Validation of a fibula graft cutting guide for mandibular reconstruction: experiment with rapid prototyping mandible model.

OBJECTIVE: We examined whether cutting a fibula graft with a surgical guide template, prepared with computer-aided design/computer-aided manufacturing (CAD/CAM), would improve the precision and accuracy of mandibular reconstruction. METHODS: Thirty mandibular rapid prototype (RP) models were allocated to experimental (N = 15) and control (N = 15) groups. Thirty identical fibular RP models were assigned randomly, 15 to each group. For reference, we prepared a reconstructed mandibular RP model with a three-dimensional printer, based on surgical simulation. In the experimental group, a stereolithography (STL) surgical guide template, based on simulation, was used for cutting the fibula graft. In the control group, the fibula graft was cut manually, with reference to the reconstructed RP mandible model. The mandibular reconstructions were compared to the surgical simulation, and errors were calculated for both the STL surgical guide and the manual methods. RESULTS: The average differences in three-dimensional, minimum distances between the reconstruction and simulation were 9.87 ± 6.32 mm (mean ± SD) for the STL surgical guide method and 14.76 ± 10.34 mm (mean ± SD) for the manual method. DISCUSSION: The STL surgical guide method incurred less error than the manual method in mandibular reconstruction. A fibula cutting guide improved the precision of reconstructing the mandible with a fibula graft.

Precision of fibula positioning guide in mandibular reconstruction with a fibula graft.

BACKGROUND: This study examined the usefulness of the fibula positioning guide for boosting the accuracy of mandible reconstructions. METHODS: Thirty mandibular rapid prototype (RP) models were allocated to experimental (N = 15) and control (N = 15) groups. For reference, we prepared a reconstructed mandibular RP model with a three-dimensional printer, based on surgical simulation. In the experimental group, a fibula positioning guide template and fibula cutting guide, based on simulation, were used to reconstruct the mandible with a fibula graft. In the control group, only the fibula cutting guide, with reference to the reconstructed RP mandible model, was used to reconstruct the mandible with a fibula graft. The two mandibular reconstructions were compared to the surgical simulation by registering images with the non-surgical right side of the mandible. On the reconstructed side, 3D measurements were compared between the surgical simulation and actual surgery, and the sum of differences was taken as the total error. RESULTS: The combined use of the fibula cutting and positioning guides produced a smaller total error (mean ± SD: 10.0 ± 7.9 mm) than the fibula cutting guide alone (12.8 ± 8.8 mm; p = 0.015). The greatest point error was the vertical error at the mesial point of the anterior fibula segment. The anteroposterior and lateral errors were not significantly different between groups. These results showed that these two methods were not significantly different, except in the total and vertical errors. CONCLUSIONS: Considering the CAD/CAM processes required for creating positioning devices, the benefit provided with a positioning guide justified its use over the fibula cutting guide alone.

Genioplasty using a simple CAD/CAM (computer-aided design and computer-aided manufacturing) surgical guide.

BACKGROUND: The present study introduces the design and fabrication of a simple surgical guide with which to perform genioplasty. METHODS: A three-dimensional reconstruction of the patient's cranio-maxilla region was built, with a dentofacial skeletal model, then derived from CT DICOM data. A surgical simulation was performed on the maxilla and mandible, using three-dimensional cephalometry. We then simulated a full genioplasty, in silico, using the three-dimensional (3D) model of the mandible, according to the final surgical treatment plan. The simulation allowed us to design a surgical guide for genioplasty, which was then computer-rendered and 3D-printed. The manufactured surgical device was ultimately used in an actual genioplasty to guide the osteotomy and to move the cut bone segment to the intended location. RESULTS: We successfully performed the osteotomy, as planned during a genioplasty, using the computer-aided design and computer-aided manufacturing (CAD/CAM) surgical guide that we initially designed and tested using simulated surgery. CONCLUSIONS: The surgical guide that we developed proved to be a simple and practical tool with which to assist the surgeon in accurately cutting and removing bone segments, during a genioplasty surgery, as preoperatively planned during 3D surgical simulations.

