Korean J Orthod.  2011 Jun;41(3):200-210. 10.4041/kjod.2011.41.3.200.

Changes in mandibular transversal arch dimensions after rapid maxillary expansion procedure assessed through cone-beam computed tomography

• Baysal A
• Veli I
• Ucar FI
• Eruz M
• Ozer T
• Uysal T

• KMID: 1975432
• DOI: http://doi.org/10.4041/kjod.2011.41.3.200

Abstract

OBJECTIVE
This study aimed at evaluating the changes in mandibular arch widths and buccolingual inclinations of mandibular posterior teeth after rapid maxillary expansion (RME).
METHODS
Baseline and post-expansion cone-beam computed tomographic (CBCT) images of patients who initially had bilateral posterior cross-bite and underwent RME with a banded-type expander were assessed in this study. The patients included 9 boys (mean age: 13.97 +/- 1.17 years) and 11 girls (mean age: 13.53 +/- 2.12 years). Images obtained 6 months after retention were available for 10 of these patients. Eighteen angular and 43 linear measurements were performed for the maxilla and mandible. The measurements were performed on frontally clipped images at the following time points; before expansion (T1), after expansion (T2), and after retention (T3). Statistical significance was assessed with paired sample t-test at p < 0.05.
RESULTS
T1-T2 comparisons showed statistically significant post-RME increases for all measurements; similarly, T2-T1 and T3-T1 comparisons showed statistically significant changes. The maxillary linear and angular measurements showed decreases after expansion, and mandibular linear and angular measurements increased after retention.
CONCLUSION
All mandibular arch widths increased and mandibular posterior teeth were uprighted after RME procedure.

Keyword

CT; Arch form; Expansion

MeSH Terms

Cone-Beam Computed Tomography
Humans
Mandible
Maxilla
Palatal Expansion Technique
Retention (Psychology)
Tooth

Figure

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  Fig 1. Mandibular linear and angular measurements. A, External mandibular measurements performed at 3 different levels: alveolar crest, most prominent point of the crown, and buccal cusp tip; B, internal mandibular measurements were performed at 2 different levels: alveolar crest and most prominent point of the crown; C, mandibular long axis measurement performed between the long axis of the mesial root and to the reference plane, which passes through the most prominent point of the lower borders (right and left) of the mandible.

• 

  Fig 2. Maxillary linear and angular measurements. A, Nasal and palatal floor measurements; B, external maxillary measurements performed at 4 different levels: apical, alveolar crest, most prominent point of the crown, and buccal cusp tip; C, internal maxillary measurements were performed at 3 different levels: apical, alveolar crest, and most prominent point of the crown; D, maxillary long axis measurement performed between the long axis of the palatal root and to the palatal plane.

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