Maxillary expansion: clinical implications

Evaluation of opening pattern and bone neoformation at median palatal suture area in patients submitted to surgically assisted rapid maxillary expansion (SARME) through cone beam computed tomography

Surgically assisted rapid maxillary expansion (SARME) is the treatment of choice to adult patients even with severe transversal maxillary discrepancies. However, the adequate retention period to achieve the bone remodeling, thus assuring treatment stability, is controversial.Objective To evaluate the opening pattern and bone neoformation process at the midpalatal suture in patients submitted to surgically assisted (SARME) through cone beam computed tomography (CBCT).Material and Methods Fourteen patients were submitted to SARME through subtotal Le Fort I osteotomy. Both the opening pattern and the mean bone density at midpalatal suture area to evaluate bone formation were assessed pre- and post-operatively (15, 60 and 180 days) through CBCT.Results Type I opening pattern (from anterior to posterior nasal spine) occurred in 12 subjects while type II opening pattern (from anterior nasal spine to transverse palatine suture) occurred in 2 individuals. The 180-day postoperative mean (PO 180) of bone density value was 49.9% of the preoperative mean (Pre) value.Conclusions The opening pattern of midpalatal suture is more related to patients' age (23.9 years in type I and 33.5 years in type II) and surgical technique. It was not possible to observe complete bone formation at midpalatal suture area at the ending of the retention period studied (180 days).

Does rapid maxillary expansion affect nasopharyngeal airway? A prospective Cone Beam Computerised Tomography (CBCT) based study

BACKGROUND AND PURPOSE

There is limited literature discussing the three dimnesional (3D) impact of rapid maxillary expansion (RME) on upper airway. The purpose of this prospective Cone Beam Computerised Tomography (CBCT) based study is to assess the immediate 3D effects and to correlate the volumteric changes in the upper naspharyngeal airway spaces secondary to RME.

MATERIALS AND METHODS

Seventeen participants (8 male, 9 female, with a mean age of 12.6 ± 1.8 years), who required RME for the management of narrow maxillary arch, were recruited for this study. The prescribed expansion regimen was quarter turn (0.25 mm), twice a day until over-expansion was achieved. The mean period for the active phase was 14 days with a range of 12-21 days. Pretreatment (T1) and immediate post-expansion (T2) CBCT images were obtained and then processed using ITK snap and OnDemand3D softwar packages. Paired t-test and Interclass Correlation Coefficient (ICC) were used to assess the reproducibility of the measurements, student t-test (P < 0.05) and Pearson Correlation Coefficient (PCC) were applied to evaluate the volumetric changes in the nasopharyngeal airway spaces, linear dentolaveolar changes and correlate these changes.

MAIN FINDINGS

Though, the data of one patient was excluded from the study, owing to major differences (>5 degrees) in the head and neck posture between T1 and T2 CBCT scans, the study' findings shows that bonded RME is an effective dentoalveolar expander in growing patients (P= 0.01) with an average expansion of 3.7 mm and 2.8 mm in males and females respectively. Likewise, the upper nasopharynx (UNP) expanded significantly (15.2% in males and 12% in females). In comparison, the upper retropalatal space (URP) was significantly reduced, by almost one sixth of its original volume, more in males than females, 11.2% and 2.8% respectively. A strong direct correlation between the maxillary sinus volumetric changes, and between appliance expansion and dentoalveolar expansion were evident (PCC = 0.86, 0.75, respectively). There was also a moderate correlation between changes in the UNP and URP spaces.

CONCLUSIONS

RME was found to be an effective dentoalveolar expander and significantly augment the UNP and minimize the URP space. A similar comparative clinical study with long-term follow-up would be beneficial in accurately deteremining the clinical impact of RME on the airway and breathing as well as the stability of these effects.

Evaluation and comparison of root resorption between tooth-borne and tooth-tissue borne rapid maxillary expansion appliances: A CBCT study

OBJECTIVE

To compare volumetric root resorption after rapid maxillary expansion (RME) between tooth-borne and tissue-borne appliances using CBCT. Repair in resorption cavities after 6 months of fixed retention was also compared.

MATERIALS AND METHODS

A sample of 33 subjects were randomly divided into two groups: Hyrax (n  = 16) and Haas (n = 17). CBCT scans were taken 6 months before expansion, immediately after expansion, and 6 months after fixed retention. Mimics Innovation V 16.0 software was used for segmentation and volumetric measurement of 198 teeth. Bland-Altman plots, independent samples t test, repeated measures analysis of variance, and the Friedman test were used for statistical analysis.

RESULTS

Differences in root resorption after RME and repair after retention were not significant between the hyrax and Haas appliances or between male and female. Significant differences were found between preexpansion and postexpansion root volumes in the first premolars and molars--even in unattached second premolars. When the percentage of root volume loss is considered, no significant difference was found between the first premolar, second premolar, and first molar. Volumetric changes after 6 months of retention were not statistically significant.

CONCLUSIONS

More resorption was observed in the Hyrax expander group. But it was not statistically significant. Repair was observed after 6 months of retention. Heavy RME forces affected premolars and molar similarly.

Periodontal, dentoalveolar, and skeletal effects of tooth-borne and tooth-bone-borne expansion appliances

INTRODUCTION

The purposes of this study were to evaluate and compare the periodontal, dentoalveolar, and skeletal effects of tooth-borne and tooth-bone-borne expansion devices using cone-beam computed tomography.

