JCO Interviews H.P. Bimler on Functional Appliances

DR. GOTTLIEB Peter, you are one of those rare pioneers and innovators in orthodontics. You developed an appliance that bears your name, and you developed a system of diagnosis and cephalometric analysis. You were very close to those who were responsible for the development of removable and functional appliances in Europe. Tell us how that all carne about.

DR. BIMLER It started in Europe in the beginning of this century. A Frenchman named Robin had certain ideas about growth of the facial structures and he tried to influence it.

DR. GOTTLIEB With an appliance called a "monobloc"?

DR. BIMLER Yes. Around the same time, Andresen was teaching in Norway. Nobody took him seriously. He had a long white beard, which, at that time, was considered to be a sign of an old-fashioned person. You can see how things change. Now a full beard is very modern and progressive. By coincidence, an Austrian named Haupl was also lecturing at the Oslo dental school, in the field of periodontics. Haupl had a medical degree, as I did, and it may be that the same thing happened to Haupl as happened to me when I saw functionally treated kids in my father's office. I saw kids without any irritation of the gums. I disliked the clumsy appliances, but as a physician I definitely liked the appearance of the teeth and gums. Haupl, as a physician and a periodontist, may have felt the same way. At any rate, he became interested in the biomechanical approach of Andresen. Andresen never talked about function. He called this a biomechanical apparatus. When Haupl translated Andresen's ideas into dental language and simplified them, for the first time a number of practitioners in the German-speaking countries of Western Europe became interested in these ideas. These were dentists with a medical degree, and this new approach appealed to the eye of a physician.

At the same time in Germany, we had compulsory continuing education and from 1935 to 1945, Korkhaus, Simon, and Haupl were in charge of it. They helped spread the functional treatment idea, and the Andresen/Haupl book was published in 1936. Haupl was influenced by Roux and other workers in adaptation. If you had a broken leg that healed in a poor position, in time it would improve by natural adaptation. Roux said that by tension in the bony tissue there would be a rearrangement of molecules, by which resorption and apposition of bone would be controlled. The Andresen/Haupl book refers to this rearrangement of molecules. Haupl used three dogs in an experiment. One did not survive, leaving a young one and an old one. The old one was used for the fixed appliance therapy, and the young one for what they thought was the equivalent of what an activator was doing. They were just tapping on the bone by tapping on the teeth, with the idea of producing this rearrangement; and it looked as if only the functional approach would produce changes in the bone.

In the same laboratory in Oslo and at the same time, Kaare Reitan conducted experiments which reached a different conclusion. Many of us, with the notable exception of Haupl, believed that this disproved the hypothesis put forth by Haupl. Reitan had 36 dogs in a well-controlled experiment. He made it clear that the tissue cannot differentiate where a force comes from - from an elastic, from a screw, from a wire. A certain amount of force over a certain period of time will give you an effect. What is important is to have just the right amount of force and time.

DR. GOTTLIEB What is your own view of how the functional appliance works?

DR. BIMLER My personal view of functional treatment is that it means treatment with some appliance that can be introduced into the reflex system which controls mastication. We call it a freeloader. All those using a functional approach are freeloaders on Nature's controlling mechanismwithin the stomatognathic system. In the early days we were told that it was the muscle that was doing the magic. Now we know that this was wrong. Muscles only work through nervous stimulation. It is intrinsic force control, provided by the patient's own neuromuscular reflex system, which brings mastication to a high level of efficiency. You bite differently into a piece of cake than you do into an overdone piece of steak.

DR. GOTTLIEB But the appliances don't all work the same.

DR. BIMLER In the U.S., there is a lot of confusion. Removable appliances are always included with functional appliances, but there is a lot of difference. A Hawley type retainer or a Schwarz type plate with clasps is removable, but not functional. The control mechanism can't work as long as you have a force on the dental arch. Nature can wait. As soon as the kids go on vacation, they forget to wear the clasped appliance and you get relapse of the forced expansion. This is what I saw in 1938 with Schwarz plates, when my father sent me to Vienna to study with Schwarz.

DR. GOTTLIEB Was the idea that you get something more out of a loose plate and the natural effort to hold it in the mouth?

DR. BIMLER Definitely.

DR. GOTTLIEB What is the difference how the expansion occurs?

