[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.

[Soft tissue profile changes in micrognathia after distraction osteogenesis].

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.