Abstract
The presence of 2-rooted mandibular canines has been described in only a limited number of case reports however studies of anatomical features have demonstrated substantial variation in the number of roots and root canals in different teeth. The mandibular canine usually has one root while this report describes the incidence of 2 cases of mandibular canines with 2 roots and 2 root canals. The report outlines the steps necessary to identify and treat such cases, which starts with thoroughly examining the internal anatomy of the tooth using clear radiographs taken from different angles, while treatment relies on using advanced equipment like dental operating microscope, ultrasonic tips for conservative access, and accurate apex locator for accurate working length determination.
Keywords
anatomical variation, internal anatomy, mandibular canine, root canal, two roots
Introduction
The principle objective of root canal treatment is to relieve pain, eliminate bacteria from the root canal system, and prevent reinfection. A clear understanding of root morphology and canal anatomy is an essential prerequisite to achieving clean, disinfected and 3-dimentionally obturated root canal systems. Undetected extra roots or root canals are a major reason for the failure of root canal treatment(1). Many of the challenges faced during root canal treatment may be directly attributed to an inadequate understanding of the canal morphology of teeth. Variations in root canal morphology are a constant challenge for diagnosis and is a huge contributing factor in the success of root canal treatment. Usually, the mandibular canine has only one root and one root canal (2). The incidence of two roots and even more than two root canals in canine is rare, ranging from 1% to 5% (3,4). Despite the low prevalence, clinicians should consider the possible variations in the number of roots and root canals of mandibular canines. Root canal treatment of two-rooted mandibular canine had been documented in several clinical reports. Many authors (5, 6, 7) reported that the occurrence of mandibular canines with one and two root canals is approximately 15%. At the same time, the incidence of mandibular canines having two roots and two canals was documented to be up to 5% (3, 8). In addition, mandibular canine with three canals in one root had been reported(9), or three canals in two roots(10). All these cases suggest abnormal morphological features of the canine root system.
Radiographs are an important and necessary adjunct for root canal treatment, and accurate radiographic techniques and correct interpretation are essential for sound diagnosis and treatment. The use of preoperative radiographs is the best way to detect and evaluate root canal morphology and anatomy. Further radiographs should be taken at different angles to confirm any variations in anatomical features(11). In recent years, significant technological advances for imaging teeth have been introduced, including digital radiography, densitometry, magnetic resonance imaging, ultrasound, and computed tomography(12). Conebeam computed tomography systems (CBCT) have gained increasing significance in the study of hard tissues in endodontics as it offers a reproducible technique that can be applied quantitatively as well as qualitatively, allowing for a three-dimensional image of the root canal system(13).
The purpose of this clinical report is to describe endodontic treatment of two mandibular canines with two roots and two canals in two Arab nationals. Additionally, the following two case reports have been written according to Preferred Reporting Items for Case reports in Endodontics (PRICE) 2020 guidelines.
CASE DESCRIPTION AND RESULTS
Case 1
A 27-year- old male was admitted to the Endodontic Department of [Redacted] Medical Center for the past three days pain in the right front region. Medical history was noncontributory. Patient gave a history of spontaneous pain lasting from a few seconds to several hours. Also, pain is caused when hot and cold liquids are used, and is felt longer and more pronounced when hot, while cold relieve pain. Clinical examination revealed a carious cavity lesion penetrating the pulp of tooth # 43 (lower right canine). Tooth was tender to percussion. No swelling or fistula intra or extra orally. A diagnosis of irreversible pulpitis was made. Careful examination of the radiograph demonstrated a long root and the possibility of more than one canal (Fig.1)
Fig 1
After the patient provided signed informed consent, the tooth was anesthetized and isolated with a rubber dam. Caries was removed and access to the pulp chamber was made using a round diamond bur. The pulpal floor was examined using dental operating microscope (Global Dental Microscopes, Global Surgical Corporation, USA). The DG-16 endodontic explorer (American Eagle, CA, USA) was used to determine the bifurcation level of the root. Ultrasonic tips (Pro Ultra Endo Tips Dentsply Maillefer, Ballaigues, Switzerland) were then used to remove cervical dentin that obstructing the path to lingual canal in mandibular canine. The internal anatomy confirmed the presence of 2 root canal orifices, one located buccally and the other lingually. The working lengths of each canal were estimated by means of electronic apex locator (Root ZX, Morita, Tokyo, Japan), then confirmed by a radiograph.
