Categories of this blog are
Tooth vital- tooth necrotic
# teeth with MB2 present- able to cleanse and shape the MB2 – MB2 join MB1 – teeth I consider calcified that no MB2 was found – total # of 2nd molar treated
MB2 distance from MB1 – join MB1
This MB2 appears to be a nothing more than a fin. I also found same situation on this patient a couple years ago on #15. Her #14 does have an MB2, which was not found in initial treatment and I was able to retreat. It may be that the MB2 joins the MB1 at what the Root ZX II was measuring as the apex. There was definitely a definitive direction change at that spot like either an apex or 2 canals joining.