxillary first premolars
Two hundred and sixteen (13%) maxillary right first premolars and 188 (11%) maxillary left first premolars were studies wherein off the 216 maxillary right first premolars 199 (93%) had 2 canals and 17 (7%) had single canals, and of the 188 maxillary left first premolars, 180 (95%) had 2 canals and 8 (5%) had single canal.
In the maxillary right first premolar with two roots and two canals, the coronal section RCCSS of the buccal canal was predominantly circular (50%) followed by flattened – 34%, oval – 9%, eight-shaped canals – 3%, trapezoidal – 3%, and drop-shaped canals – 1%. In the middle section, RCCSS was circular in 91% of the buccal canals, flattened in 7% canals, and oval in 2% canals. The apical section consisted of a 95% – circular-shaped canal, 4% – flattened canal, and 1% – oval canal. The palatal canal followed the same pattern [Table 1]. Whereas in maxillary right first premolars with one root and one canal, 82% of the RCCSS in the coronal section were circular, 12% had oval, and 6% were circular. In the middle and apical section, the circular shape was the most common followed by flattened and oval RCCSS [Table 1] and [Figure 2].
|Figure 2: CBCT image of root canal cross-sectional shape of maxillary first premolar. A(P): Apical section of the palatal root, A(B): Apical section of the buccal root, M: Middle section, C: Coronal section|
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|Table 1: Frequency and distribution of root canal cross-sectional shapes in maxillary premolars|
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In the maxillary left first premolars, the coronal section RCCSS of the buccal canal was predominantly circular – 50% followed by flattened – 34%, oval – 12%, eight-shaped – 2%, and trapezoidal – 2%. In the middle section, RCCSS was circular in 93% of the canals, flattened in 4% canals, oval in 2% canals, and eight-shaped in 1% canals. The apical section consisted of 94.5% circular-shaped canal, 4.5% flattened canal, and 1% oval canal. The palatal canal followed the same pattern [Table 1] and [Figure 2]. Maxillary left first premolars with single canal had circular shape in 75% of the teeth followed by 12.5% flattened and oval RCCSS. In the middle section, 63% of RCCSS were circular, 25% were flattened, and 12% oval. In the apical section, 100% of RCCSS was circular [Table 1] and [Figure 2].
Maxillary second premolars
Two hundred and seven (12.4%) maxillary right second premolars and 179 (10.7%) maxillary left second premolars were examined in the study, of which 118 (57%) maxillary right second premolars had two canals and 89 (43%) had single canal. 110 (61%) maxillary left second premolars had 2 canals and 69 (3.5%) had single canal.
In the maxillary right second premolars, coronal section of the buccal canal had the most common RCCSS as flattened shape (71%) followed by circular (14%), oval (10%), eight-shaped (2%), and trapezoid-shaped canals (3%). In the middle and apical sections, the most common shape was circular followed by an oval and flattened shape. In the palatal canal, the predominant RCCSS in the coronal section was circular (52%), followed by flattened (37%) and oval shape (8%), and this pattern was also observed in the middle and apical sections and also in maxillary right second premolars with single canals [Table 1].
In maxillary left second premolars, the coronal section of the buccal canal had the most common cross-sectional shape as circular (75%) followed by oval (18%) and flat (5%) shape. In the middle and apical sections, the most common shape was circular followed by flattened and oval shapes. In the palatal canal, the predominant RCCSS was circular (59%), followed by flattened (34%) and oval shape (6%). Similar pattern was also observed in the middle and apical sections [Table 1]. Maxillary left second premolars with single canal had circular RCCSS as most prominent in coronal section (71%), middle section (72%), and apical section (93%), followed by oval shape (14.5%) and flattened shape (13.5%) in the middle section and flattened (4%) and oval (3%) shape in apical section, respectively [Table 1].
Mandibular first premolars
In the present study, 220 mandibular right first premolars and 224 mandibular left first premolars were examined. All the premolars had a single root and one canal. The most predominant RCCSS in the coronal section of mandibular right first premolars was oval (44%), followed by flattened (37%) and a circular shape (18%). In the middle section, the circular (70%), oval (22%), and flattened (7%) canals were more common. In the apical section, the circular (95%), flattened (4%), oval-shaped canals (1.5%), and trapezoid-shaped canals (0.5%) were more common [Table 2].
|Table 2: Frequency and distribution of root canal cross-sectional shapes in mandibular premolars|
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The most predominant RCCSS in the coronal section of mandibular left first premolars was oval (45%), followed by flattened (42%), circular (25%), and C-shaped (1%) canals. In the middle section, the circular (71%), oval (23%), and flattened (7%) canals were more common and in the apical section, the circular (96%), flattened (2%), and oval-shaped (2%) canals [Table 2] and [Figure 3].
|Figure 3: Cone beam computed tomography image of root canal cross-sectional shape of mandibular premolar. A: Apical section, M: Middle section, C: Coronal section|
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Mandibular second premolars
The most predominant RCCSS in the coronal section of mandibular right second premolars was oval (40%), followed by flattened (33%) and circular (27%) canals. In the middle section, the circular (77%), oval (18%), and flattened (5%) canals were more common. In the apical section, the circular (96%), flattened (2%), and oval-shaped (2%) canals were more common [Table 2].
