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ORIGINAL ARTICLE
Year : 2017  |  Volume : 7  |  Issue : 2  |  Page : 77-81

Root canal morphology of mandibular first premolars in Saudi Arabian southern region subpopulation


Department of Restorative Dental Sciences, Endodontic Division, College of Dentistry, Jazan University, Jazan, KSA

Date of Web Publication25-Apr-2017

Correspondence Address:
Hemant Ramesh Chourasia
Department of Restorative Dental Sciences, Endodontic Division, College of Dentistry, Jazan University, P.O Box 114, Jazan
KSA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1658-5984.205130

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  Abstract 

Introduction: The aim of this study was to investigate the root canal morphology of Saudi Arabian mandibular first premolars by tooth clearing technique.
Materials and Methods: One-hundred mandibular first premolars were collected from different dental schools and primary health care centers of the southern region of Saudi Arabia. Access cavities were prepared, the pulp tissue was dissolved, and teeth were subjected to clearing technique protocol. The transparent teeth were examined under dental microscope and following features were analyzed: number of roots, number of root canals, number of apical foramina, root canal configuration (Vertucci's classification), number of lateral canals, and intercanal communications.
Results: Of the 100 mandibular first premolars, 80% had a single root, 18% had two roots, whereas 2% were three rooted. Seventy-two percent had a single canal, 26% had two canals, and 2% teeth had three canals. Seventy-three percent had a single apical foramen, 19% had two foramens, 2% had three apical foramens, and 6% had multiple apical foramina (apical delta). Sixty-nine percent had Type I, 8% had Type III, 4% had Type IV, 16% had Type V, 2% had Type IX, and 1% had an additional root canal configuration. Lateral canals were found in 38% and intercanal communications in 16% teeth.
Conclusions: Although the majority of the study samples had a single root and one root canal, two roots were found in 18% and two canals in 26%. Such morphological variations should be taken into consideration to ensure successful root canal treatment of these teeth.

Keywords: Apical foramina, clearing technique, mandibular first premolars, root canals, Vertucci's classification


How to cite this article:
Chourasia HR, Boreak N, Tarrosh MY, Mashyakhy M. Root canal morphology of mandibular first premolars in Saudi Arabian southern region subpopulation. Saudi Endod J 2017;7:77-81

How to cite this URL:
Chourasia HR, Boreak N, Tarrosh MY, Mashyakhy M. Root canal morphology of mandibular first premolars in Saudi Arabian southern region subpopulation. Saudi Endod J [serial online] 2017 [cited 2017 Oct 23];7:77-81. Available from: http://www.saudiendodj.com/text.asp?2017/7/2/77/205130


  Introduction Top


The main objective of root canal therapy is thorough shaping and cleaning of all pulp spaces and its complete obturation with an inert filling material. The root canal system is complex and canals may branch, divide, and rejoin.[1] One of the main reasons for the failure of root canal treatment is the inadequate removal of pulp tissue and microorganisms from the root canal system. It is therefore of utmost importance that the clinician must have a thorough knowledge of root canal morphology of the tooth and its possible variations to achieve a high level of success. The mandibular first premolar is a good example of complex anatomy. It may have extra root, not obvious in preoperative radiograph or fine ribbon-shaped canal system, challenging for shaping, cleaning, and obturation.[2] The study at the University of Washington reported higher failure rate of 11.4% for nonsurgical root canal treatment of mandibular first premolars.[3] The radicular grooves present on the proximal aspects of the root of mandibular first premolars are commonly associated with the presence of additional canals.[4],[5]

Root canal anatomy and root morphology may have definitive racial influences, thereby necessitating the identification of root canal morphologies of different races.[6] Studies on the root canal anatomy of mandibular premolars have been performed on several populations.[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18],[19],[20] An extensive review of the literature on the root canal morphology of Saudi Arabian population showed no clinical or laboratory study on mandibular first premolars.[21] Therefore, the aim of this study was to prepare detailed investigation of root canal morphology of mandibular first premolar in a Saudi Arabian subpopulation by using clearing technique and to compare these findings with the published reports of different population.


