Does rapid maxillary expansion increase nasopharyngeal space and improve nasal airway resistance?

Medium-term effects of rapid maxillary expansion on nasal cavity and pharyngeal airway volumes considering age as a factor: A retrospective study

OBJECTIVES

The medium-term effects of rapid maxillary expansion (RME) on nasal cavity (NC) and upper airway (UA) dimensions based on chronological age are still unclear. This retrospective study evaluated the medium-term changes occurring in the NC and pharyngeal airways (PA) after RME in two distinct age-based cohorts of patients.

METHODS

This retrospective study included 48 subjects who underwent RME grouped in two cohorts: a 6-9-year-old group (EEG group: early expansion group - 25 subjects) and an 11-14-year-old group (LEG group: late expansion group - 23 subjects). NC and PA volumes were analyzed from CBCT imaging segmentation before RME (T0) and twelve months after RME (T1). The amount of maxillary expansion (PW) and minimal cross-sectional area (CSmin) were also considered.

RESULTS

All PAs' volumetric sub-regions, CSmin and PW showed a significant volumetric increment (p < 0.05). Inter-group comparisons showed significant differences (p < 0.05) for nasopharynx and CSmin parameters (p < 0.05), while no significant changes were recorded for the other UA's sub-regions and PW (p > 0.05). According to a deviation analysis, part of the UA increase (more marked for the nasopharynx area) may have occurred due to reduced adenotonsillar tissues, which were larger in the EEG group.

CONCLUSIONS

Twelve months after treatment, clinicians should not expect changes in the UAs dimensions to be solely related to treatment effects of RME; instead, normal craniofacial growth changes and spontaneous regression of the adenotonsillar tissue could represent the most significant factors influencing UAs changes.

CLINICAL SIGNIFICANCE

From the clinical perspective, the results of the present study encourage caution when considering the therapeutic effects of RME on airways dimensions.

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.

Rapid Maxillary Expansion (RME): An Otolaryngologic Perspective

Background. To evaluate the possible effects of Rapid Maxillary Expansion (RME), such as nasal breathing problems, middle ear function, Obstructive Sleep Apnea (OSA) in the otolaryngology field. RME has already been introduced in orthodontics to expand the maxilla of young patients affected by transversal maxillary constriction. Methods. A literature search was performed using different databases (Medline/PubMed, EMBASE, and CINAHL), from May 2005 to November 2021, according to the PRISMA guidelines. Results. The application of RME in children has shown good results on nasal function, reducing nasal resistances, independently from a previous adenotonsillectomy. These results are not only related to the increasing of nasal transverse diameters and volume, but also to the stiffening of airway muscles, enabling the nasal filtrum function and avoiding mouth opening, thereby decreasing respiratory infections. Positive effects have also been reported for the treatment of conductive hearing loss and of OSA, with the reduction of Apnea Hypopnea Index (AHI), possibly due to (i) an increased pharyngeal dimensions, (ii) a new tongue posture, and (iii) reduced nasal respiratory problems. Conclusions. Otolaryngologists should be aware of the indications and benefits of the RME treatment, considering its possible multiple beneficial effects.

Three-dimensional image study of accelerated maxillary expansion in oral breathing kids

OBJECTIVE

To evaluate, by a three-dimensional study, the volumetric and integumentary effects of rapid maxillary expansion on the nose, in mouth breathing kids with maxillary hypoplasia, in the short term, assessing the possible interference of gender, growth and age on the results achieved.

METHODS

120 mouth breathing patients with maxilla hypoplasia were divided into an Experimental Group treated by rapid maxillary expansion (n = 104, 62 males and 42 females, mean age 10.1 years, SD = 2.10, ranging from 5.1 to 13.9 years); and Control Group, constituted by 16 patients (9 males and 7 females, mean age 9.3 years, SD = 2.1 years, ranging from 6.1 to 13.2 years). Patients in the experimental group underwent multislice computed tomography examinations at two different times: (T1) pre-expansion and (T2) post-expansion. The control group was submitted to the same tests at the same time intervals. Six soft tissue variables of the nose were studied, besides the volume and area of the nasal cavity, and the measurement and comparison of data between T1 and T2 were performed using the Dolphin Imaging 11.7 Premium software.

