Evaluation of two noninvasive repositioning systems for computer-assisted oral implant surgery in oral cancer patients.

PURPOSE: Reconstructive surgery in oral cancer patients uses thick flaps, which may render the placement of miniscrews for stabilizing radiosurgical templates difficult. The realization of noninvasive systems for the repositioning of surgical templates has been proposed. The present study aimed to assess the clinical usefulness of these noninvasive repositioning systems. MATERIALS AND METHODS: Two noninvasive (ie, without osseous anchorage) repositioning systems (one intraoral, one intra- and extraoral) were tested. They were coupled with a computer-aided system for oral implantation. The criteria for evaluation were: accuracy, cost, time for placement and removal, and six additional subjective criteria (ease of use and production, bulk of the device, patient comfort, stability during surgery, and ergonomics). RESULTS: Nine edentulous patients undergoing surgery to the oral cavity, oropharynx, or pharynx; external radiotherapy of the mandible; or microvascular flap reconstruction were included. Twenty-seven implants were placed in the mandibles of seven patients. For the extraoral system, the angular deviation between planned and achieved position was 6.04 degrees, with differences of 2.14 mm at the tip and 2.16 mm at the base. For the intraoral system, deviations were 5.05 degrees, 1.13 mm, and 1.82 mm, respectively. Subjective criteria were consistent with expected values, especially ease of use, comfort, and ergonomics. CONCLUSIONS: Noninvasive systems remain less accurate than templates stabilized by miniscrews and should be reserved for treating arches in which miniscrews cannot be placed. These methods may be unacceptable in areas where vital structures may be damaged by a misguided implant, and further studies are required. More satisfactory results should be obtained in partially edentulous patients.