Fig. 1

This is how the map looks like. Asymmetrical cross like figure could be associated with map of orifice of four canal maxillary first molar.

Fig. 2

In cases like this we can see clues which is suggesting MB2 location, like in this image, we can move dentinal shelf to mesial wall with ultrasound tips and do probing with DG16 to fill the entrance and direction of MB2.

Fig. 3

Tooth 16. Referral case, doctor accidently finds after treatment of tooth  MB2 on CBCT but was not able to trace it in tooth. Other three canals were already treated and obturated. You can see wrong MB2 searching path. Location was perpendicular to distal and inwards to mesial wall as shown on image.

Fig. 4

Ultrasound tips was used for taking excess dentinal deposition on the suggested place, high shank carbide burrs with smallest diameter of  head on low speed was used to make a groove, where DG16 was used to identify direction of the canal. Rotary instruments was used for mechanical scouting and shaping of MB2 .Canal was obturated with bioceramic sealer and warm gutta-percha technique.  

Fig. 5

Retreatment case of tooth 16 with ignored MB2.Canal was searched on intersectional line between mb1/ palatal and distal and inwards to mesial wall up to 0,5mm.

Fig. 6

Tooth 26 vital case , after access cavity is done and all the canals are located looking for MB2 is easy. Right on the perpendicular intersection of two lines and bit mesial, it’s been there.

Fig. 7

Tooth 26, retreatment case with ignored MB2. Searching for Mb2 is done based on location of distal canal and intersectional lines .

Fig. 8

Tooth 26 retreatment case. located on the line of intersection but closer to mesial wall  more than 0,5 mm.

Fig. 9

Tooth 16 retreatment case with ignored MB2. Retreatment here was done in 2 appointments , MB2 was searched at the end. Location strategy is same. 

Fig. 10

Tooth 26 retreatment case with ignored MB2 .First gutta-percha was evacuated form canals, afterwards searching for MB2 was done with ultrasound tips, negotiation of the canal was fully mechanical with rotary instruments. Obturation warm vertical compaction and ah plus sealer.


It is of highest importance to have knowledge of  variability of Maxillary Molar anatomy and the distribution of MB2 in your region, as well as be prepared to deal with hidden MB2. Although, we can't state that there is always standard location of Mb2 , but we can be sure that in Majority cases this method will help with identifying its place. Using magnification , ultrasound tips , endodontic probe, rotary instruments from the beginning  is crucial to be successful with MB2 canals.


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Buhrley LJ, Barrows MJ, BeGole EA, Wenckus CS. Effect of magnification on locating the MB2 canal in maxillary molars. J Endod. 2002 Apr;28(4):324-7. doi: 10.1097/00004770-200204000-00016. PMID: 12043874.