RESULTS

The experimental group showed significant mean increases in all soft tissue variables studied (p < 0.005), yet there were no significant changes in the control group. In the comparison between groups, only inclination of the nasal dorsum did not present any significant change.

CONCLUSION

Rapid maxillary expansion may alter the nasal shape and physiology, by anatomical changes in the nose soft tissues, making it an important aid in the treatment of mouth breathing in childhood.

LEVEL OF EVIDENCE

The soft tissues of the nose play an important role in nasal shape and physiology and facial esthetics, and since they are directly related to the nasal valves, they are fundamental for maintenance and stability of the nasal breathing pattern.

Opening up on airways: the purported effect of nasorespiratory obstruction on dentofacial growth

Nasorespiratory obstruction has been purported to influence dentofacial growth adversely. This has sparked considerable debate for decades with a resurgence in interest in 'airway friendly orthodontics' among both general and specialist dental practitioners. This critical review aims to evaluate the current literature relating to two questions: does nasorespiratory obstruction alter dentofacial growth, and does early intervention targeted at alleviating nasorespiratory obstruction improve dentofacial growth? The strength of association between nasorespiratory obstruction, mouth breathing and a long face is weak. The common methodological flaws in research include unblinded and cross-sectional study designs, a lack of adequate controls, inadequate follow-up, subjective assessments and inadequate statistical power. Vertical dentofacial growth has a strong genetic influence, which implies a relatively minor contribution of environmental factors including airway obstruction. The current evidence does not support recommending procedures, such as adenotonsillectomy and maxillary expansion, with the singular aim of negating a hyperdivergent (vertical) dentofacial growth pattern. In light of low-quality evidence, both the World Health Organization guidelines and ethical principles dictate that greater emphasis is placed on avoiding harm and wastage of resources over alternative options. These findings call for quality improvement in undergraduate and postgraduate curricula and continuing professional development for health professionals.

Short-term and long-term effects of rapid maxillary expansion on the nasal soft and hard tissue

OBJECTIVES

To evaluate nasal soft and hard tissue changes immediately post-rapid maxillary expansion (RME) and to assess the stability of these changes using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 35 treatment group (TG) patients (18 girls, 17 boys; 9.39 ± 1.4) had a pre-RME CBCT and a post-RME CBCT approximately 66 days after expansion, and 25 patients had a follow-up CBCT 2.84 years later. A total of 28 control group (CG; no RME) patients (16 girls, 12 boys; 8.81 ± 1.6) had an initial CBCT and a CBCT an average of 2.25 years later. Soft and hard tissue nasal landmarks were measured in transverse, sagittal, and coronal planes of space on CBCT scans. Differences within the same group were evaluated by paired t-tests or Wilcoxon signed-rank tests. Long-term comparisons between TG and CG were evaluated by independent-sample t-tests or Wilcoxon rank-sum tests.

RESULTS

Immediately post-RME, there were statistically significant mean increases of 1.6 mm of alar base width, 1.77 mm of pyriform height, and 3.57 mm of pyriform width (P < .05). CG showed the significant increases over 2.25 years (P < .001). Compared with CG, the long-term evaluation of TG demonstrated only pyriform height and pyriform width showed a statistically significant difference (P < .01).

CONCLUSIONS

Although RME produced some significant increase on the nasal soft tissue immediately after expansion, it regressed to the mean of normal growth and development over time. However, long-term evaluation of TG compared with CG showed only pyriform height and pyriform width to be affected by RME.

The role of pediatric maxillary expansion on nasal breathing. A systematic review and metanalysis

OBJECTIVE

A reduced transversal dimension of the maxilla leads to narrower nasal cavities, which may reduce airflow to the lungs. Maxillary expansion widens nasal floor. However, there is huge controversy regarding whether this increase does actually lead to increased airflow. In this systematic review and meta-analysis we aim to resolve this question by evaluating studies that have undertaken rhinomanometric measurements.

