CBCT evaluation of the upper airway morphological changes in growing patients of class II division 1 malocclusion with mandibular retrusion using twin block appliance: a comparative research

Evaluation of Upper Airway Growth Patterns With Cephalometric Analysis Based on Cervical Vertebral Maturation in the Japanese: A Cross-Sectional Study

Objective This study aims to establish standard values for the upper airway cross-sectional area and evaluate growth patterns using the cervical vertebral maturation stage (CVMS) in a Japanese population. Methods A cross-sectional sample of 400 patients, aged 6-20 years, was selected randomly from the Orthodontic Clinic at Tokyo Medical and Dental University (TMDU) dental hospital. Cervical vertebral maturation stages (CVMS I-V) guided the classification of participants into five equal groups. Lateral cephalometric radiographs taken prior to orthodontic treatment were used to measure the upper airway's cross-sectional area. The growth spurt and sex differences in growth patterns were assessed through these measurements. Results Standard values for the upper airway dimensions at each CVMS stage were established. Significant growth spurts were noted between CVMS II-III and CVMS III-IV in males and at CVMS II-III in females. The weighted kappa coefficient (κ) demonstrated almost perfect intra- and inter-evaluator agreement, confirming the reliability of CVMS in growth assessment. Conclusion CVMS provides a reliable framework for assessing growth patterns of the upper airway, with distinct variations between sexes noted. These findings support the utility of CVMS in clinical growth evaluation and orthodontic treatment planning.

Association between orthodontic treatment and upper airway changes in children assessed with cone-beam computed tomography (CBCT): A systematic review

BACKGROUND

Some orthodontic devices used in children share similar design principles to appliances used to treat obstructive sleep apnoea in adults. As well as treating malocclusion, orthodontic appliances used in children may therefore also have effects on the upper airway.

OBJECTIVE

A review of the literature to assess the effects of orthodontic treatment on the upper airway dimensions in children assessed on CBCT.

MATERIALS AND METHODS

Following registration of the protocol (PROSPERO CRD42023439056), a systematic electronic search of published studies was performed using several databases (PubMed; Scopus, Web of Science and Science Direct) in accordance with the PRISMA guidelines. Inclusion criteria were as follows: age under 18 years, orthodontic treatment with any appliance, a control group who received no treatment or a non-active alternative treatment and airway measurement using CBCT. RoB-2 and ROBINS-I tools were used to assess risk of bias and quality of the evidence.

RESULTS

In total, 341 studies were identified following the initial search. Title and abstract screening resulted in 45 studies for further full-text analysis. On completion of the screening process, a total of 23 studies met the inclusion criteria. Study interventions included functional appliances (10 studies), rapid maxillary expansion (RME) (9 studies), reverse-pull headgear (1 study) and 4 premolar dental extractions (3 studies). The included studies had moderate to high risk of bias, and the quality of evidence was low.

CONCLUSION

The scientific evidence shows that functional appliances are associated with significant improvements in both upper airway volume and constriction when used in children however, the effects on the nasal cavity are limited. RME was associated with a significant increase in nasal cavity and nasopharyngeal dimensions, but not the upper pharyngeal airway. Neither reverse-pull headgear nor dental extractions were associated with any change in airway dimensions; however, the evidence is limited. Functional appliances may reduce the severity of obstructive sleep apnoea (OSA) in children.

Current Trends in Pediatric Orthodontics: A Comprehensive Review

Pediatric orthodontics is a critical field focusing on the diagnosis, prevention, and treatment of dental and facial irregularities in children. This comprehensive review explores current trends and methodologies in pediatric orthodontics and discusses the multifactorial etiology of malocclusions, including genetic, environmental, and disease-related factors. The importance of proper diagnosis is highlighted, and the extraoral, intraoral, and functional evaluations essential for effective treatment planning are detailed. Various orthodontic conditions such as Class III and Class II malocclusions, abnormal oral habits, arch length discrepancies, anterior and posterior crossbites, open bites, and deep bites are examined in depth. The review also addresses the role of temporomandibular joint disorders (TMDs) and obstructive sleep apnea (OSA) in pediatric patients, emphasizing the need for early and accurate diagnosis to facilitate appropriate intervention. The use of clear aligners in early orthodontic intervention is evaluated given their efficacy and improved patient satisfaction compared to traditional appliances. Additionally, the article discusses the non-advisability of early interception for certain self-correcting malocclusions and the limitations of pediatric orthodontic treatment, including compliance-related issues and the unique anatomical considerations of deciduous dentition. This review aims to provide a detailed understanding of contemporary practices and challenges in pediatric orthodontics, offering insights for clinicians to enhance treatment outcomes and patient care.

Cephalometric evaluation of pharyngeal airway and tongue space following treatment with Herbst and AdvanSync appliances : A prospective randomized clinical trial

OBJECTIVES

To evaluate and compare pharyngeal airway and tongue space changes after treatment with fixed functional appliances-Herbst and AdvanSync™ (Ormco, Orange, CA, USA) appliances-in skeletal class II patients in pre- and posttreatment lateral cephalograms.

METHODS

For this randomized, controlled trial, 40 patients (21 male, 19 female) were divided into two groups-a Herbst group (mean age 12.6 ± 0.67 years) and an AdvanSync group (mean age 12.8 ± 0.66 years). Pre- and posttreatment (appliance therapy duration-8 months) lateral cephalograms were traced using a software program to evaluate pharyngeal airway and tongue space changes.

RESULTS

Nasopharyngeal airway, velopharyngeal airway, glossopharyngeal airway, and hypopharyngeal airway increased in the Herbst group by 2.12 mm (p ≤ 0.001), 2.33 mm (p ≤ 0.001), 2.40 mm (p ≤ 0.01), and 1.57 mm (p ≤ 0.05), while in the AdvanSync group the increases were 1.89 mm (p ≤ 0.001), 1.21 mm (p ≤ 0.001), 1.18 mm (p ≤ 0.001), and 1.53 mm (p ≤ 0.001), respectively. In the Herbst group, tongue length and height increases were 2.04 mm (p ≤ 0.01) and 3.74 mm (p ≤ 0.001), while the values in the AdvanSync group were 2.41 mm (p ≤ 0.05) and 2.69 mm (p ≤ 0.001). The change of the tongue tip from the lower occlusal plane was 0.69 mm (p ≤ 0.001) in the Herbst group and 0.77 mm (p ≤ 0.001) in the AdvanSync group. The velopharyngeal airway dimension was correlated positively with that of the retroglossal oropharyngeal airway, which in-turn positively correlated with the laryngopharyngeal airway which correlated well with the distance of the tongue tip from the lower occlusal plane.

CONCLUSIONS

The airway dimensions and tongue parameters increased significantly in both treatment groups in the present study. These changes were higher in the Herbst appliance than in the AdvanSync group, except for the distance of the tongue tip from the lower occlusal plane. A significant difference between the pharyngeal airways was found only for the retropalatal oropharyngeal airway.

Effect of functional appliances on sleep-disordered breathing in Class II division 1 malocclusion children: Randomized controlled trial

OBJECTIVES

A randomized controlled trial was undertaken to investigate the orthopaedic effect of functional appliances on the pharyngeal airway space and nocturnal breathing of children with skeletal class II due to mandibular retrusion.

MATERIALS AND METHODS

Forty patients were randomized into a 1:1 ratio study (Twin block) group and a control (fixed appliance) group. Each group included equal numbers of boys and girls. Diagnosis with sleep-disordered breathing was not an inclusion criterion. The duration of the trial was 12 months (T0 - T12). Eligibility criteria included skeletal Class II division 1 malocclusion with mandibular retrognathism, SNA ≥82, SNB ≤78, ANB ≥4, overjet ≥6 mm, and patients in circumpubertal stage CVM2 and CVM3. The main outcomes were pharyngeal airway volume, oxygen desaturation index (ODI), and maximum expiratory pressure (MEP), while the secondary outcomes were skeletal and dental changes of the maxilla and mandible. Randomization was accomplished with random blocks of 20 patients with allocation concealed in sequentially numbered, opaque, and sealed envelopes. Blinding was only applicable for data analysis of radiographic measurements and data extracted from the pulse oximeter.

