ortho - the international C.E. magazine of orthodontics

ortho1_201312 I I C.E. article_ orthognathic surgery to make certain that the five goals are obtainable. The surgical splint can also be constructed from the surgicalsetup.Thesurgicalsplintisusedtoplacethe skeletal parts in their correct position. _Steps in pre-surgical setups First, we need to get the maxilla positioned in the articulator. We still recommend that you use the ar- ticulatorasatooltodoyoursetup.Virtualsetupstend not to include the patient’s true functioning hinge axis. If you don’t have the axis, you’re liable to setup an arc of closure that distracts the condyle. We establish the functioning terminal hinge ac- cess of the patient on both the left and right. We’re then transferring the hinge access to the side of the face. Once we have it on the side of the face, we can do our axis-horizontal transfer. The dot shows the functioning hinge axis on the patient, represented on both the right and left sides. Theaxio-pathtracingthatwecreatedwhiletrying tofindtheterminalhingeaxisofthispatientallowed us to look at the angle of eminence. What we like to seeisasteepangleofeminenceasthathelpsdisclude the posterior teeth in lateral border movements. Moreover, we like to see nice, smooth curved lines in the jaw motion, as that tells us the condyle and disc are working in harmony with each other. We determine the best centric relation position in the mouth. Nevertheless, remember, you can’t believe what you see in the mouth. That means this may even be worse, especially when we do a true hinges-axis mounting. Figure12showsatruehinges-axismounting.We havethetruehingeaxis,wehavetheaxis-horizontal plane and we have the teeth position according to this setup. That means the pin, which was removed for the photograph, would be the true vertical line. The articulator mounting is now the same as the CBCT imaging. What we see in the next image is that this patient only hits on the left side. Nothing touches on the right.Asyoucanalsosee,theopenbiteisevenworse on hinge-axis mounted models (Fig. 13) _Diagnostic setup The diagnostic setup we’ve been discussing is based on the VTO, STO and the articulated cast mounting. The orthodontic setup, as well as a surgi- cal setup, can be done on the same set of hinge-axis mounted models. We can also include in the diag- nostic setup the correct arch form so a mutually protected occlusion can be obtained (Fig. 14). _Surgical setup The surgical setup allows us to plan the surgery casebeforewegototheoperatingroom.Weperform this after we’ve finished the pre-surgical orthodon- tics and we’re getting ready for the surgery itself. Whatyoushouldfindwhenyoucomparethepre- treatment setup with the surgical setup is that the bony part should look very similar on the articulated mounting as the pre-treatment. In this case, we’ve leveled the occlusal plane as part of our surgical setup. In doing so, we gained a large correction of the mandible without doing gen- Fig. 14 Figs. 14a–h_Diagnostic setup . Fig. 15_Measuring Glabella to subnasale. Fig. 16_Surgical models mounted according to axis-horizontal plane. Fig. 15 a e g cb f h d Fig. 16