DR. BIMLER As far as tooth movement is concerned and as far as tissue reaction is concerned, I don't think there is much of a difference. The point is that you have to have the right amount of force in the right place, and you have to know how far you can go before you invite relapse. I have called this intrinsic force control.DR. GOTTLIEB An intrinsic force as opposed to an applied force.

DR. BIMLER Exactly. There are a lot of delusions in this functional treatment, and many are putting a lot of magic into it. You have the leaders and the followers, and many of the true believers follow exactly what the guru has told them .

DR. GOTTLIEB Aren't you now a guru, too?

DR. BIMLER I'd have to say I am not a follower. I have to talk to others to understand their teaching, but I am not a follower. I have to have facts and proof. I had been trained by my father to keep excellent records. He was one of the very early birds in cephalometrics.

DR. GOTTLIEB When did cephalometrics come into Europe?

DR. BIMLER As you know, it was originated in 1922 by Carrea in Argentina, by Broadbent in this country in 1931, and by Hofrath in Germany more or less at the same time. My father and I had our first cephalometer in 1937. In 1938, I made my first film composite, combining photography and cephalometrics.

DR. GOTTLIEB Whose analysis were you following?

DR. BIMLER My father was a disciple of Simon of Berlin. Simon developed the gnathostat, which oriented models in space, using Frankfort horizontal as a reference. I was trained to see everything oriented towards Frankfort horizontal.

DR. GOTTLIEB We seem to be drifting back to Frankfort.

DR. BIMLER The smarter ones are coming back to Frankfort. In the late '40s men like Brodie and Bjork suddenly found that the distance between Frankfort horizontal and NS plane increased. Up to that time, we had the idea that there were certain stable planes and points. Now we know that this does not exist. They are all relative one to the other. Brodie, sitting in sella, saw the Frankfort horizontal going down and said, "I better stick to NS line". Whereas I, sitting on Frankfort horizontal, said, "Look up there. Sella moves about and is not reliable". I think I saved the detour of 40 years that the rest of the orthodontic world has spent discussing what is the best plane of reference. It took half a century before the anthropologists agreed, in 1872, that Frankfort horizontal was the best compromise from among dozens of reference lines. Now, for the past 40 years, we have had this discussion in orthodontics over which is better, SN or Frankfort horizontal.

There is another problem in cephalometrics, which is the way you measure. Before the AAO insisted on standardizing the distance at five feet, everybody had a different target-film distance and, therefore, everybody had a different percentage of enlargement in the head-plates. The only chance to evaluate the material was by angular measurements, which offer indirect inferences about what you are really interested in. I think I have always been in a good position with my orthogonial reference system based on Frankfort.

DR. GOTTLIEB It was pretty good intuition on your part. Did you use your system to analyze what really happens as a result of functional treatment?

DR. BIMLER In 1953 in London, I was displaying my variation of the activator to an international audience, and afterwards an American came up to me and said, "Dr. Bimler, do you really mean that you can bring the mandible forward?" I said, "Yes, I can". He said, "I just don't think you can do it". I said, "Of course I can". He said, "But,-Doctor, can you prove it?" That challenged me, and I went back to study my old headplates.

DR. GOTTLIEB Did you have your orthogonial analysis system at that time?

DR. BIMLER I developed it at that time. I needed a way to relate the maxilla and mandible. The only connection, other than the occlusion, is over the middle part of the cranial base and the middle of the temporomandibular joints. I decided that the best way to handle these three entities was to use the posterior limit of the maxilla, the pterygomaxillary fissure. I decided to take a plane or line through pterygomaxillary fissure. In order to make direct linear measurements, I decided to form an orthogonial diagnostic polygon. I set the anterior limit as Point A of Downs. I used Point B. Point C of Bimler is the center of the head of the condyle. This is the posterior limit of this facial stomatognathic system. I began measuring projections of these three points on Frankfort horizontal, and I came out with the depth of the maxilla. I made measurements using PTM projected on Frankfort, or the position of the TMJ on Frankfort; and I was using a projection between B and C points as the effective length of the mandible, but this was not the right approach. Muzj of Italy had a better approach. He was using the diagonal length of the mandible from menton to condylion, and this is what I am using now.

DR. GOTTLIEB And you devised this diagnostic polygon in order to confirm your feelings about growing mandibles?

