Indian Journal of Dental Research

ORIGINAL ARTICLE
Year
: 2022  |  Volume : 33  |  Issue : 1  |  Page : 14--17

Root canal morphology of primary molars – A cone beam computed tomography (CBCT) study


Jatinder K Dhillon1, Sujoy Ghosh2, Vijay P Mathur3,  
1 Department of Pediatric Dentistry, College of Dental Medicine, Nova Southeastern University, Florida, USA
2 Department of Oral Medicine and Radiology, Maulana Azad Institute of Dental Sciences, New Delhi, India
3 Division of Pedodontics and Preventive Dentistry, Centre for Dental Education and Research (CDER), All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Dr. Jatinder K Dhillon
Department of Pediatric Dentistry, College of Dental Medicine, Nova Southeastern University, Florida
USA

Abstract

Objectives: To evaluate the root and canal morphology of primary maxillary and mandibular molars in an Indian population using cone-beam computed tomography (CBCT). Methods: A retrospective cross-sectional study was performed, where CBCT scans of children less than 10 years of age taken for valid diagnostic purposes previously were considered and images were analyzed. The number of roots, root canals, and variations in morphology were recorded. Left–right symmetry was also noted. Results: A total of 433 deciduous maxillary and mandibular primary molars were studied. It was observed that two separate roots with three separate canals were common in primary mandibular first molars, whereas two separate roots with two canals in each root were common in mandibular second primary molars. In primary maxillary molars, three separate roots with one canal each were the most common. Maxillary first molars (17.21%) and 17.35% second molars had fused distobuccal and palatal roots. It was observed that primary maxillary molars showed more left–right symmetry (86.7% in first molars and 82.7% in second molars) compared to primary mandibular molars (54.05% in first molars and 68% in second molars). Conclusions: It was concluded that in both primary maxillary first and second molars, three separate roots, a mesiobuccal root, a distobuccal root, and a palatal root with one canal in each root, were the most common. Two separate roots with three separate canals were the most common in primary mandibular first molars, whereas two separate roots with two canals each in both roots were more common in mandibular second primary molars.



How to cite this article:
Dhillon JK, Ghosh S, Mathur VP. Root canal morphology of primary molars – A cone beam computed tomography (CBCT) study.Indian J Dent Res 2022;33:14-17


How to cite this URL:
Dhillon JK, Ghosh S, Mathur VP. Root canal morphology of primary molars – A cone beam computed tomography (CBCT) study. Indian J Dent Res [serial online] 2022 [cited 2022 Nov 27 ];33:14-17
Available from: https://www.ijdr.in/text.asp?2022/33/1/14/353543


Full Text



 Introduction



Primary teeth often show bizarre root canal anatomy,[1] and exception is often the norm. This necessitates that the clinician acquires a thorough knowledge of the root canal anatomy and morphology. The various methods of studying the root canal morphology include radiographic methods,[2],[3] clearing techniques,[4],[5] direct observation with a microscope,[6] 3D re-construction,[7] macroscopic sections,[8] and computed tomography.[9]

Recently, cone-beam computed tomography (CBCT) has gained traction as a diagnostic tool in endodontic procedures because of its accuracy in determining the root and canal morphology in permanent teeth. The scanning times are shorter with CBCT, and the radiation dosage is 15–100 times less than that in conventional CT. CBCT has isotropic voxels which are equal in all three dimensions, which helps in achieving a sub-millimetre resolution.[10] Moreover, the image could be analysed, altered, and re-constructed by the computer, and it is non-invasive. However, few studies have been performed using CBCT to study the primary teeth morphology. Thus, this study was undertaken to evaluate the root and canal morphology of primary maxillary and mandibular molars in an Indian population using CBCT.

 Methodology



The study was a retrospective cross-sectional study, where CBCT scans of children less than 10 years of age taken for valid diagnostic purposes previously were considered and images were analysed. The collection of data was approved by the institutional ethics committee via a letter dated 25/02/2011; Ref. No.IEC/NP-23/2011. CBCT images taken using a single machine [iCAT machine (Imaging Sciences International, Hatfield, PA)] were used to ensure uniformity. The scans were viewed and analysed using i-CAT Vision software (version 1.9.3.14) with a scan time of 22 seconds and a re-construction time of 2–3 minutes (FOV- 13/16, resolution 0.250 Voxels in three axes, horizontal and vertical sections - 0.25 mm). Teeth with root resorption, peri-apical lesions, and/or root canal treatment were excluded to ensure the integrity of the original morphology. The number of roots, the number of canals, and variations in morphology were recorded by two examiners. Left–right symmetry was also noted when both the left and right counterparts of a tooth were present in the respective arch. The experimental data are represented as categorical variables.

