Journal Article

Variations in cyclic mandibular movements during treatment of Class II malocclusions with removable functional appliances

Kirsten M. Thieme, Hans Nägerl, Wolfram Hahn, Dankmar Ihlow and Dietmar Kubein-Meesenburg

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 33, issue 6, pages 628-635
Published in print December 2011 | ISSN: 0141-5387
Published online January 2011 | e-ISSN: 1460-2210 | DOI:
Variations in cyclic mandibular movements during treatment of Class II malocclusions with removable functional appliances

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The aim of the study was to establish whether juveniles with a Class II malocclusion change the neuromuscular control of mandibular movements during the course of orthodontic treatment with removable functional appliances (RFAs).

Neuromuscular control can be indirectly evaluated by recording cyclic planar mandibular movements which were freely carried out by the patients (28 girls, 14 boys, aged 11.1 ± 1.1 years at the start of treatment) and measured with an ultrasonic device before, during, and after Class II functional appliance therapy, with either an activator or a bite jumping plate. The cyclic movements represented simultaneous rotations of the mandible around a maxillary and mandibular fixed axis (MFHA) and could be characterized by μ(α)-diagrams (μ = swing angle of MFHA, α = mouth opening angle) and path length (L) of the MFHA. The μ(α)-diagrams clearly divided into four parts: movement representing protrusion, mouth opening, and two parts of backward closing as known from Posselt diagrams. Parameters from the Posselt and μ(α)-diagrams were checked by one-factor analysis of variance on a 5 per cent significance level for group dependency.

For one-third of the patients investigated, no significant changes were seen in any parameter pre- or post-therapy. However, patients showing an initially large mouth opening capacity or a very short condylar path changed their neuromuscular control to that of Class I subjects.

Analysis of μ(α)-diagrams provides the possibility of assessing changes in the neuromuscular control of the mandible during Class II treatment.

Journal Article.  5219 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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