Three-dimensional finite element analysis of craniofacial skeleton protraction at medium position / 中华整形外科杂志

<p><b>OBJECTIVE</b>The purpose of this study was to investigate the biomechanical changes of midface skeleton protraction at its medium position in the craniofacial complex, using the three-dimensional finite element method (FEM).</p><p><b>METHODS</b>A three-dimensional FEM model was developed from the CT scan images by the technologies of three-dimensional reconstruction, image processing and meshing. The protraction forces were applied to the following locations: the first molar, full maxillary arch, and the floor of aperture piriforms. Biomechanical changes from different position protraction were investigated by means of finite element analyses.</p><p><b>RESULTS</b>Protraction forces at the level of the floor of aperture piriforms produced a more forward movement of the upper maxilla in sagittal direction. Vertical and lateral displacements were less than those in loading with teeth or denture. Compressive stress on the radix nasi decreased obviously in midface skeleton protraction at its medium position.</p><p><b>CONCLUSIONS</b>Compared with traditional orthopedic protraction, midface skeleton protraction at its medium position could advance maxilla en bloc, decrease the counterclockwise rotation of the maxilla, and reduce the constriction of the anterior part of the palate.</p>

Trans-sutural distraction osteogenesis for early correction of midfacial hypoplasia in children: a primary clinical report / 中华整形外科杂志

<p><b>OBJECTIVE</b>To probe the possibility of trans-sutural distraction osteogenesis for correction of children midfacial hypoplasia.</p><p><b>METHODS</b>The trans-sutural distraction system of mid-facial skeleton consisted of the bone-borne traction hooks of titanium, the face-bow, and the elastic loops. Nine children with midfacial hypoplasia were treated at their 6 - 12 years of age. No osteotomy was made in them. Bone holes were drilled with a dental bur at each side of the lateral-inferior rim of the aperture, or at the anterior part of the hard palate. The traction device was hatched to the holes through the nostrils. Protraction began 3 days postoperatively, with the forces adjusted dependently upon the rate of progress. When the skeleton reached to the planed position, it was retained with a minor force for 8 weeks.</p><p><b>RESULTS</b>The mid-facial skeleton of the nine children showed a balanced advancement. Their facial profile and cross-bite were corrected satisfactory.</p><p><b>CONCLUSIONS</b>Patients with severe mid-facial hypoplasia could be corrected ideally by the new technique, with minor trauma, easy manipulation. The design of protraction system was reasonable.</p>

Responses of dogs at different ages and long-term effects for midface skeleton protraction / 中华整形外科杂志

<p><b>OBJECTIVE</b>To explore the factor of age related to protraction response.</p><p><b>METHODS</b>Four 12-week mongrel dogs in the same nest were randomly assigned into two groups: the control (n = 1) and the experimental groups (n = 3). Four pairs of titanium bone markers were fixed on either side of the bone sutures of all animals. Distraction device was fitted in the experimental group, A forward elastic force was exerted through the device for 1 month. Midface skeleton protraction was applied to experimental group at different age. Dog 2 was started at 12 weeks of age. Dog 3 was started at 16 weeks of age. Dog 4 was started at 20 weeks of age. The protraction force was 600g. All the animals were sacrificed at their age of 9 months. The results were evaluated clinically, radiographically, and cephalometrically.</p><p><b>RESULTS</b>All the animals in the experimental group showed progressively forward movement of the maxilla at the end of the experiment. In the same condition, the younger age appeared to have more effective in treatment than the older age. After 3 approximately 4 weeks stagnation, the maxilla gradually recovered normal growth.</p><p><b>CONCLUSION</b>The younger age lead more effective protraction than the older age. Persistent elastic distraction at the medium position of midface brought stable effects and no influence on facial growth.</p>

Le Fort III osteotomy and medium position distraction for mid-facial hypoplasia / 中华整形外科杂志

<p><b>OBJECTIVE</b>To probe the possibility of distraction osteogenesis for correction of mid-facial hypplasia using a new technique.</p><p><b>METHODS</b>The distraction system of mid-facial skeleton consisted of a face-bow, the elastic loops and a device that hitched to bone holes made in the aperture rim. Flllowing Le Fort III osteotomy, a bone hole was drilled at each side of the external-inferior rim of the aperture by a dental bur. The traction device was hitched to the holes through the nostrils. Distraction began three days postoperatively, with the force adjusted dependently upon the rate of progress. When the skeleton reached to the planed position, distraction was retained with a minor force for 8 weeks. Three adults with mid-facial hypoplasia underwent this treatment.</p><p><b>RESULTS</b>The mid-facial skeleton showed a balanced advancement. The patients' facial contour and occlusal relationship recovered completely.</p><p><b>CONCLUSIONS</b>Patients with severe mid-facial hypoplasia could be corrected ideally by the new technique, with balanced advancement of mid-facial skeleton, minor trauma. The design of distraction system was reasonable. The manipulation of the procedure was easy.</p>

Mid-premaxillary sutural distraction osteogenesis for repair of alveolus cleft: an experimental study in dogs / 中华整形外科杂志