REVIEW METHODS

Pubmed (Medline), the Cochrane Library, EMBASE and Trip Database were checked by two authors. Two authors extracted the data. Main outcome was expressed as the difference between resistance before and after treatment and the 95% confidence interval.

RESULTS

30 studies were selected for full text reading. A total of 12 studies (301 patients) met the inclusion criteria. All selected articles found reduced resistance after palatal expansion. The data pooled in the meta-analysis reveals a statistically significant difference of 0.12 Pa s/cm³ mean reduction after palatal expansion (CI 95% 0.06, 0.18) for nine uncontrolled studies. Regarding nasal airflow, the pooled data show a statistically significant difference of 29.9 cm³/s increase after palatal expansion (CI 95% 9.17, 50.64).

CONCLUSION

According to the available evidence, palatal expansion in pediatric patients decreases nasal resistance and increases nasal flow.

Volumetric Changes in the Upper Airways after Rapid and Slow Maxillary Expansion in Growing Patients: A Case-Control Study

The aim is to evaluate changes in the volume of the upper airways before and after slow maxillary expansion (SME) obtained with the flexible properties of a nickel titanium leaf spring and rapid maxillary expansion (RME) with a conventional Hyrax appliance in growing patients. The records of 1200 orthodontic patients undergoing maxillary expansion from 2018 to 2019 were analyzed; among these pre and post treatment CBCT scans of 22 patients (mean age 8.2 ± 0.6 years old) treated by SME were compared with those obtained from 22 patients (mean age 8.1 ± 0.7 years old) treated by RME banded on the second primary molars. The following inclusion criteria were used: Maxillary transverse constriction, good general health, and no previous orthodontic treatment. Volumes of nasal cavity (NCavV), nasopharynx (NsPxV), and right and left maxillary sinuses (MSV) were calculated with ITK-SNAP. Shapiro–Wilk test revealed a normal distribution of data in each group. Paired t-test was used for within-group comparisons and independent t-test for between-group comparisons. Statistically significant increases occurred in NCavV, NsPxV, and MSVs after treatment with both appliances. No statistically significant difference between the appliances occurred in NCavV, NsPxV, and MSVs. Method error was considered negligible (mean intra-operator and inter-operator intraclass correlation coefficient were 0.928 and 0.911, respectively). It appears that both appliances produce similar effects on the different segments of the upper airway tract.

Effects of symmetric and asymmetric rapid maxillary expansion treatments on pharyngeal airway and sinus volume

OBJECTIVE

To evaluate pharyngeal airway and maxillary sinus volumes following symmetric rapid maxillary expansion (RME) and asymmetric rapid maxillary expansion (ARME) treatment using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The study consisted of 60 patients presenting to the orthodontics clinic with an indication that they required symmetric or asymmetric rapid maxillary expansion treatment. Individuals were included if they were aged 12-15 years and had symmetric (RME group; 14 girls, 16 boys) or asymmetric (ARME group; 16 girls, 14 boys) maxillary deficiency. Maxillary sinus volume (mm3) and pharyngeal airway volume (upper, lower, and total; mm3) were evaluated using CBCT records. The parameters were compared before treatment (T1) and after 3 months in retention (T2).

RESULTS

All measurements at T2 were increased significantly compared with T1 in the RME group (P < .05). In the ARME group, changes in the lower pharyngeal airway and the nonaffected maxillary sinus volumes (non-affected side of maxillary sinus volumes) were not significant; however, the other measurements increased significantly from T1 to T2 (P < .05). Intergroup comparisons revealed that total pharyngeal airway volume and total maxillary sinus volume changes were significantly greater in the RME group.

CONCLUSIONS

Pharyngeal airway and maxillary sinus volumes increased with both RME and ARME treatment. Both were found to be effective for treating transverse maxillary deficiency.

[Orthodontic management of obstructive sleep-disordered respiratory disorders]

Through his/her knowledge of cranio-facial growth, the orthodontist plays a leading role within the multidisciplinary team that tracks and treats sleep-disordered breathing (SDB) in children. Correction of craniofacial risk factors (maxillary deficiency and retrognathia) is commonly used by practitioners alongside orthodontic treatment such as OMA and RME in the optimal conditions afforded by childhood growth. Myofunctional therapies are performed to restore correct stomatognathic function and play a central role in the management of SDB in children. The orthodontist is therefore a key player in the medical treatment chain of these children.

