In this lecture Dr. William M. Hang (presenting John Mew’s work) illustrates how chronic mouth breathing, often triggered by nasal obstruction, drives a cascade of adverse craniofacial changes. He opens with a striking case of a child who developed a collapsed maxilla, flaccid lower lip, and flat cheeks after becoming allergic to a gerbil and switching from nasal to oral breathing. He then cites Egil Harvold’s monkey experiments, where plugging the noses of normal monkeys produced narrow, long faces, low tongue posture, and malocclusions mirroring human pathology. Hang explains the biomechanical chain: nasal obstruction forces the tongue down, the mandible drops and rotates back, the chin recedes, and the maxilla collapses, leading to a “cosmetic line” that signals facial unattractiveness. He connects these changes to clinical sequelae such as supra‑eruption of upper molars, increased facial height, and eventual sleep apnea. The talk advocates myofunctional therapy and BioBlock/Orthotropic approaches to restore proper oral posture, and warns restorative dentists that ignoring oral posture can cause prosthetic failures (e.g., implants appearing to “move” as the surrounding bone and teeth shift). Throughout, Hang emphasizes that these observations are evident in everyday practice and that early intervention can prevent lifelong facial deterioration.
Chapters
This is John Mew's pictures, and if you understand what goes on in this case, you understand more orthodontics than most orthodontists do. How can a gerbil change a face? This kid is a physician's son in England, and he was absolutely fine in the first picture over here. You can look at him, he looks great. His lips are together and his face is in nice proportion. Over here, he's not looking so good. These are the same age. You can see his lower lip is flaccid, his chin is falling back, and his cheek is getting very flat. He bought a gerbil, kept it in his room, and was allergic to it. Went from being a total nose breather with his lips together to hanging his mouth open. And that's what happens with our children. Children all the time. The same thing has been shown by Egil Harvold where he took monkeys, perfectly normal monkeys, and plugged their noses up and their faces got long, their maxillas got narrow, their tongue posture was low, and they developed malocclusions like humans have. But of course, in our profession we ignore that because it's only on monkeys and we're not monkeys. Well, if you didn't think it was going to happen the same way in the human, why did you do the experiment on the monkey? That's my thought. And yet, we're all the monkeys every day. Our children are the lab monkeys for what we're doing with the lifestyle we have. So here you see the whole maxilla falling down from here to here. The maxilla drops. The tongue is not to the palate. The first thing to change is the tongue will drop. The tongue has to drop for the patient to stay alive. If they can't get air through their nose, what did the monkeys do? They drop their mouth open. They'd rather do that than die. They'd also put their head forward and tilt it back because their airway gets better. Because as your mandible drops down, your tongue goes back and you have to tilt it forward to get the air in. The chin over time falls back and the cheek starts to fall back. The closer this line is here, if you drop a tangent from the eyelid To the cheek. The closer that is to paralleling the line of the nose, the more attractive the face is going to be. And I'll show you that some later today and tomorrow. But you see the flaccid lower lip that's rolled out. Right in here you'll see the very shiny part of the inner— it's the inner mucosa, which should be— it's all shiny, it's not keratinized. But you'll see a lot of kids, you'll see that. Shouldn't be that way. Doesn't have to be that way, and that's what myofunctional therapy is all about. That's what BioBlock Orthotropics is all about. And you see up here the white under the iris like this. If you see that, that's a maxilla that's deficient and falling back. That's a lot of deficiency before you'll see that. It's not attractive. But when you see that line under there, you've got a very deficient maxilla. This picture pretty much says it all, and it's the crux of everything. If you really understand this, you understand everything. The little baby is born and he has his lips together. You go to the hospital, they're all laying there and their lips are all together. But then, you know, you go to a kindergarten and you see them, many of them will have their mouths hanging open by the time they're in kindergarten. And as they have their mouth hanging open, The easiest thing to think about is what you say to Mrs. Jones. Mrs. Jones, I'm really sorry. We've tried to save your lower molar here, but we've done everything. You fractured it. It's unsalvageable. We can't send it to the endodontist to save. It's a done deal. It's gone. And in the same breath, you then say, you need to get an implant. Why? Because the upper molar is going to supraerupt, come down because it doesn't hit the antagonist tooth. And so the That you're going to have supereruption of the upper molar. Same thing's happening for the patient who hangs their mouth open all the time. I'm going to show you later on that Bill Proffitt at the University of North Carolina says if you have your teeth in contact 4 to 8 hours a day, then this vertical relationship is going to stay. If they're in contact intermittently 4 to 8 hours a day, this will stay. If it's less than that, your face height is going to get longer. So as soon as that upper molar comes down a little bit, then the mandible rotates down. As the mandible rotates down, it also rotates back, and the chin begins to fall back. Now, as they get older, it starts to go like this, and you see it more and more and more. But again, every case you measure the cosmetic line, and it's going to be too big in every one of the cases, and it's going to say, uh-oh, I smell the smoke, there must be a fire. And that's your key. Everything is so simple. You get the cosmetic line on the number, bring the mandible forward, and you're done. You can go home now, I just told you the whole course. That's what you're going to try to do. It's that simple. By the time you get to age 50, the face is falling back like this, and the forehead slopes back, and the nasal bone, which is perfectly positioned, looks like it's sticking out. And we tell people that the nose continues to grow throughout life. And people like this, of course, come when they had extreme makeover, they fly in. We had a Army sergeant from Virginia flew in to see, to see the group that was doing this whole thing. And so there's this guy with a bump in his nose and no chin, and his little kid says, Daddy, you don't have a chin. So here he flies in, this Army sergeant, gets the nose job done, knocks down the best part of the face. In reality, this needs to go up, and then puts the chin augmentation on. He looks great. And he'll look fine in his casket. When he dies early of sleep apnea. But you're gonna look at this, and when you go back, you're gonna sit in the airport drinking your Starbucks, and you're gonna be looking at people. I want you to look at their forehead sloped back. I want you to look at the bends in the nose. I want you to look at their flat cheeks. It's everywhere. It's in your practice all the time. Look at the head posture like this. Look at how they walk. People are a wreck. By the time they're my age, half of them can't walk. It's sad. The bump in the nose happens because the nasal bone is exactly where it always was. The cartilage of the nose falls back as the whole maxilla falls back. I have patients who have— I don't have it in this lecture— where you put implants in the maxilla and the lips are apart and the lips And the implants stay there, but the maxillary anterior teeth are dropping back because the mouth's open. The implant looks like it's going up. Have you ever seen an implant move? Never. They don't move, but everything else changes. Now, if you're the restorative dentist and you put all that nice porcelain in there and the whole face is melting away, whoa, still your fault, isn't it? Doctor, you put this in here. What's the matter? The patient's lips are apart. You see how this applies to your restorative practice as well? You can't just ignore the oral posture.