RESULTS

The mean age of the patients was 10 ± 1.5 and 10 ± 1.2 at (T0) for the Twin Block and the control groups, respectively. The changes in the oropharyngeal (2.66 cc and 0.056; P = .03) and nasopharyngeal (1.3 cc and 0.84; P = .053) airway volumes for the Twin block and control groups, respectively, were significantly different for the oropharynx. There was a significant decrease in ODI by [median -3.55 (-5.05 to 0.50); P ≤ .001] and a significant increase [median 45 (0.0-110); P ≤ .001] in MEP for the Twin block group. A significant inverse correlation (r = -.589; P = .006) could be found between the total volume of the oropharynx and ODI. No serious harm was observed.

CONCLUSIONS

The Twin block group showed significant change in oropharyngeal airway volume and improvement of nocturnal breathing.

REGISTRATION

This trial was registered at https://www.

CLINICALTRIALS

gov, registration number NCT04255511.

Cephalometric changes in pharyngeal airway dimensions after functional treatment with twin block versus myobrace appliances in developing skeletal class II patients: a randomized clinical trial

BACKGROUND

Several appliances have been used for correction of developing skeletal Class II, including different myofunctional appliances as Twin block (TB)as well as the new pre-fabricated Myobrace (MB) appliance. However, the effects of these devices on the pharyngeal airways have not been compared in the literature. Thus, the aim of this study was to compare the effects of two Class II correction appliances; TB and MB on the sagittal pharyngeal airway dimension (SPAD), including the nasopharyngeal airway area (NPAA), the oropharyngeal airway area (OPAA), and the laryngopharyngeal airway area (LPAA).

METHODS

This is a two parallel arms randomized comparative clinical trial. Twenty-six children of 9-12 years with Skeletal Class II malocclusion due to mandibular deficiency and normal maxillary growth as confirmed by lateral cephalometric X-ray readings (ANB angle > 4° and SNB angle < 78) and Cervical vertebral maturational index (CVMI) 1 or 2 were randomly assigned into two equal groups. Group I: TB, Group II: MB (prefabricated functional appliance, Myofunctional Research Co., Australia). Lateral cephalograms were taken for all patients in both groups before treatment (T1) and after treatment (6 months later) (T2). The primary aim was to assess pre and post treatment changes in the SPAD in each group, and compare between the two study groups. The secondary aim was to evaluate the sagittal skeletal measurements such as the SNA, SNB, ANB, Wits appraisal, as well as vertical skeletal measurements represented by the Frankfurt-mandibular plane angle (FMA) measured pre- and post-treatment. The independent samples t-test was used to compare the two study groups, and the mean difference and 95% confidence intervals (CI) were computed. The paired samples t-test was used to compare various parameters between T1 and T2 within each group. The cutoff for significance was p-value < 0.05. Data were analyzed using IBM SPSS for Windows (Version 26.0).

RESULTS

By Comparing changes in airway measurements within each group, it was found that NPAA, OPAA, and LPAA increased significantly after treatment within each group of MB and TB. TB group showed significantly higher mean difference (T2-T1) in both NPAA and OPAA than MB group with 28.39 (± 56.75) and 40.46 (± 52.16) respectively. The increase in LPAA values was not statistically significant at (T2-T1) between both groups. Regarding skeletal changes, there was a significant increase in the SNB values between T1 and T2 within each group with 2.82 (± 3.32) for MB group and 3.79 (± 3.06) for TB group Moreover, there was a significant decrease in the ANB values between T1 and T2 within each group by 2.42 (± 2.70) for MB group and 3.06 (± 1.14) for TB group. Similarly, there was a significant decrease in the ANB values between T1 and T2 within each group by -2.13 (± 0.62) for MB group and - 2.46 (± 0.72) for TB group. No significant differences were found between both groups in SNA, SNB, ANB and Wits appraisal at p = 0.06, p = 0.45, p = 0.43 and p = 0.22 respectively. FMA did not show significant difference between T1 and T2 within each group, nor showed a significant mean difference between both groups at T2-T1.

CONCLUSIONS

TB was more effective than MB in improving the upper (NPAA) and middle (OPAA) airways, while no difference was found regarding the lower airway (LPAA). Both TB and MB reduced the severity of developing skeletal class II due to mandibular retrognathism by forward posturing of the mandible. Thus, patients with airway problems would benefit more from TB than MB.

Three-dimensional evaluation of upper pharyngeal airway, hyoid bone, and craniocervical changes following stabilization splint therapy in adult patients with temporomandibular joint disorders and mandibular deviation: A retrospective study

OBJECTIVE

This study aimed primarily to analyze the three-dimensional (3D) changes in the pharyngeal airway (PA), and secondarily, the hyoid bone (HB) and the craniocervical (CC) following stabilization splint (SS) therapy in adult patients with temporomandibular joint disorders (TMD) and mandibular deviation (MD).

METHODS

Thirty-five adult patients with TMD and MD, who were treated using SS with a mean age of 25.14 ± 6.11 years, were enrolled in this retrospective clinical study. Pre- and post-therapeutic cone-beam computed tomography (CBCT) scans were analyzed. PA dimension,nasopharyngeal, oropharyngeal, hypopharyngeal, sub-hypopharyngeal, and total pharyngeal airway spaces were measured in surface area, volume, minimum constricted area (MCA) and width, HB position, and CC posture were analyzed three-dimensionally using InVivo 6.0.3 and Dolphin 11.95 software. Wilcoxon rank-sum or Paired t-test was conducted, and P < 0.05 was considered significant.

RESULTS

SS therapy was administered for a period of 9.49 ± 4.02 months. The oropharyngeal airway space showed a significant decrease in sagittal width. The hypopharyngeal surface area, volume, MCA, and sagittal width decreased significantly. In terms of HB, hyoid-mandibular plane (H-MP), retrognathia-third vertebra's most inferior-anterior (RGN-C3ia), and retrognathia-Sella (RGN-S) distances significantly decreased. The Nasion-Sella line and the line that passes through C2ip to the odontoid process posterior tangent (NSL-OPT) angle in CC posture also decreased significantly.

CONCLUSION

SS therapy in TMD patients with MD mainly results in narrowing of the hypopharyngeal region, no change in HB position and improvement in head posture. These results undoubtedly assist in diagnosis and treatment of clinical conditions.

Effects of twin-block appliance on upper airway parameters in OSA children with class II malocclusion and mandibular retrognathia: a CBCT study

Twin-block appliance had been advocated as a potential treatment option in paediatric obstructive sleep apnoea (OSA) due to their favourable effect in enhancing upper airway parameters and improving OSA symptoms. The aim of this study was to evaluate the effect of twin-block appliance therapy on upper airway parameters/dimensions and the apnoea-hypopnea indexes (AHIs) in OSA children with class II mandibular retrognathic skeletal malocclusion using cone-beam computed tomography. This prospective longitudinal study comprised 34 polysomnography-proven OSA growing children with class II mandibular retrognathic skeletal malocclusion between the ages of 8 and 12 years who had completed myofunctional twin-block therapy and matched corresponding controls. The upper airway was segmented into the nasopharynx, oropharynx, and hypopharynx, and the effect of twin-bock treatment on upper airway parameters/dimensions was assessed pre- and posttreatment using CBCT analysis, while a second standard overnight PSG was performed to determine changes in the AHI. At the nasopharynx level, minimal (nonsignificant) increases in all variables were observed within the twin-block group and between the groups (P > 0.05). At the level of the oropharynx, all variables increased significantly in the treatment group and between groups (P < 0.001), but these increases were nonsignificant in the control group. At the level of the hypopharynx, only the minimum cross-sectional area (MCA) increased significantly in the treatment group (P = 0.003). The change in MCA was also significant between the groups (P = 0.041). In addition, the upper airway length increased significantly in the twin-block group (P = 0.0154), and the AHI decreased by 74.8% (P < 0.001).

CONCLUSION

Correction of class II mandibular retrognathic skeletal malocclusion with twin-block appliance resulted in a significant increase in upper airway volume, MCA, anteroposterior and lateral distances of the MCA at the level of the oropharynx, MCA at the level of the hypopharynx and upper airway length, and a significant decrease in AHI, but it had no effect on nasopharynx parameters.

WHAT IS KNOWN

• CBCT imaging has been shown to be an effective and precise diagnostic tool for analyzing the upper airways and craniofacial structures. • Twin block appliance may be an effective treatment modality in children with OSA.

