in implant dentistry, running room refers to the apico-coronal distance between the platform of a dental implant and the gingival margin. it is a critical factor in restorative implant dentistry because it is effectively the "vertical distance [available subgingivaly] to make a transition from the smaller diameter prosthetic platform of an implant to the larger cross-sectional cervical shape of the tooth being restored." the term was coined by jonathan zamzok, a manhattan prosthodontist, in the late 1990s.