A thorough knowledge of root canal morphology is essential for successful endodontic treatment. Mandibular first premolar is typically described in textbooks as single rooted tooth with a single root canal system. The ovoid-shaped root in cross section normally has developmental grooves or depressions on the mesial and distal surfaces [1]. However, mandibular premolars have always been considered as an “enigma to Endodontist” since they have been amongst the most difficult teeth to undergo endodontic treatment due to high incidence of multiple roots or canals. A possible explanation for this could be the extreme variation in root canal morphology that occurs in these teeth [2]. Neglecting to probe, prepare, and fill all of the root canals can lead to failure of endodontic treatment [3].

Detailed literature is available with reports of extra canals in mandibular first premolars, but reports about the incidence of extra roots in these teeth are quite rare. Furthermore, the incidence, location, and morphology of roots and root canal systems may vary in different ethnic or regional populations [3-5]. Although various studies have been conducted to study the same [6,7], little literature focuses on Indian population specifically. Thus, this paper attempts at explaining the prevalence of a two-rooted mandibular first premolars in the city of Chitradurga, Karnataka, South India.

It was the purpose of this investigation to study the root canal morphology of mandibular premolars with special emphasis on the prevalence of two or more roots in mandibular first premolars. Two hundred fifteen patients in a period of three months, who reported to Dental wing, Karnataka ENT Hospital and Research Centre, Chitradurga, Karnataka for seeking treatment for decayed posterior teeth were subjected to orthopantomograph radiographs with their prior written consent. Detailed standard protocol to take orthopantomograph was strictly followed in all the patients. The radiographs were examined with a magnifying viewer by three examiners. The data obtained was tabulated and subjected to statistical analysis.

Legends for figure:

Figure 1: Orthopantomograph Showing Two Rooted (Double Rooted) Mandibular Left First Premolar (Yellow Arrow).

Out of 430 mandibular first premolars examined, in only one patient i.e., only one first premolar showed (unilateral presence of) two roots (Figure 1). This showed the prevalence of 0.23% in chitradurga city (South Indian population). On the left side two rooted first premolar was observed. The bifurcation was observed from middle third of the root.

Mandibular premolars are undoubtedly an endodontic challenge leading to high failure rate of treatment [1]. The difficulty encountered during treatment of mandibular premolars is often attributed to variable morphology of the root and root canal [2]. The literature focusing specifically on prevalence of extra root in mandibular first premolars is limited. However there are some case reports showing occurrence of two or three roots in these teeth [8,9]. Therefore, with the intention of evaluating the prevalence of two rooted first premolars in the mandibular arch of Indian ethnic group, the present study was carried out.

In this study authors have used conventional orthopantamograph radiographs as they are an important clinical diagnostic tool for assessing number of roots or canal morphology and at the same time are cost effective. Using this diagnostic tool the present study found a prevalence of 0.23% two rooted first premolars in the city of Chitradurga (South India). The bifurcation or branching was seen at the middle one third of the root. This finding was found similar to the study done in Thai population [6]. Various studies have been undertaken to show the prevalence of double rooted first premolars in different population across the world. Thanaruengrong et al [6] examined 1159 CBCT images and evaluated the prevalence of complex root canal morphology in the mandibular first and second premolars in Thai population. The most common root canal configuration was Vertucci type I, with a 63.1% in the mandibular first premolars. More than 98% of mandibular premolars had a single root. The prevalence of a bifurcation was 28.5% in the mandibular first premolars. The level of branching was mostly found at the middle 1/3 of the root. Bilateral appearance of the same root canal configuration was identified in 80.3%. There was no relationship between sex and the prevalence of a bifurcation, trifurcation, or C-shaped root canal.

Arayasantiparb R and Banomyong D [7] examined 349 first premolars from CBCT images and found 5.73% of multiple roots in mandibular first premolars while none of second premolars had. Multiple root canals were found in the first premolars at 19.48%. C-shaped canals (C1/C2) were found in the first premolars at 3.72%. In addition to these studies, Dou et al [10] in 2017 investigated root anatomy and root canal morphology of mandibular first premolars in a Chinese population. In their investigation, 178 human permanent mandibular first premolars extracted from a native Chinese population were collected, scanned using micro-computed tomography and reconstructed three-dimensionally. The number of roots and canals, canal configuration and radicular grooves were investigated. The root canal morphology was categorized according to Vertucci’s criteria. The radicular grooves were scored according to the Arizona State University dental anthropology scoring system (ASUDAS), and the correlation between scores for radicular grooves and root canal morphology was analyzed. Almost all the samples were single-rooted (99.4%). 64.04% of teeth possessed type I canal systems, whilst 34.27% had two canals and 1.69% had three canals. According to ASUDAS, the scores of radicular grooves were 56.74%, 16.85%, 12.36%, 10.11%, 3.37% and 0.56% respectively from grade 0 to grade 5. The roots with radicular grooves (grade 3 or 4) were defined as Tome’s anomalous root and these roots have a high incidence of C-shape configurations (66.67%) and multiple-canal systems (100%). Finally, they concluded from this study that there is complicated variation of the root anatomy and canal morphology of mandibular first premolars in southwestern Chinese population, which needs special attention and careful assessment for endodontic treatment.

Similar studies like Al-Zubaidi et al [11] using CBCT images, examined 507 first premolars and found 484 (95.5%) having one root, whereas 23 (4.5%) having two roots. In 2017 Chourasia et al [12] evaluated in Saudi Arabian population for presence of multiple roots in first premolars and found as out of the 100 mandibular first premolars  examined, 80% had a single root, 18% had two roots, whereas 2% were three rooted.

Findings from this survey emphasize the importance of radiographic assessment for diagnosing multiple roots which might present unusual characteristics such as multiple and bilateral appearance. Thorough clinical judgement and radiographic assessment can thus help us reduce the treatment failures in mandibular first premolars.

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