Dentoalveolar Curvilinear Distraction Osteogenesis To Reconstruct Unilateral Maxillary Defect

Patient undergone unilateral maxillectomy are the most cases of those who received various maxillectomy because of tumor resection, trauma and/or congenital deformity, which cause many functional and cosmetic problems to patients and there were two main treatment methods: prosthetic rehabilitation and surgical reconstruction, and prosthetic rehabilitation is still the main way to restore the defect. But prosthetic rehabilitation is always not satisfactory because of the instability, leakage and particularly the insufficient masticatory efficiency. Because of those disadvantages of conventional prosthetic rehabilitation, the reconstruction of the bony structure in the defect is very essential for the following denture restoration. More and more studies have focused on the reconstruction with bone structure and implant supported denture. Autogenous bone transplantation and implants was the most common reconstruction method, however, which need the donor site and bring additional trauma to the patient. So the surgical reconstruction without additional surgery may be more essential.Since 1997, distraction osteogenesis was first instructed as an alternative treatment approach for the patients with maxillary deficiency1. Numerous applications of the distraction osteogenesis have been found in treating patients with craniofacial deformities. Many patients being treated with maxillectomy have severe maxillary deformities or defect, which require complex three-dimensional distraction to alter both the shape and size of the maxilla. Because of the complex anatomical structure of the maxilla, the three- dimensional distraction of the maxilla is much more complicated than the relatively simple unidirectional distraction of the long bones described by Ilizarov. Therefore, careful presurgical planning and/or simulation are very necessary to achieve predictable outcomes in maxillary distraction osteogenesis. Computerized virtual reality and RP technique are the great innovations in the presurgical treatment planning for the craniofacial surgery, orthognathic surgery, preprosthetic surgery, dental implants, reconstruction of sever maxillofacial defects, design and manufacture of the facial prosthesis (ear, nose and orbital prosthesis). Up to now, there is no article to report the method to develop the animal model with unilateral maxillary defect, the reconstruction of unilateral maxillary defect by dentoalveolar DO, which with the assistance of computer-assisted surgical planning.To explore the method to resolve the above problems preliminarily, the authors have developed the canine animal model with unilateral maxilla defect and reconstructed 3D virtual model and rapid prototyping (RP) model of the canine's craniofacial skeleton based on CT data. The individual 3D distractor was designed and matched on the 3D model. The osteotmies and distraction processes were simulated separately on the virtual 3D model in the virtual environment and on the RP physical model. This protocol allows for a precise planning process and increases the predictability of the outcomes for the distraction osteogenesis for the patients with unilateral maxillary defect. The results are listed below:1. It's the first time to develop the conception to reconstruct the new alveolar crest at the position of the natural one using distraction osteogenesis, and insert dental implants in the new alveolar ridge to restore the missed dentition.2. It's the first time to develop the animal model with unilateral maxillary defect according to the method to resect the unilateral maxilla of patients and testified the feasibility to reconstruct the unilateral maxillary defect using distraction osteogenesis.3. Designed and manufactured the personal distractor through virtual reality and numerical controlling technology, and verified the usefulness of distractor by animal experiments and feasibility to reconstruct the alveolar crest at the position of natural one in unilateral maxillary defect using distraction osteogenesis.4. It's the first time to designed and processed the distractor for dentoalveolar distraction osteogenesis and for combined alveolar, zygoma distraction osteogenesis to reconstruct the bony supporting structure in unilateral maxillary defect for clinical cases.5. According to the relation between the alveolar crest and dental arch, the author developed the conception to design the osteotomy method for making bone transport disc through the theory of vertical bisector, and the osteotomy method can make the residual defect cavity be the smallest and provide the necessary autogenous soft tissue to reconstruct the partition between oral and nasal cavity.