A unique lesion mimicking a root fracture due to a patent furcation canal

The MB2 canal of upper molars is highly variable. It can join the MB1 canal, it can be completely absent, and (as in this case) it can have its own separate foramen far short of the radiographic apex.
This patient presented with unilateral sinus congestion, pain to percuss tooth #14, and a 6mm periodontal probing defect along the tooth’s buccal aspect. A CT scan confirmed that the tooth was necrotic, but also revealed maxillary sinusitis in the area, as well as furcal bone loss that could be misdiagnosed as a fracture.
Root canal therapy was performed and at the 6-month recall visit, the patient was asymptomatic without congestion, and the periodontal probing defect had resolved. Another CT scan confirmed the sinus healing…and it is always nice to see a puff of sealer when the MB2 foramen is in an unusual place.  Below you will find pre- and post-operative radiographs, as well as pre- and post-operative CBCT slices.  The CBCT slices illustrate, first, the resolution of the sinusitis after root canal therapy, and secondly, the unusual location of the MB2 canal near the furcation area.