WHAT IS NEW

• Minimal cross-sectional area of upper ways may be the most relevant potential parameter when explaining how the upper airway anatomy plays role of in the pathogenesis of pediatric OSA. • Twin block appliance induced favorable changes in upper airway morphology (oropharynx area mainly) and respiratory parameters in OSA children with class II malocclusion.

Three-dimensional evaluation of the effects of Bionator and Forsus appliances on oropharyngeal airway volume in patients with mandibular retrognathia

OBJECTIVE

To evaluate whether there is a difference between the effects of Bionator and Forsus appliances on airway volume.

METHODS

Forty patients with mandibular retrognathia were divided into two groups. The Bionator appliance was applied to Group 1, while the Forsus FRD EZ2 appliance was applied to Group 2. Three-dimensional images were captured before and after functional appliance use in both groups. Dolphin 3D software was used for airway measurements.

RESULTS

No statistically significant difference was found between the groups in terms of volumetric and area measurements. There was a statistically significant difference between the minimum axial T and O-N border T measurements of the groups.

CONCLUSION

The use of functional appliances may contribute to an increase in oropharyngeal airway dimensions, but there was no difference between the Bionator and Forsus groups in terms of volumetric measurements.

Volumetric changes in the upper airway on CBCT after dentofacial orthopedic interventions - a systematic review

OBJECTIVE

To provide a critical overview of the effect of various orthodontic and/or dentofacial orthopedic interventions on three-dimensional volumetric changes in the upper airway.

MATERIALS AND METHODS

Four databases were searched for clinical studies concerning 3D volumetric assessments based on CBCT before and after orthodontics interventions. The quality of the studies was assessed using the quality assessment tool of the National Heart, Lung and Blood Institute. After the use of inclusion and exclusion criteria, the pre-and post-treatment volumes were used to visualize the effect of various orthodontics interventions.

RESULTS

A total of 48 studies were included in this review and none of which were RCTs. The quality of all included studies was assessed as medium. Overall, there is a tendency for an increase in airway volumes after various orthodontic interventions, except for studies concerning extraction therapy with fixed appliances in adults, in which both increases and decreases in airway volumes have been reported.

CONCLUSION

Orthodontic treatment by growth modification and non-extraction therapy with fixed appliances, regardless of the malocclusion, generally showed positive effects on the airway volume. Orthodontic treatment in combination with extractions does not provide an unambiguous insight. A consensus on the methodology of the airway measurement and nomenclature is urgently needed in order to gain insight into the effect of different interventions on three-dimensional airway changes.

CLINICAL RELEVANCE

Various orthodontic treatments do not negatively influence the upper airway volume. However, extraction therapy in adults should be chosen with caution, especially in subjects belonging to a group susceptible to airway obstruction.

3D Evaluation of Upper Airway Morphological Changes in Growing Patients with Class II Malocclusion Using Sander Bite Jumping Appliance

Class II malocclusion due to mandibular retrognathia is associated with a posterior positioning of the tongue and the hyoid bone, reducing the oropharyngeal volume. This could be a contributing factor to the development of respiratory and cardiovascular problems. This study evaluates the oropharyngeal volume variation in 13 patients with class II malocclusion undergoing functional orthopedic treatment with Sander Bite Jumping Appliance (SBJ). CBCT scans were performed before treatment (T0) and approximately after 12.5 months (T1): the retropalatal volume and retroglossal volume were quantified in mm3 using a segmentation software. At T1, the retropalatal volume increased in 2523 ± 2088 mm3, and the retroglossal volume increased in 2258 ± 1717 mm3. Both values were statistically significant (p < 0.05). This widening of the airways may allow prevention and treatment of sleep-disordered breathing, including obstructive sleep apnea syndrome.

Effectiveness of orthopaedic treatments on the enlargement of the upper airways: Overview of systematic reviews

OBJECTIVE

The aims of this overview are to evaluate the three-dimensional effects of orthopaedic treatment (OT) and myofunctional therapy (MT) on the enlargement of the upper airways (UA).

METHODS

A search of the MEDLINE/PubMed and EMBASE databases was conducted up to July 2022 and completed by hand search. After selection of the title and abstract, systematic reviews (SR) dealing with the impact of OT and/or MT on UA containing only controlled studies were included. The methodological quality of the SR was assessed by the AMSTAR-2, Glenny and ROBIS tools. A quantitative analysis was done with Review Manager 5.4.1.

RESULTS

Ten SR were included. The risk of bias was judged low for one SR according to ROBIS. Two SR presented a high level of evidence according to AMSTAR-2. In the quantitative analysis and about the orthopaedic mandibular advancement therapies (OMA), while a significant increase in superior (SPS) [(Mean difference (MD): 1.19; CI 95% [0.59; 1.78]; P<0.0001)] and middle (MPS) pharyngeal space [(MD: 1.10; CI 95% [0.22; 1.98]; P=0.01)] existed in the short-term for both OMA, it was greater for removable. On the other hand, there was no significant change in the inferior pharyngeal space (IPS). Four other SR targeted the short-term efficacy of class III OT. Only treatments with face mask (FM) or face mask+rapid maxillary expansion (FM+RME) allowed a significant increase in SPS [(MD FM: 0.97; CI 95% [0.14; 1.81]; P=0.02/MD FM+RME: 1.54; CI 95% [0.43; 2.66]; P=0.006)]. This was neither the case for chin cup nor in all cases in IPS. The last two SR explored the effectiveness of RME, whether or not associated with bone anchorage, on the dimensions of the UA or on the reduction of the apnoea/hypopnea index (AHI). A significant superiority of the effects of the devices with mixed or only bone anchorages existed concerning the width of the nasal cavity, the nasal airflow and the reduction of the nasal resistance. But, the qualitative analysis showed no significant reduction in AHI after RME.

CONCLUSIONS

Despite the heterogeneity of the included systematic reviews and their unfortunately not always low risk of bias, this synthesis showed that orthopaedics could provide some short-term improvement in AU dimensions, mainly in the upper and middle areas. Indeed, no devices improved the IPS. Class II orthopaedics improved SPS and MPS; class III orthopaedics, except for the chin cup, improved only SPS. RME, optimised with bone or mixed anchors, mostly improved the nasal floor.

Condylar morphology and position changes after miniscrew-assisted rapid palatal expansion in skeletal Class III malocclusion adult patients with mandibular deviation and unilateral posterior crossbite

BACKGROUND

To evaluate the morphological and positional changes of mandibular condyle after miniscrew-assisted rapid palatal expansion (MARPE) in skeletal Class III malocclusion adult patients with horizontal mandibular deviation (MD).

METHODS

The sample consisted of 15 patients with MD (6 males and 9 females, mean age 21.58 ± 3.12 years). The CBCT scans were taken before and after MARPE immediately. The pre- and post-registered images of the cranial base and mandible were measured, respectively, by Mimics.

RESULTS

After expansion, the distance between superior condylar point and the Frankfort horizontal plane on the deviated side and the non-deviated side increased by 0.96 ± 0.60 mm (P = 0.011) and 0.70 ± 0.65 mm (P = 0.046); coronal condylar angle of the deviated side increased by 0.39° ± 0.34 (P = 0.028) and 0.06° ± 0.49 (P = 0.917) on the non-deviated side. No statistically significant differences were found when comparing the condylar position on both sides before and after treatment. The degree of mandibular deviation decreased 0.43 mm (P = 0.270).

CONCLUSIONS

This study suggested that for skeletal Class III malocclusion adult patients with horizontal MD, the condyle on the deviated side rotated toward the non-deviated side in the coronal direction; the condylar remodeling occurred mainly on the deviated side after MARPE in the vertical direction.

Effectiveness of functional orthodontic appliances in obstructive sleep apnea treatment in children: literature review

INTRODUCTION

Obstructive sleep apnea syndrome is a common condition in childhood and if left untreated can result in many health problems. An accurate diagnosis of the etiology is crucial for obstructive sleep apnea treatment success. Functional orthodontic appliances that stimulate mandibular growth by forward mandibular positioning are an alternative therapeutic option in growing patients.

OBJECTIVE

To perform a literature review about the effects of functional orthodontic appliances used to correct the mandibular deficiency in obstructive sleep apnea treatment.

