Multi-stage Unet segmentation and automatic measurement of pharyngeal airway based on lateral cephalograms

OBJECTIVES

Orthodontic treatment profoundly impact the pharyngeal airway (PA) of patients. Airway examination is an integral part of daily orthodontic diagnosis, and lateral cephalograms (LC) are reliable to reveal PA structures. This study attempted to develop a simple method to help clinicians make a preliminary judgement of patients' PA conditions and assess the impact of orthodontic treatment on their airways.

METHODS

LCs of 764 patients were used to train a multistage unit segmentation model. Another 130 images were used to validate the model and more 130 images were used to test the model.

RESULTS

Unet was used as the backbone, with a mean dice value of 0.8180, precision of 0.8393, and recall of 0.8188. Furthermore, we identified seven key points and measured related indices. The length of the line separating the nasopharynx and oropharynx and the line separating the oropharynx and hypopharynx were manually measured thrice and the average values was compared. The intraclass correlation coefficient (ICC) for the two lines was 0.599 and 0.855. Then, we performed a single linear regression analysis, which indicated a strong correlation between the predictions and measurements for the two lines.

CONCLUSIONS

This method is reliable for segmenting three regions (nasopharynx, oropharynx, and hypopharynx) of the PA and calculating related indices. However, the predictions obtained from this model still have errors, and it is necessary for clinical practitioners to assess and adjust the predictions.

CLINICAL SIGNIFICANCE

Our model can help orthodontists formulate personalised treatment plans and evaluate the risk of airway stenosis during orthodontic treatment. This method may mark the beginning of a new and simpler approach for PA obstruction detection, specifically tailored to orthodontic patients.

Aerodynamic characteristics in upper airways among orthodontic patients and its association with adenoid nasopharyngeal ratios in lateral cephalograms

BACKGROUND

Adenoid hypertrophy among orthodontic patients may be detected in lateral cephalograms. The study investigates the aerodynamic characteristics within the upper airway (UA) by means of computational fluid dynamics (CFD) simulation. Furthermore, airflow features are compared between subgroups according to the adenoidal nasopharyngeal (AN) ratios.

METHODS

This retrospective study included thirty-five patients aged 9-15 years having both lateral cephalogram and cone beam computed tomography (CBCT) imaging that covered the UA region. The cases were divided into two subgroups according to the AN ratios measured on the lateral cephalograms: Group 1 with an AN ratio < 0.6 and Group 2 with an AN ratio ≥ 0.6. Based on the CBCT images, segmented UA models were created and the aerodynamic characteristics at inspiration and expiration were simulated by the CFD method for the two groups. The studied aerodynamic parameters were pressure drop (ΔP), maximum midsagittal velocity (V_ms), maximum wall shear stress (P_ws), and minimum wall static pressure (P_w).

RESULTS

The maximum V_ms exhibits nearly 30% increases in Group 2 at both inspiration (p = 0.013) and expiration (p = 0.045) compared to Group 1. For the other aerodynamic parameters such as ΔP, the maximum P_ws, and minimum P_w, no significant difference is found between the two groups.

CONCLUSIONS

The maximum V_ms seems to be the most sensitive aerodynamic parameter for the groups of cases. An AN ratio of more than 0.6 measured on a lateral cephalogram may associate with a noticeably increased maximum V_ms, which could assist clinicians in estimating the airflow features in the UA.

Long-term effect on adenoid dimensions and craniocervical angulation after maxillary expansion with fixed or functional appliances

Background

Maxillary expansion is a common orthodontic procedure that could have a positive effect also on airway patency. The aim of the present study was to evaluate the long-term effects of rapid maxillary expansion (RME) on nasopharyngeal area and cranio-cervical angulation in growing patients, compared to controls treated with a function-generating bite appliance (FGB).

Material and Methods

Sixty patients aged 6-14 consecutively treated with RME or FGB were selected retrospectively and divided into two groups. Lateral cephalograms taken before and after treatment were retrieved, and the nasopharyngeal area, delimited superiorly by a sella-posterior nasal spine (PNS) line and inferiorly by a basion-PNS line, and the cranio-cervical angulation were measured.

Results

The mean observation time was 17.6 ± 8 months. No differences were present between the two groups regarding age and gender. The nasopharyngeal area increased significantly in both groups after treatment, but with no statistically significant difference between them. The cranio-cervical angulation showed no differences within or between groups.

