Three-dimensional computed tomography comparison of the maxillary palatal vault between patients with rapid palatal expansion and orthodontically treated controls.

INTRODUCTION: The aim of this study was to use cone-beam computed tomography to compare changes of skeletal and dental structures of the maxillary palatal vault in a group of growing patients treated for posterior crossbite before and after rapid palatal expansion (RPE) with changes over time in a control group. METHODS: The sample for this retrospective study included 19 patients treated with a hyrax palatal expander at a graduate orthodontic clinic and 19 control subjects who received no RPE. Beginning and progress cone-beam computed tomography scans of all patients were analyzed to measure the anatomic volume, width, height, and anteroposterior dimensions of the palatal region. RESULTS: Progress scans (after RPE treatment for cases) showed, the mean percentages of change in palatal volume were 10.8% in the controls and 21.7% in the RPE group (P = 0.038); however, there were no statistically significant differences in palatal volume at baseline or at progress scan between the RPE patients and controls. Absolute first molar-to-molar width changes at progress scan were 0.57 mm in the controls and 3.27 mm in the RPE group (P = 0.022). Absolute canine-to-canine width changes at progress scan were 0.45 mm in the controls and 2.79 mm in the RPE group (P = 0.007). There were significant differences in percentage and absolute changes in maxillary width measured from molar to molar and canine to canine between RPE group and controls, but no significant differences in maxillary vault height or anteroposterior dimension changes. CONCLUSIONS: At progress scan, canine-to-canine width, first molar-to-molar width, and anteroposterior length of the palatal maxillary volume in the RPE group approached the measurements of the controls. Palatal volumes (at baseline and progress scan) were not statistically significantly different between the groups.

Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion.

INTRODUCTION: Rapid palatal expansion (RPE) is routinely used to correct transverse deficiencies in the maxilla, but its effects on the dentoalveolus are uncertain. The purpose of this study was to compare measurements made on cone-beam computerized tomography scans between patients with RPE treatment and controls to determine transverse dimension increases and the amounts of alveolar and dental tipping. METHODS: Twenty-five patients with posterior crossbite who required RPE treatment and 25 sex- and age-matched controls (no crossbite) were orthodontically treated and received cone-beam computerized tomography scans at the beginning and middle of treatment. Transverse widths and several angulations were measured, and matched paired t tests used. RESULTS: RPE treatment produced a significant increase in all measured transverse dimensions. Analysis of posttreatment angulation changes in the RPE group showed that the alveolus substantially tipped buccally by nearly 5.6° (measured from a horizontal reference, the base of the hard palate). The angulations of the dentition, however, remained constant before and after treatment (<1° of change) in both groups. CONCLUSIONS: These data showed no statistically significant amount of relative dental tipping after RPE treatment but significant alveolar tipping compared with the controls.

Oropharyngeal airway changes after rapid palatal expansion evaluated with cone-beam computed tomography.

INTRODUCTION: The aims of this retrospective study were to use cone-beam computed tomography (CBCT) to assess changes in the volume of the oropharynx in growing patients with maxillary constriction treated by rapid palatal expansion (RPE) and to compare them with changes in age- and sex-matched orthodontic patients. METHODS: The experimental group consisted of 24 patients (mean age, 12.8+/-1.88 years) with maxillary constriction who were treated with hyrax palatal expanders; the control group comprised 24 age- and sex-matched patients (mean age, 12.8+/-1.85 years) who were just starting regular orthodontic treatment. Beginning and progress CBCT scans, taken in the supine position, were analyzed with software to measure volume, length, and minimal cross-sectional area of the oropharyngeal airway. The 2 groups were compared with paired t tests. RESULTS: Only retropalatal airway volume was found to be significantly different between groups before treatment (P = 0.011), and this difference remained after treatment (P = 0.024). No other statistically significant differences were found relative to changes in volume, length, or minimum cross-sectional area of the oropharyngeal airway between the groups, but the molar-to-molar width after RPE increased significantly compared with the controls (P <0.001). CONCLUSIONS: Narrow oropharyngeal airways in growing patients with maxillary constriction was demonstrated. But there was no evidence to support the hypothesis that RPE could enlarge oropharyngeal airway volume.