Introduction
The discovery of additional canals in comparison to traditional canals is on a high rise and serendipitous. This should be accredited to the advances in endodontic therapy aids like magnification and thorough knowledge of the root canals’ anatomy for the past few decades. Oftentimes, endodontic treatments fail due to myriad reasons such as insufficient biomechanical preparation of root canals, inadequacies in the root canal obturation post cleaning and shaping, failure to access the miniature root canal orifices. All these may lead to acute flare ups during and after root canal therapies. 1
There is a general consensus regarding the anatomy of the permanent maxillary first molar that it shows three roots and four canals in the majority of teeth. 2 Literature reports a variation of 2.25 –2.4% of the occurrence of five root canals 3, 4 and a 0.319 – 0.88% existence of six root canals. 5 Regarding the existence of a second distobuccal canal, as low as 1.7% 6 and 1.25% 7 of cases have been reported in the literature.
An ex-vivo study showed one maxillary first molar out of 140 samples having three roots and seven canals. They identified three mesiobuccal canals, three distobuccal canals, and one palatal canal.8 Literature reports very few cases of endodontically managed maxillary first molars with seven and eight root canals.9, 10, 11, 12, 13 Contrasts in these variant root canal anatomies reported so far are listed in the Table 1. 9 This case report presents the treatment of a pulpally involved maxillary first molar which shows atypical root canal configuration of three roots and seven root canals which is later confirmed with the help of cone beam computerized tomography (CBCT) scans.
Case Report
A 28-year-old man approached us for dental treatment at our clinic with the chief complaint of a highly spontaneous toothache in his left posterior maxilla for 2 days. The upper left first molar showed tenderness to percussion and intense pain that was aggravated by thermal stimuli. History revealed that the patient had intermittent pain in the same tooth with hot and cold stimuli for the past 1 month which increased during mastication. The patient’s medical history was non-contributory.
A clinical examination unveiled a carious maxillary left first molar with no tenderness to palpation of the buccal and palatal aspects of the gingiva. The tooth was firm and the gingiva was coral pink, stippled, and resilient. Vitality testing of the involved tooth showed a premature response with electronic pulp stimulation (Parkel Electronics Division, Farmingdale, NY) whereas it caused a lingering pain with heated gutta-percha (Dentsply Maillefer, Ballaigues, Switzerland) and dry ice (R C Ice; Prime Dental Products Pvt Ltd, Mumbai, India) which was intense. A preoperative radiograph showed a mesio-occlusal radiolucency, involving enamel, dentin and the pulp space with periodontal ligament space widening in relation to the mesiobuccal root (Figure 1A). A diagnosis of symptomatic irreversible pulpitis with apical periodontitis was made after thorough clinical and radiographic examination and root canal treatment was suggested to the patient.
Radiographic evaluation of the molar did not reveal any variation in the canal anatomy. An emergency access opening and a thorough biomechanical preparation was planned in the first appointment. The tooth was anesthetized with 1.8 mL (30 mg) 2% lignocaine containing 1:200,000 epinephrine (Xylocaine; AstraZeneca Pharma Ind Ltd, Bangalore, India.) followed by rubber dam isolation. An endodontic access cavity was established. Clinical examination with a DG-16 endodontic explorer (Hu-Friedy, Chicago, IL) revealed two canal openings in each of the distobuccal and palatal root and two root canals in mesio buccal root. Further champagne bubble test revealed a third mesiobuccal canal along the mesiobucco- palatal leg of the molar triangle. A 28mm corrosion-resistant hard fiber austenite stainless steel gates glidden drill (Mani GGD #1) of size #1 was used in a coronal brushing motion to shape the orifices and clean the coronal one thirds of the root canals. (Figure 1B). The working length was determined with the aid of an apex locator (Root ZX; Morita, Tokyo, Japan) and later confirmed using a radiograph. Multiple working length radiographs were taken at different angulations (Figure 1C) to best reveal the number and morphology of root canal systems. Chemico Mechanical cleaning and shaping was carried out under rubber dam isolation using ProTaper gold nickel-titanium rotary instruments (Dentsply Maillefer) with a crown down technique. Irrigation was performed using normal saline and 5% sodium hypochlorite solution in the first appointment. An intra canal calcium hydroxide was placed inside the root canals with the help of lentulo spirals in a slow speed handpiece.