METHODS

Twenty-five patients requiring maxillary expansion were randomly allocated into 2 groups. A tooth-borne hyrax appliance was used in the first group, consisting of 13 patients (8 girls, 5 boys; mean age, 14.3 ± 2.3 years), and a tooth-bone-borne hybrid hyrax appliance was used in the second group of 12 patients (6 girls, 6 boys; mean age, 13.8 ± 2.2 years). Cone-beam computed tomography records were taken before and 3 months after expansion, and periodontal, dentoalveolar, and skeletal measurements were made on the cone-beam computed tomography images with a software program. The 2 independent-samples t test and the Mann-Whitney U test were used to evaluate treatment changes for both groups. Paired-samples t test and Wilcoxon test were used to compare the measurements at 2 time points for variables.

RESULTS

Significant skeletal changes and increases in interdental distances were observed in both groups. However, the distances between the first and second premolars increased more with the hyrax appliance (7.5 ± 4.2 and 7.9 ± 3.3 mm, respectively) than with the hybrid hyrax (3.2 ± 2.6 and 4.5 ± 3.8 mm, respectively) (P <0.05). Similar reductions in buccal bone plate thickness and increases in palatal bone plate thickness of the anchored teeth occurred in both groups, whereas changes in buccal and palatal bone thicknesses of the left first premolars significantly differed between groups (P <0.001). No significant intergroup difference was found in terms of absolute dental tipping.

CONCLUSIONS

Both tooth-borne and tooth-bone-borne rapid expansion are effective methods for treating a narrow maxilla. However, the hyrax appliance resulted in greater expansion in the premolar region. On the other hand, the hybrid hyrax appliance did not cause changes in the bony support of the first premolars.

Anchorage onto deciduous teeth: effectiveness of early rapid maxillary expansion in increasing dental arch dimension and improving anterior crowding

Background

Anchorage onto permanent dentition is a common procedure in rapid maxillary expansion. However, replacing first permanent molars with the second deciduous molars seems to be an option to reduce some negative side effects during orthodontic treatment. The purpose of this study was to evaluate the dental effect of rapid maxillary expansion with anchorage exclusively onto deciduous teeth performed in the first period of transition.

Methods

Twenty patients with a lateral cross-bite treated exclusively by a Haas expander in early mixed dentition were retrospectively analyzed before treatment, at appliance removal, and at 21 months out of retention. The sagittal and transverse dimensions, together with the inter-canine arch and irregularity index, were digitally measured on scanned images of dental casts. The patients were compared with three balanced control groups (in total, 60 individuals) matched for gender. Two control groups had the same canine dental class as the treated group at T1, were in the inter-transitional period, and either had or lacked a lateral cross-bite. The last control group was comprised of adolescents in permanent dentition with a dental class I. The statistical analysis was performed by means of repeated-measures ANOVA for paired data and one-way ANOVA, the Kruskal-Wallis test, and the Mann-Whitney test for independent measures (α-level p < 0.05).

Results

At the end of follow-up (inter-transitional period of dentition), the dental arch dimensions of treated patients were similar to those of adolescents with a dental class I and significantly wider than those of patients with a lateral cross-bite. Also, the anterior irregularity index was lower among patients who had undergone expansion treatments than in all untreated study participants.

Conclusions

The Haas expander anchored to the deciduous teeth is effective in increasing the dental arch width in patients with a lateral cross-bite. The dimensions of the dental arch were modified earlier toward the values of the permanent dentition.

Multidisciplinary treatment in a patient with temporomandibular disorder

Adult patients with a multitude of problems require seamless integration of interdisciplinary protocols. This article presents a case of an adult female who reported with temporomandibular disorders, a crossbite and a Class III skeletal pattern. An interdisciplinary approach using expansion and surgery was used to treat the condition, followed by an esthetic/restorative protocol, achieving excellent results.

Computational fluid dynamics analysis of the upper airway after rapid maxillary expansion: a case report

Background

Assessment of the upper airway volume, morphology, and mechanics is of great importance for the orthodontic patient. We hypothesize that upper airway dimensions have significant effects on the dynamics of the airway flow and that both the dimensions and mechanics of the upper airway are greatly affected by orthodontic and orthopedic procedures such as rapid maxillary expansion (RME). The aim of the current study was to assess the effect of RME on the airway flow rate and pattern by comparing the fluid dynamics results of pre- and post-treatment finite element models.

Methods

Customized pre- and post-treatment computational fluid dynamics models of the patient’s upper airway were built for comparison based on three-dimensional computed tomogram. The inhalation process was simulated using a constant volume flow rate for both models, and the wall was set to be rigid and stationary. Laminar and turbulent analyses were applied.

Results

Comparisons between before and after RME airway volume measurements showed that increases were only detected in nasal cavity volume, nasopharynx volume, and the most constricted area of the airway. Pressure, velocity, and turbulent kinetic energy decreased after dental expansion for laminar and turbulent flow. Turbulent flow shows relatively larger velocity and pressure than laminar flow.

Conclusions

RME showed positive effects that may help understand the key reasons behind relieving the symptom of breathing disorders in this patient. Turbulence occurs at both nasal and oropharynx areas, and it showed relatively larger pressure and velocity compared to laminar flow.

Dental arch changes associated with rapid maxillary expansion: A retrospective model analysis study

Introduction:

Transverse deficiency of the maxilla is a common clinical problem in orthodontics and dentofacial orthopedics. Transverse maxillary deficiency, isolated or associated with other dentofacial deformities, results in esthetic and functional impairment giving rise to several clinical manifestations such as asymmetrical facial growth, positional and functional mandibular deviations, altered dentofacial esthetics, adverse periodontal responses, unstable dental tipping, and other functional problems. Orthopedic maxillary expansion is the preferred treatment approach to increase the maxillary transverse dimension in young patients by splitting of the mid palatal suture. This orthopedic procedure has lately been subject of renewed interest in orthodontic treatment mechanics because of its potential for increasing arch perimeter to alleviate crowding in the maxillary arch without adversely affecting facial profile. Hence, the present investigation was conducted to establish a correlation between transverse expansion and changes in the arch perimeter, arch width and arch length.

