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Controlled Clinical Trial
. 2010 Mar;80(2):230-8.
doi: 10.2319/040309-192.1.

Changes in occlusal relationships in mixed dentition patients treated with rapid maxillary expansion. A prospective clinical study

James A McNamara Jr  1 , Lauren M Sigler, Lorenzo Franchi, Susan S Guest, Tiziano Baccetti
Affiliations
Controlled Clinical Trial

Changes in occlusal relationships in mixed dentition patients treated with rapid maxillary expansion. A prospective clinical study

James A McNamara Jr et al. Angle Orthod. 2010 Mar.

Abstract

Objective: To prospectively measure occlusal changes in mixed dentition patients who underwent a standardized early expansion protocol.

Materials and methods: The treatment sample consisted of 500 patients who were assigned to three groups according to molar relationship: Class I (n = 204), end-to-end (n = 166), and Class II (n = 130). All patients were treated with a bonded rapid maxillary expander (RME) followed by a removable maintenance plate and a transpalatal arch. Mean age at the start of treatment was 8.8 years (T(1)), with a pre-phase 2 treatment cephalogram (T(2)) taken 3.7 years later. The control sample consisted of the cephalometric records of 188 untreated subjects (Class 1, n = 79; end-to-end, n = 51; Class II, n = 58).

Results: The largest change in molar relationship was noted when the Class II treatment group (1.8 mm) was compared with the matched control group (0.3 mm). A positive change was seen in 81% of the Class II treatment group, with almost half of the group improving by > or = 2.0 mm. The end-to-end treatment group had a positive change of 1.4 mm, compared with a control value of 0.6 mm, and the Class I group of about 1 mm compared with controls, who remained unchanged (0.1 mm). Skeletal changes were not significant when any of the groups were compared with controls.

Conclusion: The expansion protocol had a significantly favorable effect on the sagittal occlusal relationships of Class II, end-to-end, and Class I patients treated in the early mixed dentition.

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Figures

Figure 1
Figure 1
Classification of sagittal molar relationships on cephalometric tracings. Vertical lines are perpendicular to the occlusal plane.
Figure 2
Figure 2
Change in molar relationship: Class II groups.
Figure 3
Figure 3
Change in molar relationship: end-to-end groups.
Figure 4
Figure 4
Change in molar relationship: Class I groups.
Figure 5
Figure 5
Prevalence rates for positive change in molar relationships in TG vs CG subgroups within each malocclusion group.
See this image and copyright information in PMC

References

    1. Haas A. J. Palatal expansion: just the beginning of dentofacial orthopedics. Am J Orthod. 1970;57:219–255. - PubMed
    1. Wertz R. A. Changes in nasal airflow incident to rapid maxillary expansion. Angle Orthod. 1968;38:1–11. - PubMed
    1. McNamara J. A., Jr Maxillary transverse deficiency. Am J Orthod Dentofac Orthop. 2000;117:567–570. - PubMed
    1. McNamara J. A, Jr, Brudon W. L. Orthodontics and Dentofacial Orthopedics. Ann Arbor, Mich: Needham Press; 2001.
    1. Sarver D. M, Johnston M. W. Skeletal changes in vertical and anterior displacement of the maxilla with bonded rapid palatal expansion appliances. Am J Orthod Dentofac Orthop. 1989;95:462–466. - PubMed

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