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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 28  |  Issue : 2  |  Page : 148-153

Root and canal morphology of mandibular incisors and canines in South Asian Indian population by canal staining and tooth clearing technique


Department of Conservative Dentistry and Endodontics, Government Dental College and Hospital, Mumbai, Maharashtra, India

Date of Web Publication9-Dec-2016

Correspondence Address:
Shishir Singh
Terna Dental College, Sector 22, Nerul, Navi Mumbai - 400 706, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-7212.195435

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  Abstract 


Introduction: To study the root canal morphology of mandibular incisors and canines in South Asian Indians using a staining and tooth clearing technique.
Materials and Methods: One hundred each of mandibular central incisors, lateral incisors, and canine specimens were collected from various dental schools and clinics across India. Pulp tissue was removed and the root canals were stained with Indian ink. The specimens were subjected to decalcification in 10% nitric acid followed by dehydration in ascending concentrations of alcohol. Subsequently, specimens were cleared in methyl salicylate.
Results: All hundred mandibular central incisors were single rooted with a single canal. Ninety-six percent had a single and 4% had two apical foramina. While 84% had Type I, 8% had Type II, 4% had Type III, and 4% had Type IV Vertucci's root canal anatomy. No lateral canals were seen. All hundred mandibular lateral incisors were single rooted with a single canal. While 92% had a single foramen, 8% had two apical foramina. While 80% had Type I, 8% had Type II, 4% had Type III, and 8% had Type IV Vertucci root canal anatomy. Four percent of the lateral incisors showed the presence of lateral canals. All hundred mandibular canines studied were single rooted with a single canal, one apical foramen. Ninety-two percent had a Type I and 8% had a Vertucci Type II root canal anatomy with 12% of the specimen showing the presence of lateral canals.
Conclusion: Not much variation was seen in the root canal anatomies with Vertucci Type I anatomy predominating. Lateral canals were present in the mandibular lateral incisors and canines.

Keywords: Canines; lateral incisors; mandibular central incisors; root canal anatomy.


How to cite this article:
Singh S, Pawar M. Root and canal morphology of mandibular incisors and canines in South Asian Indian population by canal staining and tooth clearing technique. Endodontology 2016;28:148-53

How to cite this URL:
Singh S, Pawar M. Root and canal morphology of mandibular incisors and canines in South Asian Indian population by canal staining and tooth clearing technique. Endodontology [serial online] 2016 [cited 2019 Mar 26];28:148-53. Available from: http://www.endodontologyonweb.org/text.asp?2016/28/2/148/195435




  Introduction Top


The root canal anatomy of human teeth has always intrigued the dentist, not knowing what to expect once access preparation is done and orifice location begins. The number and varied morphology of the canals always poses a challenge to the operator during endodontic treatment sometimes resulting in a missed canal or an unfilled canal. These dead spaces are home to the microorganisms, which proliferate and spread causing an infection, resulting in a periapical infection.[1] If the operator is provided with a robust database on the occurrence and prevalence of various root canal anatomic variations in the respective teeth according to racial or genetic characteristics, it will help in a clear and proper understanding of the root canal anatomy and morphology. It is important to be familiar with good knowledge of canal numbers and divisions, which would in turn help, locate and negotiate them, and aid in their successful management. An accurate knowledge during canal preparation and obturation of the frequency of root canals uniting or bifurcating helps to provide a better quality of endodontic treatment.

Root canal anatomy pattern linked to various racial and genetic factors prompted researchers to study root canal pattern of teeth in the Caucasians, the Indians, the Burmese, the Japanese, the Chinese, and the Thais.[2],[3],[4],[5],[6],[7],[8],[9],[10],[11] This study aims to research the root canal anatomy of mandibular central incisors, lateral incisors, and canines of Indian teeth and look for any variation in this race and compare the same with other races. A proper understanding of the root canal anatomy in Indian teeth would eventually help the operator to perform and deliver a better quality of endodontic therapy.


  Materials and Methods Top


One hundred each of extracted mandibular central incisors, lateral incisors, and canines from indigenous South Asian Indians collected from different dental schools and dental clinics in India were washed under tap water for 30 min and immersed in 2.5% sodium hypochlorite (Mumbai Healthcare Industries, India) for 30 min to remove adherent soft tissue. Any remaining adherent soft tissue was physically scraped using a scalpel blade and an ultrasonic scaler (EMS, Piezon Systems, Switzerland) for 1 min to remove calculus or stains and stored in distilled water with thymol iodide crystals.