  Materials and Methods Top


One-hundred mandibular first premolars with mature and intact external morphology were collected from different dental schools and primary health-care centers of southern region of Saudi Arabia. It was ensured that the teeth belonged to indigenous Saudi population, and no teeth from other minority ethnicities were included in this study. The process of collection was performed by a team of clinicians who were made to understand the aims of the study, and the collection of every tooth was accompanied by a case record stating and confirming the ethnicity of the patients. The teeth were washed under tap water immediately after extraction and stored in 10% formalin (Sigma-Aldrich Chemie Co., St. Louis, USA) until the collection was complete. All teeth were washed thoroughly under tap water and immersed in 2.5% sodium hypochlorite (S.D. Fine-Chem Ltd., Mumbai, India) for 30 min to remove adherent soft tissue. The residual soft tissues, bone fragments, and calculus were cleansed and removed by curettes and ultrasonic scalers. Each specimen was first examined visually and categorized by the number of roots.

Access cavities were prepared using Endo Access kit (Dentsply Tulsa Dental Specialties; Tulsa, Oklahoma) and the pulp tissue was dissolved by immersing the teeth in 5.25% sodium hypochlorite (S.D. Fine-Chem Ltd., Mumbai, India) for 24 h. The teeth were then rinsed under running tap water for 2 h. The clearing technique protocol was adopted from a previously described method.[22]

The teeth were immersed in 5% nitric acid (Loba Chemie Pvt. Ltd., Mumbai, India) at room temperature to decalcify. The acid was changed every 24 h and agitated 8 hourly with glass rod. The end point of decalcification was determined by periodic radiographs. All samples were then washed in running tap water for 4 h to remove traces of nitric acid. The teeth were dehydrated using ascending concentrations of ethyl alcohol (Petrochem, Leatherhead, UK) starting with 70% for 12 h, followed by 90% for an hour and three rinses of 1 h each for 100%. The dehydrated specimens then were placed in 2% methyl salicylate (Rankem Fine Chemicals Ltd., New Delhi, India) to render them transparent. Indian ink (Loba Chemie Laboratory Reagents and Fine Chemical, Delhi, India) was injected into the pulp chamber with a 27-gauge needle on disposable syringe. A suction tip was placed at the root apex to draw the dye through the canal system. The excess dye was removed from the root surface with gauze soaked in 100% ethyl alcohol. The teeth were returned to the methyl salicylate solution to maintain the transparency. The transparent teeth dipped in methyl salicylate were examined under Dental microscope (Zeiss OPMI Pico, Carl Zeiss Surgical, Germany) at ×20 magnification by two calibrated endodontists. Photographs of the specimens were taken at megapixels 4 and a fixed distance of 80 mm with digital camera. The following features were analyzed: The number of roots, number of root canals, number of apical foramina, root canal configuration according to Vertucci's classification,[23] number of lateral canals, and intercanal communications. Lateral canals were defined as those branches of main canal that extend in horizontal, vertical, or lateral direction to open onto the external surface of the root. Intercanal communications were defined as thin communication between two or more canals in the same root. The root canal morphology where main canal divides into multiple accessory canals at or near the apex was considered as apical delta. The specimens were finally stored in Oil of cedarwood (E. Merck, Darmstadt, Germany), a clearing agent used to keep hard tissues for long periods without damage.[24]


  Results Top


Of the 100 mandibular first premolars, 80 (80%) teeth had a single root, 18 (18%) teeth had two roots, whereas 2 (2%) teeth were three rooted. In addition, 72 (72%) teeth had a single canal, 26 (26%) teeth had two canals, and 2 (2%) teeth had three canals. Seventy-three teeth (73%) had a single apical foramen, 19 teeth (19%) had two foramens, 2 teeth (2%) had three apical foramens, and 6 teeth (6%) had multiple apical foramina (apical delta). Sixty-nine (69%) teeth had Type I canal configuration, 8 (8%) had Type III, 4 (4%) had Type IV, and 16 (16%) had Type V. Two teeth (2%) had an additional configuration Type IX (1-3) described by Sert and Bayirli [25] while one tooth had an aberrant root canal morphology (1-3–1-2). [Figure 1],[Figure 2],[Figure 3] demonstrates some of the canal configurations found in this study. Lateral canals were found in 38 (38%) and intercanal communications in 16 (16%) teeth [Table 1].
Table 1: External and internal morphological features of mandibular first premolars observed this study

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Figure 1: Proximal view of cleared mandibular first premolars showing root canal configurations; (a) Type I; (b) Type III; (c) Type IV; (d) Type V

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Figure 2: Proximal view of cleared mandibular first premolar showing Type IX root canal configuration, multiple intercanal communications and lateral canals

