Correction of the transverse discrepancy-induced spontaneous mandibular protrusion in Class II Division 1 adolescent patients


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Australasian Orthodontic Journal

Australian Society of Orthodontists

Subject: Dentistry, Orthodontics & Medicine


ISSN: 2207-7472
eISSN: 2207-7480





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VOLUME 32 , ISSUE 2 (November 2016) > List of articles

Correction of the transverse discrepancy-induced spontaneous mandibular protrusion in Class II Division 1 adolescent patients

Yanfang Yu / Mengjie Wu / Xuepeng Chen / Wen Li *

Citation Information : Australasian Orthodontic Journal. Volume 32, Issue 2, Pages 148-154, DOI:

License : (CC BY 4.0)

Published Online: 30-July-2021



Background: A Class II malocclusion is the most frequent sagittal skeletal disharmony presenting for orthodontic treatment. A transverse interarch discrepancy (TID) may be considered as a possible functional cause of a Class II relationship.

Objective: The purpose of the present study was to determine transverse interarch width dimensions before and after orthodontic therapy and their possible relationship with increased mandibular projection following treatment.

Methods: The sample included 40 adolescent patients who were divided into two groups, one possessing and one without a transverse discrepancy. Interarch width differences (including ICWD, IPWD, IMWD, IAWD) were measured before and after treatment, and Pogonion (Pog) to Nasion (N) perpendicular was similarly measured in each group. Results: The differences in arch and alveolar width dimensions between the two groups (including ICWD, IPWDI, IPWDII, IMWD, IAWD) before treatment were statistically significant (p < 0.05). A comparison of Pog to N perpendicular between the two groups showed that mandibular protrusion after treatment in the transverse discrepancy group was 2.6 ± 1.3 mm, while mandibular protrusion after treatment in the group without a transverse discrepancy was 0.6 ± 0.3 mm. The statistical comparison showed that the differences were significant (p < 0.01).

Conclusion: A transverse interarch discrepancy may have a functional relationship with mandible retrusion. If a transverse discrepancy is corrected via orthodontic treatment, the mandible may spontaneously protrude.

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