Methods:

For this purpose, 10 subjects (five males, five females) were selected who had been treated by rapid maxillary expansion (RME) using hyrax rapid palatal expander followed by fixed mechanotherapy (PEA). Pretreatment (T1), postexpansion (T2), and posttreatment (T3) dental models were compared for dental changes brought about by RME treatment and its stability at the end of fixed mechanotherapy. After model measurements were made, the changes between T1–T2, T2–T3 and T1–T3 were determined for each patient. The mean difference between T1–T2, T2–T3 and T1–T3 were compared to assess the effects of RME on dental arch measurements. Results are expressed as mean ± standard deviation and are compared by repeated measures analysis of variance followed by a post-hoc test. Arch perimeter changes are correlated with changes in arch widths at the canine, premolar and molar regions.

Results:

The intercanine arch width increased by 2.9 mm, inter first premolar width increased by 3.2 mm, inter second premolar width increased by 4.6 mm, intermolar width increased by 4.4 mm, arch perimeter increased by 3.2 mm, arch length decreased by 1.8 mm from pretreatment to posttreatment. There is a strong positive correlation of arch perimeter with intercanine width (r² = 0.99), interpremolar width (r² = 0.99) and intermolar width (r² = 0.98), indicating that there is a significant increase in arch perimeter with increase in arch width at the canine, premolars and molar regions.

Conclusion:

Findings of this study demonstrate that there was a significant increase in the intercanine, inter first premolar, inter second premolar intermolar arch width and arch perimeter from pretreatment to postexpansion, which was stable at the end of fixed mechanotherapy (PEA). There was a nonsignificant decrease in arch length from pretreatment to postexpansion that further decreased nonsignificantly from postexpansion to posttreatment.

Longitudinal stability of rapid and slow maxillary expansion

OBJECTIVE:

The aim of this retrospective study was to compare the longitudinal stability of two types of posterior crossbite correction: rapid maxillary expansion (RME) and slow maxillary expansion (SME).

METHODS:

Study casts of 90 adolescent patients were assessed for interdental width changes at three different periods: pretreatment (T₁), post-treatment (T₂) and at least, five years post-retention (T₃). Three groups of 30 patients were established according to the treatment received to correct posterior crossbite: Group A (RME), group B (SME) and group C (control- Edgewise therapy only). After crossbite correction, all patients received fixed edgewise orthodontic appliances. Paired t-tests and one-way ANOVA were used to identify significant intra and intergroup changes, respectively (P < 0.05).

RESULTS:

Except for intercanine distance, all widths increased in groups A and B from T₁ to T₂. In the long-term, the amount of relapse was not different for groups A and B, except for 3-3 widths which showed greater decrease in group A. However, the percentage of clinically relapsed cases of posterior crossbite was similar for rapid and slow maxillary expansion.

CONCLUSION:

Rapid and slow maxillary expansion showed similar stability in the long-term.

Comparison between rapid and slow palatal expansion: evaluation of selected periodontal indices

OBJECTIVES

The aim of this pilot study was to evaluate the periodontal effects during rapid palatal expansion (RPE) or slow palatal expansion (SPE) and to compare them by means of some clinical indices, in order to establish the possible differences and advantages of one of these treatments in periodontal terms.

METHODS

10 patients (aged 6 to 7 years; average age 6.3 years) were submitted to RPE treatment and other 10 patients (aged 6 to 8 years, average age 6.3 years) to SPE treatment. They were treated with the Haas expander. The selected clinical indices (plaque index, PI; papillary bleeding index, PBI; probing pocket depth, PPD) were collected three times during the treatment (t0, detected 7 days after the periodontal prophylaxis, at the beginning of the active orthodontic therapy; t1, detected during the active therapy; t2, detected after retention). All measurements were performed by the same examiner. The protocol was approved by the ethics committee.

RESULTS

The effects of the prophylaxis were excellent to control inflammation and dental plaque before the beginning of the orthodontic-orthopaedic treatment, as in both the two groups, the PI and the PBI values were equal to 0.In the group receiving slow expansion, the PPD remained unchanged from t0 to t1, while it significantly increased from t0 to t1 in the group of rapid expansion. At t2 the values of the two groups returned to be overlapping.

CONCLUSIONS

Both rapid and slow expansion treatments present potential irritation effect (increase of PI index and PBI index) on the periodontium, suggested by the significant increase of PI and PBI from t0 to t1 in both the two groups; therefore prophylaxis and periodic controls are very important. There are no long-term benefits that might be referred unequivocally to one of the two treatments in terms of periodontal consequences, as demonstrated by the lack of significant differences between the two groups at t2.

Effect of St John's wort on bone formation in the orthopaedically expanded premaxillary suture in rats: a histological study

BACKGROUND/OBJECTIVE

The aim of this study was to investigate the effect of systemic St John's wort (Hypericum perforatum) on bone formation in the expanded premaxillary suture in rats.

MATERIALS/METHODS

A total of 28 rats were randomly divided into four groups of equal numbers: control (C); only expansion (OE); St John's wort extract given only during the expansion and retention period (a total of 17 days; SJW group); and St John's wort extract given during the nursery phase before expansion (a period of 40 days), and during the expansion and retention periods (a total of 57 days; N + SJW group). After the 5 day expansion period was completed, the rats in the OE, SJW, and N + SJW groups underwent 12 days of mechanical retention, following which they were killed, and their premaxilla dissected and fixed. Histological examination was performed to determine the number of osteoclasts and capillaries, as well as the number of osteoblasts, inflammatory cell infiltration, and the amount of new bone formation.

