Journal Article

Thin‐plate spline analysis of the short‐ and long‐term effects of rapid maxillary expansion

Lorenzo Franchi, Tiziano Baccetti, Christopher G. Cameron, Elizabeth A. Kutcipal and James A. McNamara

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 24, issue 2, pages 143-150
Published in print April 2002 | ISSN: 0141-5387
Published online April 2002 | e-ISSN: 1460-2210 | DOI:
Thin‐plate spline analysis of the short‐ and long‐term effects of rapid maxillary expansion

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The aim of this study was to investigate the short‐ and long‐term effects induced by rapid maxillary expansion (RME) on the shape of the maxillary and circummaxillary structures by means of thin‐plate spline (TPS) analysis. The sample consisted of 42 patients who were compared with a control sample of 20 subjects. The treated subjects underwent Haas‐type RME, followed by fixed appliance therapy. Postero‐anterior (PA) cephalograms were analysed for each treated subject at T1 (pre‐treatment), T2 (immediate post‐expansion), and T3 (long‐term observation), and were available at T1 and T3 for the control group (CG). The mean age at T1 was 11 years and 10 months for both groups. The mean chronological ages at T3 were 20 years, 6 months for the treated group (TG) and 17 years, 8 months for the control group. The study focused on shape changes in the maxillary, nasal, zygomatic, and orbital regions.

TPS analysis revealed significant shape changes in the TG. They consisted of an upward and lateral displacement of the two halves of the naso‐maxillary complex as a result of active expansion in the short‐term, and normalization of maxillary shape in the transverse dimension in the long‐term (the initial transverse deficiency of the maxilla in the treated group was eliminated by RME therapy both in the short‐ and long‐term). At the end of the observation period, the nasal cavities were larger when compared with both their pre‐expansion configuration and the final configuration in the controls. RME with the Haas appliance appears to be an efficient therapeutic means to induce permanent favourable changes in the shape of the naso‐maxillary complex.

Journal Article.  0 words. 

Subjects: Restorative Dentistry and Orthodontics

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