Medial canthal region as an external reference point in orthognathic surgery

The aim of this investigation was to evaluate the effectiveness of using the medial canthal region (MCR) as an external reference point to determine the vertical dimension during maxillary repositioning as planned in model surgery and predictive tracing.

The analyzed group consisted of 43 consecutive patients who underwent maxillary or bimaxillary orthognathic surgery. Before downfracture, the vertical height was established from the distance of the MCR to the incisal edge of the right upper central incisor (UCI). The vertical dimension was obtained with frequent measurements by use of calipers as desired during cephalometric tracing and model surgery. After rigid fixation, the vertical height was verified again. The UCI was traced from the postoperative cephalogram and predictive tracing onto a preoperative tracing. Repositioning of the maxilla and postsurgical movements of the UCI were registered at the horizontal and vertical planes. Comparison was made between the predicted maxillary position on the cephalometric tracing and the actual position, as well as between the planned maxillary position in model surgery and the actual position.

The mean difference between the planned UCI position on predictive tracing and postsurgical position was 0.30 mm (SD, 0.21 mm; P > .05) in the vertical plane. The variation between the planned maxillary position in model surgery and the actual position was 0.37 mm (SD, 0.31 mm; P > .05) in the vertical plane.

Good surgical accuracy in positioning the mobilized maxilla can be achieved by use of the MCR as an external reference point.