Biomechanical basis of vertical dimension control during rapid palatal expansion therapy.

Rapid palatal expansion (RPE) is recognized as a very successful orthopedic therapy to correct maxillary transverse deficiencies in growing patients. However, the transverse forces delivered during RPE have been shown to create undesirable orthodontic and orthopedic side effects in patients exhibiting skeletal open bite tendency, large interlabial gap, or severe Class II skeletal patterns, with long lower facial height and increased facial convexity. The application of extraoral forces during RPE therapy by the concomitant use of a high-pull chincap is described and clinically illustrated as a method to control the vertical dimension.