Access cavities were prepared using diamond points (Mani Inc., Japan) in an NSK air turbine handpiece (Nakashi Inc., Tochigi, Japan) with water irrigation following the standard norms. The operator removed all decay at this time and identified the canal orifices visually or with a DG 16 endo explorer (Hu Friedy Mfg. Co., Chicago, IL, USA) or #8 K file (Mani Inc., Tochigi, Japan) avoiding any damage/alteration of the root canal anatomy. All possible care was taken to prevent iatrogenic damage to the floor of the pulp chamber and canal orifices, thus maintaining the naturally existing root canal anatomy. A single operator carried out the steps to standardize the procedure.

The teeth were then immersed in 2.5% sodium hypochlorite (Mumbai Healthcare Industries, India) for 24 h to dissolve the organic debris and pulp tissue remnants from the root canal systems. At the end of the procedure, the glass bottles containing the teeth and sodium hypochlorite were placed in an ultrasonic bath containing water for 30 min. Subsequently, the teeth were rinsed under running tap water for 2 h and placed on tissue paper to allow overnight drying of specimens. Drying is critical to aid penetration of ink in the next stage.

A plastic disposable endodontic irrigating syringe with a 27-gauge needle was used to inject the nonwaterproof Indian ink (GLOBAL Chemie Laboratory Reagents and Fine Chemical, India) into the root canal systems. The needle inserted into each canal orifice, and the ink injected slowly until the pulp chamber floods. At the same time, a suction tip was placed at the root apex to draw the ink through the root canal system. The appearance of ink at the apical foramen indicated the end of the process. The teeth were dried overnight again for 12 h.

The teeth were then immersed in 10% nitric acid (Fisher Scientific, Qualigens Fine Chemicals, India) at room temperature to decalcify. Taking radiographs at daily intervals determined the end point of decalcification. The nitric acid solution was changed daily and frequently agitated as demineralization occurs at the top of the static acid than the bottom. Decalcification of the specimens was verified radiographically. At the end of decalcification, the teeth were washed in running tap water for 4 h. After removing excess water, the teeth were left to dry on tissue paper.

The teeth were dehydrated using ascending concentrations of methanol (Carbimol A.R. Himedia Laboratories, India) at 80%, 90%, and 100% consecutively for 1 day each. This meticulous process of dehydration permitted adequate penetration of the clearing agent. After dehydration, the teeth were dried on tissue paper for 2 h and then immersed in 2% methyl salicylate (Oil of Wintergreen, MERCK Specialities Pvt. Ltd., Mumbai, Maharashtra, India) to make them transparent.

The transparent specimens were examined by the naked eye, as well as a ×3 magnifying lens. Specimens were dipped in methyl salicylate solution and placed on a Petri plate. Illumination was provided by four halogen lights kept around the plate with the light focused toward the center. This arrangement improved the coefficient of refraction. The observations made are for the (i) number of roots and their morphology, (ii) the number of root canals in every tooth, (iii) root canal configuration in each root using Vertucci classification and additional modifications, and (iv) presence and location of lateral canals and intercanal communications. The data collected were compared statistically using the SPSS statistical software (SPSS Inc, Chicago, IL, USA). All the specimens photographed with a Nikon D 40 camera with a macro lens were kept for records [Figure 1].
Figure 1: Photographs of injected dye and cleared specimens; mandibular central incisors (a), lateral incisors (b), and canines (c)

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  Results Top


The results summary is in [Table 1]. Of the hundred mandibular central incisors studied, all the specimens were single rooted with single root shape. While 84% had a Vertucci Type I, 8% had a Type II, 4% had a Type III, and 4% specimens with Type IV canal anatomy. While 96% had a single apical foramen 4% had two apical foramina. None of the samples showed lateral canals.
Table 1: Percentage of canal system types in mandibular central incisors, lateral incisors, and canines

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Of the hundred mandibular lateral incisors studied, all the specimens were single rooted, single root canal, and shape. Eighty percent samples had a Vertucci Type I, 8% had a Type II, 4% had a Type III, and 8% with Type IV canal anatomy. While 92% teeth had a single apical foramen, the remaining 8% had two apical foramina. Four percent showed lateral canals.

Of the hundred mandibular canines studied, all the specimens were single rooted with one canal, one apical foramen, and a single root shape. Ninety-two percent samples had a Vertucci Type I canal anatomy, and the rest had 8% had Type II anatomy with 12% lateral canals seen having a distribution of 8% in the middle third and 4% in the apical third of the root.


  Discussion Top


Selection bias reduction was done by extracting mandibular anterior teeth of indigenous Indians attending dental hospitals in India. Of the three hundred mandibular anterior teeth, hundred were central incisors, hundred were lateral incisors, and hundred were canines.

