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ORIGINAL ARTICLE
Year : 2019  |  Volume : 37  |  Issue : 2  |  Page : 120-126
 

An in vitro study of root canal system of human primary molars by using multidetector computed tomography


1 Departments of Pedodontics and Preventive Dentistry, Gurunanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India
2 Departments of Pedodontics and Oral Medicine and Radiology, Gurunanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India

Date of Web Publication26-Jun-2019

Correspondence Address:
Dr. Piyali Datta
157/F, Nilgunj Road, Panihati, Kolkata 700 114, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1319-2442.261339

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   Abstract 


Context: The primary tooth has numerous functions and is important in a child's development. Pediatric endodontic treatment has a very important role in maintaining oral health of the child. However, the morphology of root canals in deciduous teeth usually leads to complications in root canal therapy. To improve the success in endodontic, a thorough knowledge of the root canal morphology is essential. Aims: The aim of this study is to determine the thorough in vitro, morphological evaluation of root canal system of human primary molars using multidetector computed tomography. Settings and Design: A total of 64 human primary maxillary and mandibular molars without any macroscopic root resorption were selected and divided into four groups. The samples were arranged in wax block, and the scanning was done on the computed tomography scanne (GE light speed 16 slice CT). Subjects and Methods: The images were grabbed by the computer as a raw image and reformatted in a GE Advantage workstation version 4.2 (GE healthcare) with the help of Denta Scan (GE healthcare) software and volume rendering was done. Statistical Analysis Used: Descriptive statistical analysis (Student's t-test) was performed to calculate the means with corresponding standard deviations. A value of P ≤ 0.05 was taken to be statistically significant. Results: It enlightens the clinicians view to access the morphological variations of the root canals for the effective pediatric endodontic treatment. Conclusions: The images showed the complexity of the root canals of the primary mandibular molars and also the several capabilities of the CT scan in advance endodontic research in primary teeth were observed.


Keywords: Computed tomography, primary molars, root canal anatomy


How to cite this article:
Datta P, Zahir S, Kundu GK, Dutta K. An in vitro study of root canal system of human primary molars by using multidetector computed tomography. J Indian Soc Pedod Prev Dent 2019;37:120-6

How to cite this URL:
Datta P, Zahir S, Kundu GK, Dutta K. An in vitro study of root canal system of human primary molars by using multidetector computed tomography. J Indian Soc Pedod Prev Dent [serial online] 2019 [cited 2019 Nov 22];37:120-6. Available from: http://www.jisppd.com/text.asp?2019/37/2/120/261339





   Introduction Top


The knowledge of the structure of any parts of the human body from gross anatomy down to the molecular level is fundamental not only to understand the structure, function, and their alteration by the diseases but also to find the pathway for targeting therapy to a specific site.

Endodontic treatment of primary teeth is considered highly complicated as primary teeth exhibit bizarre internal geometry of the root and canal system. Familiarity with the complexity of root canal anatomy of human primary molars dictates the parameters that affect the probability of success of endodontic therapy.

Conventionally, different methodologies have been successfully used for decayed in the anatomical study of the root canal system, but most of them are invasive or only reflect a two-dimensional (2D) image of a 3D object, and therefore, may not reveal the morphology of the structure being studied accurately in clinical scenario. Thus, these inherent methodological limitations encouraged the search for new methods able to produce more accurate results.

Multidetector computed tomography (MDCT) scan technology has the ability to acquire the images in sub-millimeter slice thickness in a shorter duration of time which allows seeing images in different cross-sectional planes without any distortion and provides detailed images of various types of tissues.[1] Therefore, the aim of the study was to evaluate the root canal system of human primary molars using MDCT, and the specific objectives were to evaluate the number of roots, the number of the root canals in each root, and the length of the roots.


