Why Do We Measure the Effects of Growth
Instead of the Growth Increments?
The basic growth increments which cause the mandible to move forward and downward were identified in 1960 and published in comprehensive detail in 1964 and 1965. This work was declared a classic by the American Association of Orthodontics in 1991. In these discussions, condylar growth was divided into component parts, vertical and horizontal, each having a different function.
In the 39 years since these concepts were established, only Isaacson, Creekmore and George Schudy have recognized them in publications; however recently Pancherz et al. made a distinction between vertical effective condylar growth and horizontal condylar growth. .
Through the years since 1960 I have had considerable correspondence with heads of Orthodontic departments of Universities, and for the most part they have failed to show that they understand the effects of basic growth increments. All of this correspondence has been preserved, so it is easy to verify the above statements. .
Sadly, one professor thinks that we know nothing about "cause and effect." Many articles have been published based on the effects of growth, not on the growth increments. All of the analyses of which I am aware are based on the effects of growth increments..
These analyses report the forward development of the teeth and jaws in mm and the downward development of the teeth, the palatal plane, the occlusal plane and the mandibular plane in mm and degrees. They do not report the growth of increments which cause these movements. .
If one is slow it takes about five minutes to measure the basic growth increments which control the forward and downward movement of the mandible and teeth. However, the exact location of the increments which cause the maxilla to grow forward cannot be located at this point in time. Sutural growth and growth of localized areas are a big factor. Scotts thinks that the growth of the nasal septum may pull the nose forward. .
About twelve years ago I received correspondence from a professor, a personal friend, who stated that we should avoid the extraction of teeth in low angle patients because the strong musculature causes a relapse of overbite. It is most regrettable that a person in his position would not know that the relapse of overbite is due to (1) either the eruption of the lower incisors due to their intrusion during treatment, (2) insufficient torque of the upper incisors, and/or (3) posttreatment growth of the condyles. I requested that he send me evidence of instances where molars had been intruded posttreatment. I am still waiting! .
In 1963 I attended a series of lectures by a very prominent professor at a very prestigious university. He requested that those who had questions place them in a receptacle for that purpose. My question was, "What causes the increase of the distance from nasion to menton?" When my question came up, the speaker took ten to fifteen minutes to discuss it. Among the causes presented, the growth of the condyles was the major cause of the increase in the N/Mn distance. The growth of the condyles is the one increment which does not cause an increase in this distance. I knew that the vertical growth of molar teeth is the sole cause of an increase in facial height, but I said nothing. I was there to listen and learn. .
It is my prayer that my colleagues will soon begin to study the causative growth increments of the human face.
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