RESULTS

Statistical analysis showed that the number of osteoclasts and capillaries, and the inflammatory cell infiltration, as well as new bone formation, were higher in the SJW and N + SJW groups than in the other groups. However, statistical analysis demonstrated that among these two groups, all parameters, with the exception of the number of capillaries, were higher in the N + SJW group than the SJW group.

CONCLUSIONS/IMPLICATIONS

Although more effective in long-term usage, systemic use of St John's wort hastens new bone regeneration at the premaxillary suture and may help prevent relapse after expansion.

Asymmetric rapid maxillary expansion in true unilateral crossbite malocclusion: a prospective controlled clinical study

OBJECTIVE

To investigate the short-term effects of the asymmetric rapid maxillary (ARME) appliance on the vertical, sagittal, and transverse planes in patients with true unilateral posterior crossbite.

MATERIALS AND METHODS

Subjects were divided into two groups. The treatment group was comprised of 21 patients with unilateral posterior crossbite (mean age  =  13.3 ± 2.1 years). Members of this group were treated with the ARME appliance. The control group was comprised of 17 patients with Angle Class I who were kept under observation (mean age  =  12.3 ± 0.8 years). Lateral and frontal cephalograms were taken before the expansion (T1), immediately after expansion (T2), and at postexpansion retention (T3) in the treatment group and at preobservation (T1) and postobservation (T2) in the control group. A total of 34 measurements were assessed on cephalograms. For statistical analysis, the Wilcoxon test and analysis of covariance were used.

RESULTS

The ARME appliance produced significant increases in nasal, maxillary base, upper arch, and lower arch dimensions (P < .01) and a clockwise rotation of the occlusal plane (P  =  .001).

CONCLUSION

The ARME appliance created asymmetric increments in the transversal dimensions of the nose, maxilla, and upper arch in the short term. Asymmetric expansion therapy for subjects with unilateral maxillary deficiency may provide satisfactory outcomes in adolescents, with the exception of mandibular arch expansion. The triangular pattern of expansion caused clockwise rotation of the mandible and the occlusal plane and produced significant alterations in the vertical facial dimensions, whereas it created no displacement in maxilla in the sagittal plane.

Density of the midpalatal suture after RME treatment - a retrospective comparative low-dose CT-study

Introduction

Rapid maxillary expansion (RME) is a common technique to improve the dental and skeletal transverse width in cases of constricted maxillary arches. Although retention after RME has been widely examined, there is still no clear statement about the minimal retention time in postpubertal patients and many practitioners have retention concepts varying between three and six months.

Methods

This retrospective study consisted of 14 patients who were either treated with a Haas-type RME (6 patients) or a Hybrid-RME (8 patients). The average age was 15.8 years (min. 13.5 years, max. 23.0 years).

Low-dose CT scans were taken initially before placement of the RME (T0), directly after maximal activation (T1) and (in six cases) also in retention after 6 months (T2). Using a 3D-software (“OnDemand3D”/Cybermed Inc.) in analogy to the method published by Franchi et al. (AJODO Volume 137/ Number 4) all values were measured twice at an interval of 1 month to assess the method error and the intraoperator reliability.

Statistical analysis was performed using SPSS 21 for Mac. Possible influences of the RME-type were assessed using the univariate ANOVA. Changes in the sutural density between the different points of time were examined using paired t-tests.

Results

The density of the suture decreased significantly after expansion (T0-T1) with both types of RME (p = 0.000). In the retention period there was a significant increase of the sutural density (p = 0.007) although it did not achieve the initial level (p = 0.002).

Conclusions

1. The midpalatal suture was opened in all analysed patients.

2. In postpubertal patients a retention time of six months does not allow sufficient reorganization of the suture.

3. Therefore, a retention period longer than six months seems to be beneficial to prevent relapses in postpubertal patients.

Midpalatal suture maturation: classification method for individual assessment before rapid maxillary expansion

INTRODUCTION

In this study, we present a novel classification method for individual assessment of midpalatal suture morphology.

METHODS

Cone-beam computed tomography images from 140 subjects (ages, 5.6-58.4 years) were examined to define the radiographic stages of midpalatal suture maturation. Five stages of maturation of the midpalatal suture were identified and defined: stage A, straight high-density sutural line, with no or little interdigitation; stage B, scalloped appearance of the high-density sutural line; stage C, 2 parallel, scalloped, high-density lines that were close to each other, separated in some areas by small low-density spaces; stage D, fusion completed in the palatine bone, with no evidence of a suture; and stage E, fusion anteriorly in the maxilla. Intraexaminer and interexaminer agreements were evaluated by weighted kappa tests.

RESULTS

Stages A and B typically were observed up to 13 years of age, whereas stage C was noted primarily from 11 to 17 years but occasionally in younger and older age groups. Fusion of the palatine (stage D) and maxillary (stage E) regions of the midpalatal suture was completed after 11 years only in girls. From 14 to 17 years, 3 of 13 (23%) boys showed fusion only in the palatine bone (stage D).

CONCLUSIONS

This new classification method has the potential to avoid the side effects of rapid maxillary expansion failure or unnecessary surgically assisted rapid maxillary expansion for late adolescents and young adults.

An assessment of the maxilla after rapid maxillary expansion using cone beam computed tomography in growing children

INTRODUCTION

With the advent of cone beam computed tomography (CBCT), it is now possible to quantitatively evaluate the effects of rapid maxillary expansion (RME) on the entire maxillary complex in growing patients.