During the second appointment, the patient was asymptomatic. Access cavity was reopened and root canals were irrigated with 5% sodium hypochlorite, and normal saline solutions respectively. Master cone radiograph was taken (Figure 1D) and canals were irrigated with normal saline, 17% EDTA further 2% chlorhexidine digluconate was used as the final irrigant. The canals were dried with absorbent points (Dentsply Maillefer), and obturation was performed using cold lateral compaction by using gutta-percha (Dentsply Maillefer) and AH Plus resin sealer (Maillefer, Dentsply, Konstanz, Germany). (Figure 1E) Post obturation access cavity was documented with an intraoral camera image (Figure 1F). The tooth was then restored with a posterior composite resin core (P60; 3M Dental Products, St Paul, MN). A CBCT x-ray was taken to confirm the canal morphology. (Figure 1G) The patient has been advised a full-coverage porcelain crown and was asymptomatic during the follow-up period of 3 months.
Table 1
Variations of roots and the canal anatomy of maxillary molars, as reported by various authors, with the numerous terms that have been used to name these aberrancies.
Table 2
Bansal R,Hegde S and Astekar M. Classification of Root Canal Configurations: A Review and a New Proposal of Nomenclature System for Root Canal Configuration Journal of Clinical and Diagnostic Research. 2018 May, Vol-12(5): ZE01-ZE05.
|
Configuration |
Gulabivala K et al |
Sert S |
|
3-1 |
Type I |
Type XVIII |
|
3-2 |
Type II |
Type XV |
|
2-3 |
Type III |
Type XVI |
|
2-1-2-1 |
Type IV |
Type XIX |
|
4-2 |
Type V |
Type XIV |
|
4-4 |
Туре VI |
Type XX |
|
5-4 |
Type VII |
Type XXII |
Discussion
Although CBCT evaluation of root canals in the preoperative stage is a sure way to assess the root canal anatomy, at times of emergency this option may not be feasible. In these scenarios- magnification with the assistance of surgical loupes and surgical microscopes, fiber optic transillumination, angled preoperative radiographs, examination of the pulp‑chamber floor with a sharp explorer, troughing of the grooves with ultrasonic tips, staining the chamber floor with 1% methylene blue dye, performing the sodium hypochlorite “champagne bubble test,” and visualizing canal bleeding points are all essential aids in locating the root canal orifices. 14 In this present study loupes were used as an aid for magnification along with champagne bubble test to locate the additional orifices while following the access cavity preparation laws advocated by Krasner and Rankow.
The crucial variation found in the maxillary first molars is the presence of 54 percent chances of the second mesiobuccal canal (Hess 1925). This number seems to vary in the range of 70 to 80 percent (Hartwell and Bellizzi), 56.8 percent incidence of two canals (Cleghorn et al 2006), and a 95 percent chance by (Studebaker B et al 2017). In vivo studies typically report a lower frequency of two canals in the mesiobuccal root because of the clinician’s inability to manipulate the tooth in hand and inconsistency of obturating all root canals leading to high failure rates in endodontic treatment. 6, 15, 16, 17
Root canals are formed due to the secondary dentin apposition that occurs during tooth maturation. This results in dentinal vertical partitions inside the root canal cavity. A third root canal may also be created inside the root canal cavity of maxillary molars by this process. Chances of a second MB, extra DB, and an additional palatal canals occurrence are very sleek yet the possibility should never be ignored and thorough negotiation of the root canal floor has to be done for the ultimate success of the endodontic therapy. Guided troughing under high magnification enables the location of these extra root canals. The diameter of such extra canals is usually smaller than that of the other two. The third mesial canal is defined as being independent when a distinct coronal orifice and apical foramen are observed 18 and defined as being confluent when converging into one of the other two main canals and terminating at a common apical foramen. 19 Oftentimes, due to thin dentinal structure apposed between the root canal chambers, a coalition of confluent canals into a single canal is possible during the biomechanical preparation of root canals which happened in the present case.
Over the years, numerous root canal configurations have been identified resulting in the proposal of numerous classifications and their modifications. Depending upon the configuration, root canal may exit apically through one or more than one apical foramen. Kottor J et al (2010) presented a case with an MB1, MB2, MB3, DB1, DB2, MP, DP canals which is similar to the present seven canal morphology of maxillary first molar. Although preoperative CBCT evaluation was not done in this case, in the post obturation CBCT presence of seven root canal orifices can be precisely appreciated. Furthermore, this case shows 3-1 configuration in the mesiobuccal root which is classified as type1 anatomy according to Gulabivala, and type XVIII anatomy according to Sert S and Bayirli GS which was an extension to Vertucci classification 20 (Table 2). Adding further, a Vertucci type II classification was evident in the distal and palatal canals. The pulp space separates into three and joins in its course into one. In this present case, CBCT radiograph post obturation shows three apical foramina with seven orifices.
Conclusion
A thorough root canal floor inspection following access cavity preparation aided with a magnifying microscope or loupes can ease up the errors encountered due to aberrant canals. Chances of missing root canals can be eliminated when laws are followed meticulously in parallel with magnification. Therefore, the clinician has to consider this step with paramount importance while doing routine root canal therapy.
Article DOI
