2022, Number 1
Management of maxillary second molars with two palatal roots: report of two cases
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Language: English/Spanish [Versión en español]
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ABSTRACT
Introduction: these case reports aim to highlight the importance of always considering the possible anatomical variations present in the dental organs that need root canal treatment. Despite the research dedicated to reporting the prevalence of these anatomical variations, variations in the number of palatine roots of maxillary molars are rarely accounted due to their extremely low incidence. Material and methods: this report presents two clinical cases in which maxillary molars with additional palatal roots are present. The first case was a 41-year-old woman, with no apparent pathological data, who had a previous access cavity but no radiographic signs of periapical pathology. Periodontal probing was normal. The pulpal diagnosis was previously initiated pulp therapy and the periapical diagnosis was healthy periapical tissues. During the inspection of the pulp chamber floor, the palatine canal was located more distally than normal, making the operator suspicious of the presence of an additional root canal. The access cavity was slightly enlarged in the mesio-palatine direction, which resulted in the location of a second palatal canal in an extra palatal root. The second case was a 28-year-old woman with a non-contributory medical history who presented pain upon thermal changes in the maxillary right second molar. The pulpal diagnosis was symptomatic irreversible pulpitis and the periapical diagnosis was symptomatic apical periodontitis. The access cavity had a quadrangular design and four root canals were located. One canal corresponded to a second palatal root canal in its own palatal root. After locating the extra palatine roots in these two cases, both could be negotiated, instrumented, and obturated. Results: during root canal treatment, types I and II of the palatal root classification system proposed by Chritie et al. for maxillary molars were identified. Conclusions: it is important to take into consideration these anatomical variations in the number and shape of the palatal roots of maxillary molars. Although its prevalence may be considered extremely low, such complex cases can be encountered in daily endodontic practice.INTRODUCTION
The three essential steps of endodontic therapy are cleaning, shaping, and obturation of the root canal system.1 Inadequate performance of one or more of these three steps along with the presence of additional root canals that may be missed during root canal therapy is among the main causes of endodontic treatment failure. Endodontic failure results in the permanence of bacteria in untreated root canals and the development of apical periodontitis.2 Therefore, to avoid inadequate management of root canal treatment, the endodontist must have a broad knowledge of the anatomy of the root and root canal system, as well as its possible anatomical variations.
The conventional anatomy of the maxillary second molar presents three roots.3 However, the possible presence of four roots is well established. Libfeld et al. found that in 1,200 maxillary molars, 90% had three roots, 7% had two roots, 2.6% had one root and only 0.4% had four roots.4 Pécora et al. found in 200 maxillary second molars that 116 (58%) of them had three root canals, while 84 (42%) had four root canals. No additional roots or additional palatal root canals were found in this study.5 The presence of additional palatal root canals in one palatal root has been well documented,6 however, the frequency of two palatal roots is extremely low and underreported.7 Peikoff et al. analyzed 520 treatments in second molars and found two palatal roots in 1.4%.3 The aim of this article is to report for the first time in Mexican patients the management of two upper second molars with two palatal roots during root canal treatment.
CASE PRESENTATIONS
Case 1A 41-year-old woman was referred for root canal treatment of the maxillary left second molar. The patient had no apparent pathologic data. The presence of a previous access cavity was noted but no radiographic signs of periapical pathology were observed during the radiographic examination. The clinical exam revealed a prolonged response to cold and the percussion test performed both horizontally and vertically was negative. Periodontal probing was within normal limits. Therefore the pulpal diagnosis was previously initiated pulp therapy and the periapical diagnosis was: healthy periapical tissues.
After the local anesthesia technique using lidocaine/epinephrine at 1:80000, root canal treatment was performed with absolute isolation with a rubber dam and magnification through loupes (3.5x). The access cavity was made with carbide burs and Endo-Z burs (Dentsply Maillefer, Ballaigues, Switzerland). No cracks or fracture lines were observed. Three root canals were initially located using a DG16 explorer (Hu-Friedy, Chicago, IL, USA), but the palatal canal was located more distally than normal, and that made the operator suspect the presence of an additional root canal. Therefore, a careful inspection of the pulp chamber floor was performed and the access cavity was slightly enlarged in the mesio-palatal direction. Once the 4 root canals were located, each was negotiated with a 10/02 file (Dentsply Maillefer, Ballaigues, Switzerland). The working length was taken with an apex locator (Root ZX, J. Morita, Tokyo, Japan) and confirmed with a digital dentoalveolar radiograph. Instrumentation was performed with the Reciproc® system (VDW, Germany) with the technique suggested by the manufacturer and supplemented with the Mtwo® system (35/05) (VDW, Germany). The same instrumentation protocol was used for all four root canals. Disinfection was performed with ultrasound-activated 5.25% NaOCl (3 cycles of 20 seconds) and 17% EDTA (Asia Chimi Teb, Tehran, Iran). After EDTA irrigation, 0.9% saline was irrigated to inactivate EDTA. Finally, 20 ml of 5.25% NaOCl was used to irrigate each root canal using an apical negative pressure system such as Endovac® (SybronEndo) as the final irrigation protocol. The obturation technique was performed using continuous wave compaction and AH + sealer (Dentsply Maillefer, Ballaigues, Switzerland) (Figures 1A-C).