 Results



A total of 433 deciduous molars were studied, which included both 220 maxillary primary molars (99 first and 121 second molars) and 213 mandibular primary molars (95 first and 118 second molars). The root canal morphology of primary mandibular molars was categorized into seven main variants [Table 1], [Figure 1]a as given by Yang R et al. (2013).[11] Another variant (variant eight) was seen, in which deciduous molars had two roots with one mesial canal and two separate distal canals. However, a taurodont was observed in a primary mandibular first molar and C- shaped canal and was observed in two primary mandibular second molars. The morphology of mandibular primary molars as observed in the present study is depicted in [Figure 1]a. The root canal morphology of primary maxillary molars was also categorised into nine main variants [Table 1], [Figure 1]b. The distribution of variants in primary maxillary molars is shown in [Table 2], and the distribution of variants in mandibular primary first and second molars is shown in [Table 3]. It was observed that two separate roots with three separate canals (variant 2) were the most common in primary mandibular first molars, whereas two separate roots with two canals in the mesial root and two canals in the distal root (variant 3) were more common in mandibular second primary molars. In both primary maxillary first and second molars, three separate roots with one canal in each root (variant 1) were the most common. Maxillary first molars (17.21%) and 17.35% second molars had fused distobuccal and palatal roots. Primary maxillary molars showed more left–right symmetry (86.7% in first molars and 82.7% in second molars) as compared to mandibular molars (54.05% in first molars and 68% in second molars) [Table 4]. The inter-examiner reliability (Kappa) was found to be 0.87, which indicates a high level of agreement between the different examiners.{Table 1}{Figure 1}{Table 2}{Table 3}{Table 4}

 Discussion



In the present study, we used CBCT to evaluate the numbers of roots and canals in 433 primary molars. Canal staining and tooth clearing are generally considered the gold standard for studying the root canal morphology. The drawbacks of this method include disturbance of the pulp space and its surrounding structures during preparation of the teeth, difficulty in collecting a large number of extracted teeth, infection control, storage of teeth, extensive laboratory set-up, time spent, and inability to use in vivo.[12] The most commonly used method in vivo is conventional radiography. However, this technique has the drawbacks of super-imposition of roots and root canals. Moreover, it is a 2D representation of a 3D object. Studies involving contrast radiography have shown that it results in the entrapment of air bubbles, hampering proper visualisation.

Several studies using CBCT have been performed for studying the root and canal morphology of permanent teeth. It is non-invasive and can provide an accurate 3D image in vivo of the dentomaxillofacial region. CBCT scanning is as accurate as canal staining and clearing techniques in identifying root canal anatomy. Studies have also shown that CBCT is more accurate and reliable than peri-apical radiographs for tooth-length and root-length determination because there is no distortion.[13] The volumetric data can also be re-constructed to produce a view that is perceived as true 3D. All teeth can be visualised in a single scan, thus obviating the need for several exposures for multiple 2D images.[14] Thus, CBCT was used in the present study to study the morphology of primary molars.

Zoremchhingi et al. (2005) observed that 53.3% maxillary first molars had fused distobuccal and palatal roots and 46.7% had three roots using CT. All the primary maxillary second molars had three roots. It was observed that 93.33% maxillary first molars had three canals and 6.67% had four canals. It was observed that 53.3% maxillary second molars had two mesial canals, 26.6% had two distal canals, and 40% had two palatal canals.[9],[10]

In the present study, however, 17.31% primary maxillary first molars had fused distobuccal and palatal roots and 78.81% had three roots. It was observed that 83.9% primary maxillary first molars had three canals and 12.11% had four canals. This is similar to the study conducted by Ozcan G et al. (2016),[15] who observed that maxillary molars often had a single canal in each root. In another study by Katge F and Wakpanjar M (2018),[16] all maxillary molars had three roots with one canal each and mesial roots of mandibular first (80%) and mandibular second (100%) molars showed two canals, which is similar to our study.

Aminabadi et al. (2008)[17] observed that 29.1% (n = 10) primary second molars had four canals, namely, a mesiobuccal canal, a distobuccal canal, a palatal canal, and a separate distal canal. In the present study, 21.48% primary maxillary second molars had four canals.

Bagherian et al. (2010)[18] observed that 7.4% primary first molars had an MB2 canal and 3.7% had two canals in the DB root, whereas all the second primary molars had three canals. Gaurav V et al. (2013)[19] used CBCT to study the root canal morphology in primary molars and reported that all molars (n = 15) in their study had three canals. In the present study, 12.11% primary maxillary first molars and 22.31% second molars had an MB2 canal.

In the study by Yang R et al. (2013),[11],[12] the majority of primary mandibular second molars had two (72.28%) roots. The symmetrical incidence of three-root primary mandibular second molars was 50.65%. Three canals were seen in 25.26% of primary mandibular second molars, and four canals were seen in 73.31%.