Conclusions

Maxillary deficiency treatment with either RME or FGB was followed by a comparable increase in nasopharyngeal area.

Key words:Rapid maxillary expansion, Airway, Nasopharyngeal area, Adenoid.

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.

Three-dimensional analyses of short- and long-term effects of rapid maxillary expansion on nasal cavity and upper airway: A systematic review and meta-analysis

INTRODUCTION

The purpose of this systematic review was to evaluate the three-dimensional (3D) changes occurring at short- and long-term follow-up after rapid maxillary expansion (RME) in nasal cavity (NC) and upper airway (UA) in growing patients.

METHODS

A literature search up to 1 July 2019 was performed. Randomized and non-randomized clinical trials and cohort studies comparing the effects of RME in a paediatric population using 3D analyses based on computed tomography (CT), cone-beam CT and MRI were included. The risks of bias of the included studies were assessed using the Cochrane Collaboration's risk of bias tool, the GRADE approach and a customized tool. The random-effects meta-analyses of the mean differences and 95% confidence intervals of NC and UA volume changes were carried out, followed by subgroup analyses.

RESULTS

Twenty-seven studies were included, with 18 selected for quantitative synthesis. Immediately after expansion, the nasopharynx and oropharynx increased significantly. After 3 months of retention, only the NC and nasopharynx showed a significant volume increase. Two studies mentioned the use of a sleep-disordered breathing questionnaire, and one study reported the difference before and after RME. None of the 27 articles included assessed the correlation between the skeletal widening and NC or UA volume changes after RME.

CONCLUSIONS

The existing evidence confirmed only the short-term positive effect of RME on expanding the volume of the NC and the upper part of the UA. However, long-term stability could not be sustained.

Effects of maxillary expansion on the upper airways: Evidence from systematic reviews and meta-analyses

BACKGROUND

Constricted maxilla is frequently associated with reduced nasal airway dimensions. Wheatear skeletal maxillary expansion (ME) is effective on the dimension of the upper airways is still a debated issue.

OBJECTIVES

This overview aimed to report the evidence provided by systematic reviews (SRs) on the effect of ME on the upper airways and to assess the methodological quality of the included SRs.

METHODS

Six electronic databases have been explored up to November 2017. After title and abstract screening, SRs addressing the effects of fixed palatal expanders on the dimension and function of the nasal airways were included. The methodological quality of the included SRs was assessed using the updated version of A Measurement Tool to Assess Systematic Review (AMSTAR-2).

RESULTS

Eight SRs were included. The methodological quality of most of the included SRs ranged between low and critically low. One SR was rated of high quality. A significant increase in nasal linear dimensions was reported both in the short and long term, but supported by low-/critically low-quality SRs. The significant increase in nasal cavity volume was the only outcome supported by a high-quality SR Controversial results were found with regards to nasal function.

CONCLUSION

Whenever a constricted maxilla is present general dentists, paediatricians and ENTs should be familiar with the potential improvement provided by ME. However, due to the low/critically low quality of SRs supporting these results, ME cannot be indicated only for upper airways enhancement, but should be supported by an orthodontic indication.

Transverse Skeletal Effects of Rapid Maxillary Expansion in Pre and Post Pubertal Subjects: A Systematic Review

OBJECTIVE

The aim of this systematic review was to assess the transverse skeletal effects of rapid maxillary expansion (RME) in pre and post-pubertal subjects.

MATERIAL AND METHODS

Five databases were searched till May 2018; Pubmed, Cochrane, Scopus, Lilacs and Web of science in addition to the manual search of other sources. There were no language restrictions. Methodological Index for Non-Randomized Studies MINORS was used to assess the quality and risk of bias of the trials included.

RESULTS

Six studies were finally included in the qualitative analysis. A meta-analysis wasn't performed due to the heterogeneity of methodologies and outcomes. All of the included studies showed drawbacks in their structure yielding weak evidence. On the short term, RME caused an increase in the maxillary and lateral-nasal widths in pre-pubertal subjects by 3.4 mm and 3.3 mm, and by 2.8 and 2.2 mm respectively in post-pubertal subjects. Although statistically insignificant, the maxillary width increase was more than that of the post-pubertal subjects by 0.6 mm. Over the long term, expansion produced permanent increases in the transverse dimensions of both the dento-alveolar and skeletal components of the maxilla and circum-maxillary structures in pre-pubertal subjects. The post-pubertal subjects presented with a statistically significant increase only in the later-nasal width by 1.3 mm than the untreated controls with no permanent increase in the skeletal maxillary width.

