In recent years close consideration of the biomechanical principles of treatment of mandibular fractures has led to the use of operative as well as conservative methods. Since this combined method of treatment appeared cumbersome, a new kind of osteosynthesis plate was developed for functionally stable internal fixation of mandibular fractures, without the necessity of additional fixation elements. After consideration of the biomechanics of the mandible, an even greater indication for the use of the lag-screw osteosynthesis is found. Use of both the tension band plate and the lag screw makes it possible to perform the operation intraorally. This is a further indication for the use of the operative internal fixation of fractures in the treatment of mandibular fractures, since it has many advantages for the patient.