Summary
Objectives
To compare the long-term skeletal effects of tooth-borne (TB) and tooth-bone-borne (TBB) rapid maxillary expansion in growing children, using 3D imaging.
Materials and methods
In total, 52 consecutive patients who met the eligibility criteria were recruited and allocated to either the TB group, mean age 9.3 years (SD 1.3), or the TBB group, mean age 9.5 years (SD 1.2). Cone-beam computed tomography records and plaster models were taken before (T0), directly after (T1), 1 year after (T2), and 5 years after expansion (T3).
Randomization
Participants were randomly allocated in blocks of different sizes, using the concealed allocation principle in a 1:1 ratio. The randomization list was also stratified by sex to ensure homogeneity between groups.
Blinding
Due to clinical limitations, only the outcome assessors were blinded to the groups to which the patients were allocated.
Results
At T1, the midpalatal suture at its anterior part showed a statistically significant difference between the groups with a mean of 0.6 mm (CI 0.2–1.1) more expansion in the TBB group (P < 0.01). This difference was also more evident in boys at T1 with a mean of 0.8 mm (CI 0.2–1.4) (P < 0.01). These differences, however, blotted out at T2 and T3. The nasal width also showed similar differences between the groups, with a significantly larger expansion in the TBB group by a mean of 0.7 mm (CI 0.1–1.4) (P = 0.03). This group difference in favour of the TBB group was maintained at T2 (1.6 mm) and T3 (2.1 mm) (P < 0.01 T2 and T3, respectively).
Conclusions
Skeletal expansion in the midpalatal suture was significantly higher in the TBB group; however, the magnitude of this expansion was around 0.6 mm more and may not be clinically significant. Skeletal expansion at the level of the nasal cavity was significantly higher in the TBB group. There were no differences between boys and girls with regard to skeletal expansion.
Trial registration
This trial was not registered on any external sites.
Introduction
In adolescents with transverse discrepancy and constricted maxilla, orthopaedic skeletal expansion involving separation of the midpalatal suture is the treatment of choice (1). The most common orthodontic appliance for separation of the midpalatal suture is rapid maxillary expansion (RME), which first was described by Emerson C. Angell in 1860 (2). The traditional tooth-borne (TB) expanders induce both dental tipping and midpalatal suture opening (3). The primary goal of maxillary expansion is to maximize dentofacial orthopaedics and minimize movements of the teeth (4).
In recent years, an alternative to the TB-RME appliance has been introduced. The new hybrid design anchors the RME appliance both to the posterior teeth and, by means of two miniscrews, directly to the palatal surfaces of the maxilla. Bone-anchored expanders are intended to apply the expansion forces directly to the maxilla and the midpalatal suture. In this way, one could possibly reduce the side effects of the original design by means of dental and alveolar bone tipping (5). The long-term effects of the hybrid, also called tooth-bone-borne (TBB)-RME, on dental and skeletal structures have not yet been thoroughly studied.
Cone-beam computed tomography (CBCT) allows clinicians to assess quantitatively the skeletal and dental effects of rapid maxillary expanders. CBCT technology also allows the creation of volumetric images, facilitating a three-dimensional (3D) cephalometric analysis that can be used to evaluate the actual anatomy without superimposition of the neighbouring structures. Previous studies using two-dimensional (2D) cephalometric radiograph or dental models may provide imprecise identification of dental and skeletal structures that limits the information concerning skeletal changes in the maxillary region. CBCT images with adequate resolution can offer an accurate evaluation of a target area with no distortion or overlap (6).
Thus, the aims of this randomized controlled trial were to three-dimensionally assess and compare the influence of the conventional TB-RME and TBB-RME on skeletal structures in growing children with the constricted maxilla, further to investigate whether or not the expansion affects boys and girls differently and also to evaluate a long-term effect of both appliances 5 years post-expansion.
Materials and methods
Trial design
The study was a two-arm, parallel-group randomized controlled trial (RCT) performed at a single centre. The regional ethical review board, which follows the guidelines of the Declaration of Helsinki, and the regional radiation protection committee approved the study protocol (Dnr: 2009/334).
Participants, eligibility and settings
In total, 54 consecutive subjects examined at the Department of Orthodontics in Örebro, Sweden, who met the eligibility criteria, were recruited from September 2010 to December 2015. Two declined participation and were excluded. After receiving oral and written information about the clinical trial, the included patients and their parents/guardians signed the consent forms.
The following inclusion criteria had to be fulfilled by all participants enrolled in the study:
uni- or bilateral crossbite with the constricted maxilla and
age at diagnosis of 8–13 years, with dental stage in the early or late mixed dentition.
Patients with previous or ongoing orthodontic treatment, craniofacial syndromes, or cleft lip or palate were considered ineligible for the study.
Randomization
All 52 participants were randomly allocated in blocks of different sizes, using the concealed allocation principle in a 1:1 ratio, to two groups, a TB group, and a TBB group. The randomization procedure was as follows: a computer-generated randomization list was created using SPSS software (version 17.0; SPSS, Chicago, IL, USA) and stored with a research secretary. Each time a patient gave his/her consent, the secretary was contacted by email to provide the information about which type of expander the patient should receive.
The randomization list was also stratified by gender, ensuring the inclusion of equal numbers of boys and girls in each group.
Interventions
After informed consent was obtained from both patients and their parents/guardians, the patients were randomized into two groups: Group A was treated with a TB expander (Figure 1a), and Group B with a TBB expander with two 1.7 mm × 8 mm miniscrew implants (Orthoeasy; Forestadent, Pforzheim, Germany) attaching the expander to the palate surface (Figure 1b). No pre-drilling was undertaken.
Figure 1.
(a) Tooth-borne rapid maxillary expansion (TB-RME). (b) Tooth-bone-borne rapid maxillary expansion (TBB-RME).
Both expanders were activated two quarter turns per day (0.5 mm) until the palatal cusps of the maxillary first molars contacted the buccal cusps of the mandibular first molars. Hence, both groups were over-expanded and had the same endpoint. All expanders were removed after a retention period of 6 months. All patients in both groups were treated by the same orthodontist (FB).
Study casts were taken from all subjects pre-treatment (T0); directly after removal of the RME appliance 6 months after that the desired overexpansion was achieved (T1); 1 year post-expansion, which coincided with 6 months after the removal of the expanders (T2); and 5 years post-expansion (T3). The results from study casts analyses are published earlier in 2022.
Between the time points T0 and T3, no additional orthodontic treatment was carried out on the patients.
Radiographic examination
The study participants were examined using CBCT at pre-treatment (T0), directly after expansion (T1), 1 year post-expansion (T2), and 5 years post-expansion (T3).
Radiographic examinations were performed using CBCT Accuitomo 170 (J. Morita, Mfg. Corp., Kyoto, Japan) with 140 mm × 100 mm FOV (field-of-view). The general exposure parameters used were 90 kV, 4 mA corrected for patient size and a 360° rotation with an exposure time of 17.5 s. Voxel size was 0.250 mm, the minimum value for the current FOV setting.
After examination, image data, comprising axial slices with slice thickness and interval of 0.250 mm, were exported using DICOM format (Digital Imaging and Communications in Medicine).
