There has been discussion of posterior crowding as a factor in the development of Class 111 malocclusions.3 The theory suggests that a squeezing out effect can occur because of crowding in the molar regions, which can contribute to an anterior open-bite malocclusion in a mandible with poor vertical growth in the ramus area (Fig. 8.9). Alternatively, good ramus growth can lead to a Class III malocclusion.
This concept is not well understood, and has not been fully investigated. However, some carefully selected Class III cases4 (see Case KB, p. 242) and some open-bite cases5 respond well to a treatment approach involving second molar extractions. This suggests some validity to the theory of a squeezing out effect. It may be an important etiological factor in some cases.
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