METHODS

The literature search was conducted in June 2020 using Cochrane Library; PubMed, EBSCO (Dentistry & Oral Sciences Source), LILACS Ovid; SciELO Web of Science; EMBASE Bireme and BBO Bireme electronic databases. The search included papers published in English, until June 2020, whose methodology referred to the types and effects of functional orthopedic appliances on obstructive sleep apnea treatment in children.

RESULTS

The search strategy identified thirteen articles; only four articles were randomized clinical studies. All studies using the oral appliances or functional orthopedic appliances for obstructive sleep apnea in children resulted in improvements in the apnea-hypopnea index score. The cephalometric (2D) and tomographic (3D) evaluations revealed enlargement of the upper airway and increase in the upper airspace, improving the respiratory function in the short term.

CONCLUSION

Functional appliances may be an alternative treatment for obstructive sleep apnea, but it cannot be concluded that they are effective in treating pediatric obstructive sleep apnea. There are significant deficiencies in the existing evidence, mainly due to absence of control groups, small sample sizes, lack of randomization and no long-term results.

A semi-automatic approach for longitudinal 3D upper airway analysis using voxel-based registration

OBJECTIVES

To propose and validate a reliable semi-automatic approach for three-dimensional (3D) analysis of the upper airway (UA) based on voxel-based registration (VBR).

METHODS

Post-operative cone beam computed tomography (CBCT) scans of 10 orthognathic surgery patients were superimposed to the pre-operative CBCT scans by VBR using the anterior cranial base as reference. Anatomic landmarks were used to automatically cut the UA and calculate volumes and cross-sectional areas (CSA). The 3D analysis was performed by two observers twice, at an interval of two weeks. Intraclass correlations and Bland-Altman plots were used to quantify the measurement error and reliability of the method. The relative Dahlberg error was calculated and compared with a similar method based on landmark re-identification and manual measurements.

RESULTS

Intraclass correlation coefficient (ICC) showed excellent intra- and inter-observer reliability (ICC ≥ 0.995). Bland-Altman plots showed good observer agreement, low bias and no systematic errors. The relative Dahlberg error ranged between 0.51 and 4.30% for volume and 0.24 and 2.90% for CSA. This was lower when compared with a similar, manual method. Voxel-based registration introduced 0.05-1.44% method error.

CONCLUSIONS

The proposed method was shown to have excellent reliability and high observer agreement. The method is feasible for longitudinal clinical trials on large cohorts due to being semi-automatic.

Effect of fixed functional appliances on pharyngeal airway dimensions in Skeletal Class II individuals - A scoping review

BACKGROUND

Skeletal Class II malocclusion due to a retrognathic mandible produces a backwardly positioned tongue and soft palate, emanating compromised upper airway dimensions and breathing difficulties.

AIMS

The present review aims to explore and concise the findings of the existing studies assessing the effects of fixed functional appliances on pharyngeal airway dimensions by advancing the mandible.

DESIGN

A literature search was carried out on MEDLINE/PubMed, Cochrane Library, Science direct, Semantic Scholar and Google Scholar databases for studies up to December 2020, resulting in 1037 studies. Specified inclusion/exclusion criteria guided the selection of 18 relevant articles. The sample size, type of the appliance, method of assessment and outcomes of these articles were assessed in detail and tabulated.

RESULTS

Out of 18 studies included, 12 were retrospective longitudinal and the remaining were clinical trials. Majority of the studies (72%) reported a positive influence of the fixed functional appliances on the dimensions of the oropharyngeal and hypopharyngeal airways with minimal effects on nasopharyngeal airway.

CONCLUSION

Thus, it can be concluded that fixed functional appliances have a beneficial effect on the middle and lower pharyngeal airway dimensions by advancing the mandible.

Pharyngeal airway dimensional changes after orthodontic treatment with premolar extractions: A systematic review with meta-analysis

INTRODUCTION

The objective of this research was to evaluate the effect of orthodontic extraction on the pharyngeal airway volume and Minimum cross-sectional area (MCA) in growing and adult patients.

METHODS

Seven databases, unpublished gray literature, and the references list of the identified articles were electronically searched for relevant studies that met our eligibility criteria. Included studies assessed the effect of dental extraction or sagittal dental movements on pharyngeal airway dimensions. The quality of the included studies was assessed using the methodological index for nonrandomized studies. In addition, a meta-analysis was conducted using the RevMan 5 (Nordic Cochrane Centre, Cochrane Collaboration, Copenhagen, Denmark).

RESULTS

In 7 studies, 268 treated patients with a mean age of 19.1 ± 7.6 years and 342 nonextraction control group subjects with a mean age of 19.3 ± 7.2 years were included. Compared with the control group, no statistically significant difference was found in total, nasopharyngeal, glossopharyngeal, oropharyngeal volume, or MCA (P >0.05) in the extraction group except in oropharyngeal volume in which a statistically significant increase in the volume 0.41 cm³ (95% CI, 0.05-0.80; P = 0.03) was detected. The clinical significance of this increase is questionable. Included studies showed a moderate to high risk of bias.

CONCLUSIONS

There is no strong evidence to support the concept that premolar extractions in bimaxillary protrusion or crowded growing and adult patients reduce either pharyngeal airway volume or MCA. Moreover, as the level of evidence was considered very low for all variables, the magnitude, and direction of the summaries have to be interpreted with caution. Future studies with better quality could significantly affect the direction and strength of the results.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42018089924.

Three-dimensional changes of the upper airway in patients with Class II malocclusion treated with functional appliances: a systematic review and meta-analysis

BACKGROUND/OBJECTIVE

To evaluate the three-dimensional (3D) changes of the upper airway in patients with Class II malocclusion treated with functional appliances (FAs).

SEARCH METHODS AND ELIGIBILITY CRITERIA

A comprehensive search of seven electronic databases was conducted from the date of inception to 12 July 2020. Manual search was also performed in relevant Chinese and English periodicals. Prospective and retrospective studies evaluating the 3D airway changes after FAs applied on growing patients with skeletal Class II malocclusion were included.

DATA COLLECTION AND ANALYSIS

Risk of bias assessment of each included study was performed referring to ROBINS-I. The effects of FAs on upper airway were evaluated by meta-analysis using STATA software. The outcome variables were the changes of oropharyngeal airway volumes (OAVs), nasopharyngeal airway volumes (NAVs), minimum cross-sectional area (MCA) and antero-posterior position of hyoid bone (HB). The overall quality of evidence for each outcome was rated based on Grading of Recommendations Assessment, Development and Evaluation recommendations.

RESULTS

Nine studies were ultimately included in the systematic review and five were included and analyzed in meta-analysis. The results indicated that the pooled mean differences among these studies were 2162.80 [95 per cent confidence interval (CI): 1264.97, 3060.62), 382.20 (95 per cent CI: 140.95, 623.44), 59.91 (95 per cent CI: 41.45, 78.38), and 0.63 (95 per cent CI: -1.97, 3.23) for changes of OAVs, NAVs, MCA, and antero-posterior position of HB, respectively.

CONCLUSION

Weak evidence suggests that FAs can increase OAVs, NAVs, and MCA in growing patients with Class II malocclusion. Weak evidence also suggests that antero-posterior position of HB cannot be affected by FAs. Further studies are necessary to assess the stability of its effect on the upper airway in the long term.

REGISTRATION

The review protocol was not registered prior to the study.

Cone beam computed tomographic evaluation of pharyngeal airway in North Indian children with different skeletal patterns

BACKGROUND

In growing patients with skeletal discrepancies, early assessment of functional factors can be vital for the restoration of normal craniofacial growth.

AIM

To compare airway volumes in patients with mandibular retrognathism with the normal anteroposterior skeletal relationship, thereby assessing the association between cephalometric variables and airway morphology.

METHODS

Cone-beam computed tomography volume scans, and lateral cephalograms, 3-dimensional airway volume and cross-sectional areas of 120 healthy children (54 boys and 66 girls mean age 15.19 ± 1.28) which were done for orthodontic assessment were evaluated. The subjects were divided into 2 groups based on the angle formed between point A, Nasion and point B (ANB) values and cephalometric variables (such as anterior and posterior facial height, gonial angle etc.) airway volumes, and cross-sectional measurements were compared using independent t tests. Pearson’s correlation coefficient test was used to detect any relationship of different parts of the airway and between airway volume and 2-dimensional cephalometric variables.

