Maxillary transverse deficiency.

It is a pleasure for me to contribute a few thoughts to this issue honoring the illustrious career of Dr Thomas M. Graber, retiring Editor-in-Chief of the American Journal of Orthodontics and Dentofacial Orthopedics. I have known Tom (perhaps first as “Lee’s dad”) for over 30 years, and my career has been influenced and enhanced on numerous occasions by our interactions, spanning the time from his introducing me to Rolf Fränkel in the very early 1970s to his establishing the Graber Professorship at the University of Michigan in 1998. I am deeply indebted to Tom for his friendship and support over the years. One of the continuing themes of Tom Graber’s career has been growth modification. My own career has taken a similar course. After having been involved in experimental and clinical studies for over 30 years, some general themes have emerged that have influenced the way in which my partners and I practice orthodontics and dentofacial orthopedics on a day-to-day basis. My initial research efforts were focused on modifying the growth of the mandible, with particular emphasis on adaptations within the temporomandibular joint. Today, there is no question that short-term and longterm condylar adaptations can be produced in a variety of animal species. There also appears to be general agreement among those who have studied this question that the growth of the mandible can be increased in human beings over the short-term, perhaps 2 to 4 mm more than that which occurs normally. The long-term effects of orthopedic intervention, however, remain controversial and open to question. For example, longterm investigations of the Herbst appliance1,2 demonstrate minimal skeletal increases over what would occur during normal growth, whereas long-term studies of the FR-2 of Fränkel3 are more encouraging. In the patient with Class III malocclusion, the length of the mandible also can be affected by therapeutic intervention (eg, chincup, facial mask) over the short-term, particularly with regard to altering the direction of its growth (usually downward and backward), but there is little evidence to date to support the concept that the length of the mandible can be reduced over the long-term by Class III mechanics. I am much more enthusiastic today about treatment possibilities within the maxilla, particularly with regard to the management of the transverse dimension. Maxillary transverse deficiency, in fact, may be one of the most pervasive skeletal problems in the craniofacial region. Its aThomas M. and Doris Graber Endowed Professor of Dentistry, Department of Orthodontics and Pediatric Dentistry, School of Dentistry; Professor of Anatomy and Cell Biology, School of Medicine; and Research Scientist, Center for Human Growth and Development, The University of Michigan, Ann Arbor, Mich. In private practice of orthodontics, Ann Arbor, Mich. Reprint requests to: Dr James A. McNamara, Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1078; e-mail, mcnamara@umich.edu. Copyright © 2000 by the American Association of Orthodontists. 0889-5406/2000/$12.00 + 0 8/1/105879 doi.10. 1067/mod.2000. 105879 Maxillary transverse deficiency