DR. BIMLER Exactly. And, taking these measurements, I found out to my astonishment that the very polite American gentleman in London was right; I and all the functionalists were wrong. Wehad been told by Haupl that we are bringing the mandible forward to correct the Class II, with resorption in the glenoid fossa and growth in the head of of the condyle. This is definitely wrong, as I found out twenty years ago.

DR. GOTTLIEB But it is still believed.

DR. BIMLER It doesn't matter if a wrong opinion is disproved. It takes years and years to convince the profession.

DR. GOTTLIEB Once something gets into print, it is very hard to erase.

DR. BIMLER Most of the functional men in Europe still believe they are bringing the mandible forward and that they are growing mandibles. This is sheer nonsense.

DR. GOTTLIEB What did you conclude was happening?

DR. BIMLER The distance from the mandibular joint to the pterygomaxillary fissure, the far end of the maxilla, never becomes smaller. It may stay the same, but mostly it increases. So the joints sitting in the petrous portion of the temporal bone are usually carried backward from the maxilla, through growth in the sutures of the cranial bones. You have to expect that the distance between the maxilla and the temporomandibular joint is increasing in a growing child, and this increase can be up to 10mm.

DR. GOTTLIEB Over what period of time?

DR. BIMLER Let's say five or six years

DR. GOTTLIEB Two millimeters a year?

DR. BIMLER It can. In others, nothing happens.

DR. GOTTLIEB Can you predict the amount of growth?

DR. BIMLER I have seen between 20,000 and 30,000 tracings with all the measurements, and I don't dare to predict growth. Each individual is growing a different amount, in a different location, at a different time. If you think you have a so-called horizontal facial type or dolichoprosopic with a deep face, and you think this case will only grow forward, you can find periods in which they just grow vertically. I have found a range of variation for maxillary depth from 40mm to 60mm, for the temporal position to pterygomaxillary fissure between 20mm and 40mm, and for the size of the mandible in oblique measurement between 90mm and 150mm.

DR. GOTTLIEB For how pure a group?

DR. BIMLER This is for the mixed group of Europeans, blacks, and orientals that I see in myregion. Wiesbaden is a headquarters for the American Air Force, so we have all sorts of people in our city and in my office. I now know a lot about the size of these three components of our stomatognathic system, and I can prove that the joint will never come forward. If you see a diminution of pterygomaxillary fissure-temporomandibular joint distance, you have a dual bite.

DR. GOTTLIEB What happens in the non-growing situation?

DR. BIMLER As a believer in functional theories in the early '50s, I tried to do the same thing in adults as I did in children. It never worked. All you can get in adults by such an approach is a dual bite. In my father's office they were using a forced protrusion of the lower jaw with the Herbst appliance, a fixed pin and tube mechanism. My father rejected it. I tried it. It doesn't work. It doesn'tmake any sense.

DR. GOTTLIEB Do you treat all of your patients with a Bimler appliance?

DR. BIMLER No, around 90 percent. The first approach is nearly always with what is called the Bimler appliance. Forgive me if I also use the name. I have gotten used to it, but it is a funny feeling. The German name I originally gave the appliance of my design was the "Gebissformer". We tried calling it an Adapter, but the name was never accepted. So, let's call a Bimler a Bimler.

DR. GOTTLIEB Is it your feeling that 90 percent of orthodontic patients can be treated with a Bimler?

DR. BIMLER In my office, yes. Otherwise, I wouldn't do it. Of course, there are certain things that cannot be taken care of with a Bimler, and I have a fixed appliance department with an American-trained lady using edgewise.

DR. GOTTLIEB You use combinations as well, I guess.

DR. BIMLER Very, very rarely.

DR. GOTTLIEB Because you don't need them?

DR. BIMLER Because I don't need them.

DR. GOTTLIEB What did you use before the Bimler appliance?

DR. BIMLER I was brought up with fixed appliance therapy. My father preferred a labiolingual approach, first in precious metal and later in stainless steel. He had prefabricated arches, bands, and attachments. He was in light wire, using a Simon appliance labially, which was a translation of the old Angle pin and tube appliance into a light-wire technique - very similar to a Jarabak. It was highly efficient and could do everything that is now done with modern appliances. We could put in tip and torque and bodily movement. We were used to quick effects, but always with root resorptions, gum irritation, and hygiene problems. Lingually we were using a sort of expansion appliance, now called a quadhelix. It was the old Coffin spring.