RESULTS

Means and standard deviations for cephalometric, cross-sectional, and volumetric variables were compared. ANB, mandibular body length and facial convexity were statistically highly significant (P < 0.01) whereas condylion to point A, nasal airway and total airway volume (P < 0.05) were statistically significant. The nasal airway volume and the superior pharyngeal airway volume had a positive correlation (P < 0.01), nasal airway was correlated to middle (P < 0.05) and total airway superior had a relation with middle (P < 0.05), inferior and total airway (P < 0.05), middle was related to all other airways; inferior was also related to all the airways except nasal. Lateral cephalometric values were positively correlated with the airway volume with Frankfurt Mandibular Plane Angle and facial convexity showed significant correlations with total airway volume (P < 0.05). Additionally, ANB angle was significantly correlated with total airway volume and superior airway (P < 0.05).

CONCLUSION

The mean total airway volume in patients with retrognathic mandible was significantly smaller than that of patients with a normal mandible.

Volumetric Evaluation of Pharyngeal Airway after Functional Therapy

The aim of this study was to evaluate three-dimensional (3D) effects of Twin-block functional appliance (TB) on the pharyngeal airway by using cone beam computed tomography (CBCT). A total of 30 patients (14 females, 16 males; mean age 12.50 ± 1.23 and 12.83 ± 1.17 years, respectively) with skeletal Class II malocclusion were included in this study and were treated with TB. On the pretreatment (T1) and posttreatment (T2) CBCT scans, volumetric changes in the pharyngeal airway; SNA, SNB, and ANB angles; and bilateral effective mandibular (Co-Gn) and midfacial length (Co-A) were also evaluated. The statistical differences were accessed by Wilcoxon signed-rank tests, and Mann-Whitney U tests were used to analyze the scores of male and female subjects. In this study, an increase was observed in SNB and Co-Gn (p < 0.01) while a decrease in ANB and SNA (p < 0.01 and p < 0.05, respectively) was found. However, increase in midfacial length was not statistically significant (p > 0.05). In the evaluation of volumetric pharyngeal airway changes, statistically significant increases (p < 0.01) in the upper and lower division and total airway volume were determined. Gender differences were insignificant for all measurements (p > 0.05). Volumetric changes in the pharyngeal airway after functional therapy can be successfully evaluated by CBCT images. The anterior repositioning of the mandible by TB increases the mandibular length and pharyngeal airway volume in patients with retrognathic mandible.

Advanced interdisciplinary treatment protocol for pediatric obstructive sleep apnea including medical, surgical, and orthodontic care: a narrative review

OBJECTIVE

To suggest an updated interdisciplinary treatment protocol for pediatric obstructive sleep apnea (POSA) based on the integration of craniofacial growth modification into medical and surgical sleep practice.

METHODS

PubMed, Scopus, and Cochrane library were searched up to February 2020 using keywords. Among 184 articles, 80 studies were finally included. An integrated treatment protocol for POSA encompassing craniofacial skeletal management as well as medical and surgical care was attempted.

RESULTS

A differential diagnostic workflow for identifying the phenotype of POSA was suggested, and a phenotype-based treatment protocol for POSA was proposed. Despite the lack of high level of evidence, timely skeletal growth modification in three dimensions using craniofacial growth potential could be valuable treatment for upper airway development in POSA patients with craniofacial phenotypic cause.

CONCLUSION

A novel precision treatment protocol will advance clinicians to determine the primary option or to apply the combined strategy for POSA patients.

Effect of functional appliances on the airway in Class II malocclusions

The proximity of the orofacial structures to the upper airway has led to enormous interest in their influence on the airway maintenance mechanism. The recognition of Sleep disorders and the evolution of dental sleep medicine has fueled further interest in the role of orthodontic treatment on the airway particularly in Class II malocclusions. With abundant literature on class II malocclusions and growth modification, it is natural that focus would shift on the effect of functional appliances on the airway. Most studies on the subject show an improvement in the airway in response to functional appliances and these include both two dimensional and three dimensional study of the airway. This review showcases the most significant literature on this field of study against the background of the information that is needed to gauge its clinical relevance.

[Morphological change analysis based on cone beam CT of the upper airway for obstructive sleep apnea syndrome patients treated with oral appliance in skeletal class Ⅱ malocclusion with different vertical patterns]

OBJECTIVE

To analyze the morphological changes in the upper airway of obstructive sleep apnea syndrome (OSAS) patients treated with oral appliance in skeletal class Ⅱ malocclusion with different vertical features by using cone beam CT (CBCT).

METHODS

Thirty-six patients diagnosed with OSAS by polysomnography and daytime sleepiness scale and skeletal class Ⅱ malocclusion were treated with oral appliance for 4 months. The changes based on CBCT in the morphology of glossopharyngeal and palatopharyngeal before and after treatment in OSAS patients with different vertical features were compared.

RESULTS

After treatment with oral appliance, the glossopharyngeal and palatopharyngeal morphologies of patients with mild OSAS showed significant changes. After treatment with oral appliance, the glossopharyngeal morphology of all patients showed significant changes (P<0.05). The palatopharyngeal morphology of patients in the lower and average groups also exhibited significant changes (P<0.05). Sagittal changes in the glossopharyngeal measurements of high-angle patients demonstrated significant difference, whereas the other measured values showed no significant difference.

CONCLUSIONS

The morphological changes in the upper airway were significant in OSAS patients with lower and average vertical patterns when treated with oral appliance, but the changes in high vertical patterns were not significant.

Evaluation and quantification of airway changes in Class II division 1 patients undergoing myofunctional therapy using twin block appliance

Background

The purpose of the present study was to determine the airway changes in skeletal class II division 1 malocclusion patients with mandibular retrognathism, treated with Twin-Block (TB) appliance.

Methods

Airway assessment was carried for twelve patients (mean age 11.7 ± 1.1 years) who underwent myofunctional therapy using TB appliance for correction of skeletal class II division 1 malocclusion with mandibular retrognathism. Acoustic pharyngometry (AP) was used to assess and quantify the comparative changes in the upper airway, pretreatment and posttreatment.

Results

Data acquired was subjected to appropriate statistical analysis. The paired 't' test was used to compare pre-treatment (T0) and after the positive pterygoid response (T1). TB appliance increased mean minimum airway area by 0.28 ± 0.25 cm² and mean airway by 0.47 ± 0.44 cm² with 95% CI. Posttreatment minimum airway and mean area changes were found to be statistically significant (P-value<0.01).

Conclusion

TB appliance therapy has a positive effect on upper airway and is beneficial for the treatment of sleep-related disorders associated with Class II division 1 malocclusion for achieving positive functional changes, esthetics, and healthier quality of life.

Changes in Upper Airway Dimensions Following Orthodontic Treatment of Skeletal Class II Malocclusion with Twin Block Appliance: A Systematic Review

Objective

This systematic review intends to evaluate the dimensional changes in upper airway dimensions (UAD) of the respiratory tract subsequent to orthodontic treatment of skeletal Class II malocclusion with Twin Block Appliance (TBA).

Methods

The quality of reporting systematic reviews and meta-analyses was decided by the PRISMA standards with PROSPERO registration number CRD42017060317. The systematic search included EMBASE, MEDLINE, Psych INFO, Scopus, CINAHL, and other reference journals and review articles. The article search was performed from March 2017 until November 2017. Cochrane's risk of bias in non-randomized studies - of interventions (ROBINS-I) was used to grade the methodological quality of the included studies.

Results

The screening procedure identified 302 studies, among which seven studies satisfied the inclusion criteria for eligibility. The UAD at the pretreatment time varied from 7.2 mm to 41.9 mm with a mean of 14.16 mm. The post-treatment change in UAD ranged from 8.2 mm to 43.7 mm with a mean of 15.6 mm.

Conclusion

There was a significant increase in UAD following the TBA treatment in the patient group as compared to the control group.

Three-dimensional changes of the upper airway in patients with Class II malocclusion treated with the Herbst appliance: A cone-beam computed tomography study

INTRODUCTION

This study aimed to determine the volumetric effects on the upper airways of growing patients with Class II malocclusion treated with the Herbst appliance (HA).

METHODS

Volumetric measurements of the upper airways of 42 skeletal Class II malocclusion patients (mean age: 13.8 ± 1.2 years; ranging from 12.0 to 16.9 years) were assessed using cone-beam computed tomography scans acquired before treatment (T0) and approximately 1 year later (T1). The sample comprised a Herbst appliance group (HA group [HAG]; n = 24), and a comparison group (comparison group [CG]; n = 18) of orthodontic patients who had received dental treatments other than mandibular advancement with dentofacial orthopedics.

