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cone beam international magazine of cone beam dentistry

I CE article _ orthognatic surgery Inapre-surgicaldiagnosticsetup,whichisatrial treatment, the case can be diagnosed and treated before you start. This way you have the result in mindbeforebeginning(fivegoals).Theorthodontic, surgical and restorative modalities can all be com- bined pre-treatment. This way the patient knows what is needed to solve his or her particular mal- occlusion. Thesepre-treatmentsetupsarebasedontheVTO (toothmovement)andtheSTO(skeletalmovement). Once all treatment modalities have been tried, the clinicianwillknowiforthognathicsurgerywillwork for the patient. The surgical setup is performed just before surgery to determine the skeletal changes needed to correct the skeletal malocclusion and see if the prediction setup is correct. We use our ruler again to make certain that the five goals are obtainable. The surgical splint can also be constructed from the surgical setup. The surgical splint is used to place the skeletal parts in their correct position. _Steps in pre-surgical setups First, we need to get the maxilla positioned in thearticulator.Westillrecommendthatyouusethe articulator as a tool to do your setup. Virtual setups tend 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 access 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. The axio-path tracing that we created while trying to find the terminal hinge axis of this patient allowed us to look at the angle of eminence. What weliketoseeisasteepangleofeminenceasthathelps disclude the posterior teeth in lateral border move- ments.Moreover,weliketoseenice,smoothcurved 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. Figure 11 shows a true hinges-axis mounting. We have the true hinge axis, we have the axis- 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. Whatweseeinthenextimageisthatthispatient only hits on the left side. Nothing touches on the right.Asyoucanalsosee,theopenbiteisevenworse on hinge-axis mounted models (Fig. 12) _Diagnostic setup The diagnostic setup we’ve been discussing is based on the VTO, STO and the articulated cast mounting.Theorthodonticsetup,aswellasasurgi- calsetup,canbedoneonthesamesetofhinge-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. 13). _Surgical setup The surgical setup allows us to plan the sur- gery case before we go to the operating room. We perform this after we’ve finished the pre- surgical orthodontics and we’re getting ready for the surgery itself. Figs. 16a & b_Intermediate surgical splint. 12 I cone beam3_2014 Fig. 16a Fig. 16b CBE0314_06-15_Freeland 30.09.14 14:13 Seite 7

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