In the present study, it was observed that 90.67% primary mandibular second molars had two roots and 40.68% had three canals and 55.08% had four canals. Sim D and Mah Y (2019)[20] observed that the canal morphology was more symmetric in primary mandibular molars than in maxillary molars, whereas in our study, symmetry was observed more in maxillary molars, and this could be because of different populations studied. This can help clinicians predict the root canal morphology on the opposite side if endodontic treatment is needed in molars on both sides.

 Conclusion



It was concluded that in both primary maxillary first and second molars, three separate roots with one canal in each root were the most common type of morphology seen. Two separate roots with three separate canals were the most common morphologic type seen in primary mandibular first molars, whereas two separate roots with two canals in each root were more common in mandibular second primary molars.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Kurthukoti AJ, Sharma P, Swamy DF, Shashidara R, Swamy EB. Computed tomographic morphometry of the internal anatomy of mandibular second primary molars. Int J Clin Pediatr Dent 2015;8:202-7.
2Pineda F, Kuttler Y. Mesiodistal and buccolingual roentgenographic investigation of 7,275 root canals. Oral Surg Oral Med Oral Pathol 1972;33:101-10.
3Weine FS, Hayami S, Hata G, Toda T. Canal configuration of the mesiobuccal root of the maxillary first molar of a Japanese sub-population. Int Endod J 1999;32:79-87.
4Singh S, Pawar M. Root canal morphology of South asian Indian mandibular premolar teeth. J Endod 2014;40:1338-41.
5Vertucci FJ. Root canal morphology of mandibular premolars. J Am Dent Assoc 1978;97:47-50.
6Sempira HN, Hartwell GR. Frequency of second mesiobuccal canals in maxillary molars as determined by use of an operating microscope: A clinical study. J Endod 2000;26:673-4.
7Mikrogeorgis G, Lyroudia KL, Nikopoulos N, Pitas I, Molyvdas I, Lambrianidis TH. 3D computer-aided reconstruction of six teeth with morphological abnormalities. Int Endod J 1999;32:88-93.
8Baisden MK, Kulild JC, Weller RN. Root canal configuration of the mandibular first premolar. J Endod 1992;18:505-8.
9Zoremchhingi, Joseph T, Varma B, Mungara J. A study of root canal morphology of human primary molars using computerised tomography: An in vitro study. J Indian Soc Pedod Prev Dent 2005;23:7-12.
10John GP, Joy TE, Mathew J, Kumar VR. Fundamentals of cone beam computed tomography for a prosthodontist. J Indian Prosthodont Soc 2015;15:8-13.
11Yang R, Yang C, Liu Y, Hu Y, Zou J. Evaluate root and canal morphology of primary mandibular second molars in Chinese individuals by using cone-beam computed tomography. J Formosan Med Assoc 2013;112:390-5.
12Neelakantan P, Subbarao C, Subbarao CV. Comparative evaluation of modified canal staining and clearing technique, cone-beam computed tomography, peripheral quantitative computed tomography, spiral computed tomography, and plain and contrast medium–enhanced digital radiography in studying root canal morphology. J Endod 2010;36:1547-51.
13Sherrard JF, Rossouw EP, Benson BW, Carrillo R, Buschang PH. Accuracy and reliability of tooth and root lengths measured on cone-beam computed tomographs. Am J Orthod Dentofacial Orthop 2010;137:S100-8.
14Scarfe WC, Levin MD, Gane D, Farman AG. Use of cone beam computed tomography in endodontics. Int J Dent 2009;1-20.
15Ozcan G, Sekerci AE, Cantekin K, Aydinbelge M, Dogan S. Evaluation of root canal morphology of human primary molars by using CBCT and comprehensive review of the literature. Acta Odontol Scand 2016;74:250-8.
16Katge F, Wakpanjar MM. Root canal morphology of primary molars by clearing technique: An in vitro study. J Indian Soc Pedod Prev Dent 2018;36:151-7.
17Aminabadi NA, Farahani RMZ, Gajan EB. Study of root canal accessibility in human primary molars. J Oral Sci 2008;50:69-74.
18Bagherian A, Kalhori KAM, Sadeghi M, Mirhosseini F, Parisay I. An in vitro study of root and canal morphology of human deciduous molars in an Iranian population. J Oral Sci 2010;52:397-403.
19Gaurav V, Srivastava N, Rana V, Adlakha VK. A study of root canal morphology of human primary incisors and molars using cone beam computerized tomography: An in vitro study. J Ind Soc Pedod Prev Dent 2013;31:254-9.
20Sim D, Mah Y. A study of root canals morphology in primary molars using computerized tomography. J Korean Acad Pediatr Dent 2019;46:400-8.