|Year : 2013 | Volume
| Issue : 4 | Page : 254-259
A study of root canal morphology of human primary incisors and molars using cone beam computerized tomography: An in vitro study
Vivek Gaurav, Nikhil Srivastava, Vivek Rana, Vivek Kumar Adlakha
Department of Paedodontics and Preventive Dentistry, Subharti Dental College and Hospital, Meerut, Uttar Pradesh, India
|Date of Web Publication||21-Nov-2013|
Department of Paedodontics and Preventive Dentistry, Subharti Dental College and Hospital, Subhartipuram, NH-58, Delhi-Haridwar Bypass Road, Meerut - 250 002, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Variations in morphology of root canals in primary teeth usually leads to complications during and after endodontic therapy. To improve the success in endodontics, a thorough knowledge of the root canal morphology is essential. Aim: The aim of this study was to assess the variation in number and morphology of the root canals of primary incisors and molars and to study the applicability of cone beam computerized tomography (CBCT) in assessing the same. Settings and Design: A total of 60 primary molars and incisors with full root length were collected and various parameters such as the number of roots, number of canals, diameter of root canal at cementoenamel junction and middle-third, length and angulations of roots of primary molars and incisors were studied using CBCT. Statistical analysis used: The observations were put to descriptive statistics to find out the frequency, mean, standard deviation and range for all four subgroups. Further, unpaired t-test was used to compare these parameters between subgroups and analysis of variance test was implemented to evaluate the parameters within the subgroups. Results and Conclusion: The CBCT showed the presence of bifurcation of root canal at middle third in 13% of mandibular incisors while 20% of mandibular molars had two canals in distal root. The diameter of distobuccal root canal of maxillary molars and mesiolingual canal of mandibular molars was found to be minimum. CBCT is a relatively new and effective technology, which provides an auxiliary imaging modality to supplement conventional radiography for assessing the variation in root canal morphology of primary teeth.
Keywords: Cone beam computerized tomography, primary teeth, root canal morphology
|How to cite this article:|
Gaurav 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 Indian Soc Pedod Prev Dent 2013;31:254-9
|How to cite this URL:|
Gaurav 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 Indian Soc Pedod Prev Dent [serial online] 2013 [cited 2019 Dec 7];31:254-9. Available from: http://www.jisppd.com/text.asp?2013/31/4/254/121827
| Introduction|| |
Endodontic treatment requires knowledge of root canal morphology and its commonly occurring variation. Gender, racial origin and geographic location are some of the factors causing variation in root canal anatomy. 
Endodontic treatment involves cleaning, shaping and obturation of the root canal system. To improve success in endodontics, a thorough understanding of the complexity of the root canal system is essential for understanding the principles and problems of shaping and cleaning, for determining the apical limits and dimensions of canal preparations and for performing successful surgical procedures. 
Root canal anatomy is studied by radiography, clearing technique using methyl salicylate, direct observation under microscope, three-dimensional (3D) reconstruction and macroscopic sections.  Nattress and Martin in 1991 reported that conventional radiography has problems of superimposition, magnification and moreover a two dimensional (2D) representation of 3D object. The difficulties encountered with other methods of study include disturbance of pulp space and its surrounding structures during preparation of the teeth. 
Several studies have been conducted on permanent teeth to investigate the anatomy of root canals, viz. direct observation with the aid of a microscope;  macroscopic sections;  filling of canals with inert material and then decalcification;  filling of canals and clearing.  However, all these methods had serious limitations as most of the relationship of the external structure to the pulp was lost during preparation of samples.
These shortcomings have led to the development of 3D techniques. The advent of (3D) imaging has provided the clinician with increased insight into tooth morphology and facilitated interactive image manipulation and enhancement to visualize the area of interest as a 3D volume. 
The advancements in the field of radiology have drawn upon the use of computed tomography (CT) for imaging teeth. CT has been expanding rapidly and cone beam computerized tomography (CBCT) is the latest system which has been introduced in dentistry since 1991 for imaging hard tissues of the maxillofacial region.
The advantages of CBCT are numerous. Firstly, CBCT is an office-based imaging technique so can be conveniently performed when required; secondly, CBCT acquires volumetric data in a single rotation with a short scan time; thirdly, CBCT produces quality images with higher spatial resolution than multi-slice CT and last but not least, CBCT poses fewer hazards to patients because of the reduced radiation dose required. 