Precision of a CAD/CAM-engineered surgical template based on a facebow for orthognathic surgery: an experiment with a rapid prototyping maxillary model.

OBJECTIVE: We examined the precision of a computer-aided design/computer-aided manufacturing-engineered, manufactured, facebow-based surgical guide template (facebow wafer) by comparing it with a bite splint-type orthognathic computer-aided design/computer-aided manufacturing-engineered surgical guide template (bite wafer). STUDY DESIGN: We used 24 rapid prototyping (RP) models of the craniofacial skeleton with maxillary deformities. Twelve RP models each were used for the facebow wafer group and the bite wafer group (experimental group). Experimental maxillary orthognathic surgery was performed on the RP models of both groups. Errors were evaluated through comparisons with surgical simulations. We measured the minimum distances from 3 planes of reference to determine the vertical, lateral, and anteroposterior errors at specific measurement points. The measured errors were compared between experimental groups using a t test. RESULTS: There were significant intergroup differences in the lateral error when we compared the absolute values of the 3-D linear distance, as well as vertical, lateral, and anteroposterior errors between experimental groups. The bite wafer method exhibited little lateral error overall and little error in the anterior tooth region. The facebow wafer method exhibited very little vertical error in the posterior molar region. CONCLUSIONS: The clinical precision of the facebow wafer method did not significantly exceed that of the bite wafer method.

Verification of the usability of a navigation method in dental implant surgery: in vitro comparison with the stereolithographic surgical guide template method.

OBJECTIVE: This study investigates the usefulness of a navigation method using a reference frame directly fixed to the mandible compared to the stereolithographic (STL) surgical guide template method in dental implant surgery. MATERIALS AND METHODS: Twenty rapid prototyping (RP) mandibular models were divided into two groups. Simulation surgery was performed using SimPlant software for both groups. The actual dental implants were placed in the RP models using a real-time navigation system or the surgical guide template, which was fabricated based on STL data by a 3-dimensional printer. Positional implantation errors were measured by comparing the simulation surgery implant positions to the actual postoperative implant positions. RESULTS: The vertical distance error of the top surface area in the first molar region was not significantly different between groups. Otherwise, the implantation method using real-time navigation showed greater errors except for the horizontal and vertical errors in the apical area of the canine region. CONCLUSION: The STL surgical guide template was associated with fewer errors than the real-time navigation method in dental implant surgery.

Validation of mandibular genioplasty using a stereolithographic surgical guide: in vitro comparison with a manual measurement method based on preoperative surgical simulation.

PURPOSE: Stereolithographic guidance, increasingly used in orthognathic surgery, has not been completely verified for genioplasty. This study compared the accuracy of manual measurement with that of a stereolithographic guide in vitro. MATERIALS AND METHODS: Thirty rapid prototype (RP) mandibular models (15 pairs) were included in the experimental (stereolithographic) and control (manual) groups (15 each). Surgical simulation was performed in the 2 groups by advancing the chin 5 mm and then vertically reducing the chin 5 mm using Mimics software. In the stereolithographic group, genioplasty was performed on mandibular RP models using a 3-dimensionally printed surgical guide based on surgical simulation results. In the control group, it was performed using an osteotomy line drawn according to simulation measurements. For the 2 groups, anterior horizontal transverse error and anterior and posterior vertical errors were compared, as were data from the osteotomized chin segment and the preoperative surgical simulation. Positional difference error was calculated and the differences were evaluated with t tests. RESULTS: For advancement genioplasty, the absolute anterior transverse error value was 0.47 ± 0.35 (mean ± standard deviation) with the stereolithographic guide, less than with the manual method (0.77 ± 0.45; P = .001). For reduction genioplasty, the absolute anterior vertical error value was 0.27 ± 0.23 mm with the stereolithographic guide versus 0.58 ± 0.49 mm with the manual method (P < .001). CONCLUSION: Use of a stereolithographic surgical guide increased accuracy, but the difference in mean error values between methods was only approximately 0.3 mm. The superior accuracy may not be compelling in favor of stereolithographic surgical guides.