Data collection
Two software’s were used to superimpose and measure all study casts pre-treatment (T0), directly after removal of the RME 6 months after that the desired overexpansion was achieved (T1), 1 year post-expansion, which coincided with 6 months after the removal of the expanders (T2) and 5 years post-expansion (T3). First, the 3D slicer software (version 4.11.2, https://www.slicer.org/) was used to create 3D segmented standard tessellation language (STL) files, superimpose and measure the CBCT images T0, T1, T2, and T3. Image segmentation is a method for delineating image regions. It is a very common procedure in medical imaging, as it is required for visualization of certain structures, quantification (measurement of volumes and surfaces), and 3D printing. 3D slicer software is a free and open-source software, which is widely used in medical, biomedical, and associated imaging sciences (7). The software is used to visualize and analyse medical image data. All image processing such as registration and 3D image segmentations in 2D, 3D, and 4D are supported. The software has a 3D coordinate system with three orthogonal planes indicated by red (coronal), green (axial), and yellow (sagittal) colours. These planes were used as a reference for the orientation of the CBCT images. The second software, ITK-SNAP (version 3.6.0, http://www.itksnap.org) was used to transform the CBCT images T0, T1, T2, and T3 at the stable anatomical structure of the anterior cranial base (ACB). The ACB served as a region of reference of the superimposition (Figure 2a). ITK snap is also a free and open-source software, which provides users to navigate medical image data sets, manual delineation and automatic segmentation using active contour methods. Cevidanes et al. (8–10) introduced the superimposition method to dental research, known as voxel-based superimposition. The method is widely used in many research purposes. The voxel-based superimposition uses radiolucencies and radiopacities in volume and is fully automated (Figure 2b and 2c).
Figure 2.
(a) 3D segmentation of the anterior cranial base (ACB) in 3D Slicer. (b) Superimposition of the 3D models (Coronal view), TBB-RME. (c) Superimposition of the 3D models (Coronal view) TB-RME.
Analysis overview
The DICOM data of CBCT images T0, T1, T2, and T3 from all 52 participants of the TB and TBB groups were uploaded to the 3D Slicer software. Using the ‘Threshold’ effect in the ‘Segment Editor Module’, 3D-segmented STL files of the CBCT images T0, T1, T2, and T3 were created using semiautomatic workflow. This module was used to identify structures of interest in the 3D image by working on 3D arrays of voxels (11). The ‘Threshold’ effect was used to determine a threshold range, which was used as an editable intensity range and the results were saved to the selected segmentation. After completing the previous step, the final corrections were made using a combination of the paint and erase tools, along with the option to edit the intensity range to achieve accurate segmentations. In order to accurately map the ACB in the CBCT images at time points T0, T1, T2, and T3, a segmentation of the ACB was created in the CBCT image T0 (Figure 2a). The ACB segmentation was cut out by using the scissor in the ‘Segmentation Editor Module’ (Figure 3). The CBCT image T0, T1, T2, and T3 as well as the ACB segmentation were uploaded to the ITK-SNAP software for transformation at the anterior cranial base. As some of the images had low contrasts, the ‘Image Contrast’ tool in the ITK-SNAP provides a windowing dialogue for adjusting the mapping between intensities in the CBCT images and the intensities of displayed slices in the ‘Image Contrast’ tool. The CBCT images T0, T1, T2, and T3 were automatically transformed at the anterior cranial base by using mutual information similarity metric and rigid transformation model (rotations and translations) in the ‘Registration’ tool (Figure 4). The transformation files were saved and uploaded to the 3D Slicer software. The CBCT images T0, T1, T2, and T3 were automatically matched after applying the transform file in the ‘Transform module’ so that all images were superimposed at the anterior cranial base. The registration process was repeated until stable results were achieved and evaluation of accuracy of each registration was carried out slice by slice.
Figure 3.
Axial, sagittal, and coronal view of cutting out the anterior cranial base in the 3D slicer.
Figure 4.
Registration tool in ITK-SNAP toolbox.
Measurements
Image volume reformatting was done to achieve optimal and standardized visualization of the facial skeleton in three orthogonal image planes: axial, sagittal, and coronal. Reformatting was done using predefined anatomical landmarks for orientation in sagittal view according to the direction of the hard palate (anterior nasal spine-posterior nasal spine (ANS-PNS)), in coronal view according to the crista galli and in axial view according to the midpalatal suture. Mark-up lines were created in the ‘Mark-ups’ module (line mark-up), which showed the distance in mm All measurements were made on the CBCT images under optimal viewing conditions using a 24-inch monitor (Surface Laptop 3 13.5 inches, 2256 × 1504 pixels, Intel Iris Plus graphics) (Figure 5).
Figure 5.
Some of the parameters used for assessment/measurements according to their references in Table 1.
Error of method
Ten of the 52 cases were randomly selected to measure the accuracy of the method. The measurements were made as described above.
Outcomes
Primary outcome
The primary outcome was the amount of expansion in the midpalatal suture.
Secondary outcomes
Skeletal expansion at the level of the apertura piriformis (nasal base).
Marginal bone level at the buccal aspect of the first molars.
Skeletal differences between boys and girls.
Blinding
Due to clinical limitations, only the outcome assessors were blinded to the groups to which the patients were allocated. This applied to assessors measuring the CBCT volumes, who were also unaware of the trial protocol.
Sample size calculation
The calculated sample size for each group was based on a significance level of 0.05 per cent and 90 per cent power to detect a difference of 1.5 mm (SD ± 1.5) of the midpalatal suture expansion between the groups. The standard deviation was adapted from earlier studies (3,13). The sample size calculation indicated that 22 patients would be required in each group. To compensate for dropouts, we decided to include at least 26 patients in each group (an addition of 15% per group).
Statistical analysis
Every outcome variable was evaluated as the change from baseline (T0) with a random intercept linear mixed model with first-order autoregressive correlation structure between times (T1, T2, and T3). Study groups, times and their interactions were fixed factors and the baseline outcome as a covariate, and the model’s estimated marginal mean differences of outcome between study groups were reported with 95 per cent confidence intervals (CIs). The analysis was stratified by sex, and interaction tests by the intervention groups were performed. Because of the many outcome variables evaluated, we used significance level 0.01 for all statistical tests, to avoid type 1 error, in other words, to reduce the risk of false significant findings. A P-value below 0.01 was, therefore, considered statistically significant, and the analyses were performed with STATA release 17 (Stata Corp., College Station, TX, USA).
Error of method
To evaluate the reliability of the outcomes, 10 randomly selected participants’ CBCT examinations at T0, T1, and T2 were measured twice on two separate occasions at an interval of at least 2 weeks. The intraclass correlation (ICC) was estimated by linear mixed model with patients as random factor. ICC is the ratio of outcome variability between patients by the total (between and within patients); the standard deviation between and within patients was also presented. An ICC > 0.9 indicates excellent reliability, 0.75–0.9 good, 0.5–0.75 moderate, and <0.5 poor (12).
Registration
The protocol of this trial was not registered on any external sites. When the trial was commenced in 2010, it was not very common to register trials.
Results
A total of 54 patients were assessed for eligibility. Two patients declined to participate in the trial and were therefore excluded. Fifty-two consecutive patients who met the eligibility criteria were recruited and allocated to either the TB group, mean age 9.3 years (SD 1.3), or the TBB group, mean age 9.5 years (SD 1.2). One patient in each group missed a CBCT appointment at T1. All patients were followed 1- and 5-year post-expansion (Figure 6 CONSORT).
Figure 6.
Flow diagram according to PRISMA.
