Journal Article

The influence of functional orthodontics and mandibular sagittal split advancement osteotomy on dental and skeletal variables—a comparative cephalometric study

Bettina Lohrmann, Rainer Schwestka-Polly, Hans Nägerl, Dankmar Ihlow and Dietmar Kubein-Meesenburg

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 28, issue 6, pages 553-560
Published in print December 2006 | ISSN: 0141-5387
Published online December 2006 | e-ISSN: 1460-2210 | DOI: http://dx.doi.org/10.1093/ejo/cjl022
The influence of functional orthodontics and mandibular sagittal split advancement osteotomy on dental and skeletal variables—a comparative cephalometric study

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Lateral head films of 200 Class II patients (106 females, 94 males) with a mean pre-treatment age range of 9.9–10.25 years successfully treated with functional orthodontics were analysed before (T1) and after (T2) treatment. The resulting data and findings were compared with lateral head films (T1, T2) of 20 patients (15 females, five males) with a mean pre-treatment age of 25.75 years whose Class II malocclusion and antero-posterior jaw discrepancy had been corrected by a mandibular sagittal split advancement osteotomy. The median and interquartile distances were calculated for every variable, at T1 and T2. The difference between the medians (T2−T1) was analysed using a signed rank test. The changes in scattering (T2−T1) were assessed by means of a F-test.

Significant differences regarding the therapeutic influence on skeletal [ANB, Wits, Index, mandibular line–nasal line (ML–NL)], functional (β′, μ), and dental (1-NA°, 1-NB°) variables were found. In the group initially treated with functional appliances in order to enhance mandibular prognathism, the antero-posterior (A-P) jaw discrepancy was reduced (ANB, Wits). The vertical skeletal pattern (Index) changed towards a more skeletal open relationship, whereas the ML–NL angle was reduced, which indicates a deepening of the bite. The comparison between biomechanical incisor position analysis (β′, μ) and dental variables (1-NA°, 1-NB°) revealed different changes in incisor inclination depending on the type of analysis used. The findings for the dental variables (1-NA°, 1-NB°) showed a protrusion of both upper and lower incisors after therapy. The results for the functional variables (β′, μ) showed a retrusion of the upper and a protrusion of the lower incisors. This change in incisor inclination is a dental compensation of the remaining sagittal jaw discrepancy. This effect is most clearly reflected by the functional analysis and the changes of the biomechanical variables β′ and μ.

For the orthognathic surgery group, a clear improvement in the dental and skeletal relationship was observed: the skeletal discrepancies in the A-P plane were completely corrected (ANB, Wits) and the inclination of the incisors according to biomechanical and functional aspects was optimized (β′, μ).The alteration in both the Index and ML–NL angle in this group indicated an increase of the open bite components.

Journal Article.  4244 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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