The Z4 dental articulator is a specially designed instrument that can be utilized for mounting dental casts for patients undergoing the surgery-first approach (SFA) (Fig. 3.1). The main components of this articulator are the detachable magnetic plates that hold the maxillary and mandibular models. The thin magnetic plates have a uniform thickness and can be stacked; the final models of the upper and lower arches are ultimately attached to a transparent acrylic plate, using conventional gypsum. Another characteristic part of this articulator is the throttling plate that allows three-dimensional (3D) control of the maxillary surgery. The regulator allows the desired surgical position of the maxilla to be simulated, without cutting the gypsum board.

Like mounting a conventional surgical patient on a dental articulator, a face-bow application is needed to view the 3D spatial location of the maxilla relative to the rest of the skull (Fig. 3.2). Clinically, careful attention is required to compare the extent of left and right canting of the maxilla. Based on the Frankfort horizontal plane, the maxilla is positioned, and the bite fork is fixed. Often, when the vertical positions of the right and left external ear rods are different, the surgical plan may need to be calibrated.

First, three pairs of models are mounted onto the Z4 Articulator, using the maxillary face-bow and bite occlusion information (Fig. 3.3). One model pair is set up to allow individual tooth movements (Fig. 3.4). The remaining pairs are used to create an intermediate wafer, which will guide the later maxillary surgery, and a final wafer that will allow the final postoperative occlusion.

Before moving teeth, a horizontal line is drawn parallel to the mounting plate to establish a baseline on the mounted model that allows for isolated tooth movements among three pairs of mounted models. In the same way, a vertical reference line is drawn, perpendicular to the mounting plate, for each reference tooth (Fig. 3.5).