OBJECTIVE

The purpose of this study is to use three-dimensional images to evaluate the displacement that occurs at the circummaxillary sutures (frontonasal, zygomaticomaxillary, intermaxillary, midpalatal, and transpalatal sutures) following rapid maxillary expansion in growing children.

METHODS

The CBCT scans of 25 consecutively treated RME patients (10 male, 15 female) with mean age of 12.3±2.6 years, were examined before expansion and immediately following the last activation of the expansion appliance.

RESULTS

Statistically significant (P<0.05) amounts of separation were found for the displacement of the bones of the frontonasal suture, the intermaxillary suture, the zygomaticomaxillary sutures, and the midpalatal suture. The change in angulation of the maxillary first molars due to RME was also statistically significant. There was no statistically significant displacement of the transpalatal suture.

CONCLUSIONS

Rapid maxillary expansion results in significant displacement of the bones of circummaxillary sutures in growing children.

Evaluation of mechanical properties of three different screws for rapid maxillary expansion

BACKGROUND

The aim of this in vitro study was the evaluation of the mechanical properties the screws for rapid maxillary expansion (RME).

METHODS

Three commercially available screws for RME were tested: Leone A2620; Dentaurum Hyrax; Forestadent Palatal Split Screw. All expansion screws were 10 mm in size. For the evaluation of mechanical properties, the screws for RME were adjusted using the same maxillary dental model. An Instron 3365 testing machine with a load cell of 5 kN recorded the forces released by the screws at different amounts of activation (1, 5, 10, 15 and 20 quarters of a turn). Each type of screw was tested 10 times. Comparisons between the forces released by the different types of screws at different amounts of activation were carried out by means of analysis of Kruskal-Wallis test with post-hoc test di Tukey (P < 0.05).

RESULTS

The results of this study showed that all 3 expansion devices were able to develop forces that could produce a separation of the palatine processes. The Hyrax and A2620 expanders developed force values over 20 kg and the Palatal Split screws about 16 kg. Both the A2620 and Hyrax expanders showed significantly greater amounts of forces at all the different amounts of activations with respect to the Palatal Split screw.

CONCLUSIONS

All tested devices showed the capability of developing expansion forces (16-20 kg) adequate for RME. The A2620 and Hyrax expanders showed a greater level of rigidity than the Palatal Split screw.

Three-dimensional computed tomographic analysis of changes to the external features of the nose after surgically assisted rapid maxillary expansion and orthodontic treatment: a prospective longitudinal study

INTRODUCTION

The aim of this prospective, longitudinal study was to evaluate changes to the external shape and form of the nose after surgically assisted rapid maxillary expansion and orthodontic treatment. The changes were registered using a 3-dimensional computer tomography technique, based on superimposition on the anterior base of the skull.

METHODS

The subjects comprised 35 patients (mean age, 19.7 years; range, 16.1-43.9 years). Low-dose, helical computerized tomography images were taken at treatment start and after orthodontic treatment, about 18 months postsurgery. The 3-dimensional models were registered and superimposed on the anterior cranial base.

RESULTS

There were in general significant widening and overall anterior and inferior displacement of the nasal soft tissues. The changes varied in size and direction. No correlation was found between the initial and final widths of the nose, or between the initial and final widths of the nostrils.

CONCLUSIONS

After surgically assisted rapid maxillary expansion, the most obvious changes to the external features of the nose were at the most lateral alar bases. The difference in lateral displacement profoundly influenced the perception of a more rounded nose. Patients with narrow and constrained nostrils can benefit from these changes. The 3-dimensional superimposition applied in this study is a reliable method, circumventing projection and measurement errors.

CBCT of skeletal changes following rapid maxillary expansion to increase arch-length with a development-dependent bonded or banded appliance

OBJECTIVE

To assess the three-dimensional (3D) skeletal response to a standardized 5 mm of rapid maxillary expansion (RME) in growing children (6-15 years) with maxillary width deficiency and crowding.

MATERIALS AND METHODS

A bonded appliance was used prior to the eruption of the maxillary first premolars (Mx4s), and a banded appliance was used thereafter. A consecutive sample of 89 patients (29 boys and 60 girls) from a large pediatric dentistry and orthodontics practice was divided into four groups: 1) 6-8 years old (n = 26), 2) 9-11 years old with unerupted Mx4s (n = 21), 3) 9-11 years with erupted Mx4s (n = 23), and 4) 12-15 years (n = 19). For all patients, the 3D evaluation of dental and skeletal effects was performed with cone-beam computed tomography (CBCT).

RESULTS

For both appliances in all patients, CBCT confirmed a triangular pattern of expansion in both the frontal and sagittal planes. Overall, both appliances produced significant maxillary expansion (>80% of the 5-mm activation), but older children showed a progressively more dental (less skeletal) response. Comparison of the two types of expanders in the crossover sample, children aged 9-11 years, showed that the bonded RME produced the most efficient skeletal expansion in the preadolescent sample. Increased maxillary width at the level of the zygomaticomaxillary suture was the best indicator for development of maxillary arch circumference.

CONCLUSION

Development-dependent appliances (bonded RPE before Mx4s erupt, and a banded device thereafter) provided optimal RME treatment for all children from age 6-15 years.