A clearing technique as described by Okumura,[12] Robertson et al.,[13] and Robertson and Leeb [14] was adopted to study the root canal anatomy of these teeth. The advantages of the dye injection and clearing technique for studying the morphology and anatomy of root canals are many; from retaining the original form to maintaining the relationship between internal root surfaces and external contour of the tooth. The canal shape and the minute structures can be seen clearly. The failure rate in the preparation of specimens is rare, the specimen preservation for a long time, little equipment, and space is required, and the chemicals used are less toxic and inexpensive. Omer et al.[15] in their comparative study on the clearing technique and radiographic technique in the study of root canal anatomy felt that radiographs alone had a limited use when examining certain aspects of the root canal system. Some studies use cone beam computed tomography to study root canal anatomy in the clinical situation.[16],[17]

The techniques used in this study are similar to the techniques that have been followed by Gulabivala et al.,[2] Wasti et al.,[3] Gulabivala et al.,[5] Alavi et al.,[4] Al-Qudah and Awawdeh [6] Ahmed et al.,[8] Rwenyonyi et al.,[9] and Singh and Pawar [10],[11] in their research on the root canal morphology of human teeth. The clearing technique followed in this research resulted in very clear specimens, which allowed for proper visualization of the canal anatomy, and subsequently resulted in good photographs. Examining the samples with a magnifying glass under good lighting to study their root canal morphology was used to make the observations. The universally accepted Vertucci classification was used to examine the root canal anatomy.[18]

It is interesting to note that quite a few researchers as shown in [Table 2] have studied the mandibular central and lateral incisors anatomy separately or together.
Table 2: Percentage of mandibular central incisors, lateral incisors and canines, root canal numbers, and number of apical foramen in various studies

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Mandibular central incisors

Laws [19] studied the American teeth in vitro and showed 57% had a Type I anatomy and 43% had a Type II anatomy. Pineda and Kuttler [20] used the radiographic method, and it showed a different finding with 72.4% having a Type I anatomy, 2% having a Type II, 23.5% having a Type III, 1% having a Type IV, and 1.1% having a Type VI canal anatomy. Bellizzi and Hartwell [21] using an in vivo technique showed 83.1% Type I anatomy and 16.9% Type II root canal anatomy in mandibular central incisors. Vertucci [18] used the clearing technique wherein he found 70% Type I, 5% Type II, 22% Type III, and 3% Type IV anatomy with 20% lateral canals and 5% apical deltas. Kaffe et al.[22] studied the root canals of 400 Israeli mandibular central incisors and found 67.5% Type I and 32.5% Type II anatomy. Caliskan et al.[23] studied Turkish teeth using a clearing technique and found 68.63% Type I, 13.73% Type II, 13.73% Type III, 1.96% Type V anatomy, and 1.96% had a Type VIII canal anatomy with 31.78% lateral canals and 9.8% apical deltas. In the present study, it is interesting to note that the 84% of Indian mandibular central incisors have Vertucci Type I anatomy, with 8% Type II, 4% Type III, and another 4% Type IV anatomy with no lateral canals or apical deltas.

Mandibular lateral incisors

The initial studies done in the USA by Laws [19] studied 170 lateral incisors in vitro and found 54.7% Type I and 45.3% Type II. Pineda and Kuttler [20] studied 184 lateral incisors radiographically. They found 76.2% Type I, 3.2% Type II, 19.3% Type II, and 1.3% Type IV anatomy with a 28.5% prevalence of lateral canals and 2.1% apical deltas. Bellizzi and Hartwell [21] studied 163 lateral incisors in vivo. They reported 79.8% Type I and 20.2 Type II canal anatomy, while Vertucci [18] used the clearing technique to study one hundred lateral incisors and showed 75% Type I, 5% Type II, 18% Type II, and 2% Type IV anatomy with 30% lateral canals and 8% apical deltas. Kaffe et al.[22] studied the root canals of 400 Israeli mandibular lateral incisors radiographically and found 57.5% Type I and 42.5% Type II anatomy. Caliskan et al.[23] studied one hundred Turkish lateral incisor teeth using a clearing technique and found 68.63% Type I, 13.73% Type II, 15.69% Type III, and 1.96% Type V anatomy with 31.66% lateral canals and 23.53% apical deltas. In the present study, it is interesting to note that 80% of Indian mandibular central incisors have Vertucci Type I anatomy, 8% Type II, 4% Type III, and another 8% Type IV anatomy with 4% lateral canals seen.

