Accuracy of computer-assisted mandibular reconstructions using patient-specific implants in combination with CAD/CAM fabricated transfer keys

Abstract

Background: A new method in mandible reconstruction has recently been developed using patient-specific mandible reconstruction plates (PSMP) after preoperative computer planning using CAD/CAM procedures. To transfer the virtual planned position of the PSMP into the intraoperative situs resection margins and plate position is determined by using surgical guides made by CAD/CAM procedures as well (PSMP-method).

Methods: Mandibular reconstruction with the PSMP-method was performed on 18 patients. The study included sole alloplastic reconstruction cases (AP, n = 10) and microvascular osseous reconstruction cases (MV, n = 8). Pre- and postoperative CT-scans were evaluated by measuring distances between corresponding landmarks on the mandibular rami. The difference was used to evaluate reconstruction accuracy.

Results: The median deviation of all distances was 1.13 mm for PSMP-method including all cases. For AP-group, the median deviation was 0,80 mm, for MV-group it was 2,47 mm. There was a high significant difference between both groups (AP and MV). Larger mandibular resections in combination with the need of positioning the surgical guides in the region of the upper condyle seemed to reduce reconstruction-accuracy. This was found more often in MV-group as in the AP-group.

Conclusions: PSMP-method seems to be an effective and satisfying method for accurate mandibular reconstruction. Microvascular reconstruction seems less accurate than sole alloplastic reconstruction. Larger resections of the mandible and technical more challenging approaches up to the mandibular condyle might explain this result.

Keywords: CAD/CAM; Mandibular reconstruction; Patient-specific implants; Patient-specific mandibular reconstruction plates; Virtual planned surgery.