Conformity of the Actual to the Planned Result in Orthognathic Surgery

Abstract

Background: Virtual surgical planning has facilitated preoperative planning, splint accuracy, and intraoperative efficiency in orthognathic surgery. The translation of the virtual surgical plan to the actual result has not been adequately examined. The authors examined the conformity of the virtual surgical plan to the postoperative result. They hypothesize that the greatest conformity exists in the anteroposterior dimensions. Methods: The authors examined patients who underwent Le Fort I maxillary advancement, bilateral sagittal split osteotomy, and genioplasty. The preoperative virtual surgical planning file and postoperative cone beam computed tomographic scan were registered in Mimics using unchanged landmarks. The conformity to the virtual surgical plan was quantified using linear and angular measurements between bone surface landmarks. Results were compared using t tests, with p < 0.05 considered statistically significant Results: One hundred patients who underwent Le Fort I maxillary advancement, bilateral sagittal split osteotomy, and genioplasty were included. Three-dimensional analysis showed significant differences between the plan and outcome for the following landmarks: A point (y, p = 0.04; z, p = 0.04), B point (y, p = 0.02; z, p = 0.02), pogonion (y, p = 0.04), menton (x, p = 0.02; y, p = 0.01; z, p = 0.03), and anterior nasal spine (x, p = 0.04; y, p = 0.04; z, p = 0.01). Angular measurements sella-nasion-A point, sella-nasion-B point, and A point-nasion-B point were not statistically different. Conclusions: There is a high degree of conformity comparing the orthognathic virtual surgical plan to the actual postoperative result. However, some incongruency is seen vertically (maxilla) and sagittally (mandible, chin). Departures of the actual position compared with the plan could be the result of condylar position changes, osteotomy locations, aesthetic intraoperative decisions, and/or play in the system.

A Complete Digital Workflow for Planning, Simulation, and Evaluation in Orthognathic Surgery

“…Similar results regarding the larger vertical error were also reported in previous studies [19,38]. Considering the aesthetic outcome of the upper lip, which was related to displacements of the midline (center of the incisors) in the left-right direction, the linear discrepancy in the impactionelongation direction could be ignored when determining the appropriate position of the maxilla [38]. In addition, the means of absolute translational discrepancies showed a tendency to increase from the anterior tooth to the posterior tooth in the left-right and the anterior/posterior directions, but showed similar values in the impaction-elongation direction (Table 2).…”

“…In another study, the mean absolute difference of 1.1 mm in the impaction-elongation direction was larger than the 0.5 and 1.0 mm in left-right and advance-setback directions [37]. Similar results regarding the larger vertical error were also reported in previous studies [19,38]. Considering the aesthetic outcome of the upper lip, which was related to displacements of the midline (center of the incisors) in the left-right direction, the linear discrepancy in the impactionelongation direction could be ignored when determining the appropriate position of the maxilla [38].…”

“…On the other hand, the planned yaw displacement showed a negative correlation with the yaw outcome. The yaw displacement was related to the displacement in the left-right direction of the midline (center of the incisors), which was also closely related to the aesthetic outcome of the orthognathic surgery [38]. Since one of the most important objectives of orthognathic surgery is to improve the aesthetic outcome, the surgery should be performed to minimize the discrepancies between the planned displacements and the surgical outcomes in the yaw and left-right directions.…”

Randomized Clinical Trial of the Accuracy of Patient-Specific Implants versus CAD/CAM Splints in Orthognathic Surgery

“…The other disadvantage is that intraoperative changing of the plan is difficult, which is a common issue for all patient-specific implant techniques. 24 If adjustment of the plan is required, the surgeon has to abandon patient-specific plates and complete the operation using standard titanium plates with the conventional method.…”

Orthognathic Surgery to Improve Facial Profile: Assessment, 3-Dimensional Planning, and Technique

“… 3 Postoperative results of orthognathic surgery planned virtually demonstrate good conformity with presurgical plans and improved aesthetic outcomes compared with conventional planning. 4 , 5 …”