Bleeding on probing
Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
Bleeding on probing is a term used by dentists when referring to bleeding that is induced by gentle manipulation of the tissue at the depth of the gingival sulcus, or interface between the gingiva and a tooth. In order to determine the periodontal health of a patient, the dentist records the sulcular depths of the gingiva as well as observe for any bleeding on probing. This is often accomplished with the use of a periodontal probe.
Bleeding on probing, often abbreviated BOP, is a sign of inflammation and indicates some sort of destruction and erosion to the lining of the sulcus. Peer-reviewed dental literature thoroughly establishes that bleeding on probing is a poor positive predictor of periodontal disease, but conversely is a very strong negative predictor. The clinical interpretation of this research is that while BOP presence may not indicate periodontal disease, continued absence of BOP is a strong predictor (approximately 98%) of continued periodontal health.