Patient-specific Printed Plates Improve Surgical Accuracy in Vitro

Publication date: Available online 16 August 2018

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Kasper Stokbro, R Bryan Bell, Torben Thygesen

Abstract

Purpose

It remains unclear to what extent patient-specific printed (PSP) plates can improve surgical outcomes in orthognathic procedures. This study aims to quantify the surgical accuracy of PSP plates in vitro and to compare the result with patients' actual surgical outcomes.

Methods

This in vitro study enrolled 20 postoperative orthognathic surgical patients, all treated with inferior maxillary repositioning. The preoperative midfaces were recreated in a 3D-printed model. The osteotomy and screw holes were placed at prespecified positions using a 3D guide. The dental segment was repositioned by means of the patient-specific plates. The primary outcome was the mean reposition at 3 dental reference points. The primary predictor variable was the obtained surgical reposition in vitro compared with the virtual surgical plan. Confounding variables were sex, age, occlusion and bimaxillary surgery. The secondary outcome was the surgical accuracy, and the secondary predictor was the in vitro outcomes versus the patients' surgical outcomes. The surgical accuracy was defined as the difference between the obtained reposition and the virtual surgical plan on a continuous scale. The differences were recorded in 3 dimensions according to the positive value of the 3 axes: right, anterior and posterior. Results were analyzed using mixed model regression and 1-sample t-tests.

Results

In the 20 patients (age: 18–64, 40% female), the mean planned reposition was 2.9 mm anterior and 1.8 mm inferior. In all models, the osteotomy edge was rounded off to position the plate in the predetermined position. Overall, the maxilla was positioned 0.5 mm anterior and 0.3 mm inferior to the planned position using patient-specific plates.

Conclusion

The patient-specific plates positioned the maxilla in close approximation to the planned position without surgically relevant differences. The osteotomy edge must be carefully inspected for interferences with the patient-specific plates to avoid displacement of the planned maxillary repositioning.

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