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Figure 3: Aberrant root canal morphology where one canal leaves the pulp chamber, divide into three canals in middle third, reunite at apical third, and finally exit as two distinct foramina

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  Discussion Top


Different methods have been used to study root canal morphology of mandibular first premolars including radiographic examination,[7],[8],[10],[13],[16] canal staining and clearing technique,[9],[11],[14],[15],[19],[20] cross sectioning of teeth,[12],[16] microcomputed tomography,[5] and more recently, cone beam computed tomography.[17],[18] The canal staining and clearing technique are most commonly used because of its accuracy. It provides a three-dimensional view of the root canal system, maintains original form and relationship of the root canals and fine details like intercanal communications, apical deltas can be seen clearly. Furthermore, the transparent teeth can be used in the teaching of preclinical endodontics to appreciate the three dimensional picture of root canal system.[26] The canal staining and clearing technique were used in the present study. The transparent teeth specimens were examined under the Dental microscope which resulted in higher accuracy.

The most commonly observed root morphology was the single rooted mandibular first premolars (80%), followed by 2 (18%), and 3 rooted (2%). It is interesting to note the higher prevalence of two rooted mandibular first premolars in Saudi population compare to Caucasians (10.9%), Turkey (0%), Iran (2%), Jordan (3%), Egypt (3.2%), and South Asian Indian (6%) populations.[7],[9],[14],[15],[19],[20] The study from Kuwait population reported a high incidence of two rooted teeth (15%), but it assessed only twenty mandibular first premolars.[10] The prevalence of three-rooted mandibular first premolar in Saudi subpopulation (2%) was higher compared to the Indian (0.2%) population.[13] Although there was a prevalence of 28% of Saudi mandibular first premolars having more than one root canal, 36% of Chinese,[8] 29% of Iranians,[14] 19.2% of Egyptians,[19] 0.2% of Koreans,[18] 39.5% of Turkish,[25] 19.4% of Japanese,[27] and a range of 14%–30.7% of Americans [23],[28],[29] exhibited more than one root canal.

The majority of the specimens corresponded to Vertucci's classification,[23] Type I (69%) being most prevalent followed by Type V (16%), Type III (8%), and Type IV (4%). Type IX canal morphology where the main canal divided into three root canals at the middle or apical third was observed in 2 (2%) teeth. Ordinola-Zapata et al.[30] correlated the presence of radicular grooves in the proximal aspects of mandibular premolar roots with the presence of additional canals and found Type IX configuration in 15.2% of mandibular premolars with radicular grooves. Aberrant root canal pattern not described in previous classifications was noted in one tooth, where one canal left the pulp chamber, divided into three canals in middle third, reunited at apical third and finally exit as two distinct foramina (1-3–1-2). Identification, preparation, and obturation of Type I and Type IV are relatively straightforward. However, identification of canals in Type III, Type V, and Type IX where the canal further divides within the root needs extra efforts. The diagnostic methods like cone beam computed tomography and use of surgical operating microscope could be useful to treat such complex root canal system. Further, the access should be extended in buccolingual directions to achieve the straight line access.

In the current study, high prevalence of lateral canals (38%) and intercanal communications (16%) was reported. In addition, 6% of the teeth had apical deltas. These canal aberrations are of a clinical significance because it is difficult to clean and seal them. Failure of root canal treatment in cases where there appears to be simple anatomical configuration could be related to tissue and bacteria in apical delta.[12] Sodium hypochlorite is the endodontic irrigation solution with the best proteolytic effect [31] preferably agitated by passive ultrasonic irrigation may help to promote tissue removal and tissue dissolution from un-instrumented parts of the root canal system.[32]


  Conclusions Top


Within the limitation of this study it can be concluded that mandibular first premolar in Saudi Arabian subpopulation exhibited higher incidence of two canals. Although the majority of the study sample had single root, two and even three rooted forms were reported. Further studies are recommended with larger sample size to apply the results to the general population. The outcomes of nonsurgical and surgical endodontic procedures are influenced by highly variable root canal anatomy of mandibular first premolars. Therefore, clinician must use all the armamentaria at their disposal to locate and treat the entire root canal system to achieve long-term success.

Acknowledgment

The authors wish to thank Clinicians and Interns from Dental Schools and Primary Health Care Centers of Kingdom of Saudi Arabia for the collection of teeth for this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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