The most predominant RCCSS in the coronal section of mandibular left second premolars was oval (39%), followed by flattened (35%), circular (25.5%), and eight-shaped canals (0.5%). In the middle section, the circular (77%), oval (18%), and flattened (5%) canals were more common. In the apical section, the circular (96%), flattened (2%), and oval-shaped (2%) canals were most frequently observed [Table 2].
The association between the maxillary and mandibular premolars and canals types was tested by Chi-square test, and it was found to be significant.
| Discussion|| |
The cross-sectional shape of the root canal system differs along the longitudinal axis, therefore making the cross-sectional dimension more intricate than the longitudinal dimension.
Root canal shapes were first described by Lautrou et al. They classified the root canals into a laminar type which comprised of semilunar canals, canals with “figure of an 8” shape or straight, whereas tubular canals were round, triangular, or oval-shaped., The cross-sectional shapes of the root canal were previously characterized using 2D radiographs. However, with the advent of CBCT, minute details of the canal shapes have been studied and reported. Cross-sectional shapes of root canals have been described as circular, oval/long oval, pyramidal, eight-shaped, flat/ribbon-shaped, and irregular, for example, C-shaped. These metaphors are mainly based on the minimum and maximum “working widths,” otherwise known as diameters. For an instance, a circular root canal cross-section has roughly equivalent maximum and minimum diameters, while the oval or long oval horizontal dimensions have the minimum diameter which is 2–4 times lesser than the maximum diameter.
In the present study, the RCCSS for maxillary and mandibular premolars were evaluated. Root canal cross-sectional shape of premolars in the Saudi population was for the first time evaluated in the present study. It was observed that, in the buccal canal of maxillary first premolars, coronal, middle, and apical thirds of the canals were circular in cross-section in the majority of the cases followed by flat and oval shape. The palatal canal also followed the same pattern. This finding corresponded to the findings of Bueno et al. who reported that the most common cross-sectional shape of the buccal canals of maxillary first premolars at the middle and apical section was circular, followed by flat and oval canals but in the coronal section the most common cross-sectional shape was eight shape followed by flat and circular shape. Eight-shaped canals were described by Lautrou et al. as canals that had circular buccal and palatal canals which were connected. Palatal root canals of maxillary first premolars followed the same pattern. The change in the cross-sectional shape of the canal was found to be more prevalent in the middle and apical sections as observed by Razumova et al. in a similar study conducted on the Russian population. Hu et al. conducted a study on the changes in the cross-sectional shapes of root canals of the maxillary first premolars in a Chinese population using CBCT in diverse age groups and reported that the cross-sectional shapes in most age groups were flat and oval.
In maxillary second premolars, variations in the right and left premolars were observed. In the right second premolars, it was found that the most common shape in the coronal section was flattened followed by circular and oval, whereas in left second premolars, the most prominent RCCSS was circular followed by flat and oval, but in the middle and apical section, the shape was predominantly circular followed by flat and oval. This finding differed from the findings of Wu et al., who reported that more than 50% of the maxillary second premolars in their study had a long oval shape in the apical section. This difference could be attributed to genetics and racial factors. The reports of Bueno et al. were similar to our results wherein the canals of maxillary second premolars had a flat form in the coronal section that changed to circular in apical section in the majority of the cases. In another study conducted by Arfianti et al., cross-sectional shapes in the apical third of maxillary second premolars were examined, and it was reported that the most common shape was oval RCCSS followed by flat and circular.
The findings of the present study coincided with the reports of the study conducted by Kacharaju et al. in the Malaysian population where the predominant canal shape in the coronal section was oval followed by irregular shapes and circular shapes. The same pattern was observed in the middle section, but in the apical section, most canal shapes were circular followed by irregular and oval.
The present study reveals that the most frequent change in RCCSS was among the mandibular premolars, in which the shape changed from oval in the coronal third to round in the apical third. Oval canals are complex and difficult to prepare during root canal treatment despite the ever-evolving endodontic instruments that are manufactured with precision and modification to suit the canals being prepared. According to a report by Wu et al., 65% of the oval canals in mandibular premolars remain unprepared with hand instruments. This observation can be explained by the fact that the taper of endodontic instruments must resemble the canal taper, for the reason that if the taper does not match, there will be incomplete preparation and the goal of the biomechanical preparation will not be attained. If the instrument taper is increased, there will excess removal of dentin and weakening of the root, and once this happens, the apical segment of the root cannot be filed or reamed adequately. To overcome this, new endodontic instruments such as XP-endo Shaper, TRU Shape, and Self-Adjusting Files have been used for the biomechanical preparation of oval canals. It was found that these instruments touched a larger part of the canal walls without unnecessary dentin removal, which is desired in endodontic treatment.,
Thus, within the limits of this study, it can be established that changeability of the RCCSS is an important aspect to comprehend for instrument selection and adequate biomechanical preparation of the canal so that a satisfactory prognosis of treatment can be achieved. Further research with more advanced software must be conducted to institute a better association between the root canal shapes and the designs of the endodontic files that are available in the market or that ought to be developed.
| Conclusion|| |
It can be concluded that the RCCSSs in premolars are inconstant according to tooth group and root thirds. The predominance of the circular-shaped canal in the apical section was seen in maxillary and mandibular premolars with oval shape predominating in the coronal section. Thus, dentists should examine the RCCSSs of premolars before making any clinical decision such as selecting endodontic files and performing root canal therapy. Such knowledge helps in achieving better cleaning of the dentinal walls, a better adaptation of the gutta-percha master cone, fewer endodontic errors, and a favorable prognosis.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]