Magical NiTi expander

A 24-year-old male patient was referred to our department for expansion of the constricted maxillary arch as a presurgical procedure for the correction of congenital facial disfigurement. On examination, the patient had a convex profile, increased interlabial gap, tongue thrust, limited mouth opening, posterior crossbite, asymmetric 'V'-shaped maxillary arch with severe constriction, crowding of anterior teeth in the maxillary arch and a massive open bite. Radiographic investigations included orthopantomograph and occlusal radiographs. The patient photographs and models were analysed. On careful evaluation, the treatment for maxillary arch expansion was planned with a nickel titanium (NiTi) slow maxillary expander along with fixed mechanotherapy for alignment of teeth. An unexpectedly successful outcome was appreciated from the treatment. An emphasis should be laid on selecting and treating the case of constricted arches with a surgical or non-surgical approach, as expansion can be achieved orthodontically by using NiTi expanders.

Stress distribution analysis during an intermaxillary dysjunction: A 3-D FEM study of an adult human skull

Background:

With the increased interest in adult orthodontics, maxillary width problems in the nongrowing patients have been encountered with greater frequency. In view of the negative outlook for successful nonsurgical palatal expansion in adult patients it seemed appropriate to evaluate the biomechanical effects of nonsurgical rapid maxillary expansion (RME) in adults using the finite element method (FEM).

Objectives:

To evaluate the biomechanical effects of RME on the craniofacial complex as applied to three-dimensional (3D) model of an adult human skull using the finite element method.

Settings and Design:

The Department of Orthodontics and Dentofacial Orthopedics at Government Dental College and Hospital, Nagpur. The study was done on an analytical model developed from a dry human skull of an adult female with an approximate age of 20 years.

Materials and Methods:

A 3D finite element analysis of the craniofacial complex was developed from sequential computed tomography scan images. Known transversal (X) displacement with magnitudes of 1, 3, and 5 mm were applied and the displacement and Von-Mises stresses in different planes were studied on different nodes located at various structures of the craniofacial complex.

Results:

Transverse orthopedic forces not only produced an expansive force at the intermaxillary suture but also high forces on various structures of the craniofacial complex, particularly at the base of the sphenoid bone and frontal process of the zygomatic bone. Lateral bending of the free ends of the pterygoid plates were noted.

Conclusion:

RME must be used judiciously in adults because of its far-reaching effects involving heavy stresses being noted at the sphenoid bone, zygomatic bone, nasal bone, and their adjacent sutures.

Complicações após expansão de maxila cirurgicamente assistida

INTRODUÇÃO: O tratamento da deficiência transversal de maxila, em adultos, exige a expansão de maxila cirurgicamente assistida. Diversas técnicas cirúrgicas são conhecidas para a realização desse procedimento, porém estas relacionam-se com complicações. OBJETIVO: Avaliar a incidência de complicações associadas ao procedimento de expansão de maxila cirurgicamente assistida. MATERIAL E MÉTODO: Trinta e três indivíduos com deficiência transversal de maxila foram submetidos ao procedimento de expansão pela técnica da osteotomia Le Fort I subtotal com degrau no pilar zigomático-maxilar, disjunção ptérigo-maxilar e osteotomia da sutura intermaxilar. Durante os períodos trans e pós-operatório, as complicações relacionadas ao procedimento e as distâncias interdentais foram registradas. RESULTADO: Doze homens e 21 mulheres, com idade média de 24,64 anos, submeteram-se ao procedimento. As mensurações das distâncias interdentais evidenciaram aumento das mesmas entre os períodos pré-operatório e pós-operatório de 2 meses. As complicações prevalentes foram sinusite (6%) e deslocamento associado à inclinação dental (6%). CONCLUSÃO: A expansão de maxila cirurgicamente assistida é um procedimento eficaz e de baixa morbidade para o tratamento da deficiência transversal de maxila em indivíduos adultos.

Evaluation of immediate soft tissue changes after rapid maxillary expansion

OBJECTIVE: To evaluate immediate soft tissue changes following rapid maxillary expansion (RME) in growing patients, using cone beam computed tomography (CBCT). METHODS: Twenty-three consecutive patients (10 male, 13 female) treated by RME were selected. Patients were scanned using CBCT prior to placement of the rapid maxillary expander (T0), then immediately following full activation of the appliance (T1). Defined landmarks were then located on the pre- and post-treatment orientated images. Change in landmark position from pre- to post-treatment was then measured. In addition to landmarks, 10 direct measures were made to determine distance change without regard to direction to measure soft tissue change of the lips. RESULTS: Significant transverse expansion was measured on most soft tissue landmark locations. All the measures made showed significant change in the lip position with a lengthening of the vertical dimension of the upper lip, and a generalized decrease of anterior-posterior thickness of both the upper and lower lips. CONCLUSIONS: Significant changes in the soft tissue do occur with RME treatment. There is a transverse widening of the midface, and a thinning of the lips.

Three-dimensional computed tomography analysis of airway volume changes after rapid maxillary expansion

INTRODUCTION

In this retrospective study with 3-dimensional computed tomography, we evaluated airway volume, soft-palate area, and soft-tissue thickness changes before and after rapid maxillary expansion in adolescents. Another purpose was to determine whether rapid maxillary expansion caused changes in the palatal and mandibular planes and facial height.

METHODS

The sample comprised 20 patients who were treated with rapid maxillary expansion. Spiral tomographs were taken before and 3 months after treatment. Reliability studies were performed, and then volumetric, soft-palate area, soft-tissue thickness, and cephalometric parameters were compared on the tomographs. Intraclass correlations were performed on the reliability measurements. Before and after rapid maxillary expansion measurements were compared by using Wilcoxon signed rank tests. Spearman correlation coefficients were used to evaluate the associations among the airway volume, soft-palate area, soft-tissue thickness, and cephalometric measurements. Significance was accepted at P ≤0.05 for all tests.

