The use of a functional appliance in the mixed dentition often produces a substantial and pleasing change for a young patient with a Class II malocclusion, with consequent improvement in the facial appearance. The reason for this pleasing change is that functional appliances have the potential to produce dental and skeletal change. They have the potential to proel i ne lower incisors, retrocline upper incisors, favorably modify mandibular growth, and restrict maxillary growth.
Over the years, there has been much discussion and research to establish whether functional appliances can consistently increase the final length of the mandible, beyond what it would have been without the functional appliance. This is a difficult topic to investigate, and at present the research evidence does not confirm that it is possible to modify' the quantity of mandibular growth using functional appliances.
Despite this, many orthodontists feel that functional appliances have a useful place in the management of Class Il/l malocclusions, because they produce a substantial early improvement for the patient (CaseTS, p. 198), and can reduce the amount of treatment needed in the fixed appliance phase.
In 1998, Pancherz et al15 investigated 98 Class \\j\ malocclusions treated with the Herbst appliance, to assess 'effective condylar growth'. 1'his term was used to describe the summation of the condylar remodeling, glenoid fossa remodeling, and condylar repositioning changes. In individuals with anterior mandibular autorotation, they found relatively more forward change in chin position. In individuals with posterior mandibular autorotation, they found relatively more backward change in chin position.
In practical terms, if a functional appliance is to be used in a case, it is helpful to use it in the late mixed dentition. At this time, there is plenty of growth available, and it is possible to move straight into the fixed appliance phase, as the functional appliance phase ends. If the functional appliance is introduced in the early mixed dentition, it can be difficult and time consuming to manage the inevitable retention phase before fixed appliances can be placed.
Some functional appliance effects may accrue during the use of C,lass II elastics in a fully bracketed fixed appliance case. For example, this 'functional effect' is frequently seen when Class II elastics are used in the second phase of a Class 11/2 treatment in a growing individual.
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