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OBJECTIVE: To investigate the application of computer aided design-computer aided manufacture (CAD-CAM) technique in the reconstruction of mandible defect with individual titanium prosthesis. METHODS: Six patients with large mandibular ramus and angle tumor were spiral CT scanned preoperatively, and the CAD-CAM was used to design and make individual titanium prosthesis for reconstructing the mandibular defects after resection of the tumor. The prosthesis were assembled during operation. Postoperative follow-up period was 9 - 38 months. RESULTS: The design and manufacture of titanium prosthesis by use of CAD-CAM technique was convenient and the prosthesis fitted the defects very well. The outline of the face, the occlusion and function were restored. After 9 - 38 months of follow-up, the mandibular symmetry was good. CONCLUSIONS: The application of CAD-CAM provided accurate simulation and fast manufacturing process for the titanium prosthesis in the repair of mandibular defect.

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OBJECTIVE: To observe the effect of artificial bone implantation of hard cleft palate on the development of maxilla. METHODS: From January 1997 to December 1999, 40 patients with hard cleft palate were randomly divided into two groups: control group and implantation group (n = 20 each). The patients in the implantation group received an implantation of compound artificial bone of HA-Bone cement. All patients had a follow-up since 16 years old. A three dimensional model was established with computed tomography and rapid prototype technique to analyze the maxilla in three dimension. At the same time, a dentognathic model was employed. RESULTS: There were no differences in the results between the three dimensional and dentognathic models. No difference was found in the development of maxilla in length and height between the control and implantation groups. There were marked differences in the development of maxilla in width between two groups (67.6 mm ± 4.3 mm vs 61.3 mm ± 4.1 mm, 63.5 mm ± 3.9 mm vs 57.3 mm ± 3.1 mm, 26.2 mm ± 1.8 mm vs 26.4 mm ± 1.9 mm, all P < 0.05). The width of maxilla in the implantation group was markedly wider than that in the control group. CONCLUSIONS: The application of three dimensional model for evaluating the development of maxilla is both straightforward and accurate. Bone implantation of hard cleft palate is an obvious boost to the development of maxilla in width. It should be included into a comprehensive orthodontic treatment for patients with hard cleft palate.

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OBJECTIVE: To investigate the feasibility of using computer-aided design (CAD) in double-step distraction osteogenesis in the reconstruction of mandibular segmental defects after tumor resection. METHODS: Eight cases of unilateral mandibular segmental defects were reconstructed using distraction osteogenesis secondary to oncologic surgery, with the help of CT and CAD system. The mandibular body was lengthened first, and then the residual defect of mandibular ramus was restored using a distraction device. RESULTS: No incidence of infection or other complications were observed. The maximal amount of the lengthening reached 55 mm in the mandibular body, and 45 mm in the mandibular ramus. The average amount of the lengthening reached 49 mm in the mandibular body, and 36 mm in the mandibular ramus. The aesthetic and functional results of bone lengthening were excellent in all cases. The retractor was removed eight months postoperatively. CONCLUSIONS: Using CAD in double-step distraction osteogenesis in the reconstruction of unilateral mandibular segmental defects has the advantages of precise diagnosis, operation planning and assuring success of operation. It has the disadvantage of a long period for the overall treatment time.

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OBJECTIVE: To evaluate the effect of distraction osteogenesis for severe micrognathia by comparing the pre- and post-operative profile and mentolabial relationship. METHODS: 16 cases underwent temporal-mandibular joint plasty and temporal fasciomuscular flap transfer. The mandibular distraction began at the 5th postoperative day at a rate of 0.8 mm a day, two times a day. Bony and soft tissue cephalometry were performed before and after operation. T-test was used to study the change after distraction osteogenesis. RESULTS: There were significant differences in facial convexity, lower facial height, lower lip length, inter-labial distance, the ratio of lip to mental, the distance from lip to esthetic plane, the depth of mentolabial crease and the thickness of mental soft tissue. CONCLUSIONS: Mandibular distraction osteogenesis can markedly improve the soft tissue profile of the middle and lower face for severe micrognathia.

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OBJECTIVE: To investigate the application of double-step distraction osteogenesis in the reconstruction of mandibular segmental defects after tumor resection. METHODS: From January 2002 to December 2006, six cases of post-tumor unilateral mandibular segmental defects were reconstructed using distraction osteogenesis. The mandibular body was lengthened first, following by mandibular ramus distraction. RESULTS: No infection or other complication was observed. The maximal distraction length reached 55 millimeter in the mandibular body, and 42 millimeter in the mandibular ramus. The average distraction length was 52 millimeter in the mandibular body, and 34 millimeter in the mandibular ramus. Both the aesthetic and functional result was excellent in all cases. CONCLUSIONS: Double-step distraction osteogenesis is effective and easily performed in the reconstruction of unilateral mandibular segmental defects with less morbidities and complications. There is no need for donor site. However, the treatment period is relatively long with three staged operations.