RESULTS

Intraclass correlation coefficients were ≥0.90 for all reliability measures. Significant increases from before to after rapid maxillary expansion were found in nasal cavity and nasopharynx volumes, and for the measurements of MP-SN, S-PNS, N-ANS, ANS-Me, and N-Me. Significant positive correlations existed between changes in PP-SN and N-ANS, and ANS-Me and N-Me.

CONCLUSIONS

Rapid maxillary expansion causes significant increases in nasal cavity volume, nasopharynx volume, anterior and posterior facial heights, and palatal and mandibular planes.

Does hyrax expansion therapy affect maxillary sinus volume? A cone-beam computed tomography report

Purpose

The aim of this study was to investigate the initial effects of maxillary expansion therapy with Hyrax appliance and to evaluate the related changes in maxillary sinus volume.

Materials and Methods

Thirty patients (20 females, 10 males; 13.8 years) requiring maxillary expansion therapy, as part of their comprehensive orthodontic treatment, were examined. Each patient had cone-beam computed tomography (CBCT) images taken before (T1) and after (T2) maxillary expansion therapy with a banded Hyrax appliance. Multiplanar slices were used to measure linear dimensions and palatal vault angle. Volumetric analysis was used to measure maxillary sinus volumes. Student t tests were used to compare the pre- and post-treatment measurements. Additionally, differences between two age groups were compared with Mann-Whitney U test. The level of significance was set at p=0.05.

Results

Comparison of pre-treatment to post-treatment variables revealed significant changes in the transverse dimension related to both maxillary skeletal and dental structures and palatal vault angle, resulting in a widened palatal vault (p<0.05). Hard palate showed no significant movement in the vertical and anteroposterior planes. Nasal cavity width increased on a mean value of 0.93mm(SD=0.23, p<0.05). Maxillary sinus volume remained virtually stable. No significant age differences were observed in the sample.

Conclusion

Hyrax expansion therapy did not have a significant impact on maxillary sinus volume.

Comparison of the effects of rapid maxillary expansion and surgically assisted rapid maxillary expansion in the sagittal, vertical, and transverse planes

OBJECTIVE

The aim of this study was to evaluate and compare the effects of rapid maxillary expansion (RME) and surgically assisted RME (SARME) in the sagittal, vertical, and transverse planes.

STUDY DESIGN

Orthodontic records of 28 patients were selected retrospectively and divided into two treatment groups. Group 1 comprised 14 patients (4 boys, 10 girls, mean age 14.2 ± 0.74 years) who had been treated with RME. Group 2 comprised 14 patients (4 boys, 10 girls, mean age 19.6 ± 2.73 years) who had been treated with SARME. Measurements were performed on lateral and posteroanterior cephalograms and dental casts obtained before (T0) and after (T1) expansion.

RESULTS

Statistically significant differences were found in soft tissue convexity angle, anterior face height, and upper nasal width in group 1, and in U1-NA length and posterior face height measurements in group 2 (P<.05). In both groups significant increases were found in interpremolar, intermolar, maxillary, and lower nasal widths and in anterior lower face height (P<.01). Statistically significant intergroup differences were found in the ANB angle (P<.05) and maxillary intercanine (P<.01) measurements.

CONCLUSION

With both RME and SARME, successful expansion of maxillary dentoalveolar structures and nasal cavity and palatal widening were achieved. Sagittal plane effects of SARME were similar to those of RME on dental skeletal and airway measurements.

Nasal cavity size, airway resistance, and subjective sensation after surgically assisted rapid maxillary expansion: a prospective longitudinal study

INTRODUCTION

The aims of this study were to measure changes in nasal minimum cross-sectional area and nasal airway resistance after surgically assisted rapid maxillary expansion and to explore a possible correlation with the subjective sensation of nasal obstruction.

METHODS

Minimum cross-sectional area and nasal airway resistance were measured in 39 consecutive patients treated with surgically assisted rapid maxillary expansion. Subjective nasal obstruction was assessed by a questionnaire at pretreatment and at 3 and 18 months postoperatively.

RESULTS

Subjective nasal obstruction had improved significantly by 3 months postoperatively. Minimum cross-sectional area increased and nasal airway resistance decreased. No correlations were found. In subjects with pretreatment subjective nasal obstruction and initially narrow anterior minimum cross-sectional area, there was a significant correlation between a moderate increase in anterior minimum cross-sectional area and improvement in perceived nasal obstruction. Eighteen months postoperatively, no changes were found from pretreatment values for subjective nasal obstruction, minimal cross-sectional area, or nasal airway resistance, and there were no correlations. Subjects with a sensation of nasal obstruction at treatment start reported a lasting significant subjective improvement.

CONCLUSIONS

The postoperative effects of surgically assisted rapid maxillary expansion did not persist in the long term. No correlation was found between objective and subjective findings. Subjects with pretreatment nasal obstruction, however, reported a lasting sensation of improved nasal function after surgically assisted rapid maxillary expansion.

Immediate effects of rapid maxillary expansion with Haas-type and hyrax-type expanders: a randomized clinical trial

INTRODUCTION

The purposes of this study were to evaluate and compare the immediate effects of rapid maxillary expansion (RME) in the transverse plane with Haas-type and hyrax-type expanders by using cone-beam computed tomography.

METHODS

A sample of 33 subjects (mean age, 10.7 years; range, 7.2-14.5 years) with transverse maxillary deficiency were randomly divided into 2 groups: Haas (n = 18) and hyrax (n = 15). All patients had RME with an initial activation of 4 quarter turns followed by 2 quarter turns per day until the expansion reached 8 mm. Cone-beam computed tomography scans were taken before expansion and at the end of the RME phase. Maxillary transversal measurements were compared by using the mixed analysis of variance (ANOVA) model and the Tukey-Kramer method.