CBCT utility and relevance to the practice of endodontics is reported with increasing frequency in the field of endodontics. Therefore, the present study was undertaken to assess the variation in number and morphology of the root canals of primary incisors and molars and to study the applicability of CBCT in assessing the root canal morphology of the primary incisors and molars.
| Materials and Methodology|| |
Nearly, 2000 primary teeth were collected from private clinics and dental institutions of the nearby area. Out of the sample procured, 60 molars and incisors teeth with full root length without any evidence of root fracture were used in the study. These samples were then divided into two main groups Group A and Group B, which was further divided into subgroups.
Group A: Primary incisors - 30
- Subgroup A 1 - 15 maxillary incisors
- Subgroup A 2 - 15 mandibular incisors
Group B: Primary molars - 30
- Subgroup B 1 - 15 maxillary molars
- Subgroup B 2 - 15 mandibular molars.
The teeth were cleaned with soap and washed in running water. Hand scalers were used to remove calculus if present on the root surface and stored in individual glass container containing 10% formalin solution. The teeth were mounted in a straight line on modeling wax after determining the various aspects of the tooth, i.e., buccal, lingual, mesial and distal, so as to maintain uniformity in the samples [Figure 1].
The mounted teeth were then scanned using CBCT scanner and ported to the vision preview screen for 2D and 3D reconstruction images utilizing i-CAT Imaging Sciences International, Hatfield, Pennsylvania, USA, Hatfieldsoftware in three planes, i.e., sagittal, axial and coronal.
Once the sample data was acquired or data for a sample was loaded the software immediately reconstructs the tooth images in sagittal, axial and coronal planes.
The length and the angulation of each root were measured by taking the maximum length from the apex of the tooth to the greatest area of constriction as a cementoenamel junction (CEJ) [Figure 2] and [Figure 3].
|Figure 2: Cone beam computerized tomography image showing the measurement for length of the root in primary incisors|
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|Figure 3: Cone beam computerized tomography image showing the measurement for angulation of root in primary incisors|
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The diameter of each root canal was measured at the greatest diameter from the cross section of the roots irrespective of the various aspects of the canal [Figure 4].
|Figure 4: Cone beam computerized tomography image showing the measurement for diameter of root canals in primary molars|
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The readings obtained during the scanning procedure were put to statistical analysis. Descriptive statistics was used to find out the frequency, mean, standard deviation and range for all the five parameters:
- Number of roots;
- Angulation of the roots;
- Number of the root canals;
- Diameter of the root canals;
- Length of the roots.
Further, unpaired t-test was used to compare above parameters between subgroups A 1 and A 2 and analysis of variance test was implemented to evaluate the parameters within subgroups B 1 and B 2. After statistical analysis, the power of the article was found to be 80% suggesting the validity of the paper.
| Results|| |
The observations made during the course of study are depicted in [Table 1], [Table 2], [Table 3], [Table 4], [Table 5].
In 87% of mandibular incisors, single canal was seen while in the remaining 13% samples, a single canal with bifurcation in the middle-third was found. Furthermore, mesial root of all the mandibular molars had two canals (100%) while distal roots had one canal (80%) and three samples of mandibular molars had two canals (20.0%) [Table 1].
On comparing the mean root length of incisors it was found that the mean root of mandibular incisors was more compared with that of maxillary incisors. But in molars, the mean root length was compared within subgroups and it was observed that palatal root of the maxillary molar was longest while distobuccal root was shortest and in mandibular molars, the mesial root was longer than distal root [Table 2].
On comparing the mean angulation of root of incisors it was found that the angulation of root of mandibular incisors was less when compared with maxillary incisors. In mandibular molars, the mean angulation of mesial root was more compared to distal root, but in maxillary molars the comparison was found to be statistically non-significant [Table 3].
The comparison of mean canal diameter of incisors at CEJ showed that the diameter of the canal was more in maxillary incisors compared with mandibular incisors. In maxillary molars, the maximum diameter in each third of the root was seen in palatal canal, but in mandibular molars it was seen in distal canal [Table 4].
