Fall 2001 Presentation Summary:

Vertical Malocclusions: Etiology, Development, Diagnosis & Treatment

Presented by Dr. Ib Leth Nielsen
on June 4, 2001 at the Central Regional Meeting

Summarized by Dr. Robert Quinn, Central Region Editor

The vertical component of malocclusion does not receive as much attention as the saggital aspect, but in many ways vertical problems are more challenging for the clinician. Etiologic factors influencing vertical malocclusion include growth patterns of the maxilla and mandible, function of the tongue and lips, and eruption of the teeth.

Dr. Neilsen illustrated the developmental factors involved in these malocclusions with clinical examples.

Mandibular Growth and Its Clinical Significance

Nearly 40 years ago, Bjork showed that the direction of mandibular growth in humans was extremely variable. While the normal pattern of condylar growth is vertical, extreme forward and backward patterns are present, producing malocclusions that are difficult to treat conventionally.

Individuals with upward and forward condylar patterns will have a short anterior face height and a deep overbite. A Class II div. 2 malocclusion is typical of this pattern.

When anterior growth rotation is present and the incisor occlusion is unstable, i.e., crowded or deep, the malocclusion tends to worsen during puberty and beyond. Early treatment in these cases is warranted to establish a solid and stable incisor relationship. A lingual arch and biteplate are often helpful. Extraction in these cases is contraindicated as the lower incisors generally function better with a more protrusive inclination. Crowding for such patients is better treated with arch expansion.

However, second and third molar impaction is less common in these growth patterns. Following definitive orthodontic treatment these cases must be maintained long term, ideally with a bonded lingual retainer and a bite plate incorporated into the maxillary retainer. Mandibular retention should be continued into the third decade.

The antithesis of this growth pattern is posterior condylar growth, which produces a backward rotation of the mandible and a long anterior face height. These patients frequently suffer from a dental open bite malocclusion. They usually have no appreciable horizontal development of the mandible and dental eruption tends to be vertical with the incisors retroclining over time.

Airway obstruction, whether from tonsils, adenoids, or allergies is frequently a factor in the development of this facial pattern. Impaction of second and third molars is common in such patients, along with a relapse in mandibular incisor crowding.

Orthodontic treatment in these individuals often involves extraction, although such decisions should be delayed as long as possible. The later in life these individuals are treated the more predictable the outcome. Active orthodontic intervention while the condyles are growing in a posterior direction tends to extrude posterior teeth, thus, worsening the openbite. Long-term retention of the mandibular incisors is mandatory for these patients.

Functional Appliance Update

Following nearly 60 years of experimentation with a variety of removable functional appliances, according to Dr. Neilsen, it appears that the Headgear-Activator as described by Teuscher provides the best improvement in developing Class II div. 1 malocclusions.

The high-pull headgear provides a restraining force on the maxilla, preventing the backward rotation seen with many functional appliances. This prevents the increase in vertical face height often seen with functional appliances. The cap on the lower incisors generally helps avoid the undesirable flaring of these teeth typical of most appliances.

Interestingly, the more proclined the mandibular incisors are at the start of treatment, the more upright they become after treatment. Using this functional appliance design is, therefore, not contraindicated with flared lower incisors. Note that the Teuscher torquing springs on the maxillary incisors do not seem to prevent palatal tipping of the maxillary incisors.

A recent modification incorporating the Bass torquing spring does prevent tipping of the maxillary incisors. The Class II correction was accomplished through a combination of restrained maxillary development and dentoalveolar modification. Mandibular growth beyond the norms does not seem to be a factor in correction of the malocclusion.

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