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TREATMENT OF THE CLASS III MALOCCLUSION

Although traditional orthodontic treatment, for developing Class III malocclusion, focused on the mandible as the primary cause of the discrepancy, recent studies have suggested that 63% of the skeletal Class III malocclusions display maxillary retrusion. The majority of patients tend to exhibit maxillary hypoplasia in conjunction with a normal or mildly prognathic mandible.

Unfortunately, I see too many young patients, for a second opinion, who are told there is nothing the orthodontist can do but wait until their facial growth is complete and then work them up for orthognathic surgery. Yet the majority of surgical procedures to correct Class III malocclusion involve maxillary advancements! This suggests that the problem was never excessive mandibular growth, but rather a lack of development of the maxilla. Such problems may have been caused by nasal airway blockages, when the child was younger.

Orthodontic treatment for the Class III malocclusion can be defined into the following categories:

1. Growth modification involving maxillary expansion and protraction face mask therapy

2. Growth modification involving a chin cup to restrain mandibular growth, or

3. Waiting until growth has ceased, thereby, committing the patient to either dental camouflage treatment, or orthognathic surgery.

In my orthodontic practice, children exhibiting early signs of a Class III malocclusion are given priority for treatment. My current treatment approach involves protraction and development of the maxilla, but I do not use chin cups as I feel they have an adverse effect on the patient’s temporomandibular joints.

Controversy currently exists as to the optimum time to commence Class III orthodontic treatment. Takada examined maxillary protraction therapy and reported that the pre-pubertal and mid-pubertal time frame is best, due to the maxilla’s natural growth (stage C2-C3).

TREATMENT OBJECTIVES FOR THE CLASS III PATIENT:

If we treat patient as early in the growth cycle as possible, i.e. as soon as the Class III problem can be diagnosed, the following treatment objectives may be achieved:

1. Reduce the growth in the size of the mandible.

2. Increase the size of the maxilla to its maximum genetic potential, and

3. Move the maxilla forward to its maximum genetic potential.

A cephalometric analysis is essential to confirm the diagnosis of the Class III malocclusion and to formulate either a surgical, or non-surgical, treatment plan.

I personally use the Jefferson cephalometric analysis as this is ideally suited to the correct diagnosis of a Class III patient. In the Jefferson analysis the size of the mandible and the position of the mandible can be easily related to the length and position of the anterior cranial base. The size of the maxilla and the position of the maxilla, may also be related to the size and position of the anterior cranial base.

The Jefferson cephalometric analysis provides an easy visual means to identify maxillary/mandibular disproportions.

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