   Subjects and Methods Top


A total of 117 extracted human primary molars were collected from the Department of Oral and Maxillofacial Surgery and the Department of Anatomy. The collected samples were sterilized as per the guidelines of infection control and dental health care before handling.[2],[3] On the basis of inclusion criteria (human primary molar tooth with completely formed root apices, grossly carious tooth with or without pulpal involvement, tooth with fracture in the crown but not in the root, and tooth without any macroscopic root resorption) and exclusion criteria (teeth with any root fracture, grossly carious tooth with root resorption, and nonrestorable tooth), 64 number of teeth were selected for the study. The selected teeth were divided into four groups, i.e., primary maxillary first molars (Group 1), primary maxillary second molars (Group 2), primary mandibular first molars (Group 3), and primary mandibular second molars (Group 4). The samples were arranged in wax block, and the scanning was done on the CT scanner (GE light speed 16 slice CT). The images were grabbed by the computer as a raw image and reformatted in a GE Advantage workstation version 4.2 (General Electric healthcare, USA) with the help of Denta Scan (General Electric healthcare, USA)software and volumetric rendering was done.

The number of the roots and the canals of each tooth were determined in the cross section of the images [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]. The length of the roots was measured in consecutive axial image starting from apex up to the canal orifice. The raw images were saved and volume rendering was done in bone intensity.
Figure 1: Cross-sectional image of maxillary molar showing two roots three canals

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Figure 2: Cross-sectional image of mandibular molar showing three roots four canals

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Figure 3: Cross-sectional image of maxillary molar showing three roots three canals

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Figure 4: Cross-sectional image of maxillary molar showing three roots five canals

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Figure 5: Crosssectional image of mandibular molar showing two roots four canal

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Figure 6: Cross-sectional image of mandibular molar showing two roots three canals

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   Results Top


Number of the roots and the canals

Group-1, 68.75% of the teeth had three roots (the mesiobuccal [MB] root, distobuccal [DB] root, and palatal root) and three canals (MB, DB, and palatal canals). Only 25% of the teeth had two roots (MB root and fused DB and palatal roots) and three canals (MB, DB, and palatal canals) [Figure 1]. Furthermore, 6.25% of the tooth had three roots (MB root, DB root, and palatal root) and four canals (MB 1, MB 2, DB, and palatal canal) [Table 1].
Table 1: Number of the roots and the canals of primary maxillary molars

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In Group-2, 81.25% of the teeth had three roots (MB root, DB root, and palatal root) and three canals (MB, DB, and palatal canals) [Figure 3], 12.50% of the teeth had two roots (MB root and fused DB and palatal roots) and three canals (MB, DB, and palatal canals). In addition, 6.25% of the tooth had three roots (MB root, DB root, and palatal root) and five canals (MB 1, MB 2, DB 1, DB 2, and palatal canal) [Figure 4] and [Table 1].

In Group-3, 75% of the teeth had two roots (mesial root and distal root) and four canals (MB canal, DB canal, mesiolingual canal, and distolingual canal), 18.75% of the teeth had two roots (mesial root and distal root) and three canals (MB canal, mesiolingual canal, and distal canal), and 6.25% of the teeth had three roots (mesial root, distal root, and distolingual root) and four canals (MB canal, DB canal, mesiolingual canal, and distolingual canal) [Figure 2] and [Table 2].
Table 2: Number of the roots and the canals of primary mandibular molars

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In Group-4, 75% of the teeth had two roots (mesial root and distal root) and four canals (MB canal, DB canal, mesiolingual canal, and distolingual canal) [Figure 5], 12.50% of the teeth had two roots (mesial root and distal root) and three canals (MB canal, mesiolingual canal, and distal canal) [Figure 6], and 12.50% of the teeth had three roots (mesial root, distal root, and distolingual root) and four canals (MB canal, DB canal, mesiolingual canal, and distolingual canal) [Table 2].