Table 2 shows the skeletal and dental differences between the appliances and sexes at all time points. Directly after expansion (T1), the midpalatal suture at its anterior part (AMPS) showed significant differences between the groups with mean 0.6 mm (CI 0.2–1.1) more expansion in the TBB group (P < 0.01). This difference was also more evident in boys at T1, with a mean of 0.8 mm (CI 0.2–1.4) (P < 0.01). These differences, however, disappeared at T2 and T3. There were no significant differences between the groups of the posterior-midpalatal suture (PMPS).
Table 2.
Comparing outcomes between TBB and TB groups (mm) adjusted for T0 with linear mixed model for repeated measurements, for all patients and for boys and girls.
| T0 | T1 | T2 | T3 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean (SD) | Mean (SD) | Mean diff (95% CI) | P | Mean (SD) | Mean diff (95% CI) | P | Mean (SD) | Mean diff (95% CI) | P | ||
| FMS Frontomaxillary suture | |||||||||||
| All | TBB groupa | 16.5 (1.8) | 17.3 (1.8) | 0.0 (−0.4 to 0.4) | 0.95 | 17.4 (1.6) | 0.5 (0.1–0.9) | 0.02 | 17.6 (1.6) | 0.8 (0.4–1.2) | <0.01 |
| TB groupb | 16.7 (1.8) | 17.4 (1.9) | Ref. | 17.1 (1.6) | Ref. | 17.0 (1.6) | Ref. | ||||
| Boys | TBB groupa | 16.2 (1.3) | 17.7 (2.2) | 0.1 (−0.5 to 0.6) | 0.84 | 17.8 (1.8) | 0.9 (0.4–1.5) | <0.01 | 18.0 (2.0) | 1.1 (0.5–1.6) | <0.01 |
| TB groupb | 16.5 (1.5) | 17.6 (2.2) | Ref. | 16.9 (1.8) | Ref. | 17.0 (1.6) | Ref. | ||||
| Girls | TBB groupa | 16.2 (1.3) | 16.8 (1.1) | −0.1 (−0.6 to 0.5) | 0.74 | 16.9 (1.2) | 0.0 (−0.6 to 0.5) | 0.93 | 17.2 (1.1) | 0.4 (−0.1 to 1.0) | 0.12 |
| TB groupb | 16.5 (1.5) | 17.2 (1.5) | Ref. | 17.2 (1.4) | Ref. | 16.9 (1.7) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.2 (−0.6 to 0.9) | 0.70 | 1.0 (0.2–1.7) | 0.02 | 0.6 (−0.2 to 1.4) | 0.12 | |||||
| ZMS1 Zygomaticomaxillary suture | |||||||||||
| All | TBB groupa | 83.6 (4.8) | 84.9 (4.7) | 0.0 (−0.8 to 0.8) | 0.94 | 85.9 (4.8) | 0.7 (−0.1 to 1.5) | 0.09 | 86.4 (5.1) | 1.3 (0.4–2.1) | <0.01 |
| TB groupb | 83.0 (3.3) | 84.4 (3.2) | Ref. | 84.8 (3.0) | Ref. | 84.7 (3.2) | Ref. | ||||
| Boys | TBB groupa | 85.8 (4.7) | 87.3 (4.3) | −0.2 (−1.4 to 1.0) | 0.74 | 88.3 (4.6) | 0.6 (−0.6 to 1.8) | 0.32 | 88.8 (5.1) | 1.5 (0.3–2.7) | 0.02 |
| TB groupb | 81.8 (3.2) | 83.7 (2.7) | Ref. | 84.0 (2.8) | Ref. | 84.1 (2.8) | Ref. | ||||
| Girls | TBB groupa | 81.2 (4.1) | 82.5 (4.1) | 0.1 (−1.1 to 1.3) | 0.83 | 83.6 (3.9) | 0.8 (−0.4 to 2.0) | 0.20 | 84.1 (4.1) | 1.1 (−0.2 to 2.3) | 0.09 |
| TB groupb | 84.1 (3.2) | 85.2 (3.6) | Ref. | 85.5 (3.1) | Ref. | 85.4 (3.5) | Ref. | ||||
| Interaction test (Boys vs. Girls) | −0.3 (−2.1 to 1.4) | 0.71 | −0.2 (−1.9 to 1.6) | 0.84 | 0.4 (−1.4 to 2.2) | 0.64 | |||||
| ZMS2 Zygomaticomaxillary suture | |||||||||||
| All | TBB groupa | 82.3 (5.0) | 84.4 (5.1) | 0.0 (−1.1 to 1.1) | 0.98 | 86.0 (5.0) | 1.5 (0.4–2.6) | <0.01 | 86.2 (5.3) | 2.3 (1.1–3.4) | <0.01 |
| TB groupb | 83.2 (5.9) | 85.3 (5.9) | Ref. | 85.6 (5.8) | Ref. | 85.3 (6.0) | Ref. | ||||
| Boys | TBB groupa | 83.2 (5.7) | 86.2 (5.8) | 1.0 (−0.4 to 2.4) | 0.18 | 87.7 (5.8) | 2.2 (0.7–3.6) | <0.01 | 88.1 (6.1) | 3.3 (1.8–4.8) | <0.01 |
| TB groupb | 83.5 (7.2) | 85.5 (7.0) | Ref. | 85.8 (6.9) | Ref. | 85.9 (7.2) | Ref. | ||||
| Girls | TBB groupa | 81.3 (4.0) | 82.6 (3.7) | −1.1 (−2.6 to 0.4) | 0.16 | 84.1 (3.4) | 0.7 (−0.8 to 2.1) | 0.39 | 84.3 (3.7) | 1.1 (−0.4 to 2.6) | 0.15 |
| TB groupb | 83.0 (4.4) | 85.2 (4.7) | Ref. | 85.1 (4.6) | Ref. | 84.6 (4.8) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 2.1 (−0.0 to 4.1) | 0.05 | 1.5 (−0.5 to 3.6) | 0.15 | 2.2 (0.0–4.3) | 0.04 | |||||
| N Nasal width | |||||||||||
| All | TBB groupa | 19.1 (1.9) | 22.5 (1.5) | 0.7 (0.1–1.4) | 0.03 | 23.9 (1.9) | 1.6 (1.0–2.3) | <0.01 | 23.9 (1.6) | 2.1 (1.4–2.8) | <0.01 |
| TB groupb | 18.7 (1.8) | 21.4 (1.9) | Ref. | 21.9 (1.6) | Ref. | 21.4 (1.6) | Ref. | ||||
| Boys | TBB groupa | 20.0 (2.0) | 23.2 (1.3) | 0.9 (−0.1 to 1.8) | 0.07 | 24.4 (1.8) | 1.7 (0.8–2.6) | <0.01 | 24.6 (1.7) | 2.3 (1.4–3.3) | <0.01 |
