I have been asked to publish an update on the concepts relating to the vertical dimension of the human face -- how these concepts relate to the growth of the jaws and to the treatment of malocclusion. This request was made by the chairman of the Orthodontic Department of a highly prestigious University in the USA -- a man of outstanding leadership.

The growth of the human face does not proceed strictly vertically and horizontally, but perhaps it can be best understood when considered in this manner. Vertical growth of the molar teeth forces the mandible down and back, while horizontal growth (condylar growth) moves the chin forward. The resultant of these two forces is to move the chin downward and forward.

Some malocclusions are characterized by a deficiency of vertical growth as related to horizontal growth, while others have an excess of vertical growth as compared to horizontal growth. In case of a deficiency of vertical growth, usually causing a deep bite, we should try to stimulate the growth of the molar teeth to produce permanent overbite correction and to improve facial aesthetics. See Fig. 1. This is done by using Class II elastics and vertical elastics. A combination of Class II elastics and posterior vertical elastics can be produced by just one elastic on a side -- running from the lower second molar to the upper first or second molar and to a hook mesial to the upper cuspid (triangular). Sometimes a bite plate is used along with elastics to help open the bite.

Fig. 1. A treatment record of a male age 13 to 15.

In Figure 1 is shown a treatment record of a male 13 to 15 years. A, before and after tracings superimposed on S-N. B, diagram of maxilla showing bending of the alveolar process. We must not think of the palatal plane as a rigid bar. Instead it must be thought of as a structure which bends when subjected to physical forces. The maxilla and premaxilla join in the region of the palatine foramen. This region becomes an area of cleavage, allowing the anterior portion along with the anterior nasal spine to bend with the alveolar process.

If the chin had not moved downward, then it would have been necessary to move the maxillary incisors 8 mm posteriorly. This would have been physically impossible, as there was not enough bone on the lingual. The condyles grew just enough to match the vertical growth but not enough to move the mandibular incisors forward. This caused the maxillary incisors to move straight downward. The overjet was corrected entirely by the downward and backward movement of the maxillary incisors.

The apices moved mostly through the bone while the crowns moved with the bone. The apices moved about 5 mm through the bone and 2 or 3 mm by the bending of the palatal plane. The crowns moved about 2 mm by the bending of the anterior portion of the base of the maxilla and 6 mm by the bending of the alveolar process. C, the maxilla is registered on the cementoenamel junction with the labial and lingual cortical plates parallel to further depict the bending of the alveolar process. D, the mandible showing the behavior of the teeth. Other points of interest are:

1. the great amount of movement of the maxillary incisors
2. intrusion of maxillary incisors
3. increase in anterior dental height
4. chin moves straight downward, and
5. overbite changed from 11 mm to 1 mm

Although moving the maxillary incisors downward away from the anterior nasal spine and tipping the palatal plane downward and backward helps to correct the overjet, this should not be done if it can be avoided. Thus, we have pointed up an important physical as well as biological principle which pertains to the correction of overjet and the selection of the right headgear.

In case of excessive vertical growth of the molar teeth, usually but not necessarily always causing an open bite, we should try to inhibit the growth of the molar teeth. There are various methods to attempt this but we will mention only one -- the high pull head gear attached to the upper first or second molars. If we are successful in limiting the excessive vertical growth of the molars this will usually correct the open bite, if any, and improve facial aesthetics. (The high pull face bow was first used in our office, and was developed by Dr. Thomas Creekmore and myself.)

A vertical dysplasia is not always caused by excessive vertical growth of molars. It may be partially caused by a deficiency of condylar growth. When a malocclusion is characterized by a high palatomandibular plane angle (32° to 35°) and a high gonion angle, this is usually an indication of condylar deficiency.

Inhibiting vertical growth of molars has the same effect as causing condyles to grow. In reality the practice of Orthodontics can be considered a program of "conservation"-conserving condylar growth so it will go farther toward correcting the malocclusion. It is incredible how rapidly the effectiveness of condylar growth is used up by vertical movement of molars. Orthodontists must be alerted to expect this and be ready to "cut it off at the pass." The high pull head gear to the upper molars is usually effective in this endeavor.

We read a lot about growth prediction. Many men, including myself, have encountered bizarre growth processes in treatment. After the fact, we have sent large numbers of such cases to a commercial laboratory for growth prediction. Without exception, the results offer no help in treatment. In fact, the predictions were so far off that they were ludicrous.