Parents’ Perceptions of Breathing Pattern Changes, Sleep Quality, and Fatigue in Children after Rapid Maxillary Expansion: A Survey and Case Series Study

Background:

Rapid Maxillary Expansion (RME) aims to re-establish balance between the widths of the jaws. It is mainly utilized to treat skeletal and dental manifestations associated with transverse maxillary constriction and to improve facial structures involving the nasal cavity.

Objectives:

This study aimed to investigate parents’ perceptions of breathing pattern changes after their child had undergone RME and the associated effects on sleep quality and fatigue. We also evaluated nasal cavity changes in three dimensions in six randomly selected patients.

Methods:

Ninety-one children aged 5-13 years with transverse maxillary deficiency and no major systemic diseases or syndromes were recruited. Their parents completed a 16-item questionnaire pre-treatment and 6 months post-treatment. The questionnaire included items pertaining to changes in (1) sleep apnea and breathing patterns, (2) sleep quality and fatigue, and (3) behavior. The cone beam computed tomography scans from six randomly chosen patients were also subjected to stereolithographic reconstruction of the midface pre-RME and post-RME.

Results:

Responses in the three domains exhibited good reliability. Significant improvements were observed in 59% of the items post vs. pre-RME. The overall rates of dry mouth in the morning, snoring half of the time, and heavy breathing decreased by ≥30%. The percentage change in headache in the morning, snoring loudly, and snoring half of the time was >80%. In addition, in the series of six cases, the mean difference in nasal cavity area post-RME was 4.1 mm2.

Conclusion:

Post-RME, parents perceived that their children exhibited improved behavior and were less fatigued during the day. Enhanced sleep quality and breathing patterns were also observed, but to a lesser extent.

Effects of non-surgical rapid maxillary expansion on nasal structures and breathing: A systematic review

OBJECTIVE

This systematic review aims to determine the effects of non-surgical rapid maxillary expansion (RME) on breathing and upper airway structures.

MATERIALS AND METHODS

An electronic search of the scientific literature from January 2005 to June 2016 was done using Web of Science, Dentistry & Oral Sciences Source and PubMed databases. A combination of search terms "rapid maxillary expansion", "nasal", "airway" and "breathing" were used. Studies that involved surgical or combined RME-surgical treatments and patients with craniofacial anomalies were excluded.

RESULTS

The initial screening yielded a total of 183 articles. After evaluation of the titles, abstracts and accessing the full text, a total of 20 articles fulfilled both inclusion/exclusion criteria and possessed adequate evidence to be incorporated into this review.

CONCLUSIONS

Non-surgical RME was found to improve breathing, increase nasal cavity geometry and decrease nasal airway resistance in children and adolescents.

Nasal function before and after rapid maxillary expansion in children: A randomized, prospective, controlled study

OBJECTIVES

Children can well detect and respond to odours in order to have information about food and environment. Rapid Maxillary Expansion seems to improve dental and skeletal crossbite and increase nasal patency correcting oral respiration in children. A previous pilot study suggested that Rapid Maxillary Expansion may lead to improved N-Butanol olfactory thresholds, and peak nasal inspiratory flow values (PNIF). The aim of the present study was to prospectively evaluate olfactory threshold, nasal flows and nasal resistances in children aged from 6 to 11 years before and after Rapid Maxillary Expansion, comparing treated children with a control group of similar age, growth stage (prepubertal) and transversal skeletal deficiency.

METHODS

N-butanol olfactory thresholds, anterior active rhinomanometry (AAR) and PNIF were measured in 11 children (6-11 years) before (T0), immediately and 6 months after Rapid Maxillary Expansion application (T1 and T2 respectively), and in a control group of 11 children (6-11 years) whose members remained under observation for the period of the study.