<p><b>OBJECTIVE</b>To explore a new technique for repair of alveolar cleft by sutural distraction osteogenesis.</p><p><b>METHODS</b>Nine 8-weeks mongrel dogs were used in this study, three being in the control group, six in the experimental group. Alveolar cleft model was created surgically in all animals. Two weeks later, a U-shaped distractor made of Ni-Ti memory alloy wire was insterted into the premaxilla to distract the mid-premaxillary suture. When the premaxilla of the cleft side approached the ipsilateral maxilla, periosteoplasty of the alveolar cleft was performed. The distractor was removed at two weeks after periosteoplasty. The results were evaluated clinically, radiographically, morphologically and histologically.</p><p><b>RESULTS</b>The cleft model in dogs was stable and similar to the human alveolar cleft. In experimental dogs, the premaxilla was moved gradually toward the maxilla so that the cleft was closed. The distracted mid-premaxillary suture showed a gradually widened traingle, with its tip being posterior. The density of the distracted traingle suture was increased gradually. Bony repair was achieved completely at the cleft three months post-periosteoplasy. The morphology of the mid-premaxillary suture was restored.</p><p><b>CONCLUSION</b>The alveolar cleft could be repaired by the technique of mid-premaxilla suture distraction.</p>

Sutural distraction osteogenesis for primary cleft palate repair: a preliminary clinical report / 中华整形外科杂志

<p><b>OBJECTIVE</b>To probe the possibility of a new technique of primary cleft palate repair by sutural distraction osteogenesis.</p><p><b>METHODS</b>The distractor was made of TiNi-shape memory alloy with 2 secure and 2 active arms. Under general anesthesia, 1 hole was drilled on each maxillary process and horizontal plate of palatine. The four arms of the distractor were inserted into holes. The palatine bones would then be distracted and moved medially and posteriorly. After 4 to 5 months' distraction, the two cleft edges approached gradually. The residual cleft, according to its width, was repaired by direct stitch of muco-periosteum incised at cleft edges, or with an additional relaxing incision on one side of the palate. Direct measurement of width of maxillary arch and the cleft, and the length of the hard palate was performed before and after distraction to evaluate the effects of distraction.</p><p><b>RESULTS</b>Eight cleft children at their 2 to 4 years of age were treated by the new technique. Two of them terminated the procedure due to premature dislocation of the distractor. Six children underwent 37 to 126 days' distraction. Dramatic narrowing of the cleft and lengthening of hard palate were seen in these children, with the average narrowing of the cleft being 6.5 mm and average lengthening of the hard palate being 4.8 mm.</p><p><b>CONCLUSION</b>It is clinically demonstrated that palatal tissue regeneration and cleft closure or narrowing and hard palate lengthening could be achieved by the technique of sutural distraction osteogenesis.</p>

Long-term effects and influence on facial structure of palatal distraction / 中华整形外科杂志

<p><b>OBJECTIVE</b>The purpose of this study was to evaluate a new palatoplasty with persistent elastic distraction osteogenesis.</p><p><b>METHODS</b>Twenty mongrel dog aged in 6 month were divided into two groups: the control (n = 10) and the experimental group (n = 10). The cleft palate model was made surgically in experimental dogs. The hard palate clefts were repaired with persistent elastic distraction osteogenesis. Then the animals were observed for an additional 12 weeks before sacrifice. Direct measurements was taken on dry skulls of the dogs and the data were analyzed statistically.</p><p><b>RESULTS</b>For all experimental dogs, the clefts were closed after gradual distraction. No relapse and airway blocking occurred in observational period. There were no significant differences in the variables of facial length, height and width between the two groups (P > 0.05). The length of horizontal portion of hard palate in experimental group was significantly longer than that in the control (P < 0.01).</p><p><b>CONCLUSION</b>There was no complication and disturbance on maxillofacial structure in repairing cleft palate with persistent elastic distraction osteogenesis. It is an effective and safe technique for repairing cleft palate in animal model.</p>

The possibility of midface skeleton protraction: an experimental study in dogs / 中华整形外科杂志

<p><b>OBJECTIVE</b>To probe the feasibility of a new technique of sutural distraction osteogenesis for midface hypoplasia repair.</p><p><b>METHODS</b>A protraction system was developed, which consisted of three parts: a rigid external framework, a bone hook, and the elastic band. Four 12-week mongreal dogs were randomly assigned into two groups: the control (n = 1) and the experimental groups (n = 3). Four pairs of titanium bone markers were fixed on either side of the bone sutures of all animals. The experimental group was fitted with a distraction device, through which a forward elastic force was exerted for 1 month. Clinical observations and X-ray examinations were performed at the beginning and the end of distraction. New bone specimens were examined histologically.</p><p><b>RESULTS</b>All the animals in the experimental group showed progressively forward movement of the maxilla and manifested class II occlusion at the end of the experiment. The distance increase between each pair of bone markers showed that premaxilla advancement was more than that of the maxilla. The next was zygoma. There was no obvious difference between the control and the experimental group in terms of the basilar-maxillary angle and counterclockwise rotation. Theer was active osteogenesis in the sutures, especially in premaxilla-maxillary sutures. The number of osteoblasts and fibroblasts increased dramatically and new bone formation was found at the edge of the suture.</p><p><b>CONCLUSION</b>This technique can create effective advancement of the maxilla. The direct force can avoid counterclockwise rotation of the maxilla during distraction.</p>