Accuracy of a computer-aided surgical simulation protocol for orthognathic surgery: a prospective multicenter study.
OBJECTIVE
The purpose of this prospective multicenter study was to assess the accuracy of a computer-aided surgical simulation (CASS) protocol for orthognathic surgery.


METHODS
The accuracy of the CASS protocol was assessed by comparing planned outcomes with postoperative outcomes of 65 consecutive patients enrolled from 3 centers. Computer-generated surgical splints were used for all patients. For the genioplasty, 1 center used computer-generated chin templates to reposition the chin segment only for patients with asymmetry. Standard intraoperative measurements were used without the chin templates for the remaining patients. The primary outcome measurements were the linear and angular differences for the maxilla, mandible, and chin when the planned and postoperative models were registered at the cranium. The secondary outcome measurements were the maxillary dental midline difference between the planned and postoperative positions and the linear and angular differences of the chin segment between the groups with and without the use of the template. The latter were measured when the planned and postoperative models were registered at the mandibular body. Statistical analyses were performed, and the accuracy was reported using root mean square deviation (RMSD) and the Bland-Altman method for assessing measurement agreement.


RESULTS
In the primary outcome measurements, there was no statistically significant difference among the 3 centers for the maxilla and mandible. The largest RMSDs were 1.0 mm and 1.5° for the maxilla and 1.1 mm and 1.8° for the mandible. For the chin, there was a statistically significant difference between the groups with and without the use of the chin template. The chin template group showed excellent accuracy, with the largest positional RMSD of 1.0 mm and the largest orientation RMSD of 2.2°. However, larger variances were observed in the group not using the chin template. This was significant in the anteroposterior and superoinferior directions and the in pitch and yaw orientations. In the secondary outcome measurements, the RMSD of the maxillary dental midline positions was 0.9 mm. When registered at the body of the mandible, the linear and angular differences of the chin segment between the groups with and without the use of the chin template were consistent with the results found in the primary outcome measurements.


CONCLUSIONS
Using this computer-aided surgical simulation protocol, the computerized plan can be transferred accurately and consistently to the patient to position the maxilla and mandible at the time of surgery. The computer-generated chin template provides greater accuracy in repositioning the chin segment than the intraoperative measurements.
Department of Oral and Maxillofacial Surgery, The Methodist Hospital Research Institute, and Department of Pediatric Surgery, The University of Texas Health Science Center, Houston, TX 77030, USA.
Sam Sheng-Pin
SS
Hsu
Jaime
J
Gateno
R Bryan
RB
Bell
David L
DL
Hirsch
Michael R
MR
Markiewicz
John F
JF
Teichgraeber
Xiaobo
X
Zhou
James J
JJ
Xia
D000293:Adolescent; D000328:Adult; D003198:Computer Simulation; D005260:Female; D063172:Genioplasty / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D056948:Orthognathic Surgical Procedures; D010347:Patient Care Planning; D011446:Prospective Studies; D012986:Software Validation; D025321:Surgery, Computer-Assisted; D055815:Young Adult