The novel use of three-dimensional surface models to quantify and visualise the immediate changes of the mid-facial skeleton following rapid maxillary expansion

Does unilateral surgically assisted rapid maxillary expansion (SARME) lead to perinasal asymmetry?

OBJECTIVE

True unilateral posterior crossbite (TUPC) requires unilateral expansion to prevent nonocclusion at the noncrossbite (NC) side. The recommended osteotomies for TUPC after sutural closure are anterior, lateral, and posterior osteotomies only on the crossbite (C) side and median osteotomy of the midpalatal suture, i.e., unilateral surgically assisted rapid maxillary expansion (SARME). The goal was to assess airway and perinasal soft tissue outcomes after SARME.

METHODS

Data from 16 patients (8 males, 8 females; mean age 18.38 ± 1.45 years) were retrospectively assessed after unilateral SARME. The expansion (twice daily: 0.5 mm/day) and retention periods comprised 3 weeks and 6 months, respectively. Stereophotogrammetric images were used for soft tissue assessment; cone beam computed tomography (CBCT) was used to evaluate the anterior nasal airway. Statistical analyses were performed.

RESULTS

Using linear measurements, soft tissue distances of the alar base and alare to midsagittal plane (MSP) were significantly increased on the C side. A significant decrease was observed for the distance from the lower nostril point to the MSP on the NC side compared to a significant increase on the C side. Comparing the C and NC sides, the changes were significantly higher on the C side for all parameters except the upper nostril point to the MSP distance. Cheek volume was significantly higher on the C side. Volume changes of the anterior nasal airway (ANA) were significantly increased on the C side, but volume changes between NC and C were not significantly different.

CONCLUSIONS

Unilateral SARME led to significant expansion of ANA on the C side, but did not lead to asymmetry in the nasal region or have adverse effects on the airway or perinasal soft tissues. Thus, this novel treatment method may be useful in the treatment of patients with TUPC.

Two- and Three-Segment Surgically Assisted Rapid Maxillary Expansion: A Clinical Trial

BACKGROUND

The literature shows no consensus on whether two- or three-segment surgically assisted rapid maxillary expansion is the best operative technique.

METHODS

The present clinical trial was designed to compare the outcome of two- and three-segment osteotomy surgically assisted rapid maxillary expansion. Thirty-two adult patients with transverse maxillary deficiency greater than or equal to 5 mm were randomly assigned to two- and three-segment groups (n = 16). Dimensional and psychological assessments (Oral Health Impact Profile and Brazilian Orthognathic Quality of Life Questionnaire) were carried out before surgical intervention and at one of the following time points: completion of expansion, removal of expanding device, 6 months after completion of expansion, or 10 months after completion of expansion. Dimensional assessments for asymmetric expansion of the maxilla and for changes in the area and volume of the palatine vault were performed on digital data from tomographic and laser scanning with the aid of an engineering inspection software.

RESULTS

No statistically significant differences were found in asymmetry or stability outcomes between groups. The psychological benefit provided by the three-segment technique did not spread through the domains of the quality-of-life questionnaires.

CONCLUSIONS

The current findings suggest that three-segment surgically assisted rapid maxillary expansion outcomes do not exceed those obtained with its two-segment counterpart regarding symmetry of maxillary expansion and stability of area and volume of the palatine vault. Furthermore, psychological nuances evidenced in two- and three-segment groups with the tools used play a limited, short-lasting role, or a specific, more sensitive assessment tool needs to be developed.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Three-dimensional zygomatic changes after rapid maxillary expansion in growing patients

PURPOSE

To assess the effects of rapid maxillary expansion (RME) treatment on the zygomatic bone complex (ZBC).

METHODS

In this single-center retrospective study, pre- and posttreatment cone-beam computed tomography (CBCT) images of 38 patients treated with RME were analyzed to investigate changes in the coordinates of the ZBC landmarks. At the start of treatment (T0), the patients' mean age was 11.1 ± 3.8 years (range 8.3-14.9 years). Cohen's d test was used to evaluate statistical differences.

