A reviewer of one of our prestigious orthodontic journals in U.S.A. in discussing a manuscript stated, "He (the author) then makes generalizations about growth which conflict with conventional understanding of growth." The generalizations referred to were not generalizations but specific statements. When does a statement of an opinion become "conventional?" When does a conventional opinion take precedence over an objective documented opinion?In 1937 one of our outstanding leaders1 expressed a conventional opinion in this way, "Elongation of posterior teeth throws a strain upon the muscles of mastication and destroys the harmony of the interrelated parts. The pull of the muscles drives the teeth back into the alveoli until a slight space is present between the upper and lower teeth when the muscles are at equilibrium." The author further states that, "The only permanent changes which can be brought about by the use of a bite plane is the depression of the anterior teeth into the alveoli."
This is perfectly logical thinking without the benefit of the cephalometric radiogram, and the article was hailed as a classic. The deductions were quite classical. But the documented opinion disagrees with the author, and tells us that the statements are diametrically opposite to the facts.2 Molars do not intrude from muscle force.
In 1947 the conventional opinion3 was that the saddle angle to a great extent controlled the anteroposterior position of the chin. The documented opinion was that the vertical growth of the molars produces anterior facial height and thereby to a great extent also prevents the anteroposterior movement of the chin. The 9.3 mm of anterior facial height in the upper ten percentile over the lower ten percentile was extremely important, but it was not discussed. The documented opinion4 tells us that the vertical growth of the molar teeth, not the saddle angle, prevented the forward movement of the chin. To this day the article is considered a classic, even though its shortcomings were pointed out in 1964.
In 1957 the conventional opinion was that the anteroposterior dimension of the facial complex was the most important consideration regarding growth and treatment. At the 1957 world conference, a workshop to determine the value of cephalometrics in clinical practice, it was stated, "The5 clinician's biggest problem is the anteroposterior discrepancies." It was further stated, "Segmental6 harmony or disharmony, as face to cranium, maxillary area to mandibular and so on, are generally evaluated in the horizontal plane on the lateral x-ray film." The documented opinion7 was that the vertical dimension was by far the most important in clinical orthodontics. The intervening years have proven this to be true.
By the year 1990 there had been no published comments in the U.S.A. regarding the building blocks of growth except those of Creekmore8, George Schudy9, Isaacson10 & 11, and Fred Schudy12. Thus, the conventional opinion was, no opinion. The documented opinion is that growth increments, the building blocks, control the anteroposterior and vertical movement of the chin, the rotation of the mandible, and to a small extent the forward movement of upper teeth through occlusal contact.
As we look back over fifty years of orthodontic history, we get a feeling of sadness when we realize that so many concepts have been published which are incorrect. In 1970 Fred Schudy stated, "Honest and fair play demand that we agree on basic biologic concepts, and we have a moral obligation to our colleagues to place in print only correct concepts."
We are not so much concerned with the fact that concepts appear in the literature which are incorrect, but that when new concepts come along, which are new and different and are proven to be correct, that these principles are not logged into our collective data bank as precepts we can depend on and follow. It doesn't have to be that way.
1Mershon, John V.: Possibilities and Limitations in the treatment of Closed Bites. Internat. J. Of Ortho. and Oral Surgery Vol. 23. 1937. Bibliography
2Schudy, F.F.: The Control of Vertical Overbite in Clinical Orthodontics, Angle Orthod. 38: 19-39, 1968.
3Bjork, A.: The Face in Profile, Sevensk Tand„kare-Tidskrift Volym 40, No. 5B, translated into English, Lund, 1947 Berlingska Boktrycheriet.
4Schudy, Fred F.: Vertical Growth Versus Anterioposterior Growth as Related to Function and Treatment, Angle Ortho. Vol. 34: April 1964.
5Moyer, Robt.: Preceedings of 1957 Cephalometric Workshop.
6Krogman, W. M.: Proceedings of the 1957 Cephalometric Workshop.
7Schudy, Fred F.: Vertical Growth Versus Anteroposterior Growth as Related to Function and Treatment, Angle Ortho. Vol. 34, April 1964.
8Creekmore, T.D.: Inhibition or Stimulation of Vertical Growth of the Facial Complex, Angle Orthod. 1967; 37: 285-97.
9Schudy, G. F.: A Longitudinal Cephalometric Study of Post-Treatment Craniofacial Growth: Its Implications in Orthodontic Treatment, Am. J. Orthod. 1974; 65: 39.
10Robert J. Isaacson, D.D.S., Ph.D., Richard J. Zappel, D.D.S., M.S., Frank Worms, D.D.S., M.S.D., Richard R. Bevis, D.D.S., Ph.D., and T. Michael Speidel, D.D.S., M.S.D.: The Effects of Mandibular Growth on the Dental Occlusion and Profile, Angle Orthodontist April 1977.
11Robert J. Isaacson, D.D.S., Ph.D., Richard J. Zapfel, D.D.S., M.S.D., Frank W. Worms, D.D.S., J.S.D., and Arthur G. Erdman, B.S., M.S., Ph.D.: Effects of Rotational Jaw Growth on Occlusion and Profile, AJO September 1977.
12Schudy, Fred F.: Vertical Growth Versus Anteroposterior Growth as Related to Function and Treatment, Angle Orthodontist Vol. 34 No. 2, April 1964.
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