RESULTS

RME increased all maxillary transverse dimensions (P <0.0001). There was less expansion at skeletal than dental levels. The hyrax group had greater statistically significant orthopedic effects and less tipping tendency of the maxillary first molars compared with the Haas group.

CONCLUSIONS

Both appliances were efficient in correcting a transverse maxillary deficiency. The pure skeletal expansion was greater than actual dental expansion. The hyrax-type expander produced greater orthopedic effects than did the Haas-type expander, but this effect was less than 0.5 mm per side and might not be clinically significant.

Análise comparativa da expansão maxilar com três marcas de parafusos com limitador posterior: ensaio laboratorial em Typodont

INTRODUÇÃO: nos pacientes com fissura labiopalatina, observa-se, usualmente, uma severa atresia da maxila, especialmente na região anterior da arcada, cujo tratamento envolve expansão maxilar. OBJETIVO: o propósito desse estudo foi avaliar o padrão de expansão de três marcas de parafusos com limitador posterior na correção da deficiência transversa. MÉTODOS: foram realizadas 18 expansões em Typodont, com 6 simulações para cada grupo: G1 - parafuso Dentaurum®, G2 - parafuso Leone®, e G3 - parafuso Morelli®. Foram realizadas, para cada ensaio, 13 ativações de 2/4 de volta, totalizando 5,2mm de abertura do parafuso. Definiram-se os momentos das medições em inicial (T1), metade das ativações (T2) e final (T3). Com o auxílio de um paquímetro, foram medidas as seguintes distâncias: interprimeiros pré-molares (IP1), interssegundos pré-molares (IP2), intermolares (IM) e comprimento da arcada (CA). Os dados obtidos foram submetidos aos testes de Kolmogorov-Smirnov, de Tukey, de Friedman e ANOVA. RESULTADOS: observou-se que todos os grupos apresentaram um padrão de abertura em forma de "V" com maior expansão na região anterior da arcada, sendo mais expressivo no grupo G3 (29,58% em IP1 e 9,73% em IM). O aumento na medida CA foi semelhante para os grupos G1 e G3 (+12,65% e +12,13%, respectivamente), com menor valor para o G2 (+8,23%). CONCLUSÕES: concluiu-se que todos os parafusos com limitador posterior utilizados nesse estudo podem ser empregados no tratamento da deficiência transversa da arcada. Entretanto, o parafuso Morelli® apresentou maior abertura na região anterior em relação à posterior, característica importante no tratamento de pacientes com fissura labiopalatina. Recomenda-se a realização de estudos clínicos para confirmação desses achados.

Developing skeletal Class III malocclusion treated nonsurgically with a combination of a protraction facemask and a multiloop edgewise archwire

For a girl, aged 12 years 3 months, with a skeletal Class III malocclusion, negative overjet, severe maxillary crowding, and hyperdivergent pattern, orthognathic surgery combined with orthodontic treatment is often the treatment of choice, because it can greatly improve the patient's facial profile and ensure the long-term stability of the results. However, because of high risks and treatment expenses, patients sometimes refuse to have surgery. We report a nonsurgical combination therapy including facemask and multiloop edgewise archwires and the outcome for a patient with a developing skeletal Class III malocclusion and a long anterior facial height. Treatment included advancement of the maxilla by orthopedic means and counterclockwise rotation of the mandibular occlusal plane by the orthodontic dentoalveolar compensation of distal en-masse movement of the mandibular dentition.

Evaluation of the mesio-buccal gingival sulcus depth of the upper central incisors in patients submitted to surgically assisted maxillary expansion

PROPOSITION: The aim of this study was to evaluate the modifications that occurred in the mesio-buccal gingival sulcus depth of the upper central incisors during a 3-year post-operative period.

METHODS

The mesio-buccal gingival sulcus depth of the upper central incisors of patients submitted to surgically assisted maxillary expansion (SAME) was measured by using a periodontal probe, both in the pre-operative period and in the 2-, 6-, 24-, and 36-month post-operative period. The results were submitted for statistical analysis by using ANOVA and Tukey's test with level of significance of 5%.

RESULTS

The mesial gingival sulcus depths were statistically significant (P < 0.05) in the comparison between the pre-operative and both the 2- and 6-month post-operative periods, between the 2- and 24-month post-operative periods, and between the 2- and 36-month periods.

CONCLUSION

The gingival sulcus depths increased during the initial post-operative periods. The SAME procedure increased the gingival sulcus depth of the upper central incisors.

Ossification of the midpalatal suture after surgically assisted rapid maxillary expansion

The purpose of this study was to evaluate ossification of the midpalatal suture in adult patients immediately after surgically assisted rapid maxillary expansion (SARME) until 120 days post-surgery. The sample comprised 126 standardized occlusal radiographs of 21 adults (14 females and 7 males; mean age: 25.33 years) taken pre-expansion (T1), immediately after expansion (T2), and post-expansion (30, 60, 90, and 120 days of retention, respectively: T3, T4, T5, and T6) who had undergone SARME. The radiographs were digitized and the images were analysed and compared in relation to the morphology and radiopacity at the different treatment stages, especially concerning the characteristics of the midpalatal suture. Data were statistically analysed using analysis of variance and Tukey's test. The results demonstrated that from T2 to T6, the mean optical density (OD) increased. However, these values were not similar to those observed at T1. A retention period of 120 days was not sufficient for the re-establishment of OD and complete ossification within the suture in the evaluated patients.