Correction of mandibular retrognathia and laterognathia by distraction osteogenesis IntroductIon Distraction osteogenesis has become a wide- ly accepted procedure in orthopedics and has been applied to treat the skeletal deformities and severe bony defects in the craniofacial com- plex.1-8 With this procedure, bone volume can be increased by gradual traction of a fracture cal- lus formed between osteotomized bony seg- ments.8-10 Bone lengthening by osteotomy and distraction osteogenesis of long bones was first described in 1905 by Codvilla and popularized by Ilizarov. Mandibular lengthening by gradual dis- traction was reported in 1973 by Synder et al who used an extraoral device in a canine study; new bone formation at the elongated site was demon- strated later by Karp et al. In 1992, McCarthy et al successfully elongated the mandible by up to 24 mm.7,8,11,12 Distraction osteogenesis is particu- larly useful for treating cases of severe bony hy- poplasia where the surgical movement required to correct the malocclusion is outside the range predictably achievable with routine orthognathic surgery techniques.8,10,13 In patients for whom only mandibular deficien- cies need to be corrected surgically, bilateral sag- ittal split osteotomy (BSSO) is the most common procedure. Intra-oral distraction osteogenesis during orthodontic treatment as a solution for a Class II malocclusion has been proposed as an alternative to BSSO.14-19 Mandibular distraction is becoming a prevalent surgical treatment for ret- rognathia and asymmetry, and many reports have demonstrated that this technique provides great clinical benefits for mandibular deficiency and other craniofacial deformities.7,8,20,21 One of the shortcomings of distraction osteogenesis, how- ever, is that accurate positioning of the proximal segment can be difficult to achieve either because of an inaccurate displacement vector or because of an unpredictable soft tissue influence on the immature regenerate. It has been shown in an an- imal model and in clinical case reports that post- distraction regenerate can be molded by external forces.13,22-26 van Stiejen et al studied the complications in bilateral mandibular distraction osteogenesis and recorded a total of 28 complications in their study sample of 70 patients. They reported osteotomy related complication in 1 patient, technique and/ or device-related complications in 10 patients, infection in 5 patients, prolonged sensory loss in the distribution of the alveolar nerve in 3 patients, compliance related complications in 6 patients and condylar problems in 3 patients.27 In this paper, the results of mandibular length- ening and correction of mandibular asymmetry by distraction osteogenesis are demonstrated. subJEcts And MEtHods The procedure was carried out in 5 subjects (3 males and 2 females, mean age 18.4 years) aged between 14 years and 27 years. The orthodontic and surgical treatment of the subjects was per- formed at the same center. Written informed consent was obtained from the parent or patient before treatment. The detailed information on subjects is shown in Table 1. Two patients had mandibular asymmetry re- sulting from odontogenic infection in one and from trauma in the other and the other three had sagit- tal mandibular deficiency. Of these three patients, one had a history of trauma during early childhood and in the other two the aetiology was unclear. One of these three patients underwent mandibu- lar advancement surgery with BSSO. However, be- cause of relapse seen after treatment, a decision was made to perform mandibular advancement by distraction osteogenesis. Three of five patients underwent bilateral mandibular distraction and in the remaining two patients, unilateral mandibular distraction osteogenesis was performed to correct mandibular asymmetry. Of these 2 patients, one underwent surgically assisted rapid maxillary ex- pansion prior to unilateral mandibular distraction and the other one received surgery for the treat- ment of the ankylosis of the temporomandibular joint. However, the asymmetry remained. All five patients had pre-and post-operative orthodontic treatment with fixed appliances and distraction osteogenesis surgery was carried out under general anesthesia in all cases. Lateral and posteroanterior cephalometric and panoramic ra- diographs were taken from all patients on three different occasions (before treatment, after treat- ment and during follow-up period). The landmarks and planes used in cephalometric analysis are shown in Figure 1. Further surgical procedure in- cluded genioplasty in three patients. In patients 4 and 5, a complete oblique oste- otomy of the ascending ramus was made through 336 European Journal of Dentistry