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10 Dental Tribune Middle East & Africa Edition | November-December 2014mCME > Page 11 Concepts, goals and techniques for successful orthognatic surgery By Dr. Theodore D. Freeland, USA I n this article, you will be in- troduced to the concepts, goals and techniques need- ed to diagnosis surgical cases, when surgical cases should be started and how to gain the knowledge needed to create successful results. We’ll delve into joint status, soft- tissue analysis, surgical treat- ment objectives, pre-treatment surgical setups and surgical setups. We’ll then follow-up by looking at the concepts of natural head position, the axis- horizontal plane and the true vertical line will be introduced. By the end of this article, you should have: – An overview of the knowledge needed for successful treatment. – An introduction into what, when and how to perform suc- cessful cases. – An overview of joint health. – A summary of the soft-tissue analysis. – An outline of the surgical treat- ment objective. – An overview of diagnostic and surgical setups. Remember that this article is an introduction only; it’s not intend- ed to teach you how to do surgi- cal cases. Advanced training will be needed to master success- ful orthognathic surgical cases. So with no further ado, let’s get started. Functional occlusion The goal is to obtain functional occlusion. Before treatment, you have to determine if you have an orthognathic surgery case. You don’t want to begin orthodon- tic treatment with the idea that if orthodontics fails, we will do surgery. You’ll see in Figures 1–3 that this case involves every facet of den- tistry. Changes occurred not only in the facial features, but also in the teeth themselves. It involved orthodontic and orthognathic surgery, but also lengthening the front teeth by the restorative dentist to achieve the natural smile in balance (Figs. 1-2). To this end, we need to look at five areas: – joint status, – soft-tissue analysis, – surgical treatment objective, – pre-surgical setup/surgical setup technique, – surgery. We’ll give you a brief overview of the goals for each of the areas, then do an in-depth look into each of them individually. Joint status Starting with the first area, you need to know the joint status. Is the joint healthy, is it degenerat- ing, is there a disc problem? This means you’ll need to apply not only a good clinical exam, but also articulated models that can measure the difference between centric occlusion and centric re- lation. Soft-tissue analysis You’ll need to know how to ana- lyze the soft tissue. You’ll need this because you are looking at everything from a soft-tis- sue standpoint, or put another way, you’re recording the basic measurements that come from soft tissue, not hard tissue. If you deal with hard tissue only, then you will come up short in the soft tissue. Ignoring the soft tis- sue will result in a face that’s not improved, just different. Surgical treatment objective You need to know how to do a surgical treatment objective. You’ll need to know the tech- nique, and you’ll need to know how to apply it because the sur- gical treatment objective allows you to treat the face, the occlu- sion, in a two-dimensional me- dium. Pre-surgical setup/surgical setup technique Once you have established what you’ll need to do from the surgi- cal treatment objective, you will need to do what we call a pre- surgical setup. Otherwise you’ll need to apply the knowledge you’ve gained from the patient, soft-tissue analysis and the sur- gical treatment objective, and perform a three-dimensional workup to make sure what you have planned will work with the joints, muscles and nervous sys- tem. Surgery Finally, you need to know sur- gery. I recommend that the or- thodontist be in the operating room so you know what the sur- geon is doing, and how the sur- gery goes. It’s very important to know that the surgeon gets the joints seated in a passive man- ner. If the joint is stressed, then there’s a good chance that we’ll have some surgical relapse. Joint status Joint analysis will include three portions: history, a clinical ex- amination and imaging. Building a history will be simi- lar to traditional patient assess- ment. We need to know if there are any family members who exhibit TMJ problems. If yes, then there’s a good chance the patient will develop significant joint issues that will affect the outcome of treatment. After an oral investigation, a thorough clinical examination of the joints will need to occur. We’ll be on the lookout for any type of injuries to the mandible. If the patient has had any injury that involves the chin, there’s a good chance that the joint may have been damaged. Finally, we need to look into any past treatment. Has the patient had orthodontics before? Has the patient had a lot of restora- tive dentistry? This is important because all of the above have a tendency to affect joint status. Clinical examination Next is the clinical examination. Clinical examination includes the following: – range of motion, – symmetry of jaw motion, – palpation, – auscultation, – muscle splinting, – CR position. Range of motion should be be- tween 45 mm and 55 mm on opening and includes assessing movement. We’re looking for a symmetrical mandible mo- tion — 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 some sort of functional bite is- sue. We also listen to the joint with a stethoscope, and we apply some anterior pressure to the disc through external auditory mea- tus to make sure the disc is func- tioning properly. When trying to manipulate the mandible, one can feel the mus- cles. If the muscles will not let you obtain a centric joint posi- tion, then we cannot do a diag- nosis because the muscles aren’t holding the condyle out of the socket. This is usually due to some inflammation. Finally, we’ll check what we call the centric relation position, which you should be able to feel. It should feel solid and the pa- tient 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 the joint status. The use of imaging will help us build our base of case-specific intelligence. We’ll use two types of imaging: MRI and cone beam. Fig. 1a. Patient profile. Fig. 1c. Patient oral casting. Fig. 1b. Patient frontal. Fig. 2. Joint degeneration. Fig. 3. A state of degeneration: a condyle that is actually changing. Fig. 4. Overlaid soft tissue on top of hard tissue. mCME articles in Dental Tribune have been approved by: HAAD as having educational content for 2 CME Credit Hours DHA awarded this program for 2 CPD Credit Points Centre for Advanced Professional Practices (CAPP) is an ADA CERP Recognized Provider. ADA CERP is a service of the American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. CAPP designates this activity for 2 CE credits.