# Intermodular Mandibular Distraction Osteogenesis--A Preliminary Report
###### Abstract  
Background: Dental Class II is the most common indication for combined orthodontic-orthognathic treatment. Interm mandibular distraction osteogenesis (IMDO) treatment was performed during the growth spurt, to avoid surgery at a later age. The aim of this study is to present our first experience with IMDO. Methods: This is a retrospective case series of patients who underwent an IMDO. All patients showed mandibular retrognathism, and orthodontic treatment with functional appliances was not successful. Results: In total, 20 patients (mean age of 14.8 years (SD = 0.9 ys) were included. All patients achieved a Class I occlusion. An average length gain of 9.6 mm (SD = 3.7 mm) was reached. In one patient an abscess occurred. Nine patients presented with root fractures of the second molar; three were lost, one treated endodontically. The average time between insertion and removal of the distractors was 4.6 months (SD = 1.5 mths). In one case a premature consolidation was seen. Conclusion: We achieved satisfactory results with IMDO, although undesirable effects occurred. An advantage is the manageable overall treatment time. Open questions concern the occurrence of root fractures. Furthermore, the question of long-term stability is open. The question of dynamic distraction treatment in relation to temporomandibular joint changes can only be answered in the long term.  
distraction osteogenesis; osteotomy; orthognathic surgery; mandibular retrognathism; class II jaw relation +
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with osteosynthesis plates according to Champy finally also allowed the wide advancement of the mandible with simultaneous stable fixation. Finally, bimaxillary correction procedures completed the standard repertoire of orthognathic surgery [7; 8; 9; 10].  
Safer anesthetic and surgical procedures, treatment concepts, and digital three-dimensional planning pushed the boundaries of orthognathic correction surgery indications toward elective facial aesthetic surgery and into younger stages of life. Orthodontic treatments also benefited primarily from digital planning and simulation capabilities [11; 12]. However, some problems of combined orthodontic and orthognathic surgery remained unsolved. To name the two most important: Growth remains unpredictable and interventions in biological systems can produce undesirable effects. Early functional treatment of children in the mixed dentition phase is used to correct deficient growth and is well established in orthodontics. However, if growth is absent and the cooperation of the still young patients is insufficient, the treatment may fail. The resulting frustration must be shared by the young patients, the parents and the practitioner.  
In the case of a Class II occlusion, there are two basic options: terminate treatment without achieving the desired result or switch to a combined approach including surgery. This is often seen as critical, especially by parents. If surgical correction is considered, there are again two options: Operate while the child is still growing or wait until the end of growth and then intervene correctly. The standard treatment would be BSSO with mandibular advancement. It is the BSSO before the end of growth that cannot prevent later recurrences.  
The possibilities of therapeutically effective uses of distraction osteogenesis (DOG) in young growing individuals has been known for a long time [13]. Coceancig has recognized this potential and adapted DOG to the intermodular mandibular distraction osteogenesis (IMDO) treatment in young patients before pubertal growth has started [14].  
The advantage for the young patient results from the hypothesis that, if the result is stable, a new start of treatment with a long orthodontic procedure combined with surgery can be avoided after growth completion. The disadvantage in distraction therapy is that a second surgery is always needed to remove the devices and in the IMDO the risk of root damage of the molars in the mandible is present.  
The aim of this study is to present our experience with IMDO.