| TB groupb | 18.5 (1.5) | 21.3 (1.7) | Ref. | 21.7 (1.6) | Ref. | 21.2 (1.6) | Ref. | ||||
| Girls | TBB groupa | 18.2 (1.3) | 21.8 (1.4) | 0.6 (−0.4 to 1.5) | 0.25 | 23.4 (1.8) | 1.5 (0.6–2.5) | <0.01 | 23.3 (1.3) | 1.8 (0.9–2.8) | <0.01 |
| TB groupb | 18.8 (2.2) | 21.6 (2.1) | Ref. | 22.1 (1.7) | Ref. | 21.6 (1.7) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.3 (−1.0 to 1.7) | 0.64 | 0.2 (−1.2 to 1.5) | 0.81 | 0.5 (−0.8 to 1.9) | 0.46 | |||||
| I Incisal incisor | |||||||||||
| All | TBB groupa | 9.1 (1.4) | 11.6 (1.7) | 0.7 (0.1–1.3) | 0.02 | 8.7 (0.8) | −0.2 (−0.8 to 0.5) | 0.63 | 8.2 (1.7) | 0.1 (−0.5 to 0.8) | 0.66 |
| TB groupb | 8.9 (1.1) | 10.8 (1.7) | Ref. | 8.8 (1.1) | Ref. | 8.1 (1.2) | Ref. | ||||
| Boys | TBB groupa | 9.5 (1.5) | 12.5 (1.5) | 1.1 (0.3–1.9) | <0.01 | 9.1 (0.8) | 0.1 (−0.8 to 0.9) | 0.88 | 9.2 (1.8) | 1.1 (0.2–1.9) | 0.01 |
| TB groupb | 9.3 (0.7) | 11.2 (1.2) | Ref. | 8.9 (0.8) | Ref. | 8.0 (0.8) | Ref. | ||||
| Girls | TBB groupa | 8.6 (1.0) | 10.8 (1.5) | 0.2 (−0.6 to 1.1) | 0.55 | 8.4 (0.7) | −0.4 (−1.2 to 0.5) | 0.41 | 7.2 (0.7) | −0.8 (−1.7 to 0.0) | 0.06 |
| TB groupb | 8.5 (1.4) | 10.4 (2.1) | Ref. | 8.7 (1.4) | Ref. | 8.1 (1.5) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.9 (−0.3 to 2.0) | 0.15 | 0.4 (−0.8 to 1.6) | 0.69 | 1.9 (0.7–3.1) | <0.01 | |||||
| VCI Vestibular/cervical incisor | |||||||||||
| All | TBB groupa | 8.8 (1.0) | 12.0 (1.5) | 0.7 (0.2–1.2) | <0.01 | 9.3 (1.1) | 0.2 (−0.3 to 0.6) | 0.52 | 8.5 (1.0) | 0.1 (−0.4 to 0.6) | 0.78 |
| TB groupb | 8.6 (0.6) | 11.1 (1.1) | Ref. | 9.0 (0.7) | Ref. | 8.3 (0.6) | Ref. | ||||
| Boys | TBB groupa | 9.1 (1.1) | 12.7 (1.5) | 1.1 (0.4–1.7) | <0.01 | 9.8 (0.9) | 0.2 (−0.4 to 0.9) | 0.49 | 9.0 (0.9) | 0.3 (−0.4 to 1.0) | 0.37 |
| TB groupb | 8.6 (0.6) | 11.3 (0.8) | Ref. | 9.2 (0.6) | Ref. | 8.4 (0.5) | Ref. | ||||
| Girls | TBB groupa | 8.5 (0.7) | 11.3 (1.1) | 0.4 (−0.3 to 1.1) | 0.23 | 8.8 (0.8) | 0.1 (−0.6 to 0.8) | 0.78 | 8.0 (0.8) | −0.2 (−0.9 to 0.5) | 0.62 |
| TB groupb | 8.6 (0.7) | 10.9 (1.4) | Ref. | 8.8 (1.0) | Ref. | 8.2 (0.6) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.7 (−0.3 to 1.6) | 0.17 | 0.1 (−0.8 to 1.1) | 0.78 | 0.5 (−0.5 to 1.4) | 0.33 | |||||
| PCI Palatal/cervical incisor | |||||||||||
| All | TBB groupa | 6.9 (1.2) | 10.0 (1.2) | 0.8 (0.1–1.4) | 0.02 | 7.9 (1.1) | 0.3 (−0.3 to 1.0) | 0.29 | 7.4 (1.8) | 0.7 (0.0–1.3) | 0.04 |
| TB groupb | 6.9 (1.0) | 9.2 (1.6) | Ref. | 7.6 (1.0) | Ref. | 6.6 (1.0) | Ref. | ||||
| Boys | TBB groupa | 7.3 (1.1) | 10.4 (1.0) | 0.6 (−0.3 to 1.5) | 0.21 | 8.3 (0.9) | 0.7 (−0.2 to 1.6) | 0.15 | 8.0 (2.0) | 0.9 (0.0–1.9) | 0.04 |
| TB groupb | 7.0 (0.8) | 9.7 (0.9) | Ref. | 7.5 (1.0) | Ref. | 6.8 (1.0) | Ref. | ||||
| Girls | TBB groupa | 6.6 (1.2) | 9.6 (1.3) | 1.0 (0.0–1.9) | 0.04 | 7.5 (1.1) | 0.0 (−0.9 to 0.9) | 0.95 | 6.7 (1.4) | 0.4 (−0.6 to 1.3) | 0.44 |
| TB groupb | 6.8 (1.2) | 8.7 (1.9) | Ref. | 7.6 (1.1) | Ref. | 6.5 (1.1) | Ref. | ||||
| Interaction test (Boys vs. Girls) | −0.4 (−1.7 to 0.9) | 0.55 | 0.6 (−0.7 to 1.9) | 0.34 | 0.6 (−0.8 to 1.9) | 0.41 | |||||
| AMPS Anterior mid-palatal suture width | |||||||||||
| All | TBB groupa | 2.0 (0.7) | 3.8 (1.2) | 0.6 (0.2–1.1) | <0.01 | 2.5 (0.9) | 0.1 (−0.4 to 0.5) | 0.76 | 2.1 (0.7) | 0.1 (−0.4 to 0.5) | 0.68 |
| TB groupb | 2.0 (0.7) | 3.2 (0.8) | Ref. | 2.5 (0.9) | Ref. | 2.1 (0.6) | Ref. | ||||
| Boys | TBB groupa | 2.2 (0.8) | 4.3 (1.5) | 0.8 (0.2–1.4) | <0.01 | 2.9 (1.0) | 0.4 (−0.2 to 1.0) | 0.20 | 2.5 (0.7) | 0.4 (−0.2 to 1.0) | 0.24 |
| TB groupb | 2.1 (0.8) | 3.4 (0.5) | Ref. | 2.4 (1.1) | Ref. | 2.1 (0.8) | Ref. | ||||
| Girls | TBB groupa | 1.7 (0.5) | 3.4 (0.8) | 0.4 (−0.2 to 1.0) | 0.17 | 2.2 (0.7) | −0.3 (−0.9 to 0.3) | 0.38 | 1.8 (0.6) | −0.2 (−0.8 to 0.4) | 0.53 |
| TB groupb | 1.8 (0.6) | 3.1 (1.1) | Ref. | 2.5 (0.6) | Ref. | 2.0 (0.5) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.4 (−0.5 to 1.2) | 0.36 | 0.7 (−0.2 to 1.5) | 0.13 | 0.6 (−0.3 to 1.5) | 0.20 | |||||