RESULTS

Considering the study group, PNIF values improved at T1 respect to the T0 values (p = 0.003), while T2 values were significantly higher than T0 ones (p = 0.0002). N-Butanol Olfactory Threshold significantly improved at each control (p = 0.01, p = 0,01 and p = 0.0003, for T1 vs T0, T2 vs T1, T2 vs T0 respectively). No differences on AAR values were found during the six months follow-up in this group. Considering the control group, no significant differences were found for any of the considered variables during the time of the study. Comparing the two groups, there was a significant increase of PNIF values in the study group compared to the control group (p = 0.003) at T1, which was even more evident six months after Rapid Maxillary Expansion (p = 0.0005). This improvement was not shown by AAR values. N-Butanol Olfactory Threshold showed a significant improvement at T2 respect to T1 (p = 0.002) and T0 (p = 0.0005).

CONCLUSION

Rapid Maxillary Expansion seems to significantly improve the respiratory capacity of treated patients, at least in terms of PNIF, and their olfactory function, measured by N-Butanol Olfactory Threshold Test. Further studies should be performed to evaluate if also changes in nasal resistances, measured by AAR, could occur, maybe considering a larger group of subjects and possibly using 4-phase rhinomanometry in order to evaluate the effective resistances during the entire breath.

Pharyngeal airway changes following maxillary expansion or protraction: A meta-analysis

The aim of this meta-analysis was to investigate the changes in airway dimensions after rapid maxillary expansion (RME) and facemask (FM) protraction. Using PubMed, Medline, ScienceDirect and Web of Science, only controlled clinical trials, published up to November 2016, with RME and/or FM as keywords that had ≥6 months follow-up period were included in this meta-analysis. The changes in pharyngeal airway dimension in both two-dimensional and three-dimensional images were included in the analysis. Nine studies met the criteria. There are statically significant changes in upper airway and nasal passage airway in the intervention groups as compared to the control groups, assessed in two-dimensional and three-dimensional images. However , in the lower airway and the airway below the palatal plane, no statistically significant changes are seen in 2D and 3D images. RME/FM treatments might increase the upper airway space in children and young adolescents. However, more RCTs and long-term cohort studies are needed to further clarify the effects on pharyngeal airway changes.

Retention and relapse in clinical practice

Maintaining teeth in their corrected positions following orthodontic treatment can be extremely challenging. Teeth have a tendency to move back towards the original malocclusion as a result of periodontal, gingival, occlusal and growth related factors. However, tooth movement can also occur as a result of normal age changes. Because orthodontics is unable to predict which patients are at risk of relapse, those which will remain stable and the extent of relapse that will occur in the long-term, clinicians need to treat all patients as if they have a high potential to relapse. To reduce this risk, long term retention is advocated. This can be a significant commitment for patients, and so retention and the potential for relapse must form a key part of the informed consent process prior to orthodontic treatment. It is vital that patients are made fully aware of their responsibilities in committing to wear retainers as prescribed in order to reduce the chance of relapse. If patients are unable or unwilling to comply as prescribed, they must be prepared to accept that there will be tooth positional changes following treatment. There is currently insufficient high quality evidence regarding the best type of retention or retention regimen, and so each clinician's approach will be affected by their personal, clinical experience and expertise, and guided by their patients' expectations and circumstances.

Does pterygomaxillary disjunction in surgically assisted rapid maxillary expansion influence upper airway volume? A prospective study using Dolphin Imaging 3D

Surgically assisted rapid maxillary expansion has been used for the treatment of transverse maxillary deficiency. This prospective study aimed to evaluate the effect of this surgery (with or without pterygomaxillary disjunction) on the upper airway volume. The patients were randomly divided into two groups: without pterygomaxillary disjunction (-PD) and with pterygomaxillary disjunction (+PD). Eleven patients per group were estimated to obtain a representative sample (90% of power and 95% of confidence level). Volumetric images of cone beam computed tomography scans were obtained preoperatively, immediately after Hyrax screw stabilization and 6 months after Hyrax screw stabilization. Volumetric measurements of the nasal cavity, maxillary sinuses, nasopharynx, and oropharynx, and of the minimum oropharynx cross-sectional area were obtained using Dolphin 3D Imaging Software. The final sample consisted of 25 adult individuals (+PD group, n=12; -PD group, n=13). In the +PD group, we observed a statistically significant increase immediately after Hyrax screw stabilization for the nasopharynx volume (P=0.003), oropharynx volume (P=0.007) and oropharynx cross-sectional area (P=0.001). Pterygomaxillary disjunction resulted in a significant (P <0.05) increase in volumetric measurements of the nasopharynx and minimum oropharynx cross-sectional area 6 months after the expander device stabilization.