RESULTS

There were statistically significant differences between T0 and T1 (P < 0.01) in the measurement values for the maxillary transverse width (ΔT: 3.18 ± 2.58, d: 1.23), frontozygomatic sutures (ΔT: 1.09 ± 0.56, d: 0.43), lowest point of the zygomaticomaxillary sutures (ΔT: 3.16 ± 1.78, d: 0.78), frontomaxillary angular parameter (right side ΔT: 2.81 ± 1.63, d: 1.73; left side ΔT: 2.52 ± 1.20, d: 2.10), frontozygomatic angular parameter (right side ΔT: 2.81 ± 1.63 d: 1.07; left side ΔT: 2.21 ± 2.79, d: 0.61), anterior intermaxillary distance (ΔT: 2.11 ± 1.42, d: 0.99), interzygomaticotemporal distance (ΔT: 2.00 ± 2.42, d: 0.99), and zygomatic angular parameter (right side ΔT: 2.06 ± 1.29, d: 1.6; left side ΔT: 2.02 ± 1.86, d: 1.09).

CONCLUSIONS

After RME in growing patients, the zygomatic bone showed pyramidal expansion in the coronal plane and parallel palatal expansion in the axial plane. In addition, significant lateral relocation of the zygomatic bone occurred. The zygomatic bone tended to rotate outward in conjunction with the maxilla, with a typical center of rotation close to the superior side of the frontozygomatic suture. These results shed light on the patterns of skeletal expansion in the zygomatic bone associated with RME in growing patients.

Evaluation of the Soft Tissue Changes after Rapid Maxillary Expansion Using a Handheld Three-Dimensional Scanner: A Prospective Study

Facial soft tissue esthetics is a priority in orthodontic treatment, and emerging of the digital technologies can offer new methods to help the orthodontist toward an esthetic outcome. This prospective study aimed to assess the soft tissue changes of the face after six months of retention following Rapid Maxillary Expansion (RME). The sample consisted of 25 patients (13 females, 12 males, mean age: 11.6 years) who presented with unilateral or bilateral posterior crossbite requiring RME, which was performed with a Hyrax expander. 3D facial images were obtained before treatment (T₀) and at the end of a six-month retention period after the treatment (T₁) using a structured-light 3D handheld scanner. Linear and angular measurements were performed and 3D deviation analyses were done for six morphological regions of the face. Significant changes in various areas of the nasal and the upper lip regions were observed. Based on the results of the study and within the limitations of the study, RME with a Hyrax expander results in significant morphological changes of the face after a six-month retention period.

Evaluation of the changes of orbital cavity volume and shape after tooth-borne and bone-borne rapid maxillary expansion (RME)

Objective

To assess and compare volumetric and shape changes of the orbital cavity in patients treated with tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME).

Study design

Forty adolescents with bilateral maxillary cross-bite received tooth-borne (TB group = 20; mean age 14.27 ± 1.36 years) or bone-borne (BB group = 20; mean age of 14.62 ± 1.45 years) maxillary expander. Cone-beam computed tomography (CBCT) were taken before treatment (T1) and 6-month after the expander activation (T2). Volumetric and shape changes of orbital cavities were detected by referring to a specific 3D digital technology involving deviation analysis of T1/T2 CBCT-derived models of pulp chamber. Student’s t tests were used to 1) compare T1 and T2 volumes of orbital cavities in TB and BB groups, 2) compare volumetric changes and the percentage of matching of 3D orbital models (T1-T2) between the two groups.

Results

Both TB and BB groups showed a slight increase of the orbital volume (0.64 cm³ and 0.77 cm³) (p < 0.0001). This increment were significant between the two groups (p < 0.05) while no differences were found in the percentage of matching of T1/T2 orbital 3D models (p > 0.05). The areas of greater changes were detected in the proximity of the frontozygomatic and frontomaxillary sutures.

Conclusion

TB-RME and BB-RME would not seem to considerably affect the anatomy or the volume of the orbital cavity in adolescents.

kVp, mA, and voxel size effect on 3D voxel-based superimposition

OBJECTIVES

To evaluate the effect of changing kVp, mA, and voxel size on the accuracy of voxel-based superimposition on the anterior cranial base.

MATERIALS AND METHODS

Cone beam computed tomography (CBCT) scans were taken on a phantom skull using different kVp, mA, and voxel size combinations. CBCT scans were superimposed using commercially available software. Two separate open-source software programs were used to generate a three-dimensional (3D) color map objective assessment of the differences in seven different regions: Nasion, Point A, Zygomatic (right and left), Point B, and Gonial (right and left). Each region had around 200 points that were used to calculate the mean differences between the superimpositions.