| PMPS Posterior mid-palatal suture width | |||||||||||
| All | TBB groupa | 2.0 (1.1) | 3.0 (1.3) | 0.3 (−0.1 to 0.7) | 0.11 | 2.6 (1.6) | 0.3 (−0.1 to 0.7) | 0.18 | 2.2 (1.4) | 0.2 (−0.2 to 0.6) | 0.41 |
| TB groupb | 2.0 (1.0) | 2.7 (1.2) | Ref. | 2.4 (1.2) | Ref. | 2.1 (1.0) | Ref. | ||||
| Boys | TBB groupa | 2.4 (1.3) | 3.6 (1.6) | 0.4 (−0.1 to 1.0) | 0.13 | 3.1 (1.9) | 0.4 (−0.2 to 0.9) | 0.17 | 2.6 (1.7) | 0.1 (−0.4 to 0.7) | 0.66 |
| TB groupb | 2.0 (1.3) | 2.8 (1.4) | Ref. | 2.4 (1.6) | Ref. | 2.2 (1.3) | Ref. | ||||
| Girls | TBB groupa | 1.6 (0.8) | 2.5 (0.7) | 0.2 (−0.4 to 0.8) | 0.50 | 2.1 (1.0) | 0.1 (−0.4 to 0.7) | 0.62 | 1.8 (0.8) | 0.2 (−0.4 to 0.8) | 0.47 |
| TB groupb | 1.9 (0.6) | 2.6 (0.9) | Ref. | 2.3 (0.7) | Ref. | 2.0 (0.6) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.2 (−0.6 to 1.0) | 0.56 | 0.2 (−0.6 to 1.0) | 0.55 | −0.1 (−0.9 to 0.7) | 0.84 | |||||
| MT Maxillary tuber | |||||||||||
| All | TBB groupa | 37.0 (4.3) | 39.6 (4.1) | 0.4 (−0.6 to 1.5) | 0.42 | 38.9 (4.4) | 0.2 (−0.9 to 1.2) | 0.74 | 39.1 (4.3) | 0.9 (−0.2 to 2.0) | 0.10 |
| TB groupb | 35.2 (4.1) | 37.9 (4.1) | Ref. | 37.5 (4.2) | Ref. | 37.3 (4.4) | Ref. | ||||
| Boys | TBB groupa | 37.2 (5.1) | 39.7 (4.7) | 0.2 (−1.2 to 1.6) | 0.80 | 39.6 (5.1) | 0.6 (−0.8 to 2.0) | 0.39 | 40.4 (5.0) | 1.7 (0.3–3.2) | 0.02 |
| TB groupb | 35.9 (4.7) | 38.4 (4.5) | Ref. | 37.9 (5.1) | Ref. | 38.1 (5.1) | Ref. | ||||
| Girls | TBB groupa | 36.7 (3.5) | 39.6 (3.5) | 0.7 (−0.8 to 2.2) | 0.35 | 38.2 (3.5) | −0.3 (−1.7 to 1.2) | 0.70 | 37.8 (3.2) | 0.0 (−1.5 to 1.5) | 0.96 |
| TB groupb | 34.4 (3.5) | 37.4 (3.6) | Ref. | 37.1 (3.3) | Ref. | 36.6 (3.6) | Ref. | ||||
| Interaction test (Boys vs. Girls) | −0.5 (−2.5 to 1.5) | 0.62 | 0.9 (−1.1 to 2.9) | 0.38 | 1.8 (−0.3 to 3.9) | 0.09 | |||||
| B Buccal bone 16-26 | |||||||||||
| All | TBB groupa | 53.4 (2.8) | 56.8 (2.8) | 0.2 (−0.5 to 0.9) | 0.59 | 58.2 (3.0) | 0.5 (−0.2 to 1.2) | 0.19 | 58.0 (3.4) | 1.1 (0.4–1.8) | <0.01 |
| TB groupb | 52.4 (4.0) | 55.7 (3.7) | Ref. | 56.8 (3.8) | Ref. | 56.0 (4.3) | Ref. | ||||
| Boys | TBB groupa | 54.8 (2.3) | 58.3 (2.3) | 0.4 (−0.5 to 1.4) | 0.38 | 59.7 (2.7) | 0.5 (−0.5 to 1.5) | 0.31 | 60.0 (2.8) | 1.4 (0.4–2.4) | <0.01 |
| TB groupb | 52.6 (4.2) | 55.9 (4.1) | Ref. | 57.2 (4.2) | Ref. | 56.6 (4.4) | Ref. | ||||
| Girls | TBB groupa | 51.9 (2.5) | 55.3 (2.4) | 0.0 (−1.0 to 1.0) | 0.98 | 56.6 (2.4) | 0.5 (−0.5 to 1.5) | 0.35 | 55.9 (2.6) | 0.8 (−0.2 to 1.8) | 0.13 |
| TB groupb | 52.2 (3.8) | 55.6 (3.5) | Ref. | 56.3 (3.6) | Ref. | 55.4 (4.3) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 0.5 (−0.9 to 1.9) | 0.52 | 0.0 (−1.5 to 1.4) | 0.95 | 0.6 (−0.8 to 2.0) | 0.42 | |||||
| ANS-PNS Anterior-Posterior nasal spine | |||||||||||
| All | TBB groupa | 45.0 (3.3) | 43.9 (3.0) | 0.1 (−1.0 to 1.2) | 0.92 | 46.7 (3.6) | 0.8 (−0.3 to 1.9) | 0.16 | 48.2 (4.0) | 1.5 (0.4–2.6) | <0.01 |
| TB groupb | 44.2 (3.1) | 43.1 (2.5) | Ref. | 45.3 (3.1) | Ref. | 45.4 (2.5) | Ref. | ||||
| Boys | TBB groupa | 45.7 (3.6) | 44.8 (3.1) | 0.7 (−0.8 to 2.1) | 0.36 | 47.9 (4.1) | 1.2 (−0.3 to 2.6) | 0.12 | 50.1 (4.3) | 3.1 (1.6–4.6) | <0.01 |
| TB groupb | 44.6 (2.1) | 43.3 (2.1) | Ref. | 45.8 (2.4) | Ref. | 45.6 (2.2) | Ref. | ||||
| Girls | TBB groupa | 44.2 (2.8) | 42.9 (2.6) | −0.6 (−2.1 to 0.9) | 0.46 | 45.6 (2.8) | 0.4 (−1.1 to 1.9) | 0.62 | 46.2 (2.6) | −0.1 (−1.6 to 1.4) | 0.90 |
| TB groupb | 43.7 (3.9) | 43.0 (3.0) | Ref. | 44.7 (3.6) | Ref. | 45.2 (2.9) | Ref. | ||||
| Interaction test (Boys vs. Girls) | 1.2 (−0.8 to 3.3) | 0.24 | 0.8 (−1.3 to 2.9) | 0.46 | 3.2 (1.0–5.3) | <0.01 | |||||
aNumber of patients in TBB group: T0 n = 25 (boys n = 13, girls n = 12), T1 n = 26 (boys n = 13, girls n = 13), T2 n = 26 (boys n = 13, girls n = 13), T3 n = 24 (boys n = 12, girls n = 12).
bNumber of patients in TB group: T0 n = 26 (boys n = 13, girls n = 13), T1 n = 26 (boys n = 13, girls n = 13), T2 n = 26 (boys n = 13, girls n = 13), T3 n = 24 (boys n = 12, girls n = 12).
Table 1.