Immediate impact of rapid maxillary expansion on upper airway dimensions and on the quality of life of mouth breathers

OBJECTIVE:

To assess short-term tomographic changes in the upper airway dimensions and quality of life of mouth breathers after rapid maxillary expansion (RME).

METHODS:

A total of 25 mouth breathers with maxillary atresia and a mean age of 10.5 years old were assessed by means of cone-beam computed tomography (CBCT) and a standardized quality of life questionnaire answered by patients' parents/legal guardians before and immediately after rapid maxillary expansion.

RESULTS:

Rapid maxillary expansion resulted in similar and significant expansion in the width of anterior (2.8 mm, p < 0.001) and posterior nasal floor (2.8 mm, p < 0.001). Although nasopharynx and nasal cavities airway volumes significantly increased (+1646.1 mm3, p < 0.001), oropharynx volume increase was not statistically significant (+1450.6 mm3, p = 0.066). The results of the quality of life questionnaire indicated that soon after rapid maxillary expansion, patients' respiratory symptoms significantly decreased in relation to their initial respiratory conditions.

CONCLUSIONS:

It is suggested that RME produces significant dimensional increase in the nasal cavity and nasopharynx. Additionally, it also positively impacts the quality of life of mouth-breathing patients with maxillary atresia.

Assessment of nasal obstruction symptoms using the NOSE scale after surgically assisted rapid maxillary expansion

The Nasal Obstruction Symptom Evaluation (NOSE) scale is a reliable and valid instrument used widely in otorhinolaryngology to evaluate nasal obstruction symptoms in patients with nasal disorders. The purpose of this study was to assess nasal obstruction symptoms prospectively in patients undergoing surgically assisted rapid maxillary expansion (SARME) using the NOSE scale. Sixteen patients were studied (mean age 31±7.7 years), 10 women and six men, all with a transverse maxillary deficiency and an indication for SARME. Hyrax type devices were placed preoperatively and SARME was performed using Kraut's technique. The NOSE scale was applied prospectively to assess nasal obstruction symptoms. The results were recorded for each score on a scale ranging from 0 to 4, and these scores were multiplied by 5, generating a balanced scale from 0 to 100. Data were stratified according to NOSE scores, and nasal obstruction was categorized as mild (0-25), moderate (26-50), or severe (>50). The questionnaire was administered twice, first preoperatively and then at 6 months after surgery, and the results compared. Data were analyzed statistically using SAS statistical package software and showed that patients experienced a subjective improvement or did not have a worsening of nasal obstruction symptoms after SARME.

Dental treatment for paediatric obstructive sleep apnea

Paediatric obstructive sleep apnea (OSA) is common and its prevalence is expected to increase due to the rise in childhood obesity. Recent research has shown that many children, both syndromic and non-syndromic, who exhibit mouth breathing as a result of upper airway obstruction, may also exhibit dentofacial anomalies. Although adenotonsillectomy and continuous positive airway pressure have been classically proposed as the primary treatment modalities for paediatric OSA, there are significant limitations to both therapies. Therefore newer treatment modalities are needed. Current research has focused on emerging dental treatment options for paediatric OSA, such as rapid maxillary expansion, oral appliances and distraction osteogenesis. However, there are few randomized trials assessing the effectiveness of these novel dental therapies for paediatric OSA, and hence further research is required to advance the field.