RESULTS

Intraclass correlation showed excellent reliability (0.95). Lowering the kVp made the biggest difference, showing an average discrepancy of 0.7 ± 0.3 mm, and a high mean of 1.4 ± 0.3 in the Right Gonial region. Lowering the mA showed less of a discrepancy, with an average of 0.373 ± 0.2 mm, and the highest discrepancy, also on the Right Gonial Area, of 0.7 ± 0.1 mm. The voxel size had the least impact on the accuracy of registered volumes, with mean discrepancy values of less than 0.2 mm.

CONCLUSIONS

Using different CBCT settings can affect the accuracy of the voxel-based superimposition method. This is particularly the case when using low kVp values, while changes in mA or voxel sizes did not significantly interfere with the superimposition outcome.

Three-dimensional stereophotogrammetric analysis of nasolabial soft tissue effects of rapid maxillary expansion: a systematic review of clinical trials

The aim of this systematic review is to analyse the quality and clinical evidence in the literature analysing, through 3D stereophotogrammetry, the nasolabial soft tissue modifications that may occur after rapid maxillary expansion (RME). This systematic literature review was based on the PRISMA-P statement and was registered in the PROSPERO database with the following protocol ID: CRD42017079875. Pubmed, Cochrane, EBSCO, Scopus, Web of Science databases were searched with no restriction of year or publication status. Selection criteria were: randomised clinical trials, controlled clinical trials, cohort studies, cross-sectional studies, case-control studies on patients with unilateral/bilateral crossbite, transverse maxillary deficiency and crowding, treated with RME and monitored by 3D stereophotogrammetry. 652 articles were retrieved in the initial search. After the review process, 11 full-text articles met inclusion criteria. After the evaluation process, 4 publications were included for the present literature review. Due to the heterogeneous methodology meta-analysis was not possible; consequently, a systematic assessment of the studies and summary of the findings from the available evidence were used to answer the research question. The maximum widening of the alar cartilage is 1.41 ± 0.95 mm, whose clinical significance is open to question. The effect of RME on the mouth width remains controversial. In Altindis et al., the difference between pre-treatment and post-treatment mouth width (1.80 mm increment in the banded RME group) was statistically significant, while in Baysal 1.86 mm was considered a non-significant value. Inconsistencies and limitations in the study population and measurement protocols were detected between studies. These data underline the necessity for updated guidelines that allow to standardise, for this type of study, sample selection, measurement methods and collection of results.

Midfacial changes in the coronal plane induced by microimplant-supported skeletal expander, studied with cone-beam computed tomography images

INTRODUCTION

Our objectives were to evaluate midfacial skeletal changes in the coronal plane and the implications of circummaxillary sutures and to localize the center of rotation for the zygomaticomaxillary complex after therapy with a bone-anchored maxillary expander, using high-resolution cone-beam computed tomography.

METHODS

Fifteen subjects with a mean age of 17.2 ± 4.2 years were treated with a bone-anchored maxillary expander. Pretreatment and posttreatment cone-beam computed tomography images were superimposed and examined for comparison.

RESULTS

Upper interzygomatic distance increased by 0.5 mm, lower interzygomatic distance increased by 4.6 mm, frontozygomatic angles increased by 2.5° and 2.9° (right and left sides), maxillary inclinations increased by 2.0° and 2.5° (right and left sides), and intermolar distance increased by 8.3 mm (P <0.05). Changes in frontoethmoidal, zygomaticomaxillary, and molar basal bone angles were negligible (P >0.05).

CONCLUSIONS

A significant lateral displacement of the zygomaticomaxillary complex occurred in late adolescent patients treated with a bone-anchored maxillary expander. The zygomatic bone tended to rotate outward along with the maxilla with a common center of rotation located near the superior aspect of the frontozygomatic suture. Dental tipping of the molars was negligible during treatment.

Assessing the validity of ITK-SNAP software package in measuring the volume of upper airway spaces secondary to rapid maxillary expansion

INTRODUCTION:

The purpose of this study is to evaluate the validity of a free-access software package (ITK-SNAP) in segmenting and measuring the volume of upper airway spaces secondary to rapid maxillary expansion (RME).

