Comparison of the Planned Versus Actual Jaw Movement Using Splint-Based Virtual Surgical Planning: How Close Are We at Achieving the Planned Outcomes?

Abstract

Virtual surgical planning and interocclusal splints are commonly used in performing orthognathic surgery. The benefits are well known, but how close do surgeons come to achieving the planned movements? The aim of this study was to answer this question. This was a retrospective cohort study of patients who underwent maxillary and mandibular osteotomies to correct their dentofacial deformity. The predictor variable consisted of the virtually planned 3-dimensional (3D) positions of the maxillary and mandibular centroids and maxillary central incisor. The outcome variable consisted of the postoperative 3D positions of these points. Absolute differences were calculated using the root mean square deviation. Other variables that could affect the outcome were assessed, which included skeletal classification, osteotomy sequence, and maxillary segmental surgery. Paired t test was used to determine the mean of the error for the outcome variable. A forward stepwise regression test was used to test for associations with the other variables. This study was composed of 15 patients with a mean age of 19years. The maxillary incisor was advanced 2.5 to 8mm. The mean of the error for the maxillary incisor in the anteroposterior dimension was -2.0mm, which was a statistically relevant under-advancement (95% confidence interval). The anteroposterior error for the maxillary centroid was significantly higher for a 1- than for a 3-piece Le Fort osteotomy (P=.008). Eight patients had under-advancement of more than 50% of the planned movement, which could be clinically relevant. The maxillomandibular complex was under-advanced. This could be due to surgeon-dependent variables and other factors that are not simulated with virtual planning. This could affect the desired lip and paranasal support. The surgeon needs to take this into account when planning esthetic objectives for surgery.