Hello, I'm Dr. Gordon Bell. Today I'm going to demonstrate a simple bite acquisition technique that can be used to record a starting position for an oral appliance. The bite will be measured in three distinct dimensions, horizontal, vertical, and lateral. There are numerous gauges that can be used for this purpose. The one that I'll be using today has a horizontal sliding component. I'll also be using three interchangeable bite forks that provide different vertical positions. In addition to the horizontal and vertical components of the bite, we'll also be observing the patient's dental and skeletal midlines to determine the most desirable lateral position. This is a horizontal sliding gauge handle shown from the top and side views. The horizontal position calibration numbers appear here on the top along with a tightening screw for locking it into a specific horizontal position. Underneath is another locking screw that can be loosened to allow adjustments of the buccal lingual dimension of the lower incisal guide. When loose, this blue lingual arm can be positioned to accommodate more crowded tooth arrangements in the anterior segment. These are just a sampling of three bite gauge forks. The gray fork is flexible at its distal ends and has two millimeters of thickness in the area where the maxillary incisors will occlude with the lower incisors. The white fork is also flexible at its distal ends, but has a five millimeter thickness in the incisal area. The blue fork is non-flexible and is a uniform three millimeters of thickness from the distal end to the incisal notch. Therefore, this is the only fork of these three that would assure you of a minimum of three millimeters interocclusal distance. This is how the bite gauge appears when a fork is loaded and locked into the position with the upper screw tightened. The first step is to fit the handle to the lower incisor teeth. With the lower screw loosened and keeping the handle parallel to the occlusal plane, I will place the blue sliding arm on the lingual of the lower anterior teeth and position it to fit snugly but passively to the buccal lingual dimension of the lower incisors. When the lower screw is then tightened, it will hold that position. So Elvis, we're going to try this in your mouth. I'm just going to put it in. We're going to slide it down and we're going to lock the screw, holding it in position. It's passive on the teeth. Next, I'll remove the handle from the mouth and place a fork into position on the handle. This is the gray bite fork. It's two millimeters thick where the upper and lower incisors meet. It's inserted into the handle on the top and the upper set screw is tightened, holding it into position. I will place this back in the patient's mouth and have them bite slowly together so that I can watch and guide the front teeth into the incisal notches. So if you would, Elvis, open for me and slowly bite down. Okay, let me move that just a little bit for you. Open just a hair. Okay. Perfect. Okay, and open for me and bite together. And open and bite together. With the bite fork engaged positioned in this way in the mouth, I'll examine the patient to evaluate posterior interoclusal distances. I also want to determine if the patient is biting on the fork with their posterior teeth as that could lead to a distortion of the bite fork. What I note here is the patient appears to be contacting the fork at the position of the left canine and bicuspid. That could possibly lead to distortions in the bite. With the bite fork in place, I will examine the vertical dimension between the dental arches in the anterior and posterior. This will vary from patient to patient depending upon their occlusal arrangement, curb of Spie, curb of Wilson. I'll ask myself if the fork position has created enough interoclusal space for the device materials and the design of the appliance that I'm planning on using. The thinnest device materials require an interoclusal dimension of three millimeters for full occlusal coverage. Additionally, many materials and designs require additional space. I will also note if the patient is biting on the distal ends of the fork as the bite force on a flexible fork can introduce distortions in that bite. If it's determined that I need more vertical space, I will add additional material to increase the height of the fork at the anterior segment. In some instances, it may be necessary to increase the fork height by adding composite or acrylic materials to the incisal notch position. Next, we'll consider horizontal range of motion. Opening the top tightening screw will allow the patient freedom of movement to protrude and retrude their mandible while keeping their front teeth engaged in the incisal notches. This allows the practitioner to determine the patient's full horizontal range of motion. Some practitioners will observe and record the numbers provided by the gauge at the most protruded and most retruded positions. From there, they may choose to use a percentage calculation for determining the patient's horizontal starting position. Whichever position the clinician has chosen, it's locked into place by tightening the top screw. With the upper screw loosened, I will place the gauge assembly in the patient's mouth