This case was referred as the treating dentist was astute enough to recognise that while some lower second molars only have two canals, the majority will have at least three. Only one orifice was visible mesially. The mesial roots of lower second (and third) molars are often challenging to treat for a number of reasons. Access can be difficult, there is often a double curve in the mesio-distal and bucco-lingual plane, and often we see a single orifice with two canals. This was one of those cases where only a single orifice was visible mesially.
Before attempting to tackle this case we took a CBVT. The CBVT presented a finding indicative of a second canal in the mesial root. This is good information to have, as if we suspect there are two canals, we know where to remove dentine in an attempt to locate the canal. If we suspect only one canal after viewing the CBVT, we don’t need to be needlessly removing further dentine in the all-important pericervical area.
The CBVT also tells us where to look – buccal or lingual of the orifice. In my experience, the classic situation for these canals is for the main canal to be the mesiobuccal, with the mesiolingual canal coming off the main canal a few millimetres below the orifice. The orifice to the second canal can be quite small, and as it comes off the main canal at a sharp, almost 90 degree angle, we have to be careful to open the canal coronally with some hand files before attempting to place a rotary file in it.
So there you have it. One more little gem in your bag of tricks for treating difficult anatomy. Have you had experience in cases such as this? Share your comments below.