RESULTS

In CG, nasopharynx and oropharynx volumes decreased slightly during the observation period (9% and 3%, respectively), whereas the nasal cavity volume increased significantly (12%; P = 0.046). In HAG, there was an increase in the volume of all regions (nasal cavity, 5.5%; nasopharynx, 11.7%; and oropharynx, 29.7%). However, only the oropharynx showed a statistically significant increase (P = 0.003), presenting significant volumetric changes along the time (T1-T0) in HAG.

CONCLUSION

Mandibular advancement with the HA significantly increased the volume of the oropharynx, but no significant volumetric modifications were observed in the nasal cavity and nasopharynx.

Effects of functional appliance treatment on pharyngeal airway passage dimensions in Class II malocclusion subjects with retrognathic mandibles: A systematic review

Objective:

The objective of this study was to assess the pharyngeal airway passage (PAP) dimension changes following functional appliance treatment in Class II malocclusion subjects with retrognathic mandibles.

Materials and Methods:

Two authors independently searched various electronic databases such as PubMed, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Scopus, NCBI, and Google Scholar for the available literature within the period from January 1, 2001, to December 31, 2018. On the basis of population, intervention, comparison, and outcome, “changes in PAP dimensions following functional appliance therapy in skeletal Class II malocclusion subjects associated with mandibular retrusion” was considered as search question of the study. After the selection and removal of duplicate articles, assessment for risk of bias was calculated and the data from the included articles were extracted by two authors independently.

Results:

From six databases and additional hand searching, a total of 5784 articles were extracted. Of 5784 articles, 3754 articles were screened after removal of 2030 duplicates. After going through the title and abstract, 3197 articles were excluded and 40 articles were assessed for full text. From these 40 articles, eight articles fulfilled our inclusion and exclusion criteria for the qualitative synthesis review.

Conclusions:

The correction of mandibular deficiency by functional appliances has minimum effect on the nasopharynx. Functional appliance treatment has a significant effect on the improvement of the oropharyngeal airway. Changes of hypopharyngeal airway passage need to be studied further among Class II malocclusion subjects with retrognathic mandibles.

Pharyngeal dimensional changes in class II malocclusion treatment when using Forsus® or intermaxillary elastics - An exploratory study

OBJECTIVE

Pharyngeal airway obstruction can facilitate some forms of sleep disorder breathing (SDB) in susceptible children, especially in those having class II malocclusion. Changes in the anatomic areas surrounding the pharyngeal region during orthodontic treatment could hypothetically impact the pharyngeal airway dimensions. Management of a class II malocclusion on a growing individual with either intermaxillary elastics or different removable or fixed class II appliance designs have been proposed over the last century. The objective of this retrospective exploratory cohort study is to investigate to what extent the class II malocclusion treatment with either intermaxillary elastics (IME) or Forsus® fatigue resistance device (FFRD) leads to changes in oropharyngeal airway dimensions.

MATERIALS AND METHODS

Twenty-nine patients diagnosed as class II with an average age of 12.7years were included in this study, (11 males, 18 females). The sample was divided into group 1: IME and group 2: FFRD. CBCT's scans before (T1) and after treatment (T2) were obtained and analysed using Dolphin software. Reliability was obtained using Intraclass Correlation Coefficient (ICC). Descriptive statistics, ANOVA and paired t-test were used for analysis.

RESULTS

Intra-rater reliability test was excellent in all measurements for both groups. There were no statistically significant differences in pharyngeal airway dimensions between both groups (P=0.919). A statistically significant correlation was found for sex, where male patients had the highest increase in oro-space area (ORS), and in oropharyngeal volume. Children under 14-year-old in IME group showed statistically negative correlation for sub-mandibular (SM) and for ORS, meaning the younger the greatest increase. Additionally, individuals younger than 14years had a statistically significant increase in the vertical dimension.

CONCLUSIONS

Both orthodontic treatment approaches appear to be associated with a similar increase in oropharyngeal airway dimensions. Male patients under 14-year-old had a greater significant increase compared to female patients and older children. Normal pharyngeal dimensions changes were not accounted for.

Evaluation of changes in the upper airway after Twin Block treatment in patients with Class II malocclusion

The purpose of this prospective case control study is to describe in growing patients with mandibular hypoplasia, treatment outcomes following functional therapy in terms of volumetric changes in nasopharynx and oropharynx, that is, upper and lower pharynx. We recruited 60 study participants aged between 8 and 12 years having mandibular Class II malocclusion and a reduced upper airway (UA) size, as determined by McNamara cephalometric analyses. Forty patients received Twin Block treatment, whereas the remaining 20 patients did not receive treatment, thus constituting the control group. The control group included patients who did not start treatment after their first visit but returned for a consultation one or 2 years later. All patients underwent an initial teleradiography examination of the skull and a final teleradiography examination to measure changes using McNamara cephalometric analysis of the UA. Pretreatment and posttreatment changes were assessed using Student's t test for independent samples with a significance level of 0.05. Both anatomical structures analyzed-the upper pharynx (nasopharynx) and lower pharynx (oropharynx)-showed significant increases after treatment regardless of whether the patients were boys or girls. The controls showed a decrease in UA size on average after approximately 2 years of growth. A clear relationship exists between the mandibular advancement achieved with TB treatment and an increased UA size. Therefore, the appliance is considered suitable for improving the respiratory quality of growing patients with a decreased UA size.

Three-dimensional assessment of the pharyngeal airway in Japanese preschoolers with orofacial clefts

OBJECTIVES/HYPOTHESIS

Individuals with orofacial clefts often experience respiratory problems because of nasopharyngeal abnormalities. Pharyngeal airway morphology is thought to differ among the various cleft types. We measured three-dimensional (3D) airway volume using cone-beam computed tomography (CBCT) analysis to evaluate and compare pharyngeal airways in Japanese preschoolers with and without orofacial clefts.

STUDY DESIGN

Retrospective case-control study.

METHODS

We enrolled 83 subjects (37 boys, 46 girls; mean age = 4.66 ± 0.56 years) with nonsyndromic orofacial clefts and 16 noncleft healthy subjects (seven boys, nine girls; mean age = 5.30 ± 0.52 years) as controls. The subjects were divided into five groups. Four groups were based on the cleft type: isolated cleft palate, unilateral cleft lip and alveolus), unilateral cleft lip and palate, and bilateral cleft lip and palate. The fifth group included the noncleft controls. All subjects were examined with CBCT, and the 3D airway volume was measured. We analyzed group differences statistically using analysis of covariance with the Bonferroni post hoc pairwise comparison tests for the corrected means.

RESULTS

Compared with the noncleft group, each cleft group exhibited significantly decreased total and nasal airway volumes and increased superior and inferior pharyngeal airway volumes. The differences were all statistically significant.

CONCLUSIONS

Our findings suggest that anatomical differences exist in pharyngeal airway volumes among various cleft groups and in those without a cleft.

LEVEL OF EVIDENCE

3b Laryngoscope, 130:533-540, 2020.

Reliability of upper pharyngeal airway assessment using dental CBCT: a systematic review

Background

Upper airway analysis is an often-cited use of cone beam computed tomography (CBCT) imaging in orthodontics. However, the reliability of this process in a clinical setting is largely unknown.

Objective

Our objective was to systematically review the literature to evaluate the reliability of upper pharyngeal airway assessment using dental CBCT.

Search methods

MEDLINE, EMBASE, Web of Science, and Google Scholar were searched through June 2015.

Selection criteria

Human studies that measured reliability of upper airway assessment in patients using CBCT as part of the study protocol were considered.

Data collection and analysis

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) was followed. Data were collected on overall study characteristics and measurements, CBCT unit and machine settings used, and examination characteristics of the included studies. Methodological quality of the included studies was evaluated.

Results

Forty-two studies were evaluated, representing the CBCT scans of 956 patients. Studies included a wide variety of patients and CBCT machines with various scan settings. Only five studies were deemed high quality. The available evidence indicates that under specific restricted conditions there is moderate to excellent intra- and inter-examiner reliability. Airway volume demonstrated greater intra- and inter-examiner reliability than did minimum cross-sectional area. However, significant methodological limitations of the current literature, most importantly a lack of manual orientation of the images and selection of threshold sensitivity in study protocols, suggest that reliability has not been adequately established.

