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[A retrospective study of morphologic basis for the extraction decision in Class II, division 1 malocclusion].

OBJECTIVE
To compare the dentofacial characteristics of persons with Class II, Division 1 malocclusion treated with either an extraction or a nonextraction approach. Such comparison might help identify which parameters influence the extraction decision.


METHODS
Lateral cephalograms were available on 81 cases of Class II, Division 1 malocclusion, 42 were treated with 4 premolar extractions and 39 were treated with non-extraction. The cephalometric analysis of West China University of Medical Sciences and Model Analysis were used,


RESULTS
Patients in the extraction group had larger FMA, FMIA and lower anterior facial height. In the group of extraction, the upper anterior teeth tipped more anteriorly, and the tooth size-arch length discrepancy and the depth of Spee curve were greater significantly. But the saggital discrepancy and soft tissue's profiles had no significant difference between two groups.


CONCLUSION
The stability of the triangle of Tweed, the tooth size-arch discrepancy and the depth of Spee curve were the keys to decide weather extraction or not.