Endodontic Management of Maxillary First Molar With Two Palatal Canals Aided With Cone Beam Computed Tomography: A Case Report

The goal of root canal therapy is to perform a thorough cleaning and obturation of root canal system.¹ Having in-depth knowledge of root canal morphology is an important aspect of endodontic treatment. One of the main causes of failure in endodontic therapy is overlooking aberrent root canals and roots.² Human molars have many anatomic variations and abnormalities with respect to number of roots and root canals, particularly root canal morphology of maxillary first molars. Cleghorn et al³ performed a comprehensive review of the root and root canal morphologies of the human permanent maxillary first molar. Literature⁴ has found 2 root canals in the palatal root of a maxillary molar is 2% to 5.1%. Maxillary molars have one of the most complex root canal anatomies.

The present case report describes a permanent maxillary left first molar with 5 root canals (mesiobuccal 1: MB1, mesiobuccal 2: MB 2, distobuccal: DB, palatal 1: P1, and palatal 2: P2), with unusual palatal canal morphology in that 2 canals with separate orifices joined in the apical third. This was confirmed using cone-beam computed tomography (CBCT) scans.⁵

A brief review of recent case reports of extra palatal root canals in maxillary first molars is presented in Table 1.

A 25-year-old male patient reported to the outpatient department with the chief complaint of pain in the left upper back region of jaw for the last 2 to 3 days. The patient also gave a history of disturbed sleep. Findings from the clinical examination revealed a deep carious lesion in the maxillary left first molar. The tooth was sensitive to percussion and elicited positive response on thermal and electric pulp testing; pain persisted even after removal of the stimulus. An intraoral periapical radiograph revealed a radiolucency approximating the pulp and periodontal ligament space widening was also present (Figure 1). On correlating the clinical and radiographic findings, a diagnosis of acute irreversible pulpitis with apical periodontitis was made and a decision to perform root canal treatment of maxillary left first molar was determined. The patient was informed about the treatment, and he provided informed consent. The patient was administered local anesthesia of 2% lidocaine containing 1:80,000 epinephrine and an access opening was performed using a rubber dam isolation. The clinical evaluation of the internal anatomy revealed 3 principal root canal systems: mesiobuccal (MB), distobuccal (DB), and palatal (P). After careful probing using a DG 16 endodontic explorer (Dentsply Sirona, dentsply.com), under 2.5X magnification using surgical loupes (Keeler Instruments, keelerusa.com), a small hemorrhagic point was noticed in a groove from the MB orifice in a palatal direction. A similar hemorrhagic point was also observed near the orifice of the main palatal canal. The conventional triangular access was modified to a trapezoidal shape to improve access to the additional canals. In both areas, there was a “catch” present with the endodontic explorer. Multiple radiographs at different angulations were not conclusive, so a multislice CBCT (Kodak, Carestream, carestreamdental.com) scan was performed of the involved tooth along with adjacent teeth. All required measures were taken to protect the patient from radiation. The images were obtained in transverse, axial, and sagittal sections of 0.5-mm thickness, which is used routinely. CBCT scan slices revealed 5 canals (2 mesiobuccal, 2 palatal, and 1 distobuccal) in the axial images at the coronal (Figure 2) and middle thirds (Figure 3). In the apical third, the palatal root had only 1 canal indicating that the 2 canals were fused between middle and apical thirds (Figure 4).

The working length of each canal was estimated by means of an apex locator (Dentaport ZX, Morita, global.mortia.com) and confirmed with intraoral periapical radiograph (Figure 5). The canals were prepared using the crown-down technique with Heroshapers Rotary NiTi files (MICRO-MEGA^®, micro-mega.com), and copious irrigation was done using normal saline, 5.25% sodium hypochlorite solution, 17% ethylenediaminetetraacetic acid, and 2% chlorhexidine as the final irrigant. A clinical image of the pulp chamber floor was taken after instrumentation (Figure 6). Root canals were dried. Calcium hydroxide (Calen, SS White, sswhite.com) was used as an intracanal medicament, and the access cavity was temporarily sealed with IRM cement (Dentsply Middle East & Africa, denstplymea.com). After 1 week, the patient had no symptoms, and calcium hydroxide was removed from the root canal system using sodium hypochlorite irrigation and endodontic files. A master cone radiograph was taken (Figure 7). The root canals were dried with paper points and were then obturated with gutta-percha points (Tanari, tanari.com) and AH-Plus (Densply Sirona, dentsply.com). A post obturation radiograph was taken (Figure 8). The tooth was permanently restored with a posterior composite resin core (P60, 3M, 3m.com).

The operator’s ability to find additional canals is improved with adequate knowledge and experience to find additional canals, especially in the maxillary molars.⁶ Endodontic literature states that the maxillary first molar consists of 3 roots with 3 or 4 root canals.¹ The prevalence of maxillary first molars with two palatal canals is rare. Thews et al,⁷ Stone and Stroner,⁴ Cecic et al,⁸ Bond et al,⁹ Baratto-Filho et al,¹⁰ de Almeida-Gomes et al,¹¹ Aggarwal et al,¹² Karthikeyan and Mahalaxmi,¹³ and Kottor et al^14,15 have reported cases with 2 palatal canals, whereas Wong¹⁶ and Maggiore et al1 have described teeth with 3 palatal canals. This report highlights a maxillary left first molar with 2 palatal canals. The variable shape of the pulp cavity makes every treatment unique. Properly designed and prepared access cavities help the clinician diagnose and negotiate the root canal anatomy. In the present case, the conventional triangular access was modified into a trapezoidal form to improve access to the additional canals. Usually, the reading of a radiograph along with a careful inspection of the pulp chamber floor by probing and proper visualization enables the operator to locate and identify the root canal orifice. The use of endodontic explorer, surgical loupes, and electronic apex locator were crucial both for the detection and management of the 2 canals in the palatal and mesiobuccal roots. Clinician should thoroughly examine the pulpal floor and radiographs for the possibility of additional canals.

Introduced in endodontics in 1990,¹⁷ CBCT is a diagnostic imaging modality that can be of great help in identifying additional canals. Missed and extra canals can easily be identified in CBCT axial slices. Using periapical radiographs may cause the clinician to overlook these extra canals, even if different angles are taken of the area. CBCT analysis also helps in identifying the root canal configuration whether they are joined together or run individually. CBCT evaluations are more likely to help the clincician identify higher numbers of root canals in contrast to conventional radiographs in which the chances for missing a canal is greater. Other applications of CBCT in endodontics include detecting dental and periapicalpathosis, evaluating root fracture, and identifying internal and external root resorption. However, CBCT has inherent limitations, such as its high cost and increased radiation risk for the patient.¹⁸

Clinicians should be aware of the possible anatomic devaiations in root canal morphology that can occur with each tooth while performing root canal treatment. CBCT is state-of-the-art in endodontics, which as a complementary imaging device that helps in identifying these variations and is highly recommended in endodontics.

Jaya Pamboo, MDS
Senior Lecturer
Department of Conservative Dentistry and Endodontics
Institute of Dental Sciences
Bareily, Uttar Pradesh, India

Manoj Kumar Hans, MDS
Professor
Department of Conservative Dentistry and Endodontics
K.D. Dental College and Hospital
Mathura, Uttar Pradesh, India

Subhas Chander, MDS
Medical Officer (Dental)
District Hospital
Sriganganagar, Rajasthan, India

Kapil Sharma, MDS
Reader
Department of Oral & Maxillofacial Surgery
Institute of Dental Sciences
Bareily, Uttar Pradesh, India