Case 2A 28-year-old woman with a noncontributory medical history presented with pain upon thermal stimulus in the maxillary right second molar. Clinically, the presence of a fractured amalgam and deep caries was noted. Radiographically, the periodontal ligament space (PLS) width was normal and there was no periapical pathology. There was a prolonged response to cold and a positive vertical percussion test, with absence of periodontal pockets. The pulpal diagnosis was symptomatic irreversible pulpitis and the periapical diagnosis was symptomatic apical periodontitis. After local anesthesia technique with lidocaine with epinephrine at 1:80000, treatment was done through absolute isolation with a rubber dam and magnification with loupes (3.5x). The amalgam was removed with diamond burs and then the access cavity was designed with carbide burs and Star X ultrasonic tips (Dentsply Sirona). The access cavity had a quadrangular design and four root canals were located. Each of the four canals was negotiated using a pre-curved k10/02 file (Dentsply Maillefer, Ballaigues, Switzerland). The working length was taken with an apex locator (Root ZX, J. Morita, Tokyo, Japan) and confirmed with a digital dentoalveolar radiograph. The Mtwo® system (VDW, Germany) was used for root canal instrumentation. The buccal canals were instrumented at 35/04 and the two palatal canals at 40/04. The irrigation protocol and obturation technique were the same as in the previous case (Figure 2A-E).
DISCUSSION
Knowledge of anatomical variations is important for the proper management of endodontic treatment. Although the incidence of some of these variations may be extremely low, these anomalies should not be ruled out during the diagnosis and treatment of a tooth in need of root canal therapy. The etiology of the presence of extra roots in upper molars is not completely understood. The main cause may be due to histological phenomena such as the splitting or folding of Hertwig's epithelial sheath (HERS).8 The first mechanism results in two similar roots. The second mechanism results in the formation of completely independent roots with completely different anatomical characteristics. Other factors that may cause this anatomical variation may be trauma during the root formation stage, various genetic factors, or the individual belonging to a specific ethnic group.9
The presence of anatomical variations in upper molars has been studied previously. As mentioned above, the incidence of maxillary second molars with 4 roots can be considered extremely rare. In one study, of the 1,200 teeth analyzed, only 0.4% presented this condition.4 Despite the few case reports and studies on this condition, the bilateral and asymmetric occurrence of additional roots in maxillary molars has also been reported.10,11 In the literature, three systems have been suggested to classify the presence of accessory roots in upper molars (Table 1). Of these three systems, the most widely used seems to be the one proposed by Christie et al. Based on this classification, of the two cases presented in this article, the first one belongs to type I and the second corresponds to type II (Table 1). This is in agreement with recent studies in which these two types are reported to be the most prevalent.12 Recently, certain clinical characteristics were suggested to be used for the preoperative identification of maxillary molars with two palatal roots. These 6 clinical characteristics present only in the clinical crowns of maxillary molars with 2 palatal roots are a wider crown in the palatal half, double Cusp of Carabelli, pronounced palatal indentation, greater palatal enamel thickness, presence of palato-radicular sulcus and palatal enamel pearls.12
Preoperative radiographic identification of an additional root has some difficulties. These may include the overlapping of anatomical structures as seen in the preoperative radiographs of the two cases presented.13 If the contour of the roots is not clearly seen on a radiograph, (Figures 1A and 2B) further radiographs with different angulations should be taken to identify or rule out the presence of anatomic variations. Some of the angulation techniques for taking radiographs have been previously reviewed by Fava et al.13 Radiographs will always have certain limitations, regardless of the angulation techniques used, since the radiographic image is a shadow and also, a two-dimensional representation of a three-dimensional object.14 Despite these challenges, good quality preoperative dentoalveolar radiographs are very useful in identifying radiographic features (such as the lamina dura and periodontal ligament) that can be interpreted more consistently than others15 and may provide information for better determination of the number and shape of roots in upper molars.16 When tooth roots appear to be longer than the average length (20 mm) or maximum length (24 mm), this may be an indication of an additional root (Figures 1A-C). For example, some cases report maxillary second molars with two palatal roots showing a palatal root length equal to or greater than 26 mm.17 Usually, using the standard bisection angle technique, the palatal root can be seen behind and in the middle of the distobuccal and mesiobuccal root on a radiograph. If the palatal root could not be identified in the aforementioned position (Figures 1A and 2A), this would be an indication of an anatomical variation such as the presence of an additional palatal root. For correct identification of the palatal root in this situation, it is advisable to take further radiographs that modify the vertical or horizontal angulation to obtain a non-overlapping image of the structures of interest (Figures 1C and 2C). Working length radiographs may also confirm the presence of two palatal roots if the instrument appears to be away from the center of the root.18,19
The ideal method for accurate determination of the root canal morphology of a tooth is Cone Beam Computed Tomography (CBCT). CBCT offers a three-dimensional analysis of the tooth in need of root canal treatment without the limitations of conventional digital radiography.20 The applicability of CBCT to endodontics has been demonstrated in previous reports.21 In addition, the radiation dose produced by this method can be adjusted following the guidelines of Christoph et al. to produce an effective radiation dose of 0.56-0.06 mGy, which is equivalent to standard orthopantomography and may make it suitable for special medical conditions.22,23
CONCLUSIONS
Although CBCT is the gold standard for diagnosis and treatment planning for this kind of case, it is generally not very economically accessible, especially in countries such as Mexico. Therefore, the endodontist should have a broad knowledge of the possible anatomical variations and their clinical management.
REFERENCES
AFFILIATIONS
1 Facultad de Estomatología de la Universidad Autónoma de San Luis Potosí (UASLP).
2 Doctorado en Ciencias Odontológicas de la Facultad de Estomatología de la Universidad Autónoma de San Luis Potosí (UASLP).
3 Maestría en Estomatología con opción terminal en Ortodoncia, Benemérita Universidad Autónoma de Puebla (BUAP).
CORRESPONDENCE
Marco Felipe Salas Orozco. E-mail: marcosalasorz@gmail.comReceived: Junio 2020. Accepted: Marzo 2021.