Conclusions

The current literature reports moderate to excellent reliability, with airway volume having higher reliability than minimum cross-sectional area. However, only limited aspects of the process of airway analysis have been evaluated, indicating that further research is required to adequately establish the reliability of upper pharyngeal airway assessment of patients using dental CBCT.

Registration

None.

Cone-beam evaluation of pharyngeal airway space in adult skeletal Class II patients with different condylar positions

OBJECTIVES

To test the null hypothesis that there is no significant difference in pharyngeal airway space among adult skeletal Class II patients with different condylar positions using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The CBCT records of 60 patients with skeletal Class II malocclusion (ANB angle ≥ 4°, Wits ≥ 0) were selected from the CBCT database. According to the condyle position, the patients were divided in three groups: anterior group (CD ≤ -12%), centric group (-12% ≤ CD ≤ +12%), and posterior group (CD ≥ +12%). Three-dimensional (3D) pharyngeal airway models were reconstructed using InvivoDental software 5.1.3. The volume and area of the pharyngeal airway space were measured in the 3D airway model.

RESULTS

The volume and area of the pharyngeal airway space in the centric group were significantly smaller than those in the posterior group ( P < .01). The volume and area of the pharyngeal airway space were smallest in the anterior group and significantly increased in the centric and posterior groups ( P < .001).

CONCLUSIONS

The null hypothesis was rejected. Significant differences were noted in pharyngeal airway space among adult skeletal Class II patients with different condylar positions.

Patterns of adenoid and tonsil growth in Japanese children and adolescents: A longitudinal study

Lymphoid tissues, such as adenoids (Ad) and tonsils (Tn), are suggested to undergo hypertrophy during childhood and involution in adulthood. Enlargement of Ad and Tn can cause transient obstruction of the respiratory airways, thus inducing obstructive sleep apnoea. To date, the standard Ad and Tn sizes have not been reported, and there are no explicit objective criteria for evaluating their sizes or deducing whether they have enlarged, reduced, or remained constant over time. Our previous cross-sectional study revealed the age-dependent airway occupation ratio of Ad and Tn in Japanese individuals. We conducted a longitudinal observational study of the Ad and Tn sizes in Japanese individuals aged 6–20 years. Ninety individuals were retrospectively enrolled. The average and standard deviation of the sizes was calculated in 5 age-based groups.

Comparison of pharyngeal airway volume in different skeletal facial patterns using cone beam computed tomography

Background

This study aimed to compare the pharyngeal airway volume in class I,II and III skeletal malocclusion patients using cone beam computed tomography (CBCT).

Material and Methods

This retrospective, cross sectional study was conducted on lateral cephalograms of 71 patients derived from their CBCT scans. Using the ANB angle, the patients were divided into class I,II and III malocclusion. Two observers used Dolphin 3D software to calculate the pharyngeal airway volume, airway area, minimum axial area, minimum area location, airway length and morphology. Data were analyzed using one-way ANOVA, Kruskal-Wallis test, Tukey’s test, Spearman’s correlation coefficient and multiple regression analysis.

Results

The three skeletal classes were significantly different in airway volume, minimum axial area, mean airway area and airway morphology (P<0.05). Significant differences were found in airway volume and mean airway area between class II and III patients (P<0.05). The minimum axial area and airway morphology in class III patients were greater than those in class I and II patients (P<0.05). Every one unit increase in the ANB angle decreased the airway volume by 0.261 units. The effect of ANB angle on airway volume was statistically significant and it was shown that one unit increase in the angle decreased the airway volume by 453.509 units.

Conclusions

A significant correlation exists between the skeletal facial pattern and upper airway dimensions. In our study, the total airway volume and the mean airway area of class III patients were larger than those in class II patients.

Key words:Cone-Beam computed tomography, malocclusion, pharyngeal airway volume.

Changes in airway dimensions following functional appliances in growing patients with skeletal class II malocclusion: A systematic review and meta-analysis

OBJECTIVES

The purpose of the study was to evaluate the treatment effects of functional appliances (FAs) on upper airway dimensions in growing Class II patients with mandibular retrognathism.

METHODS

Five databases and the references of identified articles were electronically searched for relevant studies that met our eligibility criteria. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. The effects of FAs on airway dimensions were combined by meta-analysis using the RevMan and STATA software.

RESULTS

Seven studies (177 treated patients with mean age: 11.48 years and 153 untreated controls with mean age: 11.20 years) were included in this review. Compared to the control group, the oropharyngeal dimensions in the treatment group subjects were significantly increased at the superior pharyngeal space (MD = 1.73 mm/year, 95% CI, 1.13-2.32 mm, P < 0.00001), middle pharyngeal space (MD = 1.68 mm/year, 95% CI, 1.13-2.23 mm, P < 0.00001) and inferior pharyngeal space (MD = 1.21 mm/year, 95% CI, 0.48-1.95 mm, P = 0.001). No significant differences were found in nasopharyngeal and hypopharyngeal dimensions and the position of hyoid bone (P > 0.05). Soft palate length and soft palate inclination were improved significantly in the treatment group (P < 0.05).

CONCLUSIONS

The results showed that FAs can enlarge the upper airway dimensions, specifically in the oropharyngeal region, in growing subjects with skeletal Class II malocclusion. The early intervention for mandibular retrognathism with FAs may help enlarge the airway dimensions and decrease potential risk of obstructive sleep apnea syndrome for growing patients in the future.

Three-dimensional analysis of upper airway morphology in skeletal Class III patients with and without mandibular asymmetry

OBJECTIVE

To compare the three-dimensional (3D) morphology of the upper airway in skeletal Class III patients with and without mandibular asymmetry and to investigate the possible underlying correlations between the morphology of the upper airway and mandibular deviation.

MATERIALS AND METHODS

Cone-beam computed tomography images of 54 subjects with skeletal Class III malocclusion (ANB angle ≤ 0.4°, Wits ≤ -5.5°) were taken and 3D upper airway models were reconstructed using Dolphin 3D software. According to the distance (d) from symphysis menti to the sagittal plane, all subjects were divided into a symmetry group (d ≤ 2 mm) and an asymmetry group (d ≥ 4 mm). Based on the severity of mandibular deviation, the asymmetry group was divided into subgroup I (4 mm ≤d <10 mm) and subgroup II (d ≥ 10 mm). Cross-sectional linear distances, areas, and volumetric variables of the upper airway were measured in the 3D airway model.

RESULTS

Width of the inferior limit of the glossopharynx (P3W), cross-sectional area of the anterior limit of the nasal airway (P5S), and height of the glossopharynx (GPH) in the asymmetry group were significantly larger than in the symmetry group. As for subjects with severe mandibular deviation in subgroup II (d ≥ 10 mm), volume of the glossopharynx (GPV), total volume of the pharynx (TPV), length of the inferior limit of the velopharynx (P2L), and ratio of length to width of the inferior limit of the velopharynx (P2L/P2W) showed significantly negative correlations with mandibular deviation (r > 0.7, P < .05).

CONCLUSIONS

In Class III subjects with severe mandibular asymmetry, the pharyngeal airway showed a tendency toward constriction and presented a more elliptical shape as mandibular deviation became more severe (P < .01).

Effect of functional appliances on the airway dimensions in patients with skeletal class II malocclusion: A systematic review

OBJECTIVES

The aim of the present systematic review was to assess the effect of functional appliances on the airway dimensions in patients with skeletal Class II malocclusion.

MATERIALS AND METHODS

Articles were identified through a literature survey carried out through the following databases: (1) PUBMED, (2) Google Scholar, (3) The Cochrane Library, (4) Embase, (5) Lilac, and (6) Web of Scholars. The systematic review analyzed 12 articles comprising removable functional appliances, 3 articles with fixed functional appliances, and 2 articles having both fixed and removable functional appliances.

RESULTS

Qualitative assessment was done for all the 17 studies. The effect of functional appliances in the dimensions of three airway spaces - nasopharynx, oropharynx, and hypopharynx were analyzed.

