Mandibular distraction using a dynamic osteosynthesis system: MD-DOS. Concepts and surgical technic]

MD-DOS (mandibular distraction with a dynamic osteosynthesis system) is an intra-oral mandibular distractor that can be placed via the oral route, enabling application under local anesthesia. The aim of the article is to describe the technical-surgical aspects of the treatment concept, based on an initial experience of 35 cases. The device is characterised by a single horizontal posterior fixation screw-implant, a vertical hinge that copes with the lateral force vector in the condyles, a telescopic distraction module, and an anterior fixation unit that is fixed with monocortical screws. The main indication was mandibular lengthening in Angle Class II, deep bite cases. The third molars could be removed in the same session. Of importance was the horizontal placement of the posterior fixation unit (PFU), together with the distraction module, in order not to interfere with lateral jaw movements and with the lower sulcus. Equally important was the use of at least one 7.5 mm long osteosynthesis screw together with at least three 5.5 mm screws. Near complete mobilisation of the segments, firmly blocking the posterior fixation unit with the vertical hinge in a perpendicular position, and placing MD-DOS as close as possible to the dental arch, were also important parameters for success.