Document Detail

Opening rotations of the mandible during and after treatment.
MedLine Citation:
PMID:  9714278     Owner:  NLM     Status:  MEDLINE    
In this retrospective cephalometric study of mandibular rotational change, we studied 60 cases. All patients were treated with full fixed appliances and exhibited an opening rotation of at least 1.5 degrees during treatment, as measured on the basis of the angle of the Y-axis to the sella-nasion line (SN). Our objective was to determine whether this opening rotation was sustained during retention. Paired t tests were used to test the hypothesis that the treatment change or opening rotation was stable and that these patients did not return to their original mandible-to-cranium relationship in the posttreatment period. Stepwise regression analysis was used to determine which (if any) changes in the independent variables during treatment could predict the subsequent behavior of the angle of the mandibular plane to the SN and the angle of the Y-axis to the SN during retention. During treatment, the mean increase in the angle of the Y-axis to the SN was 2.43 degrees. After an average posttreatment period of 54 months, this angle was reduced on average by only 0.73 degrees. Stepwise linear-regression analysis indicated that none of the treatment changes seen in the independent variables strongly predicted the ensuing closing rotation seen during retention. The correlation coefficient between the Y-axis angle and the mandibular-plane angle during treatment was 0.67. Mandibular opening rotations as a consequence of orthodontic treatment do not invariably return to the pretreatment value, and their negative effects--although sometimes small--cannot be discounted. Because the preponderant evidence of a closing rotation occurs in the terminal pubertal growth stages, the net effect may be even more significant.
M J Ryan; B J Schneider; E A BeGole; Z F Muhl
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics     Volume:  114     ISSN:  0889-5406     ISO Abbreviation:  Am J Orthod Dentofacial Orthop     Publication Date:  1998 Aug 
Date Detail:
Created Date:  1998-08-27     Completed Date:  1998-08-27     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8610224     Medline TA:  Am J Orthod Dentofacial Orthop     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  142-9     Citation Subset:  D; IM    
Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, USA.
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MeSH Terms
Malocclusion / physiopathology*,  therapy
Mandible / physiology,  physiopathology*
Maxillofacial Development
Predictive Value of Tests
Range of Motion, Articular
Regression Analysis
Retrospective Studies
Statistics, Nonparametric
Vertical Dimension

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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