In this lecture, the speaker explains the historical origin of the Bolton Norm, derived from the 1930s Bolton Brush Study of attractive children, and describes how the norm line is superimposed on facial profiles using glabella and nasal bridge landmarks. The talk emphasizes that posterior facial retrusion of the maxilla and mandible reduces airway space, linking the Bolton Norm to predictions of obstructive sleep apnea. Various clinical scenarios are illustrated: orthotropics patients whose jaws are advanced forward, orthognathic surgery cases showing improved airway after maxillary‑mandibular advancement, and the limitations of applying a Caucasian‑based norm to African‑American and Asian faces due to shorter nasal structures. A twin case demonstrates how subtle dental and lip differences can shift facial balance relative to the norm. The speaker then correlates large deviations from the norm with obstructive sleep apnea across multiple patients. Finally, the Bolton Norm is used to critique Angle’s classification system, showing that Class I, II, and III malocclusions often involve posteriorly positioned jaws despite traditional labels, arguing for the norm as a superior communication tool for facial balance and airway health.
Chapters
Welcome back. This segment is entitled Diagnostic Criteria: The Bolton Norm. This is the Bolton Norm superimposed on a face. You say, well, where did the Bolton Norm come from? Well, in the 1930s, in Cleveland, Ohio, there was a thing called the Bolton Brush Study. Soon after the lateral head x-ray machine made its way into orthodontics, people in Cleveland at Case Western Reserve University wanted to do a long-term study. They selected a group of very attractive children, both boys and girls, and started taking head x-rays on them starting at age 8 through age 18. And they developed this line of the profile. We use it to superimpose on glabella and on the bridge of the nose. And what you see in this individual here is how the nose is down and back a bit, the maxilla, the upper lip, is back even more, and the chin is back even more. Superimposing this line on most people in Western societies, we find that the face will be back at least this much in many of them. Why are we concerned about it? Because the farther back the maxilla is and the mandible, the smaller the airway is. The farther back the soft palate is, the farther back the tongue is, and the spine doesn't get out of the way and the pharynx stays where it is, and as the soft palate and tongue fall back, the airway gets smaller. Looking at the face with the Bolton norm can help us predict who has poor airways. Here you see it used on an orthotropics patient. Remember that orthotropics is a technique which recognizes that in all malocclusions, the maxilla is back, and the mandible is back as well. So, here we see this patient's had orthotropics where the maxilla is moved forward, generally 8 to 10 millimeters, and the mandible is then moved forward with an appliance which negates the headgear effect, Resulting in this profile. Most would look at this and say he has a really good-looking face, and the Bolton Norm basically confirms that. Let's apply the Bolton Norm to someone who is going— has undergone orthognathic surgery. The picture on the left is after she's undergone traditional orthognathic treatment with a twin-block appliance and with fixed braces. Both the maxilla and the mandible are dramatically down and back, and you can even see the bend in the curve of her nose, Because of her maxilla falling back so far. The surgeon has brought her maxilla forward and the mandible forward into this virtually perfect balance relative to the Bolton norm. Now, let's look at her posterior airway space. You can see this dramatically large posterior airway space, larger than most everyone who comes to see us in our office or in any orthodontic office. You can see the metal and the fixation here. That shows how she's had her maxilla and mandible both brought forward. My point in showing this, it shows you a person with a basically perfectly balanced face relative to the Bolton Norm, and what I think the airway ought to look like in most of us, but sadly, it does not. Let's apply the Bolton Norm to African Americans and Asians. And what you need to understand is that African American and Asian noses are shorter than Caucasian noses. And the Bolton norm was made on Caucasian patients. You can use the Bolton norm on these, on African Americans and on Asians, but you have to understand this. Here then are twins. And we've already measured the cosmetic line, we've mentioned that earlier. You can see that the one on the left is 33 millimeters and the one on the right is 35 millimeters. But the twin on the left, the face is also further forward relative to the Bolton Norm, and the one on the right, it's further back. These 2 kids were basically the same, except one had their lips apart much more than the other one, and the entire dentition had started to fall back. And you can see how the face is actually that much different, and they are identical twins. Now, let's look at the Bolton Norm superimposed on a number of people here. You can see in the upper left how far back this person is, and the middle one in the upper, even further back. But he's— the one in the middle of the upper is really the only one who has any excessive weight on board. And yet, all these people, male and female, have one thing in common, and all of them have obstructive sleep apnea. So, when you see faces that are back this far, don't be surprised if they have obstructive sleep apnea. Let's then apply this to Angle's classification. And here we have the Bolton Norm superimposed on this young boy, and we've also included the cosmetic line, which says it was dramatically down and back. You see a Class I occlusion with crowded teeth, and we are told that Class I occlusion is normal. In reality, it's meaningless. Class I occlusion is completely meaningless because you can easily As in most cases, actually, have a Class I occlusion with the face dramatically back from where it ought to be. Let's then look at a Class II malocclusion. And here we— so, the cosmetic line, which we've already dealt with, is way too high, meaning that the maxilla is back. So, by the cosmetic line, it's too far back. And certainly, if you superimpose the Bolton norm on this Class II patient, you'll see how dramatically far back the maxilla is. And the mandible is even farther back. Now, you can decide what you think needs to happen for an individual like this. How about another Class II patient? Here, you can see the Bolton norm, and her maxilla, by the cosmetic line, is back about 5mm. In reality, that understates the case because her nose is so far down and back already from where it really ought to be. So, the maxilla is back dramatically, And the mandible is really back dramatically in her case. Obviously, this is a patient who needs to have both the upper and lower jaws brought forward, as is the case for virtually every Class II. This is just a more extreme case. So then, let's look at Class III. And most of us in orthodontics think of Class III, or we've been taught to think of it, as a prognathic mandible. And indeed, prognathic mandibles do exist, but they're very rare. In almost all cases, the maxilla is too far back, and the mandible is also too far back in most Class IIIs, which is one of the reasons that I don't use the angle classification and think that it should be eliminated from discussion in orthodontics. But the Bolton Norm shows just how well or poorly the face is. It's a great criteria to use in communicating to patients about their facial balance and correlating it with their airway.
