Image processing and robotics are leading technologies to improve dental surgery. The important information for physicians to perform implant surgery is 'where to start cutting' and 'when to stop cutting'. The aim of this research is to achieve automatic guide system for teaching the information of 'where to start cutting'. To achieve this aim, L-J potential field, which can realize required performance of position adjustment with human interaction are proposed in this paper. Proposed potential field has three features. First, physician can free moving the manipulator when far from the distinction. Second, the manipulator will apply adjusting force for correctly converges to the destination when approaching to the distinction. Third, the manipulator will apply adjusting force for collision avoidance when passing the distinction. The validity of proposed L-J potential are confirmed through experiment using 2DOF parallel link manipulator.