and ask him to protrude and retrude as far as he can. So Elvis, we're going to put this in here a moment. And I'm going to have you gently bite down for me. OK. And keeping your teeth in the device gently, shove your lower jaw as far forward as you can for me. Good. And pull it back as far as you can. And come forward again for me. And come back again for me. OK. And go ahead and open. In this patient's case, what we see is a range of motion of minus 8 to plus 4, hence a 12 millimeter range of motion. We would then calculate our starting position as a percentage of that number. Typically, I will use 50% as my starting position. The third positional axis I want to discuss is lateral. This begins by examining dental midlines in habitual centric bite and comparing to dental midline position at end-to-end and maximum protrusion. It also should be contrasted to skeletal midline with an examination of the buccal frenums relative to the dental midlines. There are many theories on lateral positioning of the mandible during bite acquisition when habitual midline is not the same as protrusive midline or skeletal midlines. This issue is beyond the scope of this demonstration. It is critical, however, that once the decision regarding position of the bite in the lateral axis has been made, that the clinician proceed with bite taking in a manner that allows for visualization of the midline during bite acquisition. I'll demonstrate. Elvis, if you want to rest your head back for me and bite together, and we want to take a look, what we can see is that his midlines are shifted approximately half tooth to the right on the mandible. So now if you would come forward for me, bring your teeth out edge to edge, perfect. And again, we can see that that midline shift is maintained approximately one half tooth to the right. And come as far forward as you can for me, and we're still maintaining that one half tooth shift to the right. So in all three positions, that midline shift is maintained. Now by pulling the lips out, upper and lower, we can look at skeletal midlines versus dental midlines. So we can evaluate the mandibular frenum. We can evaluate the maxillary frenum to see if they are coincident with the dental midlines. So far, I've set the lower blue incisal guide to fit the lower front teeth passively. I've decided to position the horizontal component at 50% of the patient's maximum horizontal range of motion and tighten the upper screw to that position. Since my patient's habitual midline stays the same in end-to-end position and maximum protrusion, I will make sure that the midlines retain that same relationship when my bite is taken. So now I will place the locked bite fork on the patient's lower arch and ask them to close slowly. We're going to position this and close down for me, perfect. And open, and close, and open, and close. I want the patient to do this several times so that they form muscle memory of that bite position. I will check that their midlines are in the intended relationship each time they close. Next, I will instruct them to keep their mouth open as I load the bite fork on both sides with bite gel. I will then place the loaded bite fork on the lower teeth and instruct the patient to close slowly together so that I can watch their teeth coming together and guide them if necessary. At this point, it's critical to check and see if the midline position is maintained where I intended. So having loaded the bite fork, we will then go to the patient's mouth. Now if we're using a fast-setting material, we need to move pretty quickly. So if you would, Elvis, open for me. We're going to line it up with the lower midline and then bite together for me, perfect. We want to check and make sure that we have full coverage with the material, that we've captured all the incisal edges, and that we have no distortion in the bite fork. Let the material harden and then remove it from the mouth. I'm going to give that just a few more seconds. Okay, go ahead and open for me. The best way to evaluate the bite I've taken in the mouth is to remove it from the handle and break it at the detent. The bite fork we use is scored on the bottom, and if we simply snap it, we can separate from the rest of the unit. We then take this back to the mouth. I want to evaluate the results to make sure that I have the intended midline and all three dimensions that we're trying to register. So Elvis, if you would, open for me. In evaluating the bite position, we want to make sure that we've registered the midline shift that we referenced earlier. We also want to make sure that we have good registration of the cuffs tips and that we have no apparent distortions in the bite record. In evaluating this bite, it appears we've met all those criteria. This appears to be an acceptable bite. Taking a few extra moments to plan and evaluate your bite before you send it to the lab can save you a great deal of time and avoid potential complications when you deliver your device. No matter what bite gauge you use, the bite should be considered in all three dimensions. That's crucial. I hope you found this presentation helpful. Thank you very much for watching.

Dr. Gordon Bell

oral appliance

recording technique

bite gauge

lateral position