The canals were initially instrumented with a size #15 K-file, and coronal flaring was carried out using Gates Glidden burs (numbers 3 and 2; Dentsply Maillefer, Ballaigues, Switzerland). Biomechanical preparation was completed by using rotary nickel-titanium files ProTaper Gold (Dentsply Maillefer, Ballaigues, Switzerland) up to apical file size # 30. Copious irrigation with 3% sodium hypochlorite (NaOCl) with ultrasonic Endo Activator (Dentsply Maillefer, Ballaigues, Switzerland) was applied for 30 second followed by 17% Ethylenediaminetetraacetic acid (EDTA) for 1 minute with safe 2-side vents irrigation tips IrriFlex (Produits Dentaires, Swizterland), to remove the inorganic tissues, and this was performed during the instrumentation phase. Sterile paper points were used to dry the root canals. Master cone radiograph was taken, and the two canals were obturated with Tubli-seal (Kerr UK, Peterborough, U.K.) and laterally condensed using gutta-percha points. Final radiographs were taken to ensure proper obturation. A sterile cotton pellet was then placed in the pulp chamber, and IRM cement (Dentsply De Trey GmbH, Konstanz, Germany) was applied to seal the access cavity as a temporary filling to prevent coronal leakage. The patient was referred for final restoration (Fig. 2)
Fig 2
Case 2
A-35-year-old female was referred for root canal treatment of the right mandibular canine. The general dental practitioner had started root canal treatment. The tooth was asymptomatic and free from any clinical signs. Medical history was unremarkable. Clinical examination revealed no mobility, normal periodontium, no swelling or sinus tract, and the tooth was not tender to percussion. Pulp sensitivity testing of the tooth showed no response to cold and electrical pulp testing. Radiographic evaluation of the affected tooth revealed unusual, complex root canal anatomy. The radiographic image showed the presence of two roots with periapical radiolucency (Fig. 3).
Fig 3
Based on history, clinical examination, a diagnosis of necrotic pulp and apical periodontitis was established for lower right canine (#43). Root canal treatment was decided, and informed consent was taken from the patient. Infiltration of the local anesthesia (Lidocaine HCl 2% with epinephrine 1:100,000) was administered and the rubber dam was placed. Access to the cavity was achieved using a round diamond bur. The conventional lingual access opening was modified by including more of the incisal surface to gain sufficient access to the canals . The two orifices were located one buccally and one lingually. Coronal flaring was carried out using the Sx file of the ProTaper system (Dentsply-Maillefer, Ballaigues, Switzerland). The two canals were carefully instrumented with a size 15 K-file . The working length of the canals was established with the use of apex locator (Root ZX: J Morita Co, Kyoto, Japan) and verified radiographically (Fig.4).
