Prevalence of additional canals in maxillary first molar in a Nepalese population: A Clinical Study

Background and aims: There is a wide range of variations in the literature with respect to frequency of occurrence of the number of canals in each root, the number of roots and incidence of fusion. This study aims to investigate the prevalence of additional canals in permanent maxillary first molar in the Nepalese Population. Methods: This was a descriptive study in which maxillary first permanent molars (n-201) of Nepalese population were examined using in vivo technique. Radio-graphs were taken. Access opening was done and gentle troughing of the pulpal floor was done, to look for additional canal. Results: A total of 201 patients were treated. Of these, additional canals in me-siobuccal root was found in 34.1% of the cases and in distobuccal and palatal root, the additional canals were found in 0.49% of the cases. Conclusions: Complete knowledge of the internal anatomy and anatomic varia-tion of root canal system is crucial for the success of the root canal treatment, as missed canals contribute to the failure of root canal treatment in a short dura-tion.


Introduction
Successful root canal therapy requires a thorough knowledge of root and root canal morphology. In spite of all procedural protocol if clinicians miss an addi-tional root canal it could pose a great challenge and lead to failure of root canal treatment. There is a wide range of variation in the literature with respect to frequency of occurrence of the number of canals in each root, the number of roots and inci-dence of fusion. Morphology of pulp systems varies greatly in different races and in different individuals within the same population [1].
Internal complexities of the root canal are genetically determined and have de-finitive importance in anthropology, so there is a need for the identification of root canal morphologies of different asian populations [2]. The anatomy of maxil-lary first permanent molar is complex which presents a constant challenge for the Endodontists. An awareness and understanding of the existence of additional canals and rare root canal morphology is essential [3].
The most common configuration described in the root canal anatomy of maxil-lary first molar is the presence of three roots with three canals, while the most frequent variation is the presence of second mesiobuccal canal (MB2).In maxil-lary first permanent and palatal roots [4,5]. The aim of this study was to show the prevalence of an additional canal in maxil-lary first permanent molars in a Nepalese population as there is no previous lit-erature regarding it. Copious amounts of 3% sodium hypochlorite (Prime Dental Products, Pvt, Ltd) solution irrigant was used. Pulp tissue was extirpated using barbed broaches (Nerve Broaches/ Alfred Becht-GmbH, Germany) or H-Files (Mani inc, Japan). A size 10 K file (Dentsply) was introduced into the canal to de-termine the canal patency and a working length radiograph was taken, using the paralleling technique. Apex locator (Root ZX, J. Morita, and Kyoto) was used to take a second working length as an adjunct to the radiographic method. Apical patency was confirmed with a small file (#15 or #20 NitiFlex) throughout the procedures after each larger file size. Preparation was completed using stepback of 1mm increments. Irrigants used were 2.5% NaOCl solution and normal saline. Each canal was dried using sterile paper points. Afterward, the canals were med-icated with a calcium hydroxide paste for 1

Methods
week, and then they were filled by the lateral compaction technique.

Results
In the current study, the ratio of male to females was 1.5:1.
The mean age of participants were 35.75±16.39. The additional canal in mesiobuccal root was found greater in females (59.18%) in comparison to males (40.82%) wheareas in distobuccal and palatal root, the additional canals were found in males. The in vivo study revealed that additional canals in mesiobuccal root was found in 34.1% of the cases and in distobuccal and palatal root, the additional canals were found in 0.49% of the cases (Table 1). and Indian populations [6][7][8]. The additional canal in mesiobuccal root was found less in nepalese population than that of other asian populations, this maybe because present study was in vivo. There is the ease of manipulating the tooth outside the mouth in in-vitro technique than in-vivo technique. This could be also due to the fact that surgical loupes and operating microscope were not used in this study as modifications in endodontic access preparation. There are reports of high incidence of two canals in the mesio-buccal root of the maxillary molars. Wein et. al. [9] found that teeth with a fourth canal occurred more fre-quently than those with three canals (51.5% versus 48.5%). The incidence of MB2 is lower in present study.
In palatal root, additional canal was found in 0.49% of the cases which is less than that of Chinese and Indian populations and greater than that of Pakistani population. There are fewer reported cases of two root canals present in the palatal root of the maxillary molars. A review study on the anatomy of the maxil-lary first molar from a study done by Cleghorn et. al. [10] reported an incidence of the mesiopalatal canal (MP) at 56.8% and a prevalence of the distopalatal canal (DP) at 1.7%. Bratto Filho et. al. [11] reported that the frequency of extra roots and root canals in palatal roots are 2.05% (ex-vivo results), 0.62% (clinical results) and 4.55% (CBCT results). Stone and Stroner [12] examined more than 500 ex-tracted molars and found less than 2% incidence of multiple systems in

Conclusions
Dentists should be aware of extra canals and roots when considering endodontic treatment of a maxillary first molar. Thus, it is essential to highlight the need to look for unusual morphology and additional roots and root canals for a good en-dodontic outcome.