MATERIALS AND METHODS:

Sixteen participants who required RME were recruited for this study. Preoperative (T1) and 6-month postoperative (T2) cone-beam computed tomographic scans of all participants were analyzed. OnDemand3D software packages was used for superimposition and orientation of the images, while ITK-SNAP software was used to measure the volume of airway spaces. At week one (W1), all volumetric measurements were carried out by one examiner and repeated after 1 week (W2). Paired t-test, the interclass correlation coefficient, and Dahlberg coefficients of reliability were used to assess the reproducibility.

RESULTS:

Student's t-test showed no significant difference between the W1 and W2 set of measurements (P > 0.05). Coefficients of reliability were above 95% and intraclass correlation coefficient ranged from 0.99 to 1.000, which altogether confirmed the satisfactory reproducibility of the measurements.

CONCLUSIONS:

ITK-SNAP software package is a reliable and cost-effective method to segment and measure upper airway changes subsequent to RME.

Effects of rapid maxillary expansion on facial soft tissues : Deviation analysis on three-dimensional images

OBJECTIVE

Changes in soft tissue in various morphological regions of the face immediately after rapid maxillary expansion (RME) were examined using three-dimensional (3D) deviation analyses.

PATIENTS AND METHODS

A total of 50 patients were included in the study; 25 patients (11 female and 14 male) presented with a unilateral or bilateral posterior crossbite malocclusion requiring RME. In addition, 25 patients (13 female and 12 male) were included as a control group. The mean ages of the study group and control group were 9.8 years (range 8.1-12.6 years) and 9.6 years (range 8.3-12.2 years), respectively. The 3D stereophotogrammetric images acquired immediately before the appliance was cemented and after expansion had been completed in the treatment group were compared using Rapidform software. The 3D deviation analyses were made for the complete face and in the upper and lower face, upper and lower lips and nose regions. The amount of negative and positive deviations and the mean deviations were examined on the facial meshes for the 95th percentiles.

RESULTS

Immediately after RME, the mean absolute deviation over the complete face was 0.54 ± 0.16 mm. The mean change for the upper face was 0.42 ± 0.17 mm (mean positive deviation: 0.37 ± 0.17 mm; mean negative deviation: -0.48 ± 0.18 mm). The mean absolute deviation was 0.62 ± 0.28 mm in the upper lip and 0.60 ± 0.34 mm in the lower lip. In the nose area, the absolute deviation was 0.41 ± 0.21 mm (mean positive deviation: 0.39 ± 0.16 mm; mean negative deviation: -0.43 ± 0.26 mm).

CONCLUSIONS

Changes in facial soft tissues in the upper face, lower face, nasal soft tissues, and lower and upper lip regions were observed after RME.

Immediate effects of rapid maxillary expansion on the naso-maxillary facial soft tissue using 3D stereophotogrammetry

BACKGROUND

Rapid maxillary expansion (RME) is used to expand the narrow maxilla. Dental and skeletal affects have previously been reported but few studies have reported on the overlying soft tissue changes. This study reports on the immediate effects of RME on the naso-maxillary facial soft tissue using 3D stereophotogrammetry.

METHODS

Fourteen patients requiring upper arch expansion using RME as part of their full comprehensive orthodontic plan were recruited. Cone beam CT scans and stereophotogrammetry images were taken for each patient; pre-RME activation (T0) and immediately post-RME expansion (T1). Based on twenty-three landmarks, 13 linear and 3 angular measurements were made from each of the stereophotogrammetry images. A linear measurement at ANS was taken from each CBCT image. Using a Wilcoxon signed rank test, the pre-RME and post-RME measurements were compared.

RESULTS

The mean separation of the anterior nasal spine was 3.8 mm ± 1.2 mm. The largest median increase was in nasal base width (1.6 mm), which was statistically significant (p = 0.001). Changes in the nasal dorsum height, nasal tip protrusion, philtrum width, and upper lip length were not statistically significant (p < 0.05). No significant differences were observed in the nostril linear measurements, expect for columella width (p = 0.009). Naso-labial angle decreased but was not statistically significant (p = 0.276). The only statically significant angular change was an increase in the nasal tip displacement angle (p = 0.001).

CONCLUSION

Rapid maxillary expansion produces subtle changes in the naso-maxillary soft tissue complex. There is an increase in nasal base width, retraction and flattening of the nasal tip. These changes are small, less than 2 mm and variable between patients.