DR. GOTTLIEB Were those the appliances you were using exclusively?

DR. BIMLER When I came back on leave during the war, my father - who had used Schwarz plates and activators in the early '30s - had changed from the fixed toward the removable anchored plates of the Schwarz type and activators. What caught my interest was that the gums looked so wonderful. The teeth looked like pearls. So, on the one hand I liked the appearance of the teeth and gums; on the other hand, I disliked the clumsiness of the blocs. But I went back to war, and another five or more years would pass before I returned and started to work in the mouth again.

I had an experience during the war, which I mentioned in my chapter in Graber's book. I worked in a maxillofacial hospital, not directly in the front lines, but through which wounded passed on their way back to Germany. There was a young fellow who had lost his gonial angle, and he was all wired up; but the odor of the wound was so bad that you couldn't enter his room. I decided to take out all the wires to get his mouth clean again, and I made a splint for him that was a sort of oblique activator. His lower left cuspid was occluding with the upper right cuspid. To my astonishment, within a week he had normal occlusion again with the splint in place. The hygiene situation was far better, and he began to eat and swallow. Then I saw a side effect in the upper arch. A diastema developed between the cuspid and lateral. It was a contra lateral response to the action of the oblique appliance. If you have a force moving the mandible in one direction, you will get an effect on the opposite side of the arch. This became the basis of my Bimler appliance.

DR. GOTTLIEB Did you start designing the Bimler appliance after the war?

DR. BIMLER When the war ended, I had been working almost ten years as a physician. I then spent a year In the office of an uncle who was an ENT man. My father asked me to join him in rebuilding an office, but we were refugees from Silesia. We had lost everything. The only thing myfather saved was a little suitcase with headplates and a few materials. Materials were so scarce that even if we had any money we couldn't have bought anything anyway. Professor Simon was a refugee from Berlin, making a living in the Bodensee area out of bending removable wire appliances. I couldn't afford to buy them and I couldn't master bending them as well as the old man, so I began using combinations of wire and plastic. My father had saved some heat-cured plastic material

.DR. GOTTLIEB What were those first appliances like?

DR. BIMLER They were more or less interocclusal plates - small strips of plastic combined with a lingual archwire very similar to the Coffin spring. But it didn't work. Frankel did it successfully later, coming from the outside with the lingual wire. Many others have tried to do the same. I was replacing the screw that Haupl put into the activator with a Coffin spring. I figured out that the Coffin spring and the labial arch only had an axis in the anterior region, which did not permit control of the posterior part. So instead of using a Coffin spring in the upper, I began using a lingual arch in the lower. Then I had one axis in front and one in the molar region to keep the two halves together. But I was still not happy with it, because I could not get any adjustment in the sagittal, which I thought was very important. Also, coming out of ENT I was aware that the tip of the tongue is one of the most sensitive areas in the body and that speech is one of the most human features. It does harm to deprive a child of speech. The consequence was that the activator was only used at night, and if it is lost from the mouth in the first half-hour, they don't work. So the next thing I did was to open up the activator in front by cutting it out, so that the patient could use the tip of the tongue for speech. You will find many authors in the literature quarreling over who invented the open activator or the elastic activator or the open elastic activator. I know. You can come to Wiesbaden and visit my museum, and there are all the early steps in my development from the activator to what I am using now.

DR. GOTTLIEB And what are you using now?

DR. BIMLER A Bimler is nothing more than the old labiolingual technique incorporating the lingual arch of Mershon and the labial arch of Oliver, which I learned from American textbooks. But I use them without banding.

DR. GOTTLIEB If the appliance is not tooth-borne, where does the anchorage come from?

DR. BIMLER Orthodontists are trained and work all their lives with anchorage. They can't imagine you can treat without anchorage. But you can, and very successfully. This is the difference between functional orthodontics and the rest. You can move teeth with fixed appliances, with banding, with bonding, with wires ligated to the teeth, or with removable appliances with clasps. What distinguishes functional treatment is the intrinsic force control I spoke about before. What makes a really good orthodontist is that he is able to control the forces that he is using, so that he does no harm and gets the maximum effect.

DR. GOTTLIEB Do you have any idea about the amount of force involved?

DR. BIMLER It's the amount of force the individual can stand. And who would be in the best position to know what is good for him? The patient himself. That's where the intrinsic force system comes in.