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OBJECTIVE: To investigate the application of CAD/CAM technique in reconstruction of mandible defect. METHODS: Before surgery, three-dimensional computed tomography was performed in 23 patients with mandible lesions, then the CT data were transformed into a readable format to produce facsimile models by using rapid prototyping (RP) techniques. When individual mandibular models were produced, evaluation and surgical simulation were performed on the model, which included measuring range of mandible lesions, prefabrication of mandibular reconstructive titanium plates or distractors, ascertaining precise position of transport disk, and shaping the free vascularized fibula, etc. According to the simulation, the mandible reconstruction was accomplished in operation. RESULTS: The surgical simulation on the model produced by CAD/CAM technique highly resembled the real operation. The measurements of the lesion on the model were completely correspondent with those found in operation, and the prefabricated plates and distractor fitted the contour of the mandible. The operation time shortened and the results were satisfactory. The post-operation X-ray showed that the mandible was symmetrical and the maxillofacial contour maintained. CONCLUSIONS: CAD/CAM technique was very helpful for simulation of anatomically complicated mandible defect. By preoperative simulation of the mandible and lesions, surgeons are able to improve or refine surgical planning so that better results can be assured.

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OBJECTIVE: To exploit computer-aided design and computer-aided manufactured (CAD/CAM) techniques and application in the reconstruction of mandible large-scale defect with vascularized fibular bone graft. METHODS: Before actually performing surgery, three-dimensional(3D) computed tomography(CT) was performed in 7 patients with mandibular large-scale defects, and 3D CT images were acquired by processing CT data. Then the CT data were transformed into a readable format and transferred to produce facsimile models by means of using rapid prototyping(RP) techniques. When individual mandibular models and enantiomorphous models were produced, evaluation and surgical simulation was performed in model, which included measuring range of mandible lesions, prefabrication of mandibular reconstructive titanium palate, precise position of titanium screws, shaping the free vascularized fibula by mandibular, etc. According to the simulations, the mandible reconstructions were finished in operation. RESULT: CAD/CAM techniques and application can distinctly display the mandibular lesions and ambient relationships, which is very useful for clinical assessment and surgical planning. Particular advantages were the unlimited trials with the imaging method, and the feeling of reality with the model method. The actual operative time was shortened, and surgery results were satisfactory with few complications. CONCLUSION: CAD/CAM techniques are very helpful for simulation of mandible large-scale defect with complicated anatomical and reconstructive problems. By preoperative simulation of procedures, surgeons can improve or refine treatment planning using this method and improve postoperative results.

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OBJECTIVE: To evaluate the effect of applying the three dimensional craniomaxillofacial model technique in the restoration of mandibular defects with vascularized fibular autograft. METHODS: Three dimensional craniomaxillofacial models of 24 patients with mandibular defects were achieved by CT scan and rapid prototype technique. Surgery simulation and individual prefabricated titanium board were designed on the models. Vascularized fibular autograft was obtained, remodeled with titanium implant based upon preoperative surgery simulation, and implanted into the site with mandibular defect. RESULTS: By using three-dimensional craniomaxillofacial model, all fibular flaps survived without complication in all 24 patients. Bony union was achieved between the implanted fibula and the mandible. First intention of the wound was achieved. The appearance of the mandibular bone was well recovered shown by 3-dimensional CT scan. CONCLUSION: Based upon the preoperative surgery simulation with three dimensional craniomaxillofacial model, vascularized fibular autograft has many advantages for mandible reconstruction and represents the first choice for the head and neck surgeon.

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OBJECTIVE: To research the influence of palate bone implantation to the growth of maxilla in three dimensional direction. METHODS: 40 patients of congenital cleft palate type II with palate board damage were stochastically divide into the comparison group and bone planted group. In bone planted group, HA-Bone cement was used to repair palate tabular damage. All patients are 16 full year old, cephalometric radiograph and tooth cast model were measured and contrast analysis was applied. RESULTS: Planted bone group and the comparison group does not have the significance difference in both the maxilla length and maxilla hightness( P > 0.05); But there was significance difference in the width of post-part of the maxilla (P < 0.05). CONCLUSIONS: It could promote the growth of maxilla width in use of bone implantation, that advocated the bone repair in the sequence treatment process in cases of the hard palate bone damage.

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