CONCLUSIONS

Significant increase in the dimensions of nasopharynx and oropharynx was observed with Activator. Significant increase in the nasopharynx and hypopharynx (male patients) was observed with Bionator. Insignificant increase in the oropharynx was observed with the same. Significant increase in the oropharynx and hypopharynx was observed with Twin Block. Insignificant increase in the nasopharynx was observed with the same. Significant increase was observed only in the hypopharynx for Frankel II. Decreased or insignificant change was observed with FMA, MPA IV, and Herbst appliances.

Effects of two different removable functional appliances on depth of the posterior airway space : A retrospective cephalometric study

OBJECTIVES

Aim of the study was the comparison of treatment effects upon pharyngeal depth in patients treated with either (1) S-II-appliance or (2) Activator.

METHODS

Pre- and posttreatment lateral cephalograms of 73 patients were analyzed using a customized set of measurements. According to predefined criteria, patients were either treated with S-II-appliance or Activator. Pharyngeal depth was assessed from cranial to caudal at six levels (P1 to P6). Paired t tests were used for intragroup and t tests for independent samples for intergroup comparisons. Results were considered statistically significant at p ≤ 0.05.

RESULTS

37 (22 female, 15 male) patients were treated with the S-II-appliance (mean pretreatment age 11.1 ± 1.07 years), and 36 (20 female, 16 male) patients with an Activator (mean pretreatment age 11.3 ± 1.12 years). Mean treatment time was 14 months for the S-II-appliance and 12 months for the Activator. Most measurements at the different levels showed an average increase ranging from approximately 0.5 mm to almost 2 mm. Changes were more pronounced in S-II patients. In contrast to intergroup comparisons, some intragroup comparisons revealed statistically significant differences at levels P5 (p = 0.0062) and P6 (p = 0.0155) in S-II patients and at P1-level (p = 0.0197) in Activator patients.

CONCLUSIONS

Both appliances similarly led to an increase of the pharyngeal depth. The sites of statistically significant changes differed.

Upper airway changes following single-step or stepwise advancement using the Functional Mandibular Advancer

OBJECTIVES

Purpose of the present study was to determine and compare possible changes in the dimensions of the pharyngeal airway, morphology of the soft palate, and position of the tongue and hyoid bone after single-step or stepwise mandibular advancement using the Functional Mandibular Advancer (FMA).

PATIENTS AND METHODS

The sample included 51 peak-pubertal Class II subjects. In all, 34 patients were allocated to two groups using matched randomization: a single-step mandibular advancement group (SSG) and a stepwise mandibular advancement group (SWG). Both groups were treated with FMA followed by fixed appliance therapy; the remaining 17 subjects who underwent only fixed appliance therapy constituted the control group (CG). The study was conducted using pre- and posttreatment lateral cephalometric radiographs. Data were analyzed by paired t test, one-way analysis of variance, and Pearson's correlation coefficient.

RESULT

In the SWG and SSG, although increases in nasopharyngeal airway dimensions were not significant compared with those in the CG, enlargements in the oropharyngeal airway dimensions at the level of the soft palate tip and behind the tongue, and decreases in soft palate angulation, were significant. Tongue height increased significantly only in the SWG. Compared with the CG, while forward movement of the hyoid was more prominent in SSG and SWG, the change in the vertical movement of the hyoid was not significant. No significant difference between SWG and SSG was observed in pharyngeal airway, soft palate, tongue or hyoid measurements.

CONCLUSIONS

The mode of mandibular advancement in FMA treatment did not significantly affect changes in the pharyngeal airway, soft palate, tongue, and hyoid bone.

Accuracy of a Real-Time, Computerized, Binocular, Three-Dimensional Trajectory-Tracking Device for Recording Functional Mandibular Movements

Objective

Developments in digital technology have permitted researchers to study mandibular movements. Here, the accuracy of a real-time, computerized, binocular, three-dimensional (3D) trajectory-tracking device for recording functional mandibular movements was evaluated.

Methods

An occlusal splint without the occlusal region was created based on a plaster cast of the lower dentition. The splint was rigidly connected with a target on its labial side and seated on the cast. The cast was then rigidly attached to the stage of a high-precision triaxial electronic translator, which was used to move the target-cast-stage complex. Half-circular movements (5.00-mm radius) in three planes (XOY, XOZ, YOZ) and linear movements along the x-axis were performed at 5.00 mm/s. All trajectory points were recorded with the binocular 3D trajectory-tracking device and fitted to arcs or lines, respectively, with the Imageware software. To analyze the accuracy of the trajectory-tracking device, the mean distances between the trajectory points and the fitted arcs or lines were measured, and the mean differences between the lengths of the fitted arcs’ radii and a set value (5.00 mm) were then calculated. A one-way analysis of variance was used to evaluate the spatial consistency of the recording accuracy in three different planes.

Results

The mean distances between the trajectory points and fitted arcs or lines were 0.076 ± 0.033 mm or 0.089 ± 0.014 mm. The mean difference between the lengths of the fitted arcs’ radii and the set value (5.00 mm) was 0.025 ± 0.071 mm. A one-way ANOVA showed that the recording errors in three different planes were not statistically significant.

Conclusion

These results suggest that the device can record certain movements at 5.00 mm/s, which is similar to the speed of functional mandibular movements. In addition, the recordings had an error of <0.1 mm and good spatial consistency. Thus, the device meets some of the requirements necessary for recording human mandibular movements.

Analogue simulation of pharyngeal airflow response to Twin Block treatment in growing patients with Class II(1) and mandibular retrognathia

The flow dynamics of respiratory airflow is the basic factor that influences the ventilation function of the upper airway. This research aimed to investigate the pharyngeal flow field characteristics after Twin Block (TB) treatment in growing patients with Class II(1) and mandibular retrognathia by computation fluid dynamics (CFD) simulation. Cone beam computed tomography (CBCT) scans of patients who have completed TB treatment (n = 30) and about to accept TB treatment (n = 30) were reconstructed. After CFD simulation, correlations between the pharyngeal pressure drop and morphological parameters were further analyzed. During inspiration, we found that the pressure minimum occurred in the hypopharynx, while the maximum pressure drop and velocity was located in the oropharynx. After TB treatment, the oropharynx and hypopharynx showed significant differences in airflow features, and the most obvious change was observed in the oropharynx. A significant correlation was discovered between the change amount of oropharyngeal pressure drop and volume (r = 0.694, p = 0.001), mean cross-sectional area (r = 0.859, p = 0.000), and ratio of the minimum and mean cross-sectional area (r = 0.898, p = 0.000) of the oropharynx. Our research suggested that the pharyngeal airflow characteristics response positively to mandibular advancement with the enlargement in volume, cross-sectional area and more uniform oropharyngeal area distribution.

How has our interest in the airway changed over 100 years?

Since the beginning of our specialty, our understanding of the link between function and facial growth and development has progressively improved. Today, we know that children with sleep-related breathing problems will often develop distinctive facial characteristics. In adults, sleep apnea can result in serious morbidity and mortality. Orthodontists can ask sleep-related questions in the health history to help identify sleep breathing disorders. Treating these patients presents unique opportunities for orthodontists to collaborate with other medical specialties to improve a patient's health and treatment outcome. Research presented in our Journal in the next century may shed new light that will help us better identify the problem and aid the specialty in developing more effective evidence-based treatment. Additional efforts are needed to understand the physiology, neurology, and genetics of sleep breathing disorders.

The nasal septum deviation index (NSDI) based on CBCT data

OBJECTIVE

To assess whether three-dimensional morphometric parameters could be useful in nasal septal deviation (NSD) diagnosis and, secondarily, whether CBCT could be considered an adequate imaging technique for the proposed task.

METHODS

We analysed images of 46 subjects who underwent CBCT for reasons not related to this study. Two experienced operators divided all the images into healthy and NSD subjects. Subsequently, the images were segmented using ITK Snap in order to obtain the three-dimensional model of the nasal airways and compute four morphological parameters: septal deviation angle (SDA), percentage of volume difference between right and left side of the nasal airways, nasal airway total volume and a new synthetic septal deviation index (SDI). Principal component analysis (PCA) was used to unveil relationships between each variable and the global nasal airway variability.

RESULTS

Differences between the groups were found in SDA (p < 0.001), in volume percentage difference (p < 0.05) and in SDI (p < 0.001). PCA showed high correlation between the SDI and the first principal component (0.97, p < 0.001).

CONCLUSIONS

Among the analysed parameters, SDI seemed to be the most suitable for the quantitative assessment of NSD, and CBCT allowed accurate assessment of airway morphology.