DR. GOTTLIEB How do you present the Bimler appliance to the child patient?

DR. BIMLER I don't touch the appliance when it is handed over to the child. It is presented on the models. The child is told to remove it from the models and place it in his mouth. I immediately ask him a question; and you have to be quick about it. Otherwise, the mother will interfere and say,"How can my child speak with this appliance in his mouth?" Then it is too late. You have to ask the question immediately, and it has to be a question that cannot be answered by "yes" or "no", or the child will answer by just moving his head up and down or side to side. So you ask, "What is your address?" or "What is your telephone number?" or "What is your teacher's name?" The child starts talking with the appliance in his mouth, and they are dismissed in five minutes. They return in a week and the mother may report that everything is fine; the child is wearing it all day long, except for mealtimes; he puts it in at night, but sometimes it is out in the morning. Then I know that this was too much for the child.

DR. GOTTLIEB What was too much?

DR. BIMLER Usually, it is the amount of propulsion of the lower jaw that is too much. It is uncomfortable. Just as mother will slip out of her shoe under the table, if the shoe size is too small and pinching. This is what the child does with the appliance, if it is uncomfortable. They take it out and place it on the bedside table. It is no accident. They are getting rid of it.

DR. GOTTLIEB Are the adjustments in this situation empirical?

DR. BIMLER We have documented that wherever there is a propulsion or protrusion of the lower jaw of more than 4mm, protective reflexes are invoked and the patient tries to get rid of the appliance. This is exactly what Andresen said fifty years ago. He was a keen observer and knew what a child could tolerate.

DR. GOTTLIEB Are the adjustments simple to make?

DR. BIMLER The difference between a Bimler and other functional appliances is that if the propulsion is too much, they have to make a new appliance. From the beginning, I used the simplest approach to the problem and built in the possibility of sagittal change in the upper and lower parts of the appliance. I can change the wires in a Bimler appliance by a fraction of a millimeter. The strategically placed loops can be adjusted to accommodate shedding of teeth, growth, or whatever is necessary.

DR. GOTTLIEB Is the corrective influence of the appliance related to its effect on la morphogenetic field of some kind? How does the intrinsic force system work?

DR. BIMLER This is a typical question that is always asked. The three significant linear measurements that I got out of my cephalometric analysis were the depth of the maxilla, the TMJ position, and the length of the mandible. I can't do too much with these components. I can only follow their natural growth. So my treatment is a combination of natural growth and the effect of this patient-controlled mechanical device which triggers two mechanisms that Nature always works with - the exciting or facilitating reflexes and the inhibiting reflexes. The two together bring about the highest economy in mastication, with no harm to the tissues, the teeth, or the joint. If you are eating a prune and hit the pit, what happens? You bite very carefully and then you spit the pit out. When the teeth meet the pit, which could harm the teeth, there is an immediate signal, "Danger ahead". A message goes out for inhibiting reflexes, and this happens in a fraction of a second. It is a biofeedback mechanism that we are using

Intrinsic control in orthodontics is the same as in feeding babies. You can use scheduled feeding or demand feeding. I believe in demand feeding. The baby knows when it needs something. It is intrinsic feeding control. Our body is full of such intrinsic control mechanisms. I wonder how long it will take for orthodontists to get the message that there is an intrinsic force control mechanism that they can use free of charge to decide what is adequate for this particular patient. Perhaps they will get the idea if they look upon the brain as a computer in the patient's head that takes control of this appliance. After the child has taken the appliance and placed it in his mouth and answered your questions, you may be chatting with the mother; if you glance over at the child, you will see the child looking into space. What are they doing? They are plugging into the computer. The nerves are taking over. They are exploring what this new thing in their mouth is. You see it almost 100 percent of the time. They get this funny, faraway look in their eyes. All of them. They are plugging in their freeloader.

DR. GOTTLIEB It is your concept that people have a certain amount of growth potential?

DR. BIMLER That's it.

DR. GOTTLIEB Is your goal to help the individual to develop to his potential?

DR. BIMLER To get to be adequate. This is hard for a dentist to understand. In most dental schools he is trained that he has to do the work, that he alone is responsible for the quality. It all depends on him, on his skill, his accuracy. In medical school you are taught that you may try to the very best of your knowledge, but that Nature will decide whether this helps or not in the individual case. The orthodontic situation is more like the medical one. Nature will decide what is stable and what will relapse.