Length of the roots

The mean lengths of MB root, DB root, and the palatal root of maxillary first molars (Group 1) are 7.80 ± 0.48 mm, 7.10 ± 0.64 mm, and 6.72 ± 0.38 mm, respectively [Table 3].
Table 3: The mean length of roots of primary maxillary first molars (Group 1) and maxillary second molars (Group 2)

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The mean lengths of MB root, DB root, and the palatal root of maxillary second molars (Group 2) are 8.50 ± 0.83 mm, 7.81 ± 0.71 mm, and 8.85 ± 0.98 mm, respectively [Table 3].

The mean lengths of mesial root of mandibular first molars (Group 3) and mandibular second molars (Group 4) are 9.45 ± 0.59 mm and 8.42 ± 0.40 mm, respectively [Table 4].
Table 4: The mean length of roots of primary mandibular first molars (Group 3) and mandibular second molars (Group 4)

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The mean lengths of distal root of mandibular first molars (Group 3) and mandibular second molars (Group 4) are 10.67 ± 0.73 mm and 9.83 ± 0.58 mm, respectively [Table 4].


   Discussion Top


Endodontic treatment of primary teeth involving cleaning, shaping, and obturation of the root canal system of primary teeth is considered highly complicated as because primary teeth exhibits bizarre internal geometry of the root and canal system. Quantitative and qualitative assessment of the root canal in all the possible dimensions is very essential for successful endodontic treatment.

2D imaging modalities have been used in dentistry since the first intraoral radiograph was obtained in 1896. Since then, significant advances have been made in maxillofacial imaging.

Tachibana and Matsumoto[4] studied the applicability of computerized tomography to endodontics and concluded that this method allows observation of the morphology of the root canal system in every direction along with the image could be analyzed, altered, and reconstructed by the computer.[5],[6]

MDCT scan technology has the ability to acquire the images in sub-millimeter slice thickness in shorter duration of time, without the loss of any image information. Benefits of MDCT are noninvasive, accurate, fast and simple, allow to see image of bone and soft tissue simultaneously, reveals detailed images of various types of tissue.

Number of root and root canals

Primary maxillary molars have been conventionally described as having three divergent and separated roots that flare to accommodate the developing permanent premolars. Overall, it may be inferred that the external and internal anatomy of the primary maxillary first molar roots closely resembles the primary maxillary second molar roots. Some variations in the number and shape of canal systems have also been described in the primary maxillary molars. Most studies have found only one root canal in each root of both molar types [Table 5].
Table 5: Tabulated review of number of roots and the canal system of human primary maxillary molars

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In the present study, double-canal system was observed only in the MB root of the maxillary first molars (Group 1), and 6.25% of the MB root and 6.25% of the DB root of the maxillary second molars (Group 2) which was also reported by Zoremchhingi et al.[7] and Bagherian et al., respectively.[8]

The studies (Zoremchhingi et al.;[7] Bagherian et al.,[8] and Hibbard and Ireland,[9]) found 100% of the study populations had two roots (mesial and distal roots) of the mandibular first molars. In this study, it was found that 93.75% of the samples had two roots in mandibular first molars. A study of 4050 Korean children by Song et al.[10] found an incidence of 9.7% for an additional root in the primary mandibular first molars, and Tu et al.[11] studied 121 Taiwanese children with an age range from 2.4 to 10.4 years and found that 5% of the children exhibited a three-rooted primary first molar. Some studies also (Gu et al.,[12] Winkler and Ahmad,[13] Falk and Bowers,[14] and Badger,[15]) found 3-rooted primary mandibular first molar [Table 6]. In this study, it was found that about 6.25% of the samples had three root and four canals in mandibular first molars.
Table 6: Tabulated review of literature of root canal system of human primary mandibular molars

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According to the study done by Zoremchhingi et al.,[7] Bagherian et al.,[8] Hibbard and Ireland,[9] and Liu et al.,[16] found two-rooted primary mandibular second molars in 93.8%, 95.5%, 86.7%, and 100% participants, respectively. In this study, it was found that 87.50% of the samples had two roots (one mesial and one distal) in primary mandibular second molars. A study of 4050 Korean children by Song et al.[10] found an incidence of 27.8% for an additional root in the primary mandibular second molars. According to the study done by Zoremchhingi et al.,[7] Bagherian et al.,[8] and Liu et al.,[16] three-rooted primary mandibular second molars were found in 6.2%, 4.5%, and 13.3% of the samples, respectively. In this study, it was found that 12.5% of the samples had three-rooted primary mandibular second molars.

