Controlling the functional occlusal plane by advocating intra-arch mechanics, (i.e., minimizing the side effects of mechanotherapy). Reeducation of the intra oral musculature during dimensional changes to the arches by utilizing lip bumpers, inner bows of facebows, and myofunc- tional therapy when necessary. How Does CAD Distinguish Itself From Expansion? CAD addresses all three dimensions. Expansion focuses on the transverse dimension. CAD distalizes the arches during expansion into a wider dimension of the arch, thereby reducing the amount of necessary expansion. Expansion solely relies on transverse changes. CAD coordinates upper arch dimensional changes with lower arch dimensional changes to maximize intercuspation throughout treatment. Maxillary expansion tends to overcorrect the maxillary arch with no corresponding changes in the lower arch. CAD attempts to place and maintain the teeth in the “neutral zone” throughout treatment. Rapid maxillary expansion (RME) or orthodontic expan- sion tends to violate the “neutral zone” by placing the teeth into the space of the surrounding musculature. If the musculature cannot adapt to the new transverse dimension, relapse of the teeth towards the “neutral zone” may occur long-term. CAD emphasizes the importance of placing the teeth well within cancellous bone during expan- sion by slowly and simultaneously expanding and distalizing in relatively equal increments. This allows the integrity of the periodontium to be maintained. In mesially displaced arches (eg., Class II), expanding the teeth that have already been displaced into areas of narrower cancellous bone could certainly compromise the integrity of the periodontium. CAD attempts to “re-educate” the surrounding musculature back to their original resting length by utilizing lip bumpers and the inner bows of facebows. There is no attempt to reeducate the soft tissue envelope in pure expansion. In the next JAOS issue, we will follow up with illus- trations and two severe cases treated with the CAD technique that will further seek to clarify these differ- ences and also to establish the ground rules for successfully developing the arches. Thanks to Dentsply GAC for the Education Grant provided in support of this article. (Editor’s note: Click here for references.) www.orthodontics.com May/June 2010 23
Journal of the American Orthodontic Society May-June 2010: Page 23