DR. GOTTLIEB Does overtreatment help this situation?

DR. BIMLER Overtreatment has been practiced in the U.S. with the idea that since you never know whether you will have relapse or not, you better go a little further and then allow the dentition to settle. But who decides about settling? Intrinsic force control. That's the built-in computer bringing the teeth to where they belong.

DR. GOTTLIEB So, you don't believe in overtreatment?

DR. BIMLER Never. Never. I can't afford it. I have to treat cases in the most economical way.Instead of overtreatment, I practice test treatment. I am offering the bottles to the baby, and the baby will decide how much to take. I am offering a certain amount of mechanical force to the dental arches, and the patient, via intrinsic force control, via this computer, decides to take from this force offering as much as the body can stand. Then I am interested in seeing how far the patient will go, which I call the limit of individual adaptability; and you never can say where the limit will be. You can't predict it for the individual. You may start out with a small mandible in one Class II case and, in spite of your best efforts, it stays that way. In another, you start out with a small mandible and end up with a Class III.

DR. GOTTLIEB How do you follow the progress of the test treatment?

DR. BIMLER The other doctors in my office, who mostly see the patients, plot the dental arch measurements against time to create a curve. In 50 percent of the cases, the curve slows down and then flattens on the Pont's Index line that is put on the curve.

DR. GOTTLIEB That means that in 50 percent of the cases Pont's Index doesn't work.

DR. BIMLER We use a modification of the original Pont's Index. His values were established in a square-faced population in southern France, so they have a little bit larger arches than we do in Silesia, which is a mixed population of Germans and Poles. It is different, too, from Korkhaus'values for even narrower arches in the Rhineland. We are somewhere in the middle, between Korkhaus and Pont. After one year of Bimler appliance influence, 50 percent of our patients' arches coincide with the modified Pont's Index. That is all we are saying. A majority of the rest will fall short of the Index line. There will be definite discrepancies between tooth size and bony base. Then you have to decide if it is a minor evil to leave some crowding, or if you have to go to extractions.

DR. GOTTLIEB In what percentage of cases do you extract?

DR. BIMLER Ten percent.DR. GOTTLIEB And the remaining 90 percent are nonextraction cases treated with the Bimler appliance?

DR. BIMLER That is correct.

DR. GOTTLIEB Is the idea in using the Bimler that the feedback mechanism you were describing only works maximally if the appliance is free-floating?

DR. BIMLER The minute you fix any portion of an appliance, you have tied down a portion of the system and unbalanced it. You put it out of action. It is like driving with the brakes on.

DR. GOTTLIEB Most American orthodontists have come to depend upon anchorage as a base for the action and reaction of orthodontic forces.DR. BIMLER Maybe an analogy of the free-floating, non-anchored appliance is the experience of the astronauts floating in outer space. For them, the classical law of gravity is repealed, yet they manage to get into the right position. With an appliance fixed in the mouth, you may temporarily see a change in direction and amount of growth, but growth has a way of catching up or slowing down in time, and you only get what was potential in that individual.

DR. GOTTLIEB So is the genetic influence the major factor?

DR. BIMLER The old idea that you can inherit teeth from father and bones from mother is true in a certain way. A normal mandible and a normal maxilla, matching each other in size, may be combined with a very short PTM distance. A forward position of the joint and a steep clivus in that case result in a Class III. The normal and matching maxilla and mandible may be combined with a flat cranial base and a posteriorly positioned joint, and you end up with a Class II. You can use all your tricks to improve the growth of the mandible or suppress maxillary growth, but the best you can get is a Sunday bite. In other cases, you may have a normally developed maxilla and joint position, but a maldeveloped mandible.

DR. GOTTLIEB But you do believe there are environmental influences.

DR. BIMLER Yes. Maybe twenty years ago I described one set of these as microrhinic dysplasia. Embryologists have found that in the third week of development, a lack of oxygen can slow the rate of cell division in certain key areas of the face and leave its scar for life. External influences can retard the development of the height of the nose, producing a rotational effect. With the nasal floor inclined upward, the lower jaw has to overclose to keep up with this loss of tissue, but very often you have an open bite.

DR. GOTTLIEB I think that the question on everyone's mind is whether or not you can produce increased mandibular growth with appliances.