CONCLUSION

The literature is very deficient regarding the use of skeletal age as a reference in the treatment of skeletal crossbites using RME. Only weak evidence exists supporting the increased maxillary and lateral-nasal widths after tooth-tissue borne RME in pre-pubertal subjects, with these effects being less in the post-pubertal ones.

Can rapid maxillary expansion cause auditory improvement in children and adolescents with hearing loss? A systematic review

OBJECTIVE

To evaluate whether the use of palatal expansion techniques can influence hearing loss in children and adolescents with previous hearing impairment.

MATERIALS AND METHODS

Electronic searches in PubMed, Scopus, Web of Science, The Cochrane Library, Lilacs, OpenGrey, and Google Scholar were performed with a controlled vocabulary and free-text terms relating to palatal expansion and hearing loss. No language or time restrictions were imposed. Clinical trials that focused on human patients treated with rapid or semirapid maxillary expansion in children and teenagers with hearing loss were included. Data extraction was undertaken by two authors, with conflict resolution by a third author. Risk of bias assessment and data extraction were performed on the selected studies.

RESULTS

Seventy-four citations were retrieved by the search. Initially, 12 studies were selected according to the eligibility criteria, but three studies were excluded because of the presence of adults, absence of hearing level evaluation, and oversampling, resulting in nine studies. The mean improvement in hearing levels varied from 2 to 19 dB among the studies. The risk of bias varied from low to moderate risk.

CONCLUSIONS

The evidence indicated that there was a hearing improvement after maxillary expansion in patients with hearing loss in the evaluated studies, although more controlled and randomized studies are necessary to investigate this issue further.

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.

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.

Volumetric upper airway assessment in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion

Transverse maxillary deficiency is commonly found in patients with sleep apnea and is also related to abnormal breathing patterns. Maxillary expansion procedures promote widening of the nasal floor and reduce the resistance to airflow, and have a positive influence on nasopharynx function. In order to evaluate volume changes in the upper airway, 15 adult patients with transverse maxillary deficiency underwent surgically assisted rapid maxillary expansion (RME) until a slight overcorrection of the crossbite was obtained. Cone beam computed tomography (CBCT) volumetric images were obtained at three predefined time points. The mean age of the patients was 30.2 (±7.4) years; nine were females and six were males. The area, volume, and the smallest transverse section area of the airway were assessed using Dolphin Imaging 3D software. Statistical comparisons were made of the changes between time periods. No statistically significant differences were found for volume or area. However a significant difference was found between the preoperative and immediate postoperative smallest transverse section area (P<0.05). Maxillary expansion, as an isolated procedure, does not result in a statistically significant improvement in the airway dimensions and results in an inferior relocation of the smallest transverse section area.

Changes in nasal air flow and school grades after rapid maxillary expansion in oral breathing children

Objective: To analyse the changes in nasal air flow and school grades after rapid maxillary expansion (RME) in oral breathing children with maxillary constriction. Material and Methods: Forty-four oral breathing children (mean age 10.57 y) underwent orthodontic RME with a Hyrax screw. Forty-four age-matched children (mean age 10.64 y) with nasal physiological breathing and adequate transverse maxillary dimensions served as the control group. The maxillary widths, nasal air flow assessed via peak nasal inspiratory flow (PNIF), and school grades were recorded at baseline, and 6 months and one year following RME. Results: After RME, there were significant increases in all the maxillary widths in the study group. PNIF was reduced in the study group (60.91 ± 13.13 l/min) compared to the control group (94.50 ± 9.89 l/min) (P < 0.000) at the beginning of the study. Six months after RME, a significant improvement of PNIF was observed in the study group (36.43 ± 22.61). School grades were lower in the study group (85.52 ± 5.74) than in the control group (89.77 ± 4.44) (P < 0.05) at the baseline, but it increased six months after RME (2.77 ± 3.90) (P < 0.001) and one year later (5.02 ± 15.23) (P < 0.05). Conclusions: Nasal air flow improved in oral breathing children six months and one year after RME. School grades also improved, but not high enough to be academically significant.

