Thesis abstract

Thesis abstract

650 Reviews and abstracts The entire volume is devoted to technique; it is assumed that the reader is thoroughly familiar with diagnosis and the gene...

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650 Reviews and abstracts

The entire volume is devoted to technique; it is assumed that the reader is thoroughly familiar with diagnosis and the general philosophies of orthodontic treatment. The numerous color photographs and illustrations are of excellent quality, and the treatment sequences are almost self-explanatory. This book is highly recommended reading for orthodontists interested in learning more about lingual orthodontics. In addition to being an excellence reference, it can serve as a chair-side manual. Alex Jacobson Am J Orthod Dentofacial Orthop 2004;125:649-50 0889-5406/$30.00 Copyright © 2004 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2004.03.002

THESIS ABSTRACT

Spontaneous mandibular arch response following rapid palatal expansion: a long-term study on Class I malocclusion Anna Carolina Lima Department of Orthodontics, Marquette University, Milwaukee, Wis

The purpose of this study was to investigate the spontaneous mandibular arch response to rapid palatal expansion (Haas type) as the sole orthodontic intervention. Particular attention was paid to clinically significant effects and longterm (x ⫽ 11.3 years) posttreatment outcome stability. This study differs from other published reports on the effects of rapid palatal expansion on the mandible in that many of them were of shorter duration, or the associated treatment protocols also involved the use of orthopedic and orthodontic fixed appliances. Data were obtained from orthodontic records including dental casts taken at each of 4 assessment stages for 30 patients (18 female, 12 male). All were treated without

American Journal of Orthodontics and Dentofacial Orthopedics May 2004

extractions and had Class I malocclusions and transverse maxillary/mandibular skeletal discrepancies treated during the early or mid mixed dentition. Posterior and anterior mandibular arch width, arch length, and arch perimeter were measured directly on study casts obtained at pre-expansion (x ⫽ 8.2 years), short-term follow-up (x ⫽ 9.4 years), progress (x ⫽ 13.2 years), and long-term follow-up (x ⫽ 20.7 years). Descriptive and inferential analyses of the 6 variables at the 4 assessment stages for all patients were performed. Differences between pre-expansion and short-term follow-up resulted in statistically significant (P ⬍ .001) increases for mandibular intermolar widths (lingual and occlusal values). During the transition to the permanent dentition, expected significant (P ⬍ .001) decreases occurred in arch length and arch perimeter. Also in this period, there was a decrease of 25% from the initial net gain for intermolar width (occlusal value), but the lingual values remained unchanged. Further differences between the short-term and the long-term followups resulted in a mandibular intermolar width (occlusal value) net gain of 50% and the expected significant (P ⬍ .001) decrease for the mandibular arch length and arch perimeter. Finally, there was remarkable stability in the mandibular intermolar width (lingual value) and intercanine width (occlusal value), indicating that the increase in the width dimension in the mandibular arch was in response to the orthopedic effects of rapid palatal expansion in the early or mid mixed dentition and that the stability was maintained until adulthood. Based on the findings of this study, several statistically significant changes were noted in the mandible that could be attributed to rapid palatal expansion. No clinically adverse effects were observed. The long-term effects associated with this form of maxillary intervention were positive, especially for the mandibular arch-width dimensions. Am J Orthod Dentofacial Orthop 2004;125:650 0889-5406/$30.00 Copyright © 2004 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2004.03.001