Rapid-maxillary-expansion induced rhinological effects: a retrospective multicenter study

Conventional dental-borne rapid maxillary expansion (RME) leads to a widening of the airways, followed by improved nasal breathing. Although combined skeletal-dental appliances are nowadays being inserted increasingly often and provide a force at the center of resistance in the nasomaxillary complex, no study exists so far that shows whether this treatment may improve the expansionary effect on the airways. In this study, low-dose computed tomography (CT) images from 31 patients (average age 14.63 ± 0.38 years) were examined retrospectively. Both records (T0 = before expansion and T1 = immediately after maximum expansion) were taken in a time interval of 25 days to avoid growth influence. Five patients were treated with Hyrax RME, 6 patients with Hybrid RME, and 20 patients with acrylic cap RME. The total airway volume increased highly significantly (mean +7272.6 mm(3); P < 0.001, power = 0.998), representing an average airway expansion of +11.54 % (2.35 %/mm activation). While the nasopharynx and oropharynx showed highly significant expansion (P < 0.000, power = 0.999), the airway at the laryngopharynx did not change significantly (P > 0.779, power = 0.05). Although the patients were significantly older in the Hybrid RME group (P = 0.006), the positive rhinological effects were comparable within all groups of different appliances (P > 0.316). Hybrid RME may, therefore, be an advisable procedure in patients with nasomaxillary impairment and pronounced patient's age.

Nasal airway changes in bone-borne and tooth-borne rapid maxillary expansion treatments

INTRODUCTION

Our aim was to determine the presence of a correlation between the nasal airway skeletal transverse dimension and air intake changes in rapid maxillary expansion treatments.

METHODS

Sixty-one patients with maxillary transverse deficiency (11-17 years old) were randomly allocated into three groups (two treatment groups - tooth- [hyrax] or bone-borne [miniscrew-implant-based] expander - and one control group). Cone-beam computed tomography scans (CBCT) were obtained from each patient as well as acoustic rhinometry (AR) readings. Specifically, in AR, airway volume up to minimum cross-sectional areas (Vol. 1&2) and minimum cross-sectional areas (Min. 1&2) in the nasal cavity were measured. Records were obtained at two time points (initial T1 and at removal of appliance at 6 months T2). CBCTs were analyzed using AVIZO software and landmarks were placed on the nasal base. Descriptive statistics were compiled and student's t-test was used.

RESULTS

Of the 480 pairings measured, only 9 showed statistically significant positive correlations between T1 and T2. Correlation data were highly variable in all categories, showing no clear tendencies. No statistical difference was found when comparing all groups in terms of airway changes.

CONCLUSION

With very few positive correlations observed and otherwise highly variable data, no really conclusive finding was obtained to suggest any realistic correlation between changes in the skeletal dimensions and changes in the nasal airway.

Rapid Maxillary Expansion Increases Internal Nasal Dimensions of Children With Bilateral Cleft Lip and Palate

OBJECTIVE

The transverse maxillary deficiency frequently observed in patients with cleft lip and palate (CLP) is usually treated by rapid maxillary expansion (RME). Considering that RME causes a significant increase of the internal nasal dimensions in children with unilateral CLP (UCLP), this study aimed to characterize the internal nasal geometry of children with bilateral CLP (BCLP) and transverse maxillary deficiency using acoustic rhinometry. The study also aimed to analyze changes caused by RME.

DESIGN

Cross-sectional prospective study.

SETTING

Laboratory of Physiology, Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, SP, Brazil.

PARTICIPANTS

Fifteen children with repaired BCLP of both genders, aged 8 to 15 years, referred for RME, were prospectively analyzed.

INTERVENTIONS

Subjects underwent acoustic rhinometry before the expander installation and after the active phase of expansion. Cross-sectional areas (CSA) and volumes (V) of the nasal valve regions (CSA1 and V1) and turbinates (CSA2, CSA3, and V2), were measured after nasal decongestion.

MAIN OUTCOME MEASURES

In the majority of the subjects, an increase of internal nasal dimensions was observed.

RESULTS

Percent changes of CSA1, CSA2, CSA3, V1, and V2 were: +25%, +11%, +9%, 20%, and +12%, respectively. Differences were significant for all variables studied, except CSA3 (P < .05).

CONCLUSIONS

RME promotes an increase in the internal nasal dimensions of children with BCLP, suggesting that RME is capable of substantially improving nasal patency in this population.