DR. BIMLER Old father Angle thought after 1907 that he could develop underdeveloped bone with his appliance. Today, the functionalists are being asked the same question. Can they develop underdeveloped bone? Unfortunately, I have to tell you that clinical evidence makes that more than questionable. Yet, with so many unexpected, spontaneous reactions and compensatory mechanisms, we are ending up with acceptable results in a very high percentage of cases I am treating with my approach. The unanimous evaluation of highly qualified visitors to my office has been that immediately post-treatment cases in this country may look better than mine, but that five or ten years posttreatment they look more or less the same.

DR. GOTTLIEB Because our cases relapse more than your cases?

DR. BIMLER Because, with either fixed or functional appliances, you can never get more than the individual possibilities of a child. Nobody knows about these possibilities more than the child himself, but he can't tell you this in words. He can show it to you in the way he reacts to an appliance. Our way is to follow this reaction in a test period. At the end of the test period, we cometo a decision either to be content to carry on in the same way, or to go to extraction and fixed appliance therapy, or to go to surgery.

DR. GOTTLIEB How long is usually enough of a test?

DR. BIMLER For an experienced operator, I would say within six to eight months. I can see how it may develop in that amount of time.

DR. GOTTLIEB And how long does treatment take on the average if you continue with functional appliances after the test period?

DR. BIMLER The final limit of adaptability is seen after about two years.

DR. GOTTLIEB Are the results stable?

DR. BIMLER I was taught that what you do with functional appliances will stay forever. It doesn't. If you follow the cases long enough, a certain number will revert toward the original condition, and you would call that a relapse.

DR. GOTTLIEB What causes the relapse?

DR. BIMLER That is very difficult to say. Apparently it has something to do with mesial drift, and mesial drift has something to do with the inclined plane system and muscle force. So it is likely that relapse has to do with the inclined plane system and muscle force during mastication over the years.

DR. GOTTLIEB Do you try to work with growth spurt timing?

DR. BIMLER No. I do not have the chance. Our treatment is generally through by the time the growth spurt occurs. Our government program refers children at 7 years of age. We might be able to delay them a year or two, but we are generally through by age 11 or 12, which is before the growth spurt occurs.

DR. GOTTLIEB Would being able to coincide with the growth spurt improve your treatment with a Bimler appliance?

DR. BIMLER No. I do not believe so. I say that the most appropriate time for orthodontic treatment is during the mixed dentition, when there is apparently most movement in the area we are interested in, and not when the so-called pubertal growth spurt takes place. The pubertal growth spurt was studied by Tanner in relation to body length. He was not interested in teeth and dental arches. The concept may be important for body length, but we have to work in the dental system at the appropriate time and that is during the mixed dentition-- that wonderful time in which Nature helps you.

DR. GOTTLIEB How does Nature help?

DR. BIMLER First you have to understand what Nature is doing. If you superimpose on the cranial base, the mandible seems to be growing downward and forward. However, if you superimpose by metallic implants or tooth buds, either of which work nicely, then you can see that the mandible is growing backward and upward.

DR. GOTTLIEB I believe that Dr. Storey and Dr. Enlow are saying the same thing.

DR. BIMLER All is relative. In studying paths of eruption, I found that all the tooth germs are directed forward in the anterior part of the mouth and swing downward and backward, while all the molar buds are directed posteriorly and swing forward. So I take advantage of these paths of eruption, which Nature gives me without charge. In an extraction case, for example, I extract and let Nature take over. The ectopic cuspid will slip into place and you don't have to touch it.

DR. GOTTLIEB What we call physiologic drift.

DR. BIMLER Of course. It is not done by the appliance, as it may appear, but by Nature. But you have to know the ways of Nature in order to take advantage of it.

DR. GOTTLIEB Are you saying that if you have a retruded mandible, it will only improve if it has the natural potential to improve and not because the orthodontist attempts to bring the mandible forward?

DR. BIMLER As I have said, the idea of bringing the mandible forward or growing the mandible forward is definitely wrong. If you have a retruded mandible, first you have to find out whether it is a small high angle mandible, or a well-developed mandible with a TMJ that is so far back that even with proclination of lower anteriors-- which is Nature's way of coping with this problem-- you cannot get lower incisors in touch with upper incisors to have anterior guidance or incisal guidance. If my cephalometric analysis diagnoses a posterior position of the joint and I see nicely developed arches, then I will accept this fact. You cannot change the temporal position. You cannot grow the mandible.