Anatomical reference points.
| FMS | Width between the right and left insertion of the frontomaxillary suture on the level of aperture piriformis. |
|---|---|
| ZMS1 | Width between the right and left superior of the zygomaticomaxillary suture. |
| ZMS2 | Width between the caudal right and left insertion of the zygomaticomaxillary suture. |
| N | Nose width at the widest point of the cavum nasi. Distance at the widest point of the cavum nasi between the convexity of the lateral margins |
| I | Width of the central incisors. Distance between the middle point of the incisal edges. |
| VCI | Width of the central incisors. Distance between the middle point of the vestibular cervical alveolar ridges. |
| PCI | Width of the central incisors. Distance between the middle point of the palatal cervical alveolar ridges. |
| AMPS | Width of the anterior midpalatal suture. Distance between cortical borders of the mid palatal suture of the os palatinum—3 mm posterior of the foramen incisivum. |
| PMPS | Width of the posterior midpalatal suture. Distance between the cortical edges of the mid palatal suture of the os palatinum. |
| MT | Width between the right and left dorsal wall of the maxillary sinus. |
| B | Width of the buccal bone wall at the maxillary first molars. |
| ANS-PNS | Width of the anterior and posterior nasal spine. |
The nasal width (N) also showed similar differences between the groups with a significantly larger expansion in the TBB group by 0.7 mm (CI 0.1–1.4) (P = 0.03). This group difference in favour of the TBB group was maintained at T2 (1.6 mm) and T3 (2.1 mm) (P < 0.01 for both T2 and T3).
Marginal bone level at the buccal aspect of the first molars (B) showed no statistically significant difference between the groups at any time point, except at T3 by 1.1 mm (CI 0.4–1.8) and in boys 1.4 mm (CI 0.4–2.4) in favour of the TBB group (P < 0.01).
The vestibular cervical alveolar ridge of the central incisor (VCI) showed significant differences between the groups with a mean of 0.7 mm (CI 0.2–1.2) more expansion in the TBB group (P < 0.01). This difference was also more evident in boys at T1, with a mean of 1.1 mm (CI 0.4–1.7) (P < 0.01). The palatial cervical alveolar ridge of the central incisor (PCI) showed no significant differences between the groups.
Dental differences between boys and girls were only evident at larger distances between the widths of the incisal edges of the central incisors (I) 1.9 mm (CI 0.7–3.1) at T3.
The ANS-PNS was also evident between boys and girls at T3 (P < 0.01) by 3.2 mm (CI 1.0–5.3).
Differences in the frontomaxillary suture (FMS) were only apparent at T3; in total 0.8 mm (0.4–1.2) and in boys 1.1 mm (CI 0.5–1.6). Zygomaticomaxillary sutures (ZMS) followed the same pattern with no significant differences directly after expansion between the groups.
ICC showed good to excellent reliability for all measured outcomes (Table 3).
Table 3.
The outcomes reliability estimated with ICC (intraclass correlation) in a linear mixed model among 10 randomly selected subjects measured twice on examinations T0, T1, and T2.
| Mean | SD between patients | SD within patients | ICC (95% CI) | |
|---|---|---|---|---|
| Examination T0 | ||||
| FMS Frontomaxillary suture | 16.1 | 1.0 | 0.3 | 0.93 (0.79–0.98) |
| ZMS1 Zygomaticomaxillary suture | 80.7 | 2.9 | 0.3 | 0.99 (0.96–1.00) |
| ZMS2 Zygomaticomaxillary suture | 79.4 | 3.0 | 0.3 | 0.99 (0.95–1.00) |
| N Nasal width | 17.9 | 0.9 | 0.3 | 0.93 (0.77–0.98) |
| I Incisal incisor | 9.3 | 0.8 | 0.3 | 0.89 (0.67–0.97) |
| VCI Vestibular/cervical incisor | 8.5 | 0.6 | 0.1 | 0.94 (0.81–0.98) |
| PCI Palatal/cervical incisor | 6.9 | 1.0 | 0.2 | 0.94 (0.81–0.98) |
| AMPS Anterior mid-palatal suture width | 1.9 | 0.6 | 0.2 | 0.90 (0.72–0.97) |
| PMPS Posterior mid-palatal suture width | 1.9 | 0.9 | 0.1 | 0.98 (0.93–0.99) |
| MT Maxillary tuber | 34.3 | 3.6 | 0.4 | 0.99 (0.97–1.00) |
| B Buccal bone 16-26 | 51.9 | 2.4 | 0.4 | 0.97 (0.90–0.99) |
| ANS-PNS Anterior-Posterior nasal spine | 43.3 | 1.9 | 0.4 | 0.95 (0.84–0.99) |
| Examination T1 | ||||
| FMS Frontomaxillary suture | 16.8 | 1.3 | 0.3 | 0.96 (0.86–0.99) |
| ZMS1 Zygomaticomaxillary suture | 82.7 | 3.2 | 0.2 | 0.99 (0.98–1.00) |
| ZMS2 Zygomaticomaxillary suture | 81.6 | 3.3 | 0.4 | 0.99 (0.95–1.00) |
| N Nasal width | 21.5 | 0.9 | 0.4 | 0.84 (0.56–0.95) |
| I Incisal incisor | 11.8 | 1.4 | 0.3 | 0.95 (0.83–0.99) |
| VCI Vestibular/cervical incisor | 11.6 | 1.3 | 0.3 | 0.95 (0.84–0.99) |
| PCI Palatal/cervical incisor | 10.2 | 1.6 | 0.2 | 0.98 (0.93–0.99) |
| AMPS Anterior mid-palatal suture width | 3.6 | 1.0 | 0.2 | 0.98 (0.92–0.99) |
| PMPS Posterior mid-palatal suture width | 2.6 | 1.1 | 0.2 | 0.97 (0.91–0.99) |
| MT Maxillary tuber | 37.8 | 3.1 | 0.1 | 1.00 (0.99–1.00) |
| B Buccal bone 16-26 | 55.6 | 2.4 | 0.4 | 0.97 (0.91–0.99) |
| ANS-PNS Anterior-Posterior nasal spine | 42.8 | 1.9 | 0.3 | 0.97 (0.90–0.99) |
| Examination T2 | ||||
| FMS Frontomaxillary suture | 17.0 | 1.5 | 0.4 | 0.94 (0.82–0.98) |
| ZMS1 Zygomaticomaxillary suture | 83.5 | 2.6 | 0.4 | 0.97 (0.91–0.99) |
| ZMS2 Zygomaticomaxillary suture | 82.3 | 2.2 | 0.3 | 0.98 (0.93–0.99) |
| N Nasal width | 23.0 | 1.8 | 0.3 | 0.97 (0.91–0.99) |
| I Incisal incisor | 9.0 | 0.9 | 0.2 | 0.96 (0.88–0.99) |
| VCI Vestibular/cervical incisor | 9.0 | 0.9 | 0.3 | 0.86 (0.62–0.96) |
| PCI Palatal/cervical incisor | 7.7 | 1.1 | 0.2 | 0.96 (0.87–0.99) |
| AMPS Anterior mid-palatal suture width | 2.4 | 0.9 | 0.2 | 0.95 (0.85–0.99) |
| PMPS Posterior mid-palatal suture width | 2.2 | 1.1 | 0.1 | 0.98 (0.95–1.00) |
| MT Maxillary tuber | 37.5 | 3.7 | 0.2 | 1.00 (0.99–1.00) |
| B Buccal bone 16-26 | 57.3 | 2.9 | 0.7 | 0.95 (0.83–0.99) |
| ANS-PNS Anterior-Posterior nasal spine | 45.4 | 3.0 | 0.2 | 0.99 (0.97–1.00) |
Statistical methods: The outcomes reliability was estimated in 10 study patients measured twice on each examination (T0–T2). The ICC is the ratio of the outcome variance between patients divided by total variance (between and within patients) and the SD between and within patients from the mixed models were presented. CI, confidence interval; SD, standard deviation.