Mandibular central and lateral incisors

Although quite a few studies done on the central and lateral incisors together reduce the specificity of the research, they are still worth a discussion. It was way back in 1965 that Rankine-Wilson and Henry [24] studied 111 American central and lateral incisors in vitro and found 59.5% Type I and 40.5% Type II canal anatomy. Green [25] examined a total of 500 central and lateral incisors using the grinding and dye tinting technique. He found 79% Type I and 21% Type II canal anatomy, while Benjamin and Dowson [26] the following year studied 364 central and lateral incisors in vitro and reported 58.6% Type I and 41.4% Type II canal anatomy. Kartal and Yanikoglu [27] used the clearing technique to study one hundred Turkish central and lateral incisors. They reported 55% Type I, 16% Type II, 20% Type II, 4% Type IV, 3% Type V, 1% Type VI, and 1% Type VII canal anatomy with 23% lateral canals and 8% apical deltas. Another study by Sert et al.[28] in a Turkish population came out with different results. Of the 200 central incisors, 32.5% Type I, 27.5% Type II, 27% Type III, 10% Type IV, 0.5% Type V, and 2% Type VIII and 6.5% lateral canals were seen. The 200 lateral incisors showed 37% Type I, 27% Type II, 26.5% Type III, 9.5% Type IV, and 13% lateral canals. Miyashita et al.[29] used the clearing technique to research 1085 Japanese central and lateral incisors and they found 87.6% Type I, 9.3% Type II, 1.4% Type III, and 1.7% Type IV with 5.9% lateral canals and 19.4% ramifications. Al-Qudah and Awawdeh [6] used the clearing technique to study 450 Jordanian central and lateral incisors and reported 73.8% Type I, 10.8% Type II, 6.7% Type III, 5.1% Type IV, and 3.6% Type V root canal anatomy with 6.2% lateral canals and 1.8% apical deltas.

Mandibular canines

Pineda and Kuttler researched 187 American mandibular canines radiographically and reported 81.5% Type I, 13.5% Type II, and 5% Type IV anatomy with 28.5% lateral canals and 2.1% apical deltas.[20] After that Green studied one hundred American mandibular canines using the grinding and dye tinting technique.[25] They found 87% Type I and 13% Type II canal anatomy. Bellizzi and Hartwell studied 195 mandibular canines in vivo reporting 95.9% Type I and 4.1% Type II canal anatomy.[21] After that Vertucci studied one hundred American mandibular canines using the clearing technique.[18] He reported 78% Type I, 14% Type II, 2% Type III, and 6% Type IV anatomy with 30% lateral canals and 8% apical deltas. Kaffe et al.[22] researched 400 Israeli mandibular canines radiographically and reported 86.25% Type I and 13.75% Type II anatomy. After that Caliskan et al.[23] cleared one hundred Turkish mandibular canines and found 80.39% Type I, 3.92% Type II,13.73% Type III, and 1.96% Type V canal anatomy with 33.33% lateral canals and 7.84% apical deltas. A similar study on 200 Turkish canines by Sert et al.[28] reported 76% Type I,16% Type II,6.5% Type II, and 1.5% Type IV with 14.5% lateral canals.

Surprisingly, the Indian samples studied showed very less prevalence of lateral canals as compared to the Western teeth which could be a racial characteristic. Future studies with a larger sample size would help to understand the prevalence of lateral canals and intracanal anastomoses in the mandibular incisors and canines.


  Conclusion Top


It is interesting to note that there are minor variations in the root canal anatomies of the mandibular central incisors, lateral incisors, and canines typical of Indian teeth as compared to other races. From the results of this study, it could be hypothesized that the mandibular canines of the South Asian Indians had a higher prevalence of lateral canals in comparison to the mandibular central and lateral incisors. Further research on interracial anatomical characteristics from different geographical locations would be beneficial for a comparative study.

Acknowledgment

The authors deny any conflict of interest. This original research work is a part of Ph.D. dissertation requirement of Maharashtra University of Health Sciences.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Vertucci FJ. Root canal morphology and its relationship to endodontic procedures. Endod Topics 2005;10:3-29.  Back to cited text no. 1
    
2.
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Wasti F, Shearer AC, Wilson NH. Root canal systems of the mandibular and maxillary first permanent molar teeth of South Asian Pakistanis. Int Endod J 2001;34:263-6.  Back to cited text no. 3
    
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Al-Qudah AA, Awawdeh LA. Root canal morphology of mandibular incisors in a Jordanian population. Int Endod J 2006;39:873-7.  Back to cited text no. 6
    
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Omer OE, Al Shalabi RM, Jennings M, Glennon J, Claffey NM. A comparison between clearing and radiographic techniques in the study of the root-canal anatomy of maxillary first and second molars. Int Endod J 2004;37:291-6.  Back to cited text no. 15
    
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20.
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Rankine-Wilson RW, Henry P. The bifurcated root canal in lower anterior teeth. J Am Dent Assoc 1965;70:1162-5.  Back to cited text no. 24
    
25.
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26.
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27.
Kartal N, Yanikoglu FC. Root canal morphology of mandibular incisors. J Endod 1992;18:562-4.  Back to cited text no. 27
    
28.
Sert S, Aslanalp V, Tanalp J. Investigation of the root canal configurations of mandibular permanent teeth in the Turkish population. Int Endod J 2004;37:494-9.  Back to cited text no. 28
    
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