Rethinking Occlusion: Why Your Patient's Bite is a Journey, Not a Destination

Dr. Melissa Seibert: Welcome to the Dental Digest Podcast — a show with a mission of enabling you to stay on the cutting edge of evidence-based dentistry. I'm your host, Dr. Melissa Seibert. This is Part 1 of a two-part series with Dr. John Kois — a prosthodontist, educator, and one of the most influential voices in restorative dentistry. Dr. Kois maintains a private practice limited to prosthodontics, is an affiliate professor at the University of Washington, past president of both the American Academy of Restorative Dentistry and the American Academy of Aesthetic Dentistry, and the founder of the Kois Center.

Dr. Seibert: You've been teaching for decades, and dentists wait multiple years just to get into one of your courses. How has your thinking about occlusion evolved since you first began teaching it, and what do you see as the most common misconception among general dentists?

Dr. John Kois: Quite an opening question. I trained in both periodontics and prosthodontics. I spent the first ten years of my career trying to master what I had learned in specialty training, the next ten figuring out what to do about the problems I still had — because as a specialist, I didn't think my outcomes were really much better than when I was a general dentist — and the rest of my career trying to teach what I believe is a new opportunity for us. My focus is on practice, and on having the phone ring for only two reasons: new patients, and praise. The point is to avoid the adverse events — my tooth is sensitive, my bite's not right, I have to cancel my appointment.

Dr. Kois: My specialty training was dogmatic and mechanical, and I never really could understand how it resolved the science of occlusion or the mechanics of occlusion in terms of a real person and how they chew. The number one paradigm shift for me on any new patient is this: when a new patient comes in, is their bite — and by bite I mean MIP — working, or is it breaking down? Is their existing occlusion something that will stand the test of time? In school, MIP was the origin of everything we learned to do. That's where excursive movements came from — right working, left working, protrusive. In my practice now and what I teach, MIP is the terminal position. It's how the lower jaw finds the head, and how it does that is the root of the issue. It's 180 degrees opposite from the way I was trained.

Dr. Kois: Most MIP positions that dentists observe, they observe as a static position — morphology. Class I, class II, class III. But morphology doesn't have a relationship to whether the occlusion is working. That's why no one in dentistry has been able to take occlusion the way it was defined in school and relate it to functional anomalies. That's why many oral medicine people today don't believe occlusion has anything to do with what happens to the teeth, headaches, or TMD. It's defensive — because it depends on how you define occlusion. This is a much more dynamic entity than the static cross-bite, open-bite framework we were taught.

Dr. Seibert: So we're spending too much time on MIP as a static terminal position when we should be evaluating the whole system?

Dr. Kois: MIP is taken for granted — you ask someone to close. But how they close has a huge range of variability. There are people with occlusions that look amazing — teeth I'd personally kill for — but their occlusion isn't working. They're squeezing, clenching, they need Botox, they have sleep disturbances. And dentists use convenient labels: it's bruxing, it's airway, it's anything other than something we could actually fix. Three things impact a healthy occlusion. One: the position of the lower jaw referenced to the head — when you close, do you have to force, pull, or shift? Two: the bite we call MIP — is it really amazing, or did the patient have to squeeze to get there? With scanning technology we can actually see collisions. The harder they have to work to make the teeth fit, the more symptoms they have that get confused with parafunction. Three: how the jaw is closing into the teeth on its way there. Does it rub? Does it create wear? Those are pathway issues — what we used to call the envelope of function.

Dr. Seibert: Talk to us more about pathway wear. This is critical — dentists embark on big restorative cases without recognizing it, and the case becomes a nightmare.