Discussion
To our knowledge, most of the published studies to date evaluate the immediate effects of different RME devices and very seldom assess the long-term effects and stability of the treatments with a prospective study design. Findings of this longitudinal RCT show that the midpalatal suture expansion was statistically significantly larger (0.6 mm in mean) in the TBB group at its anterior part directly after expansion, but this inter-group difference did not remain at 1- and 5-years post-expansion. One could argue that this small difference between the groups is not clinically significant. The TBB group in boys gave rise to similar results, with a mean 0.8 mm larger expansion in the anterior midpalatal suture compared with boys expanded with the TB device. Midpalatal suture in 8- to 9-year-old children is not fused, and opening of the suture usually does not require much force. Malmvind et al. (14) showed that there were no significant differences between the TB and TBB design regarding palatal volume, palatal shell area or palatal projection area directly after expansion, or at 1 year and 5 years post-expansion, which implied that the two devices gave rise to the same immediate and long-term outcomes. A recent systematic review concluded that both TB and bone-borne devices seemed to have the same outcome regarding the amount of maxillary expansion and stability, which coincides with our findings (15).
Nasal width showed larger expansion also in the TBB group, with a mean of 0.7 mm directly post-expansion. This is in accordance with earlier published data in children in the early mixed dentition (pre-peak) (16–19). The change in the nasal width remained significantly larger at both T2 and T3 in the TBB group. These changes indicate that the TBB design might be superior to the TB design concerning its influence on the nasal width, and consequently, the nasal airflow, and could be justified in patients suffering from obstructed upper airways. A systematic review indicated a reduction of apnea–hypopnoea index (AHI) following RME in growing patients (20), and the TBB-RME might be the design of choice in these cases due to its superiority in expanding the nasal width.
The widening of the frontonasal and ZMS was around 1 mm directly post-expansion, and the choice of RME appliance seemed to have no bearing, as there were no statistically significant differences between the groups directly post-expansion. However, at T3 (5 years post-expansion) these circummaxillary sutures showed a significant difference between the groups of around 1 mm in the FMS and 1.5–2.5 mm in the ZMS in the TBB group compared to the TB group, and especially in boys treated with TBB-RME. Same pattern could be seen in the ANS and PNS 5 years post-expansion with larger effects in boys than girls at T3. This could indicate that miniscrew-assisted expansion could possibly alter the growth of the sutures, particularly in boys who grow more than girls. This is just a theory and must be proven by other studies.
Marginal bone level at the buccal aspect of the first molars was similar between the groups up to 5 years post-expansion (T3). At T3 a statistically significant difference of around 1 mm was found in favour of the TBB group, which could indicate that the first molars were uprighted more between the first and fifth years post-expansion and consequently less marginal bone was regressed than in the TB group.
Looking into the costs and cost-effectiveness, the conventional TB-RME is approximately €300 cheaper than the TBB. If the outcomes of the treatment are equal, then the cost-effectiveness of the treatments is an important issue to take into consideration (5). The patients in the TBB group were subjected to local anaesthesia upon insertion and removal of the miniscrews. For some preadolescent patients, this could be an unpleasant experience and cause anxiety.
One issue that should be discussed is the radiation safety ethics. The protocol of this trial was reviewed and approved by both the regional radiation protection committee and the regional ethical committee. The principle of ALADA (‘as low as diagnostically acceptable’) concerning radiation doses was implemented by the Department of Radiology in every case, with doses associated with a given level of image quality. This issue of radiation safety was discussed earlier (5).
Our RCT was stratified by sex, and we did not find any differences between boys and girls in our preadolescent sample with regard to skeletal effects. However, the alikeness of skeletal effects between sexes should be interpreted with caution due to the lack of power for skeletal differences among boys and girls in this study. Although the sex differences in skeletal maturity in preadolescents are unlikely. Ladewig et al. (21) confirmed different maturation stages in a group of young post-adolescents with differences between the sexes, where females showed more matured midpalatal sutures than males at the same age. Lin et al. (22) argued that for patients in late adolescence, bone-borne expanders are preferable because of the advantage of bone-borne expanders in producing more orthopaedic effects in older patients. Miniscrew-assisted RME has been shown in a systematic review to produce greater transverse skeletal expansion in late adolescents compared to conventional TB-RME (23). Thus, it appears that the use of miniscrew-assisted expanders should be delayed into late adolescence.
Strengths and limitations
This study has some limitations. Double blinding was not possible due to the clinical limitations. The volume rendering in the software used for definition of bone borders and landmarks is very exact but may differ by ±0.250 mm (size of one voxel). One other limitation is possibly the lack of power regarding differences between the genders (boys and girls; n = 13 in each group). The sample size calculation was undertaken for the whole group.
The design of this prospective study was a randomized clinical trial. The randomization process, in which the patients are randomly assigned in advance, results in a similar distribution of confounding variables between the groups. This reduces the risk of selection bias. Moreover, to further reduce the risk of bias, the outcome assessors were completely blinded to allocation and to which treatment the patients had received.
Clinical implications
In young preadolescents with the constricted maxilla, it seems that conventional TB-RME induces more or less the same long-term skeletal effects as the TBB design, with good stability 5 years post-expansion. Therefore, the use of miniscrews and skeletal anchorage in young preadolescents cannot be recommended due to the similar long-term outcomes as the less invasive conventional TB-RME.
Generalization
The results of this RCT can be generalized only in a population aged 8–11 years and in the case that the inclusion and exclusion criteria are met.
Conclusions
Skeletal expansion in the midpalatal suture was significantly higher in the TBB group; however, the magnitude of this expansion was around 0.6 mm more and may not be clinically significant.
Skeletal expansion at the level of the nasal cavity was significantly higher in the TBB group.
Marginal bone level at the buccal aspect of the first molars was similar between the groups up to 5 years post-expansion. At 5 years post-expansion a statistically significant difference of around 1 mm less dental tipping was found in favour of the TBB group.
There were no differences between boys and girls with regard to skeletal expansion.
Acknowledgements
The authors would like to kindly thank Ann Kathrin Binger for her valuable assistance with the superimpositions in this article.
Contributor Information
Farhan Bazargani, Department of Orthodontics, Postgraduate Dental Education Center, Örebro, Sweden; School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
Vanessa Knode, Private orthodontic office, Traben-Trarbach, Germany.
Alexander Plaksin, Private orthodontic office, Moscow, Russia.
Anders Magnuson, Clinical Epidemiology and Biostatistics, School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Orebro, Sweden.
Björn Ludwig, Private orthodontic office, Traben-Trarbach, Germany; Department of Orthodontics, University of Saarland, Homburg/Saar, Germany.
Funding
This study was supported by the Uppsala-Örebro Regional Research Council, Sweden, (grant number RFR-72021). The funding sources had no role in the design and conduct of the study; in the collection, management, analysis, and interpretation of the data; or in the preparation of the manuscript. The authors’ work was independent of the funders.
Conflicts of interest
None to declare.
Data availability
The authors confirm that the data supporting the findings of this study are available within the article.