A prospective CBCT study of upper airway changes after rapid maxillary expansion

OBJECTIVE

The aim of this prospective study was to investigate the upper airway changes after rapid maxillary expansion utilizing CBCT.

METHODS

16 children (10 male, 6 female) with a mean age of 12.73 ± 1.73 years underwent RME as part of their comprehensive orthodontic treatment with4,6-banded hyrax expanders. The screws were activated 2 turns a day. Depending on the expansion amount (2.7-6.3mm), the activation period ranged from 2 to 3 weeks. CBCT images were taken immediately before (T1) and three months after expansion (T2) in upright position, with patients' heads kept in consistent position. All CBCT data were processed with the software EZ3D2009. After orienting the CBCT images, a set of linear, area and volumetric parameters of the upper airway were measured and calculated. Student paired t test and one-way ANOVA were applied. The significance level of P<0.0033 was used according to the Bonferroni correction.

RESULTS

After expansion, with molar-to-molar width increasing 4.4 ± 1.3 mm and molars tipping 6.2 ± 6.2°, the nasal floor width and nasal lateral width increased 1.6, 1.5, and 1.6mm and 1.3, 1.7, and 1.4mm from the anterior to the posterior part, respectively. And there was no difference among the anterior, median and posterior part. The lower nasal volume increased 1348.5mm(3) with the percentage change being 8.1%. The pharyngeal airway showed no positive change.

CONCLUSION

RME can expand the nasal cavity and the expansion pattern may follow the parallel opening configuration. However, the influence on the pharyngeal airway is limited.

Changes in CT cerebral blood flow and volume associated with rapid maxillary expansion in a rabbit model

OBJECTIVE

To evaluate hemodynamic changes of the brain under the high forces of a rapid maxillary expansion (RME) appliance in a rabbit model.

MATERIALS AND METHODS

Twenty-four male New Zealand white rabbits were selected (12 weeks old, mean weight 3.01 ± 0.22 kg). A modified acrylic resin bonded RME appliance was used for expansion. A series of perfusion computed tomography examinations was performed before expansion (T0), on the fifth day of expansion (T1), at the end of the expansion process (T2), and after 10 days of retention (T3). Cerebral blood flow, cerebral blood volume, and mean transit time maps were recorded and parametrics evaluated. Statistical analyses were performed with analysis of variance with post hoc tests.

RESULTS

Mean cerebral blood flow showed an increase from T0 to T2 and then a decrease from T2 to T3, but the change was not statistically significant. Mean cerebral blood volume and mean transit time increased significantly from T0 to T2, and all perfusion parameters increased from T0 to T3.

CONCLUSIONS

RME is a safe orthopedic method despite the high expansion force. Perfusion computed tomography is effective for evaluating the hemodynamic changes of the brain caused by some orthopedic therapies. The increase in both cerebral blood volume and cerebral blood flow may help to explain why RME could alleviate the symptoms of enuretic children.

Upper airway expansion after rapid maxillary expansion evaluated with cone beam computed tomography

OBJECTIVE

Cone-beam computed tomography (CBCT) is a reliable method of assessing the oral cavity and upper airways. We conducted this study to examine the changes introduced by rapid maxillary expansion in the nasal cavity, nasopharynx, and oropharynx as seen with images obtained by CBCT.

MATERIALS AND METHODS

We evaluated 15 patients with maxillary width deficiency treated with RME. Patients were subjected to CBCT at the beginning of RME and after the retention period of 4 months.

RESULTS

The nasal cavity presented a significant transverse increase in the lower third, in the anterior (1.08 mm ± 0.15), medium (1.28 mm ± 0.15), and posterior regions (0.77 mm ± 0.12). No significant change occurred in the nasopharynx in volume (P  =  .11), median sagittal area (P  =  .33), or lower axial area (P  =  .29) resulting from the RME. A significant change was noted in the oropharynx in volume (P  =  .05), median sagittal area (P  =  .01), and lower axial area (P  =  .04) before and immediately after the RME.

CONCLUSIONS

RME is able to increase the transverse width of the nasal cavity, but it does not have the same effect in the nasopharynx. Changes noted in the oropharynx may be due to the lack of a standardized position of the head and tongue at the time of image acquisition.