A method for precisely identifying a fixed point of reference on a human jaw including providing a mandibular c-clamp, which has a shaft, an upper prong fixedly connected to the shaft, a lower prong movable along the shaft, and a wedge configured to selectively secure the lower prong to the shaft. The upper prong of the mandibular c-clamp is inserted into a patient's mouth. The lower prong of the mandibular c-clamp is then moved along the shaft to close on a patient's chin compressing patient's soft tissue, and a position of the lower prong is secured on the shaft using the wedge so that the lower prong is no longer movable along the shaft. A sensor is then secured to a designated area of the mandibular c-clamp so as to provide a reference point.