Endodontic Management of Three Rooted Mandibular Premolar: A Case Report

Headnote

Abstract

High levels of success in endodontic treatment require an understanding of root canal anatomy and morphology. The clinician must be prepared to identify those teeth that tend to vary generally from the norm. Thorough debridement and obturation of such teeth can be challenging and failing to do so, can lead to treatment failure. Mandibular premolars have earned the reputation for having aberrant anatomy. However, the occurrence of three separate canals with three separate foramina in mandibular pre molars is very rare. The incidence of three canals is as high as 23% in mandibular first premolars, whereas in second premolars incidence is as low as 0.4%. This presentation reports one such three rooted mandibular second premolar and discusses the diagnosis and treatment recommendations for successfully treating such variation.

Keywords: Root canal morphology; mandibular premolar; three root canals; buccal bifurcation of roots; modified access cavity.

Introduction

The main objectives of root canal treatment are thorough cleaning and shaping of all pulp spaces and its complete obturation. Knowledge of both basic root and root canal morphology and its possible variations is necessary and important to achieve successful root canal therapy. The presence of an untreated or missed canal may be a reason for failure of endodontic treatment.12 Most of the times root canals are leftuntreated because the clinician fails to identify their presence particularly in teeth that have anatomical variation. Slowey as indicated Mandibular premolars as the most difficult teeth to treat, probably because of the aberrations in their canal morphology3

Incidence of number of roots and the number of canals reported in anatomical studies varies greatly in literature.4'5 Mandibular premolars can have highly variable and extremely complex root canal morphology. Also ethnicity and sexual dimorphism influence the variarion4. Picora et al., observedthat5.3%ofmandibularsecondpremolarsexam-ined, had two canals with two foramen and 44% had two canals with one foramen and only 0.46-5% showed three canals and three foramen configuration.6 Zillich and Dows-on reported 0.4% incidence of three roots and 12.5 % of two or more canals in second premolar compared to 23% in first premolar.5'7 The purpose of this article is to report and discuss the diagnosis and treatment recommendations of a rare occurrence of three rooted mandibular second premolar.

Case report

A19-year-old male patient was referred by the Department of Prosthodontics for intentional root canal treatment in relation to mandibular leftsecond premolar. Patient's chief complaint was dislodged crown and severe sensitivity on consuming hot and cold food stuffs. Clinical examination revealed crown preparation on 35 with longer mesio-distal dimension. Patient gave a history of extraction of tooth 36 and root canal treatment in relation to tooth 3 7, a year back which was mesially inclined. Teeth 35 and 37 were intended to be the abutment teeth for replacing 3 6 with three unit porcelain fused to metal (PFM) bridge. Tooth 35 was non-tender to percussion and showed positive response to cold and electric pulp testing. Intra oral periapical radiograph showed bifurcation at cervical third of both premolars with normal periapical features (Figure 1) More than two canals, were suspected in both 34 and 35.

Withadiagnosisofreversiblepulpitis,rootcanaltreatment was initiated in relation to 3 5 under inferior alveolar nerve block and rubber dam isolation. On entry into pulp chamber, the chamber was wide mesio-distally and access cavity resembled triangular shape with its apex towards mesial side (Figure 2). On careful exploration, three separate orifices (one mesial, two distal) were located with an endodontic explorer (DG 16). Canals were negotiated with No. 10 K-file (Mani) and cervical constriction was removed using Gates Glidden drills No. 3, 2, 1 (Mani) in a crown down manner. Working length was determined radiograph-ically (Figure 3, 4). Canals were instrumented and shaped with Hand ProTaper files (Dentsply) till finishing file F2, to the working length. 3% Sodium Hypochlorite was used as an irrigant and RC Prep (Premier Dental products, USA) as anlubricantduringinstrumentation. Finallycanalswere irrigated with saline and dried with paper points. Obturation was completed with ProTaper F2 Gutta Percha cones (Dentsply India) and Zinc Oxide Eugenol sealer (Figure 5). A final radiograph was taken to confirm the quality of obturation (Figure 6). Patient was rescheduled after a week for follow-up and access restoration.

Discussion

A thorough knowledge of root canal anatomy, careful interpretationofradiographandpropermodificationofthe coronal access opening seem to be essential for recognition and adequate treatment of teeth with anatomical variation. Accurate pre-operative radiograph, straight and angled are essential in providing clues as to the number of roots that exist. A second radiograph from 15-20° from either mesial or distal from the horizontal long axis is necessary to accurately diagnose the number of roots and canals in premolar teeth8. Sudden narrowing of the canal or change in radiographic density of root canal space suggests canal multiplicity.9 Use of magnification and fiber optic illumination improves clinician's ability to visualize, identify and treat additional canals.

Clinical presentation of a multi-rooted mandibular premolar is frequently atypical. Gingival recession may reflect the furcal morphology in these teeth and hint at the presence of 2 buccal roots. Probing the buccal sulcus to feel the root eminences may also help to identify the presence of 2 buccalroots.10

The pulp chamber that appears to be deviated from its classical bucco-lingual configuration and seem to be either triangular in shape or too large in mesio-distal plane should be suspected of opening into a system containing 3 canals." The case reported here showed similar access presentation. Observation of anatomical landmarks in the pulp chamber floor and use of dyes may also be helpful in locating additional canals.

Clinically negotiating the additional canals in premolars showing bifurcation or trifurcation midway along the length of the root is a difficult task which demands, time and patience (Figure 7). In case of canal division the initial scouting files (No. 6, 8, and 10) may encounter an obstruction and may deflect before it travels any further (Figure 8). Therefore, a sense of tactile feel and appropriate pre-curvingofthescoutingfilesisimportant.

Once it is established that there are 3 canals, it is important to obtain straight line access. This may be achieved by the use of Gates Glidden drills in a crown down fashion, especially in cases of single canal dividing along the length of the root. Despite the existence of complicated anatomy, use of hand or rotary Ni-Ti instruments can prepare the canal to apredictable shape.12 But obturation of such canals is not easy. Each canal should be filled one after the other. A pre-selected plugger or file has to be placed in canals to keep it patent while the canal adjacent is being obturated.10 Once all the canals are filled till the division, rest of the coronal canal can be obturated either by vertical compaction or backfilling technique.

In the present case all the canals could be found and negotiated. It was comparatively easy as the root system was characterized by complete separation of roots and 3 separate exits. The furcation division was more cervical which could be easily seen in the radiograph. Access cavity resembled that of a mandibular molar but having one mesial and two distal roots. This was confirmed in working length radiographs taken in both mesial and distal angulation. Use of Gates Glidden drills gave a straight line access to the canals and the ProTaper system for canal shaping helped in achieving cleaning and eased the obturation process. Though mandibular premolars are known to show root bifurcation bucco-lingually, the present case exhibited a rare mesio-distal branchrng, which is quite significant.

Conclusion

Mandibular premolars have gained a reputation of aberrant canal anatomy and are that's why termed as Endodontist's enigma. Given the incidence of occurrence of multiple roots and/or canals they pose a particular challenge during endodontic treatment. Knowledge of the anatomical variation, multi-angled radiographs, magnification, proper instruments and instrumentation technique can be useful in effectively treating such cases.

References

References

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