DR. GOTTLIEB What then accounts for improved relationships between maxilla and mandible?

DR. BIMLER Maxillary growth is more or less complete by age 16 or 17. The mandible grows up to age 22 or 24. I try to take advantage of the natural way to get the lower incisors in contact with the upper incisors.

DR. GOTTLIEB If the overjet is too big, the lower incisors will procline too far.

DR. BIMLER If the overjet is too big, I will do what everyone else is doing. I will take out upper first bicuspids and move the anteriors backward to adjust the upper arch to the lower. The molars will remain in a Class II relationship, and this is what I think is appropriate for this type of malocclusion.

DR. GOTTLIEB How about using an orthopedic force to hold back maxillary growth?

DR. BIMLER I believe that you cannot stop maxillary growth. I believe this is an illusion. If you superimpose headplates on SN registered at N, you get a rotational effect that gives the illusion that Point A has moved back. If you check the same thing with linear measurements, as I use in myanalysis, you will see that Point A came forward by natural growth. We have to get rid of our usual thinking. I am reminded of a conversation with Ricketts. He said, "Well, Peter, I have been in Turkey and I have seen how the columns of Ephesus came down. All the columns of Ephesus in my orthodontic training had to come down before I dared to intrude teeth". In the same way, all mycolumns of Ephesus had to come down. All my beliefs in the magical functional theories and hypotheses had to come down. I had to build a foundation in fact, to develop the understanding that I now have. But it seems as though I am speaking a different language. I can only hope that in time communication will improve.

DR. GOTTLIEB Is there any validity to the idea that functional appliances work better on brachyfacial cases and that they do not work well on dolichofacial cases?

DR. BIMLER No. They work on both types of cases. I think orthodontists are brainwashed into thinking that high angle cases are the real problem. Well, low angle, deep bite, square faces are a real problem, too. You have to get rid of the concept of good faces and bad faces, and that only certain problems are difficult. We have a lot of difficult problems. The deep bite horizontal type, the long faces, the open bites, and the Class IIIs are all problems. But, per se, vertical is not more important than horizontal. Both facial types are due to the same environmental or hereditary influences that break up the harmony of the face. If we study facial harmony in a normally developed individual, then we can figure out how disharmony developed in our malocclusion cases, and things are not as complicated as has been thought.

DR. GOTTLIEB Do you think it is a matter of timing of the environmental and hereditary influences, and that timing is more important than what the influence actually is?

DR. BIMLER The body doesn't know what the influence is. It can only answer an interference with normal development in a stereotyped manner. A certain portion of the skeleton always reacts in the same way to different influences from the outside. Coming from the medical field, I was able to see this a long time ago.

DR. GOTTLIEB Do you think a Bimler appliance somehow counteracts some of the interferences?

DR. BIMLER By trial and error, I developed a device that works in my hands. I don't intend that everyone treat cases my way. I have found a method which gives spontaneous normal growth in children an opportunity to come to a very acceptable compromise within the dentition; what other methods try to accomplish in eight hours at the chair, I can do in two. I think a key lies in the fact that Nature provided us with a very flexible region in the alveolar process, and that the alveolar process can compensate for skeletal disharmonies that result from malcombinations or maldevelopment. I think it was Bjork who said, "If I see a malocclusion with a skeletal discrepancy,it was due to the fact that the alveolar process was not able to compensate for it".

DR. GOTTLIEB Of course, cooperation is a big factor in the use of any appliance.

DR. BIMLER Yes, of course. We have cases of children in the same family-- one gave us good cooperation with the functional appliance and one did not. The one that did not ended up with a really bad malocclusion.

DR. GOTTLIEB Do you think that functional appliances will gain wide acceptance in this country?

DR. BIMLER It will not be soon. You have been working with anchorage for so long and with apparent success. With good reason, you are proud of what you are doing and of your standards of highest quality of result. If only there were not this thing called relapse, which results from surpassing the limit of individual adaptability. I think over the next thirty years, Americans will be paying increasing attention to functional appliances. They are even likely to develop a super Bimler that will be able to handle the problems in a far better fashion, through the development of better materials and improved knowledge about what I am calling intrinsic control.