It is quite impressive to be able to rather accurately predict just how much the chin will move forward in a given period of time. It titillates the ego but it is of little value in treating a given case.

To know that the chin moves downward and forward on a given trajectory and not know how many mm at what locations it takes to produce this effect is insufficient information for the most proficient orthodontic treatment.

In the middle nineties we in USA have discussed two phase treatment versus one phase treatment. There are two schools of thought. In my opinion we make too sharp a distinction between the two. There will always be a segment of the population which need early treatment. Can a deep overbite be prevented? Are there ways the causative factors can be prevented? There are a number of procedures which could be used to prevent the causative factors from happening. By starting when the lower incisors are fully erupted and continuing, with possible interruptions, until age 14, we could prevent, in most instances, a deep bite. But this would be orthodontic treatment, and we would still have to place attachments on all teeth for final alignment. Such a plan would be expensive and would involve too much time. In most cases, the result would be no better than waiting until later and doing the treatment in 18 to 24 months. This is not to say that early treatment is not very desirable for many patients, but not to prevent overbite.

Condylar growth per se is very difficult to measure accurately, but it is not essential that it be measured completely accurately. All we need is a record of a combination of:

1. the approximate number of mm of bone added at the condyle,
2. the number of mm of increase in the distance from the fossa to sella measured perpendicular to Frankfort, and
3. the amount of vertical change, if any, of the condyle in the fossa.

When we superimpose the two tracings on S-N and punch a pinhole through both tracings in the region of the condyles, superimpose on the lingual outline of the symphysis and the lower border of the mandible, then we can measure between the two pinholes. This measurement is an accurate measurement of the sn to gonion distance.

During treatment, if the distance from ANS to Mn increases as much or more than the depth of the overbite, we can be assured that the overbite correction is permanent, see Fig 2. If all growth has ceased by the end of treatment we may be assured that the overbite will not increase during the lifetime of the patient. This is contrary to popular opinion, but nevertheless true. Please note that the overbite was 6 mm in the beginning, and the distance from ANS to Menton increased 6 mm during treatment. This assures us that the overbite correction will be permanently successful. Also please note that interincisal angle changed from 161° to 134°, and the maxillary incisors changed 20°. Bite correction was accomplished by moving molars occlusally. The patient was followed for ten years and the overbite did not change.

Fig. 2. Showing that overbite is related to anterior vertical height.

In 1967 Creekmore¹ discussed inhibition and stimulation of vertical growth of the molar teeth. Pearson² has discussed inhibition of growth of the facial complex, and has had remarkable success in this effort. George Schudy³ has discussed the role of post treatment growth as it relates to success or failure of the treated case, depending upon the quality of the treatment.

Isaacson^{4, 5} has confirmed the validity of the mechanism of jaw growth, when in April 1977 he stated, "Again identical amounts and direction of condylar growth have decidedly different effects on the occlusion and profile. The relative proportionality of vertical condylar growth to molar growth is critical (emphasis added)."

In September 1977 Isaacson et al stated, "Vertical growth at the condyles (and fossa) has to exactly (emphasis added) equal the sum of the vertical growth at the maxillary sutures and the maxillary and mandibular alveolar processes."

Also in the same article Isaacson stated, "When no rotation occurs, the linear anteroposterior condylar growth is exactly (emphasis added) the amount of the anteroposterior displacement."

Thus, we know that the basic knowledge is correct. Then when Bjork's⁶ implant investigations allege that there is up to five mm of resorption on the lower border of the mandible, we have a conflict. We must choose between the two concepts. We cannot have both!

The object in writing this brief narrative was to spare the reader the necessity of going back and reading the detailed account from several publications.

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Bibliography

¹Creekmore, T.D., Inhibition and Stimulation of Vertical Growth of the Facial Complex, Angle Orthod. 1967; 37: 285-97.

²Pearson, Lloyd E., The Vertical Control in Treatment of Patients Having Backward Rotational Growth Tendencies. Angle Orthod. 1978, 43, 132-140.

³Schudy, George F., A Longitudinal Cephalometric Study of Post Treatment Growth: Its Implications in Orthodontic Treatment, Am. J. Of Orthod. 1974; 65:39.

⁴Robert 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.

⁵Robert 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.

⁶Bjork, A., Skieller, V., Facial Development and Tooth Eruption: An Implant Study at the Age of Puberty, Am. J. Orthod., 1972; 62: 339-383.

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