Length of the root

Goodacre[17] has found that the mean lengths of the MB, DB, and palatal roots of the primary maxillary first molar were 8.8, 8.2, and 7.8 mm, respectively, and in the maxillary second molars, 10.8, 9.7, and 10.8 mm, respectively, which were higher than the present results. In the present study, among the three roots of primary maxillary first molars (Group 1), the MB root (7.80 ± 0.48 mm) showed the maximum length and the palatal root showed the minimum length (6.72 ± 0.38 mm), and in the maxillary second molars, palatal root showed the maximum length (8.85 ± 0.98 mm) and the DB root showed the minimum length (7.81 ± 0.71 mm).

According to Zoremchhingi et al.,[7] the length of the roots of the primary mandibular first molars, both mesial and distal roots showed somewhat the same length, i.e., 7.57 mm and 7.51 mm, respectively. In primary mandibular second molars, the distal root (9.24 mm) was longer than that of the mesial root (8.59 mm).

In this study, the length of the mesial root of both mandibular first and second molars showed the longer length (9.45 ± 0.59 mm and 10.67 ± 0.73 mm, respectively) than that of the distal roots.

There was a discrepancy between the length of the roots of the primary molars observed in this study and the length of roots given by other studies. The explanation for this may be that in this study, the area just below the coronal orifice was taken as a cervical line (or radiographic cervical line) and measurements were made from this line. Whereas other studies had taken the cementoenamel junction as a cervical line and used a Boley gauge to take the measurement. Furthermore, racial difference may be the reason as in this study samples were collected from an Indian population.


   Conclusions Top


This study highlights the anatomical configuration of root canals and its relationship with the roots of the human primary molars.

  1. The variations of number of root and canal are more in case of maxillary primary first molars as compared to that of primary second molar
  2. Although the probability of three roots and three canal systems are equal to mandibular primary first and second molar teeth, the variation of number of root and canals is more in case of primary mandibular second molar than that of primary first molar
  3. The length of all roots of maxillary and mandibular primary first molar tooth is lesser than that of the primary second molar
  4. The MDCT was found to be an effective diagnostic tool to study the root canal system of human primary molars and is capable to render comparable data as that of other modalities used for the similar study purposes.


There are wide ranges of variations reported in the literature regarding the anatomy of the root canal system of primary molars, in comparison to the present results, has been mostly related to the diversity in sample origin, racial factors, the relatively small number of teeth in each group, the presence of initial apical root resorption in some specimens and of course, to the methodological approach. It enlightens the clinicians view to access the morphological variations of the root canals for the effective pediatric endodontic treatment.

In future, further studies of the root canal system of human primary molars can be performed while give in emphasis on racial and geographic variations.

Acknowledgment

The authors hereby acknowledge Eko X-ray and Imaging Institute, Kolkata, India, and the Department of Anatomy of Guru Nanak Institute of Dental Science and Research, Kolkata, India for their continuous efforts without which this research could never be completed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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Winkler MP, Ahmad R. Multirooted anomalies in the primary dentition of native Americans. J Am Dent Assoc 1997;128:1009-11.  Back to cited text no. 13
    
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Falk WV, Bowers DF. Bilateral three-rooted mandibular first primary molars: Report of case. ASDC J Dent Child 1983;50:136-7.  Back to cited text no. 14
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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