Furcation defect
![Bone loss from aggressive periodontitis that led to an exposed furcation on an upper molar. In health, the bone exists about a millimeter and a half away from the cementoenamel junction, which is the line that separates the crown from the root trunk (the line can be seen clearly in the photo).](/Images/godic/202501/14/MolarFurcation5224.jpg")
![Evidence of furcal bone loss on #18 (lower left permanent second molar), along with a mesial vertical defect on the same tooth. The bent](/Images/godic/202501/14/-18_furcation5224.jpg")
In dentistry, a furcation defect is bone loss, usually a result of periodontal disease, affecting the base of the root trunk of a tooth where two or more roots meet (bifurcation or trifurcation). The extent and configuration of the defect are factors in both diagnosis and treatment planning.