The Use of Cone-Beam Computed Tomography in the Endodontic Treatment of a Maxillary Central Incisor with Two Roots: Case Report

Precise knowledge of the internal root anatomy is essential before performing an endodontic procedure. A complex internal anatomy and undetected canals are among the main causes of endodontic treatment failures.¹ It is estimated that only 0.6% to 2% of maxillary central incisors have two roots.^2-4 Thus, the appearance of a second canal is extremely rare and may be related to anomalous tooth development, such as gemination, fusion, dens invaginatus, or the presence of a supernumerary root.⁴

The outcome of endodontic treatment can be directly affected by the extent of the clinician's knowledge of variations in the root canal system of all teeth.³ Because of such a low prevalence rate, clinicians may fail to observe the presence of additional channels in a maxillary incisor.³ The use of angled radiographs can assist in locating such additional canals.⁴

Additionally, other radiographic modalities, such as cone-beam computed tomography (CBCT), may be appropriate and effective for the accurate diagnosis of these anatomical variations.^5,6 A CBCT scan favors the determination of 3-dimensional location of roots and canals.^5,6 Comparisons of CBCT images of extracted teeth versus routine 2-dimensional (2D) images showed that tomography imaging consistently resulted in the revealing of a greater number of identified canals.⁷

The aim of the present study is to report on the diagnosis and endodontic treatment of a rare case of a Vertucci's type V pattern maxillary central incisor, in which a canal leaves the pulp chamber and divides into two canals with two apical foramina.⁸ A CBCT was used as a diagnostic tool. Additionally, this report demonstrates that CBCT was fundamental to the diagnosis, as it guided the choice of the most appropriate treatment plan.

A 72-year-old male patient was referred for endodontic treatment of tooth No. 9, for which a future fixed prosthesis was planned. The clinical examination revealed a coronary fracture and no response to thermal sensitivity, percussion, or palpation tests. Based on the periapical radiography, the presence of two root canals in the maxillary left central incisor was suspected (Figure 1 and Figure 2). Therefore, the clinician requested a CBCT to attain a more accurate diagnosis.

Upon review of the CBCT scan, two canals and two roots were detected (Figure 3). The final diagnosis revealed pulp necrosis and normal periapical tissues. Endodontic treatment would be performed in a single visit.

Before the coronary opening procedure, prophylaxis was performed with pumice stone and water in an effort to reduce bacterial contamination. After local anesthesia (2% mepivacaine with 1:100,000 epinephrine), the tooth was isolated with a rubber dam and the access preparation was performed with high-speed spherical diamond ultrasonic tips to improve visualization of the mesial canal due to the presence of a root bifurcation in the middle third. Root canal length was measured electronically and viewed radiographically (Figure 4). After performing a glide path with manual files #10 and #15, a rotary file system (ProDesign S, rotary files 25.06 and 25.08, Easy Dental Equipment, easy.odo.br) was used for the cleaning of the root canal system. The chemical-mechanical preparation was supplemented with manual files #30, #35, #40, and #45 with 2.5% sodium hypochlorite as irrigating solution.

To complete the cleaning of the canals, 5 ml of a 17% EDTA (ethylenediamine tetraacetic acid) solution was applied using the passive ultrasonic irrigation (PUI) technique, with an ultrasonic tip E1 for 1 minute, followed by application of 5 ml of 2.5% sodium hypochlorite. The obturation of the root canal system was performed using the hybrid technique of Tagger with endodontic zinc oxide and eugenol-based cement (Figure 5 through Figure 7).⁹

The provisional restoration was performed with composite resin, and the patient was referred for prosthetic rehabilitation. Clinical follow-up of the treatment was carried out after 1 year (Figure 8 through Figure 10).

There are few cases of maxillary central incisors with two roots and two canals reported in the literature, and most also present morphological alterations, such as macrodontia, fusion, gemination, or dens invaginatus.¹⁰ In the present case, however, because the dental crown was fractured it was impossible to analyze whether any of these alterations existed. Although the main etiology of this variation is unknown, a change in the development of the Hertwig epithelial root sheath may have been the main reason for the creation of a supernumerary root.¹¹

According to American Association of Endodontists guidelines, the use of CBCT for investigations of the anatomy of the root canal system should be reserved for selected cases when intraoral radiographs do not provide sufficiently accurate information for proper planning.¹² Traditional radiographic examinations with 2D images are limited, a fact that may result in the inaccurate diagnosis of morphological changes, further restricting the choice of treatment plan.^13,14 However, these problems may be overcome through the use of contemporary diagnostic techniques, such as CBCT, as demonstrated in the present case. The improved visualization of the internal and external anatomy in three dimensions provided by the CBCT imaging increased the predictability of the treatment and the perception of the location of the extra canal. CBCT demonstrated the presence of a single canal leaving the pulp chamber and dividing into the middle third in two canals, and two independent apical foramina, thus being classified as type V of Vertucci.

Although a clinician may have the appropriate knowledge of the internal anatomy, and the cleaning and disinfection of the root canal system typically enables viable conditions for the repair of periapical tissues, the presence of complex anatomies can make it difficult to disinfect these canals. This, in turn, may allow for the proliferation of pathogenic microorganisms, which are commonly found in pulp and periapical diseases.¹⁵

Sodium hypochlorite was the auxiliary chemical solution used in this case because of its high antimicrobial efficacy. Due to anatomical complexity of a root canal system, however, the irrigating solution not reaching the full length of the canals could be a factor in the failure of endodontic treatment. Thus, PUI has been highly prominent, and its effectiveness as an irrigation solution potentiation has been recognized. Boff et al compared the efficacy of PUI versus the conventional technique with a syringe used in cleaning the apical portion of a root canal system flattened with 2.5% sodium hypochlorite as an irrigating solution.¹⁶ The authors concluded that cleaning the apical root canal segments of the teeth used in the study yielded better results with PUI. Therefore, this was the cleaning technique advocated for the present case.

This case report highlights the clinical relevance of the existence of a complex anatomy of a root canal system in an atypical maxillary central incisor, even in the absence of dental morphological anomalies. The outcome demonstrates that an effective diagnosis in conjunction with adequate treatment may allow for a favorable prognosis in the long term.

Natália Gomes de Oliveira, DDS, MSc
Master in Dentistry, PhD Student, Dental School, Universidade de Pernambuco - UPE, Camaragibe, Pernambuco, Brazil

Casimiro Ricardo Oliveira Passos, DDS
Specialist in Endodontics, Brazilian Dental Association, Recife, Pernambuco, Brazil

Luís Felipe Espíndola-Castro, DDS, MSc
Master in Dentistry, PhD Student, Dental School, Universidade de Pernambuco - UPE, Camaragibe, Pernambuco, Brazil

Paulo Maurício Reis de Melo Júnior, DDS, MSc, PhD
PhD in Dentistry, Adjunct Professor, Dental School, Universidade de Pernambuco - UPE, Camaragibe, Pernambuco, Brazil

Sandra Maria Alves Sayão Maia, DDS, MSc, PhD
PhD in Dentistry, Adjunct Professor, Dental School, Universidade de Pernambuco - UPE, Camaragibe, Pernambuco, Brazil

Marianne de Vasconcelos Carvalho, DDS, MSc, PhD
PhD in Dentistry, Adjunct Professor, Dental School, Universidade de Pernambuco - UPE, Camaragibe, Pernambuco, Brazil