References
- 1. Lagravere, M.O., Major, P.W. and Flores-Mir, C. (2005) Long-term skeletal changes with rapid maxillary expansion: a systematic review. The Angle Orthodontist, 75, 1046–1052. doi: 10.1043/0003-3219(2005)75[1046:LSCWRM]2.0.CO;2. [DOI] [PubMed] [Google Scholar]
- 2. Angell, E.H. (1860) Treatment of irregularity of the permanent or adult teeth. Dental Cosmos, 1, 540–544. [Google Scholar]
- 3. Garrett, B.J., Caruso, J.M., Rungcharassaeng, K., Farrage, J.R., Kim, J.S. and Taylor, G.D. (2008) Skeletal effects to the maxilla after rapid maxillary expansion assessed with cone-beam computed tomography. American Journal of Orthodontics and Dentofacial Orthopedics, 134, 8–9. doi: 10.1016/j.ajodo.2007.11.024. [DOI] [PubMed] [Google Scholar]
- 4. Mosleh, M.I., Kaddah, M.A., Abd ElSayed, F.A. and ElSayed, H.S. (2015) Comparison of transverse changes during maxillary expansion with 4-point bone-borne and tooth-borne maxillary expanders. American Journal of Orthodontics and Dentofacial Orthopedics, 148, 599–607. doi: 10.1016/j.ajodo.2015.04.040. [DOI] [PubMed] [Google Scholar]
- 5. Bazargani, F., Lund, H., Magnuson, A. and Ludwig, B. (2021) Skeletal and dentoalveolar effects using tooth-borne and tooth-bone-borne RME appliances: a randomized controlled trial with 1-year follow-up. European Journal of Orthodontics, 43, 245–253. doi: 10.1093/ejo/cjaa040. [DOI] [PubMed] [Google Scholar]
- 6. Bazzani, M., et al. (2023) Three-dimensional comparison of bone-borne and tooth-bone-borne maxillary expansion in young adults with maxillary skeletal deficiency. Orthodontics & Craniofacial Research, 26, 151–162. doi: 10.1111/ocr.12595. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7. Fedorov, A., et al. (2012) 3D Slicer as an image computing platform for the Quantitative Imaging Network. Magnetic Resonance Imaging, 30, 1323–1341. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Cevidanes, L.H., Bailey, L.J., Tucker, G.R., Styner, M.A., Mol, A., Phillips, C.L., Proffit, W.R. and Turvey, T. (2005) Superimposition of 3D cone-beam CT models of orthognathic surgery patients. Dento Maxillo Facial Radiology, 34, 369–375. doi: 10.1259/dmfr/17102411. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Cevidanes, L.H., Heymann, G., Cornelis, M.A., DeClerck, H.J. and Tulloch, J.F. (2009) Superimposition of 3-dimensional cone-beam computed tomography models of growing patients. American Journal of Orthodontics and Dentofacial Orthopedics, 136, 94–99. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10. Cevidanes, L.H., Motta, A., Proffit, W.R., Ackerman, J.L. and Styner, M. (2010) Cranial base superimposition for 3-dimensional evaluation of soft-tissue changes. American Journal of Orthodontics and Dentofacial Orthopedics, 137, S120–S129. doi: 10.1016/j.ajodo.2009.04.021. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11. Pinter, C., Lasso, A. and Fichtinger, G. (2019) Polymorph segmentation representation for medical image computing. Computer Methods and Programs in Biomedicine, 171, 19–26. doi: 10.1016/j.cmpb.2019.02.011. [DOI] [PubMed] [Google Scholar]
- 12. Portney, L.G. and Watkins, M.P. (2000) Foundations of Clinical Research: Applications to Practice. 2nd edn. Prentice Hall Health, Upper Saddle River, NJ. [Google Scholar]
- 13. Hansen, L., Tausche, E., Hietschold, V., Hotan, T., Lagravere, M. and Harzer, W. (2007) Skeletally-anchored rapid maxillary expansion using the Dresden Distractor. Journal of Orofacial Orthopedics, 68, 148–158. [DOI] [PubMed] [Google Scholar]
- 14. Malmvind, D., Golez, A., Magnuson, A., Ovsenik, M. and Bazargani, F. (2022) Three-dimensional assessment of palatal area changes after posterior crossbite correction with tooth-borne and tooth bone-borne rapid maxillary expansion. The Angle Orthodontist, 6, 589–597. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15. Khosravi, M., Ugolini, A., Miresmaeili, A., Mirzaei, H., Shahidi-Zandi, V., Soheilifar, S., Karami, M. and Mahmoudzadeh, M. (2019) Tooth-borne versus bone-borne rapid maxillary expansion for transverse maxillary deficiency: a systematic review. International Orthodontics, 17, 425–436. doi: 10.1016/j.ortho.2019.06.003. [DOI] [PubMed] [Google Scholar]
- 16. Preve, S. and Garcia Alcazar, B. (2022) Interest of miniscrew-assisted rapid palatal expansion on the upper airway in growing patients: a systematic review. International Orthodontics, 20, 100657. doi: 10.1016/j.ortho.2022.100657. [DOI] [PubMed] [Google Scholar]
- 17. Chun, J.H., de Castro, A.C.R., Oh, S., Kim, K.H., Choi, S.H., Nojima, L.I., Nojima, M. and Lee, K.J. (2022) Skeletal and alveolar changes in conventional rapid palatal expansion (RPE) and miniscrew-assisted RPE (MARPE): a prospective randomized clinical trial using low-dose CBCT. BMC Oral Health, 22, 114. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18. Bazargani, F., Magnuson, A. and Ludwig, B. (2018) Effects on nasal airflow and resistance using two different RME appliances: a randomized controlled trial. European Journal of Orthodontics, 40, 281–284. doi: 10.1093/ejo/cjx081. [DOI] [PubMed] [Google Scholar]
- 19. Calvo-Henriquez, C., Capasso, R., Chiesa-Estomba, C., Liu, S.Y., Martins-Neves, S., Castedo, E., O’Connor-Reina, C., Ruano Ravina, A. and Kahn, S. (2020) The role of pediatric maxillary expansion on nasal breathing: a systematic review and metanalysis. International Journal of Pediatric Otorhinolaryngology, 135, 110139. [DOI] [PubMed] [Google Scholar]
- 20. Martos-Cobo, E., Mayoral-Sanz, P., Exposito-Delgado, A.J. and Duran-Cantolla, J. (2022) Effect of rapid maxillary expansion on the apnoea-hypopnoea index during sleep in children. Systematic review. Journal of Clinical and Experimental Dentistry, 14, e769–e775. doi: 10.4317/jced.59750. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21. Ladewig, V.M., Capelozza-Filho, L., Almeida-Pedrin, R.R., Guedes, F.P., de Almeida Cardoso, M. and de Castro Ferreira Conti, A.C. (2018) Tomographic evaluation of the maturation stage of the midpalatal suture in postadolescents. American Journal of Orthodontics and Dentofacial Orthopedics, 153, 818–824. [DOI] [PubMed] [Google Scholar]
- 22. Lin, L., Ahn, H.W., Kim, S.J., Moon, S.C., Kim, S.H. and Nelson, G. (2015) Tooth-borne vs bone-borne rapid maxillary expanders in late adolescence. The Angle Orthodontist, 85, 253–262. doi: 10.2319/030514-156.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23. Huang, X., Han, Y. and Yang, S. (2022) Effect and stability of miniscrew-assisted rapid palatal expansion: a systematic review and meta-analysis. Korean Journal of Orthodontics, 52, 334–344. doi: 10.4041/kjod21.324. [DOI] [PMC free article] [PubMed] [Google Scholar]
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Data Availability Statement
The authors confirm that the data supporting the findings of this study are available within the article.