Fig. 1

A 70 years old male with clear medical history  was referred for endodontic assessment and treatment of #46 and of #27.

Both teeth had very extensive amalgam restorations that were broken and the patient started to have pain on biting on both teeth, and on #27 sensitivity to hot and cold was getting worse.

Upon clinical examination recurrent decay was noted on both teeth, the #46 was very tender to percussion and had no response on thermal stimuli.  Tooth #27 was also tender to percussion but also hypersensitive to thermal stimuli.

The teeth were not mobile, and periodontal probing around the teeth was within normal limits.

Patient was going to have both teeth restored with crowns, and #27 was a strategic tooth to retain due to the loss of #26 a few years ago. 

A decision to perform endodontic treatment of both teeth  was made and a written informed consent was obtained from patient.

Fig. 2

Tooth #46

Diagnosis of Pulp necrosis and Symptomatic Apical Periodontitis was made for #46.

Caries removed and  the restorability of the tooth was assessed. Sufficient ferrule was present for an adequate indirect restoration.

Fig. 3

Rubber dam seal used

Access Cavity Preparation was made and  4 canal orifices were detected initially: MB, ML and D and DL. 

Troughing under high magnification with US tip and exploration using a DG 16 explorer revealed an additional MD canal. 

Working length Determination with Electronic Apex Locator .

Apical patency was achieved using 08, 10 stainless steel hand files. Cleaning and shaping of the root canals were done with rotary instruments  taper 4% under  copious irrigation with 3%% sodium hypochlorite throughout the procedure.

Fig. 4

Irrigation protocol included irrigation with 3% Sodium Hypochlorite,  17% EDTA and ultrasonic activation of irrigants with the use of Ultra-X tip..

Irrigation with 3% Sodium Hypochlorite using irriflex needle tip

Ultrasonic activation of 3% sodium hypochlorite irrigant with Ultra-x blue tip.

Fig. 5

Final x-ray of #46.

Obturation of canals with pulp canal sealer utilizing WVC using Fast Pack and Fast Fill. The MD is converging with MB canal at the apical 1/3 showing a Sert and Bayirli Type XVIII canal configuration( Sert& Bayirli 2004).

Access cavity was restored with composite resin and patient was scheduled to return for RCT on#27.

Fig. 6

Final X-ray of tooth 46.

Mesial shift.

Fig. 7

Tooth #27

Pre-operative photo of tooth #27 revealing  broken amalgam restoration and secondary decay.

Tooth was extremely sensitive to thermal stimuli and tender to percussion.

A diagnosis of Symptomatic Irreversible pulpitis and Symptomatic Apical periodontitis for #27.

Fig. 8

Removal of defective amalgam restoration, cleaned decay and pre –endo build up was performed with composite resin and access was made into pulp chamber.

Fig. 9

Access Cavity Preparation. 

Rubber dam seal used. The opening access was modified so that the pulp chamber could clearly be exposed. The chamber floor was examined with an endodontic explorer DG-16 under magnification. Five root canal orifices were revealed: three mesio buccal, one distobuccal and one palatal.

Fig. 10

Working Length determination. 

The canals were scouted with 08k and 10k stainless–steel hand files.To determine the working length an electronic apex locator was used and confirmed radiographically.

The  mesiobuccal canal anatomy was confluent with all 3 canals merging at the apical 1/3. They  originated as a separate orifices, MB1, MB2 and MB3 but apically they joined with the MB1 canal.

Cleaning and shaping of the root canals were done with 4% taper rotary instruments under copious irrigation with 3%% sodium hypochlorite throughout the procedure.

Fig. 11

Irrigation protocol included irrigation with 3% Sodium Hypochlorite, 17% EDTA and Ultrasonic activation of irrigants with the use of Ultra-X tip.

Obturation done with Pulp canal sealer and with  WVC.

Fig. 12

Photos of before and after obturation of tooth #27.

Fig. 13

Final X-ray of tooth 46.

The MB2 and MB3 are converging with MB1 canal at the apical 1/3.

Access cavity was restored with composite resin and patient was referred back to his  dentist for indirect cast restorations of both #46 and #27.

Fig. 14

Final X-ray of tooth 27.

Distal shift.

Fig. 15

Pre-op and post op radiographs of both teeth #46, and #27.

Fig. 16

About  the author: 

Andreas Louloudiadis

DMD 2001 University of Alabama USA

PGDip in Endodontics 2005 Aristotle University Greece

MSc in Advanced Endodontics 2023 Siena Italy

Full time private practice limited to Endodontics

Tutor at the 2nd level Master of Advanced Endodontics, University of Siena Italy

Certified Member of European Endodontic Society

Member of British Endodontic Society

Member of Hellenic Association of Endodontists

Fellow of SIE


Variations of anatomy do exist more often than we think and may result in frustration for some and fascination for others.

This article focuses on an uncommon anatomical variation where  both a right first mandibular molar and a left maxillary second  molar on the same patient  demonstrated a  5-canal  root canal configuration. The incidence of a third distal canal in mandibular first molar and a third mesiobuccal canal in maxillary second molar is extremely low. Nevertheless, clinicians should be alert to the variations in the number of roots and root canals and the peculiar or eccentric locations of root canals . Also, clinicians should be aware of the possibility that  more than one unusual anatomic variation can exist when they treat multiple teeth in the same patient as described in this article.

A thorough knowledge of root canal anatomy and its variations, careful interpretation of the radiograph, close clinical inspection of the floor of the chamber, proper access preparation , a detailed exploration of the interior of the tooth, proper armamentarium( magnification and illumination)  and lots of patience are essential for a successful treatment outcome. 


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