A method of enabling a control of an orientation of a tool, particularly a dental drill, in relation to a work part, particularly a jaw, is disclosed. The method includes mounting a work part inertial system unit stationary to the work part； mounting a tool inertial system unit stationary to the tool； obtaining a digital image of the work part； defining three reference spots on the digital image of the work part wherein the three reference spots are distant from each other and stationary in relation to the work part； defining a target orientation of the tool on the digital image of the work part wherein the target orientation is definite with respect to a reference plane comprising the three reference spots； and referencing the tool inertial system unit to the three reference spots of the work part.
