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ePaper created 2014-10-07, 09:31:41 | version 1.30.01
CE article _ orthognatic surgery I far forward or too far back, you may need to do genioplasty. In the example case (Fig. 8), we have performed a surgical treatment objective, established the true vertical line and we have our axis-horizontal plane. In this patient, we need to move the anterior teeth up because in the frontal analysis the patient showed too much tooth structure and too much gingival tissue. To fix this, we balance the maxillary anterior teeth based on the upper lip position. Once we’ve established the correct tooth posi- tion in the anterior, we’re able to set up our occlusal plane at 95 degrees, showing us what we need to do with the posterior segment. In the example case, we need to extrude the posterior segment. Figure9showshowwe’vecompletedtheextru- sion of the maxillary segment, and we’ve balanced the occlusal plane. The next objective is to place the mandible with the correct overbite. This is not 2 mm but 4 mm. This is because you want to have an adequate overbite to create adequate disclusion. In establishing the mandible, you can see in our example how the lower part of the face is placed normally enough with the true vertical line (Fig. 10). In establishing the surgical treatment objective, we see that we want to place the anterior section in the superior direction and the posterior in the inferior direction. These are all the measurements we need to establish a surgical setup. Hopefully, this is performed pre-treatment so the patient has a good idea of what needs to be done. _Pre-surgical and surgical setups The pre-surgical and surgical setups are tech- niques that do require the clinician’s time. It’s not somethingthatcanbeoutsourcedtoalab.Youneed tospendthetimeindoingthesesetupstodetermine if it’s something that can be treated. Remember, therearecaseswhereyoucannotachievethegoals. Before we get to the setup, it’s worth examining the three basic concepts that this whole system is based on. That’s not just orthognathic surgery, but orthodontics itself. ConceptNo.1: Youneedtostartwith aseatedcongularposition. You will need to learn techniques to know when you have a seated condyle, andifit’sinastableposition. ConceptNo.2: Youcan’tbelieve whatyouseeinthemouth. Thisisforeigntowhatwe’retaughtintheortho- donticprofession.We’retrainedthatwhenwefinish a case we have the patient bite down, and we say thattheocclusionlooksgoodoritdoesn’t.However, youneedtounderstandthatthisisalearnedmuscle position.It’snotapositionthatisusuallyconducive to normal joint function. ConceptNo.3:Quittryingtodotheimpossible withorthodontictoothmovement. This is where orthognathic surgery comes into play. Don’t try to fix skeletal aberrations with or - thodontic tooth movements. Too often cases are treated with a compromised treatment plan, but due to the skeletal dysplias it is impossible to es - tablish a functioning occlusion, thus resulting in failure. Weneedarulertomeasurehowwecomeupwith a diagnosis and then we need the same ruler to measure our successes. So in the sample case, the ruler consists of five goals: joints, face, perio, teeth and function. Fig. 14_Measuring Glabella to subnasale. Fig. 15_Surgical models mounted according to axis-horizontal plane. I 11cone beam3_2014 Fig. 14 Fig. 15 CBE0314_06-15_Freeland 30.09.14 14:13 Seite 6