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cone beam international magazine of cone beam dentistry

I CE article _ orthognatic surgery _Clinical examination Nextistheclinicalexamination. Clinicalexaminationincludesthe following: _range of motion, _symmetry of jaw motion, _palpation, _auscultation, _muscle splinting, _CR position. Range of motion should be between 45 mm and 55 mm on opening and includes assessing movement. We’re looking for a symmetrical mandible motion —meaning the chin should not deviate to the left or right on opening—and it should be rela- tively free of dental interference. Now check for palpation of the muscles of mastication. If you don’t check the muscles that move the mandible, then there’s a good chance that you’ll miss somesortoffunctionalbiteissue. Wealsolistentothejointwith astethoscope,andweapplysomeanteriorpressure to the disc through external auditory meatus to make sure the disc is functioning properly. When trying to manipulate the mandible, one can feel the muscles. If the muscles will not let you obtain acentricjointposition,thenwecannotdoadiagnosis becausethemusclesaren’tholdingthecondyleoutof thesocket.Thisisusuallyduetosomeinflammation. Finally, we’ll check what we call the centric re- lation position, which you should be able to feel. It should feel solid and the patient should be able to open from this position with relative ease, and there should be no noises. _Imaging The clinical examination will tell us a lot about thejointstatus.Theuseofimagingwillhelpusbuild our base of case-specific intelligence. We’ll use two types of imaging: MRI and cone beam. LCBCT Most of the time, we start with cone beam be- cause it’s easy to obtain a 3-D image of the joints. Thanks to the work of Rickets and Dr Ikeda, we have a way to measure joint position and get an idea if the condyle is basically seated. With cone beam, we can measure the health of the condyles. Our imaging showed a joint that is in a state of degeneration. The condylar head has changed in vertical height. Therefore, we would expect to see an asymmetrical opening where the chin deviates totheaffectedside.Inallthreeviews(saggital,coro- nal and axial), we have a condyle that is actually changing, especially when you make a comparison to the left condyle (Fig. 3). In a side-by-side presentation, you can see that theleftsideisdefinitelyinalotbettershape,having a more rounded effect to it. The size of the coronal view is one that shows a definite symmetric outline to it as compared to the other side. The axial view confirms this; you see that the shape is better and has a more dense outline. Thus, our basic imaging system helps us deter- mine that, in this case, one side is going to be the problem side, especially as it pertains to ortho- gnathic surgery. If we go to the two-dimensional images created intheconebeam,wecanseethattherightjointhas definitelylostverticalheight,andwedefinitelyhave a joint spacer that is excessive (Figs. 4 & 5). In the coronal view, we can even see that there maybesomesortofcystformation.Whenyoucom- paretherightsidetotheleftsideinthecoronalview, you get a more traditional image, which is what we’d like to see. However, there have been some changes that have occurred, because we’re starting to see a “bird-beaking” effect in the left joint. The images of the joint are ones that are important in determining if we should proceed with any kind of a surgical correction. Inthesaggitalview,therightside,thejointlooks pretty normal. However, if we look at it in a trans- verse direction, you’ll see less joint space laterally than you do medially, something we see in both the left and right joints (a much bigger joint space). That’s why it’s important that you not only look at a saggital view, but you also need to look at the coronalviewtoseeifyouhaveatransverseproblem occurring in the joints. _Soft-tissue analysis Whenwe’retrainedinorthodontics,we’retrained in hard-tissue analysis, otherwise all of our cepha- lometric analysis are based on hard structures. Fig. 3_A state of degeneration: a condyle that is actually changing. Fig. 4_Overlaid soft tissue on top of hard tissue. 08 I cone beam3_2014 Fig. 4 Fig. 3 CBE0314_06-15_Freeland 30.09.14 14:13 Seite 3

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