Dr Tony Collett

Research

Our practice has been involved in orthodontic research and some details are below. A full report can be obtained on request via e-mail. (Of course we don't use our patients as "guinea pigs" but we have a genuine interest in knowing what treatment works and why.)

FUNCTIONAL APPLIANCES AND MANDIBULAR GROWTH

Functional appliances have become part of contemporary orthodontic practice, however, their mode of action is still a controversial subject. The controversy surrounds the ability of the appliances to increase mandibular growth, and thus give a long-term change in the skeletal pattern.

In terms of practical clinical applications, a lack of significant skeletal change with functional appliances does not diminish their use in correcting overjets. The appliance is still a useful orthodontic tool for correcting Class II malocclusions. Recent findings underpin the importance of correct diagnosis and being able to differentiate between the skeletal and dental components of a malocclusion. In the severe retrognathic profile with a deficient chin suggesting surgery, use of functional appliances is unlikely to change the long-term surgical needs. However, this is not to say in many cases favourable profile changes cannot occur. The profile can be considered as being the result of skeletal, dental and soft tissue contributions. Improving dental relationships may result in a more favourable soft tissue drape and profile. For example, consider the Class II division 1 pattern with a large overjet and lower lip habit (the lower lip at rest being positioned behind the upper labial segment). It is easy to imagine that reduction of the overjet would result in a substantial improvement in facial aesthetics, without altering the skeletal base relationship.

On the basis of available studies, one cannot yet conclude functional appliances to be effective in stimulating and increasing mandibular growth. Also, the superior functional appliance has yet to be demonstrated. Many claims relating to the superiority of a particular appliance are made by persons with a proprietary interest. Although, favourable growth changes have been reported following phase 1 therapy, they are generally not substantial and long-term stability has yet to be demonstrated. The available evidence suggests the skeletal changes revert with time. In assessing functional appliances, results from prospective randomised clinical trials should be given prominence.