Key words:Maxillary constriction, oral breathing, nasal air flow, rapid maxillary expansion, school grades.

Does rapid maxillary expansion have long-term effects on airway dimensions and breathing?

INTRODUCTION

In this systematic review, we identified and qualified the evidence of long-term reports on the effects of rapid maxillary expansion (RME) on airway dimensions and functions.

METHODS

Electronic databases (Ovid, Scirus, Scopus, Virtual Health Library, and Cochrane Library) were searched from 1900 to September 2010. Clinical trials that assessed airway changes at least 6 months after RME in growing children with rhinomanometry, acoustic rhinometry, computed tomography, or posteroanterior and lateral radiographs were selected. Studies that used surgically assisted RME and evaluated other simultaneous treatments during expansion, systemically compromised subjects, or cleft patients were excluded. A methodologic-quality scoring process was used to identify which studies would be most valuable.

RESULTS

Fifteen articles fulfilled the inclusion criteria, and full texts were assessed. Three were excluded, and 12 were assessed for eligibility. Four articles with low methodologic quality were not considered. The remaining 8 were qualified as moderate. The posteroanterior radiographs showed that nasal cavity width increases; in the lateral radiographs, decreased craniocervical angulation was associated with increases of posterior nasal space. Cone-beam computed tomography did not show significant increases of nasal cavity volume. Rhinomanometry showed reduction of nasal airway resistance and increase of total nasal flow, and acoustic rhinometry detected increases of minimal cross-sectional area and nasal cavity volume.

CONCLUSIONS

There is moderate evidence that changes after RME in growing children improve the conditions for nasal breathing and the results can be expected to be stable for at least 11 months after therapy.

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

OBJECTIVE

To evaluate the effect of rapid maxillary expansion (RME) on the dimension of the nasopharyngeal space and its relation to nasal airway resistance.

METHODS

Twenty-five school-age children (from 7 to 10 year-old) with mouth and/or mixed breathing, with mixed dentition and uni- or bilateral posterior crossbite involving the deciduous canines and the first permanent molars, were evaluated. RME was placed and remained during 90 days. Rhinomanometry and orthodontic documentation were performed at four different times, i.e., before (T(1)), immediately after (T(2)), 90 days (T(3)) and 30 months (T(4)) after RME.

RESULTS

Differences in nasopharyngeal area and in nasal airway resistance were observed only 30 months after RME, and could be explained by facial growth, and not because of the orthodontic procedure.

CONCLUSION

RME does not influence on nasopharyngeal area or nasal airway resistance in long-term evaluation.

Slow or rapid palatal expansion for early treatment of unilateral posterior crossbite? Evaluation of the reverse chewing cycles correction

OBJECTIVES

It is well established that patients with a unilateral posterior crossbite, when chewing on the affected side, show an increased frequency of reverse chewing cycles. It was hypothesized that the correction of reverse cycles may be due to the characteristics of the therapy. The aim was to investigate the prevalence of reverse chewing patterns in children with unilateral posterior crossbite before and after treatment with Function Generating Bite (FGB).

MATERIALS AND METHODS

Twenty children, (9 boys, 11 girls; age, mean ± SD, 7.5 ± 1.1), 10 with a right and 10 with a left posterior unilateral crossbite were selected. Mandibular movements during chewing soft and hard boluses were measured with a kinesiograph (K7 -I, Myotronics Inc. Tukwila, Washington, USA).

RESULTS

The results showed a significant difference when comparing the percentage of reverse chewing patterns, before and after therapy with FGB, during chewing on the crossbite side both with soft and hard bolus (p<0.0001). No significant differences were observed during chewing on the non-crossbite side.

DISCUSSION

The results of this study confirmed that FGB corrects both the dental and functional asymmetries. Knowing that the rapid palatal expansion does not correct the masticatory function, it is of clinical relevance, for the orthodontists, the knowledge and the understanding of the functional outcomes with different therapies.

CONCLUSIONS

The type of treatment and the biomechanics of the appliance used are of great importance for the correction of the reverse chewing cycles and for rebalancing the functional asymmetry of children with unilateral posterior crossbite.