The canal diameter of maxillary incisors at middle-third was more compared with mandibular incisors. In maxillary molars, the palatal canal showed the widest root canal diameter where as in mandibular molars the distal canal showed the widest diameter [Table 5].
| Discussion|| |
A thorough knowledge of anatomy of the tooth is essential before beginning the endodontic treatment. It is generally accepted that the major cause of failure of root canal treatment is an inability to recognize and therefore adequately treat all of the canals of the root canal system. ,,
The number of canals was one, but in case of mandibular incisors, single canal was seen in 87% while in the remaining 13%, a single canal with bifurcation in middle-third was seen. It correlates to Type III canal configuration of permanent teeth by Vertucci,  but these findings are in contrast to the finding reported by Zurcher,  which showed the presence of two canals in less than 10% of cases. In primary mandibular molars, the mesial root of all the 100% samples had two canals, i.e., mesiobuccal and mesiolingual and the distal root showed the presence of two canals in 20% of the samples and presence of one canal in the remaining 80% samples. The findings are in accordance to the findings of Hibbard and Ireland;  Zoremchhingi et al.  and Aminabadi et al.  who found more than one canal in 25%, 40% and 20% of distal root, respectively but in Subgroup B 1 number of canals seen in each of mesiobuccal, distobuccal and palatal roots were one. Another study conducted by Yang et al.  in 2012 concluded that detailed knowledge of roots and root canal morphology is important in order to improve the success in the endodontics of the primary teeth. The author also reported that the majority of primary mandibular second molar had three to four canals similar results were seen in the present study.
Mean root length of maxillary incisors was found to be 8.14 mm with the maximum and minimum root length was 9.60 and 6.40 mm, respectively, these findings are in contrast to Black  (10.00 mm). In mandibular incisors, the mean root length was 9.52 mm, but the root length reported by Black was less compared to the present study. In maxillary molars, the palatal root was found to be longest compared to mesiobuccal and distobuccal, which was in accordance with Zoremchhingi et al.  In this present study, there was a discrepancy between the length of mesial root of mandibular molar and the length of root given by Zoremchhingi et al. (7.57 mm) and Black. The difference in the results of the present study and the study conducted by Black can be attributed to the fact that in this study samples were limited to only Indian population, whereas the samples for Black study were selected from US population and the radiographs were taken to study the morphology of primary teeth.
The present study ascertained that the angulation of root of mandibular incisors (91.41°) was more as compared to that of maxillary incisors (90.05°). On comparing the mean angulation of root of maxillary incisor and mandibular incisor, no significant difference was found. In maxillary molars the distobuccal root had the maximum angulation of 98.10° with a mean of 83.80° and minimum angulation was seen in case of mesiobuccal root of 67.00° with a mean of 81.02°. However, these observations are a contrast to what Zoremchhingi et al. reported, but in subgroup B 2 the findings are favoured by the observations reported by Zoremchhingi et al. 
The diameter of canals was measured at the CEJ and at the middle third. In incisors , the diameter of canals was more at the CEJ area compared with the middle-third, which depicts the tapering of the canal from CEJ to the middle-third. Comparison of mean canal diameter of maxillary incisors and mandibular incisors showed that the diameter of the canal was more in maxillary incisors both at CEJ and middle-third. In maxillary molars, the palatal canal showed the maximum diameter, which was found in accordance with the studies conducted by Zoremchhingi et al.  and Aminabadi et al.  whereas the findings of subgroup B 2 , showed maximum diameter of the canal at CEJ in distal root. From this study, the following conclusions were drawn:
- More gradual tapering of the root canals was found in maxillary incisors compared to mandibular incisors.
- The roots of mandibular incisors were found to have more angulation as compared to maxillary incisors.
- Mandibular incisors showed bifurcation of the root canal at the middle-third in only 13% of the cases.
- Distobuccal root canal of the maxillary molar was found to be thinnest whereas in case of mandibular molar, the mesiolingual canal was found to be thinnest.
- As far as length of the roots was concerned, palatal root of the maxillary molar was found to be longest while distobuccal root was shortest. In mandibular molars, the mesial root was longer than distal root.
- The distal root of mandibular molars had two canals, i.e., distobuccal and distolingual in 20% of the cases.
- The mesial root of primary mandibular molars was found to be more divergent than distal root while distobuccal root of primary maxillary molar showed more divergence than other two roots.
- CBCT was found to be an effective and accurate diagnostic tool to study the root canal diameter, angulation and root canal morphology of primary teeth.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]