Fig 4
Root canals preparation until F2 file size, disinfection, obturation, and temporary restoration were performed in a same manner as described for Case 1. (Fig. 5)
Fig 5
Results And Discussion
This report focused on two cases of mandibular canines with two roots and two root canals. Any morphological and anatomical variations in the root canal system should always be considered at the beginning of endodontic therapy, and the clinician is required to understand the complexity of root canals features and carefully examine any variation. Diagnosis and identification of the number of roots and root canals are essential because endodontic success is related to a thorough debridement of the root canal system. Most endodontic and dental anatomy textbooks describe the mandibular canine as a single rooted tooth with single root canal system. However, the presence of two roots in mandibular canine is a rare incident. Endodontists should always search for two canals in mandibular canines during root canal treatment, even in single-rooted teeth. The incidence of two root canals in single-rooted mandibular canine teeth has been reported to be up to 6.25% (14). Green (6) found two canals in a single root in 13 out of 100 mandibular canines examined. This is in consistent with the findings of Hess (15), who observed two canals in 15% of the cases. Vertucci (7) reported the presence of two canals in 18% of the mandibular canines. Ghoddusi and other (16) also found two separated canals in the mandibular canines. The presence of one root with two canals and two roots with two canals has also been reported by many authors (17, 18, 19, 20). Heling and other (21) reported a rare case of mandibular canine with two roots and three canals. In a previous study using a tooth clearing method, (8) studied the internal anatomy, orientation, and number of roots of 830 extracted human mandibular canines. They found that 98.3% of teeth presented a single root, and 1.2% had two roots and two canals. An even higher incidence (18.5%) of two canals was found by Pineda and Kuttler (5) who used radiographic images to study the internal morphology and anatomy of 187 mandibular canines.
In certain circumstances, the root canals may be left untreated during endodontic therapy if the practitioner is unable to detect their presence (1). The presence of extra roots can easily be determined by using routine radiography, as shown in the present cases. However, teeth with extra canals and a normal number of roots present a greater challenge in terms of diagnosis and treatment. Extra root canals can be difficult to identify because they overlap other root canals or, sometimes, they are relatively small. Careful examination of the preoperative radiographs is essential for the detection of extra canals. Knowledge of anatomic aberrations, such as root position, root shape and root outline will also decrease the failure rate of root canal therapy. It is important to carefully inspect the preoperative radiograph for signs of anatomical variations to avoid potential excessive weakening or even perforation of the roots. Recently, the availability of advanced diagnosis radiographic tools such as Cone-beam computed tomography (CBCT) have proved to be very helpful in the diagnose morphological variations where conventional radiographic techniques have failed to provide more information and details required (22). Conebeam computed tomography as it provides accurate details in the axial, sagittal, and coronal planes is recommended if a diagnosis cannot be made using conventional radiography. (23).
Access to the root canal is the initial step in canal preparation, and a properly designed and prepared access cavities will eliminate many potential problems during canal preparation and obturation. In the cases reported here, after gaining access to the root canal system, cleaning and shaping were done using rotary instruments in a crown down technique to minimize extrusion of debris. Root canal irrigation plays a pivotal role in endodontic therapy, to facilitate instrumentation by lubrication, debris removal, microorganisms, smear layer, and prevent apical debris packing. Irrigation overstrains their effects, by mechanical, chemical and biological actions (24). Incomplete removal of all the irritants from the pulp space may increase the possibility of treatment failure (25). Ultrasonic activation of irrigation solution further enhances the removal of bacteria and dentin debris, which is then to be followed by obturation to seal the inaccessible zone (26). Irrigant activation proves to be beneficial, in terms of postoperative pain intensity, canal debridement, and isthmus cleanliness.
The use of magnifying tools (magnification loupe or dental operating microscope), the use of fiber optics, and sodium hypochlorite bubble technique may be helpful in locating any additional root canals (27). In this study, a dental operating microscope was used, as our routine endodontic treatment to identify the internal morphology of the tooth, locate the canals and to detect any extra canals. Unfortunately, some endodontists who are using the dental operating microscope in their dental clinics do not use it as often as needed to be (28).
Conclusion
These reported cases emphasize the need for a clinician’s awareness of anatomical variations that can occur in teeth undergoing root canal treatment. Anatomical variation in the number of roots or root canals can occur in any tooth. It is necessary to examine clear radiographs taken from different angles and careful assess the internal anatomy of the tooth, otherwise root canal treatment may fail if no extra roots or root canals are detected. It is highly recommended for the clinician to use advanced equipment and techniques to manage such teeth with anatomical variations like dental operating microscope, ultrasonic tips for conservative access, and accurate apex locator for accurate working length determination.
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