Effect of extraosseous devices designed for vertical distraction of extreme resorbed mandibles on backward rotation of upper bone segments.

We studied the result of vertical distraction osteogenesis in 34 patients as a method of restoring vertical bone height in atrophic mandibles. Cephalometric radiographs were obtained preoperatively, immediately after the installation of the distractor, at the end of the active distraction period (1-2 weeks), before placement of implants, after a consolidation period of 12 weeks, and annually thereafter. Particular attention was paid to the changed position of the upper segment in relation to the basal segment, compared with before and after active distraction. To monitor the position of the distracted upper bone segment, both the improvement in bony height and the angle of the distracted upper bone segment were scored using the menton-pogonion line as a reference plane. Surprisingly in nearly all patients there was a backward rotation of the segment with lingual-tipping of the upper segment by a mean of 12 degrees that meant that in such cases only 87% of the maximum gain in bony height could be achieved. As a consequence of the backward tipping of the top of the distracted alveolar ridge, the position of the implants was also more lingually directed. However, in all cases sufficient bony volume was achieved to allow placement of implants. Distraction osteogenesis is a successful way of restoring atrophic mandibles to gain sufficient bony volume to allow placement of implants. However, the vector of distraction is unpredictable.

Duration of orthodontic treatment and mandibular lengthening by means of distraction or bilateral sagittal split osteotomy in patients with Angle Class II malocclusions.

BACKGROUND: The purpose of this study was to investigate the duration of treatment of patients with skeletal Angle Class II malocclusions treated with orthodontic appliances and surgical lengthening of the mandible to close residual overjets. METHODS: In this retrospective study, the patients were divided into 3 groups. Group A consisted of 10 patients (5 boys, 5 girls; mean age, 10.11 years; range, 9.1-13.9 years at the beginning of treatment) who were treated with a headgear-activator, fixed appliances, and intraoral osteodistraction of the mandible. Group B consisted of 19 patients (10 boys, 9 girls; mean age, 12.3 years; range, 9.6-16.1 years) treated with fixed appliances and intraoral distraction. In group C, 13 patients (4 men, 9 women; mean age, 27.3 years; range, 12.11-40.7 years) were treated with fixed appliances and bilateral sagittal split osteotomy (BSSO). RESULTS: In patients treated with orthodontic appliances and surgical lengthening of the mandible, treatment time was influenced by the appliances and the surgical technique used. Patients treated with a headgear-activator, fixed appliances, and intraoral distraction osteogenesis (group A) needed significantly more treatment time than patients treated with fixed orthodontic appliances and intraoral distraction (group B) or fixed appliances and BSSO (group C). Duration of treatment with intraoral mandibular distraction (group B) was significantly (P < .05) shorter compared with mandibular lengthening with BSSO (group C). However, no definitive conclusions can be drawn, because of the retrospective study design. CONCLUSIONS: The best time and the best surgical procedure for correcting mandibular length have yet to be determined, and a prospective randomized trial is recommended.

The overbite and intraoral mandibular distraction osteogenesis.

PURPOSE: The purpose of this study was to quantify the overbite reduction in skeletal Angle Class II malocclusions and discuss the management of the overbite during and after intraoral distraction of the mandible, and during orthodontic treatment with fixed appliances. MATERIAL AND METHODS: Cephalograms of 26 patients with an Angle Class II malocclusion and orthodontic appliances and distraction osteogenesis of the horizontal part of the mandible before (T0) and at least 1 year after treatment (T1) were evaluated. Mean age of the patients at the time of distraction was 14.6 years (range 12.8-15.9 years) and at the final registration 17.3 years (range 14.6-20.4 years). RESULTS: The overbite decreased significantly and the SpP/MP value increased significantly. The increase in the value of the Y-axis and the MP/SN angle before and after treatment was statistically insignificant. CONCLUSION: Opening of the bite during distraction of the mandible can be expected. The use of the 'floating bone' technique did not correct the overbite permanently. The patients in whom an open bite has already been treated are not ideal for mandibular lengthening by means of distraction osteogenesis.