Dr. Kois: I'm using my hands as puppets here since we don't have visuals. The space between the upper and lower front teeth — not the outsides, but the space inside, the clearance — that's where the work happens, because the jaw doesn't chew up and down. It has an envelope. The question is whether your restorations or your orthodontics respect that envelope. If they don't, the jaw rubs, and you get one of three things. Attrition — facets that get misread as parafunction. Mobility — primary occlusal traumatism, where opposing teeth load prematurely, with sensitivity or movement. Avoidance pattern — the jaw wants to chew, something's in the way, so it finds a different envelope, creating muscle fatigue and tenderness. So the three things dentists look at as diseases — mobility, muscle pain, attrition — are all adaptive mechanisms. The body is trying to do its four jobs: chew, speak, swallow, breathe. Anything that disrupts the system, it tries to fix.

Dr. Kois: Dentists come to the Center saying they want to learn to treat a wear case. That's the wrong focus. The focus should be: why is the patient wearing in the first place? Nobody was born grinding their teeth. Nobody was born to destroy the dentition. So we use night guards and Botox to reduce symptoms without realizing we could treat the parent cause. Ask yourself this: how many TMD patients in your practice are over 70? Where did the TMD go? It adapted. They healed themselves — at a price they now pay for the rest of their life.

Dr. Kois: The wear standard I use with patients: your teeth should not have more than one millimeter of attrition in your lifetime. When you see a 20- or 30-year-old with one or two millimeters on the front teeth, you can say, "Mr. Jones, that would normally be 200 years of use. In 100 years you shouldn't lose more than one millimeter." Dentists don't realize the standard we could hold patients accountable to is much higher than what we're allowing them to achieve.

Dr. Kois: Worn edges on the front teeth should never happen. You should chew behind your teeth, not on the edges. Tell a patient to take their lower jaw and move it to the edges of their teeth — if that feels good, something is wrong.

Dr. Seibert: So how should dentists actually evaluate occlusion on a restoration — let's say a single posterior crown?

Dr. Kois: It's not that what we're doing is inaccurate — it's that it's not enough. Articulating paper is a medical diagnostic with false positives and false negatives. We all learn to deal with premature contacts. But then we ask the patient to move right working, left working, protrusive — and nobody comes back complaining that the crown doesn't work in lateral excursion. They tell you it doesn't work when they're eating. They give you a physiologic reason. So we should have methodologies in practice that are closer to how people use their teeth. The articulator doesn't speak. The articulator doesn't chew. Patients tell you it hurts when they eat a salad or a steak — that's how they use the teeth. Nobody leaves my practice unless I cover all the teeth with articulating paper and make them simulate chewing.

Dr. Kois: Years ago, denture prosthodontists used to give people peaches or food, place wax over the teeth, and look for smudges in the wax where the teeth would rub during chewing interferences. That's 50 years ago, and it's brilliant. At the University of Washington we did jaw tracking under load — when people chew and the jaw runs into teeth, something's wrong.

Dr. Kois: "Freedom in centric" — long centric — that wasn't a concept. That was a hack. We told people, when you create guidance and it's too tight, go back and hollow out the back of the teeth. That's telling you that you made a mistake. You can't grind the back of natural teeth — that would require orthodontics. Until ortho and the restorative world come together on how occlusion actually works physiologically, we're recreating the same problem.

Dr. Kois: We're very fortunate in dentistry because we don't always manage occlusion to the precision necessary — and we get away with it because patients adapt. They chew differently. They develop avoidance patterns. They live with a little muscle soreness. The disc is an adaptation mechanism — I call it a hemorrhoid pillow. You squeeze on it, and even though the teeth don't fit right, you make it fit. Equilibration, by the way, is controlled adaptation — adjust the teeth in a predictable, dedicated way to reduce the adaptation the patient has to do. All we have to do to be successful is stay below the patient's individual threshold for adaptation. There's always 10 to 20% where that threshold is low and we have trouble. Single-tooth dentistry forgives a lot. Big cases, full-mouth, all-on-X — they don't. The modes of failure shift to broken screws, chipped ceramics, fractured restorations — different surface, same roots: Position, Place, Pathway.