[Application of computer aided design-computer aided manufacture technique in mandible defect reconstruction with individual titanium prosthesis].

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.

[Application of three dimensional model in evaluating the effect of artificial bone implantation of hard cleft palate on the development of maxilla].

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.

[Application of lateral lag screw with sagittal condylar fracture and management of articular disk].

OBJECTIVE: To evaluate the application of lateral lag screw and reduction of articular disk in management of intracapsular sagittle fractures of the condylar process. METHODS: The study group consisted of 16 cases (19 joints), including 10 males (12 joints) and 6 females (7 joints). Condylar sagittal fracture and displaced articular disk were detected in all patients. The condylar segments were repositioned and fixed by using lateral lag screw and the displaced articular disk were repositioned at the same time. The mean postoperative follow-up was 16 months (range 6-28 months). During the follow up, facial nerve function was monitored and radiologic re-examinations were performed to evaluate reposition of condylar process fractures and articular disk, while the mouth opening and occlusion were registered. RESULTS: The reduction of the displaced condylar fragments and articular disks in all patients were excellent on 3D CT and MRI. No severe complications were observed (including permanent facial nerve palsies, malocclusion, ankylosis). Three months after surgery, all patients showed their better mobility with condylar and disk, and mouth opening reached 43 mm on maximum, 32 mm on minimum, with a mean of 37 mm. CONCLUSION: The results by application of lateral lag screw and reduction of articular disk are helpful in anatomical and functional recovery of temporomandibular joint for patients with displaced sagittal condylar process fractures.

[Double-step distraction osteogenesis in the reconstruction of unilateral mandibular segmental defects after tumor resection].

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.

[Application of computer aided design/computer aided manufactured techniques in mandible defect reconstruction].

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.

[The application of three dimensional craniomaxillofacial model in the restoration of mandibular bone defects with vascularized fibular autograft].

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.

[Reconstruction of maxillary defect by prefabricated titanium mesh combined with pedicled buccal fat pad flap and bone autograft].

OBJECTIVE: To introduce individualized 3-dimensional (3-D) reconstruction of maxillary defect by prefabricated titanium mesh combined with pedicled buccal fat pad flap (PBFPF) and bone autograft. METHODS: Since May, 2001, 16 patients with maxillary defect resulted from tumor or trauma were treated. The 3-D models were created through 3-D CT and rapid prototype technique. The maxilla on the unaffected side was copied to the affected side by CAD/CAM. Then the titanium mesh was prefabricated accurately on the 3-D model. The PBFPF served as lining of the titanium mesh and the autogenous bone graft was used to reconstruct the shape and function of maxilla. RESULTS: The duration of follow-up was 6 to 36 months. All the wounds healed primarily with good facial symmetry. No food reflux to nasal cavity was observed. The dentitions in 8 of 16 cases were restored with good function by removable partial denture. They could have normal diet and were articulate. Nasopharyngoscopy showed normal tissue lining of the titanium mesh 5-12 months after operation in 3 cases. CONCLUSIONS: Satisfactory aesthetic and functional result can be achieved with this 3-D reconstruction method for maxilla defect. The PBFPF was insert better titanium mesh and mucous of maxilla sinus to avoid exposure of titanium mesh. The fat pad flap with blood supply promotes wound healing and helps partially restoring the function of the maxillary sinus.

[The effect of artificial bone implantation in cleft palate on the development of maxilla].

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.