Three-dimensional cone-beam computed tomography analysis of enlargement of the pharyngeal airway by the Herbst appliance

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.

Comparison between twin block appliance and mandibular advancement on clear aligners in the improvement of airway dimension: incremental versus maximum bite advancement

Objective

The aim of the present retrospective study was to compare the changes resulting from treatment using the MA and the TB with special regard to the oro-and naso-pharyngeal sagittal airway dimensions in subjects with dentoskeletal Class II malocclusions and positive history of Sleep Disorder Breathing (SDB) diagnosed through the Pediatric Sleep Questionnaire (PSQ).

Materials and methods

This retrospective study involved 2 groups of subjects: patients treated with Twin Block (TB group: n = 22, 10 males, 12 females; mean age 12.0 ± 1.3 years) and patients treated with Mandibular Advancement (MA group: n = 23, 11 males, 12 females; mean age 12.2 ± 1.1 years). Pretreatment (T1) and posttreatment (T2) lateral cephalograms were analyzed. All patients underwent the PSQ to diagnose SDB.

Results

In both treated groups there was an increase in the airways dimensions and an improvement in symptoms related SDB. The statistical comparison of the changes between T1 and T2 in the TB group showed a significant increment in upper airway size (PNS-AD2, +1.50 mm + -3.30; McNamara's upper pharynx dimension, +2.21 + -4.21) after active treatment. The MA group showed similar results during active treatment with a significant increase in both upper (PNS-AD2, +2.72 + -2.65; McNamara's upper pharynx dimension, +2.97 + -3.07) and lower (PNS-AD1, +2.17 mm + -3.54) airway size.

Conclusions

Despite the different structure of these two devices and the different advancement protocols, both appliances were valuable as a suitable treatment option for Class II patients with respiratory disorders, inducing an increase of upper and lower airway size and a significant reduction in diurnal symptoms.

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.

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.

Effects of Elastodontic Appliance on the Pharyngeal Airway Space in Class II Malocclusion

BACKGROUND

The present study analyzed the changes obtained on the upper airway and hyoid bone dimensions in a group of patients with skeletal Class II malocclusion treated with functional elastodontic devices compared to an untreated control group.

METHODS

A group of 33 patients (19 females and 14 males) with Class II malocclusion treated with AMCOP^® SC elastodontic device was compared with a control group of 35 subjects (17 females and 18 males) with untreated Class II malocclusion. Lateral cephalograms were available at the start (T0) and end of treatment/period of observation (T1). Cephalometric analysis was performed and linear measurements to evaluate airway space and hyoid bone position were also obtained. A multivariate analysis of variance for repeated measures (MANOVA) was performed to determine the effects of interactions for the groups for time.

RESULTS

Statistically significant differences were found in the study group from T0 and T1 with an improvement of superior upper airway (SPAS p < 0.0001), while in the control group it did not change in a statistically significant way from T0 to T1. The MANOVA test showed statistically significant differences between the two groups for the changes of SPAS (p = 0.003), IAS (p = 0.049), and H-C3 vertical (p = 0.038) values.

CONCLUSIONS

Functional elastodontic therapy produced significant favorable airway changes in skeletal class II subjects.

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.

Effects of Rapid Maxillary Expansion on Upper Airway Volume in Growing Children: A Three-Dimensional Cone-Beam Computed Tomography Study

Background: Rapid maxillary expansion (RME) is a common orthodontic procedure that widens the maxillary arch to treat moderate to mild overcrowding and transverse skeletal and dental abnormalities. Orthodontic equipment applies lateral tension on posterior maxilla teeth or palate mucosa to the mid-palatal suture. The maxilla may grow transversely when force is applied at right angles to the mid-palatal suture, which is usually inactive in children and adolescents. This study used cone-beam computed tomography (CBCT) and an authorized upper respiratory airway volume measurement approach to compare RME cohort pharyngeal airway volume changes to healthy controls. Materials and Methods: This retrospective analysis included 52 RME patients and 52 healthy controls. The RME category's expansion regimen entailed twisting the screw of expansion on a tooth-attached Hyrax-type expansion equipment by 0.25 mm daily for at least 14 days. After six months, a few RME participants used fixed orthodontic gear. The comparison group used fixed orthodontic appliances for minor malocclusions without extractions (without RME). CBCT scans from 1021 orthodontic patients who visited a dental hospital between 2012 and 2022 were examined. The registry comprised only anonymized photographs. Volume, minimum cross-sectional area (MCA), molar width, and inter-molar width were measured before and after therapy. Results: The control group had 12227.12 mm³ at T0 and 15805.54 mm³ at T1. The control group's T0-T1 volume difference was statistically significant (p = 0.007). The RME group has 12884.84 mm³ at T0 and 17471.08 mm³ at T1. The RME group had a significant volume difference at T0 and T1 (p = 0.002). The volume RME effect was ±1011.92 and statistically insignificant. (p > 0.05). MCA in the control group was 126.04 mm² at T0 and 170.61 mm² at T1. MCA at T0 and T1 in the control group was statistically significant (p = 0.041). RME group MCA was 126.53 mm³ at T0 and 164.69 mm² at T1. The RME group had a significant volume difference at T0 and T1 (p = 0.002). The MCA, RME effect was 5.92 and statistically insignificant (p > 0.05). Both the control and RME groups had statistically significant volume and MCA differences at T0 and T1. However, the intergroup analysis showed no significant differences across the groups. Conclusion: Tooth-borne RME does not affect upper airway or MCA volume in children compared to controls. Upper airway changes were better with younger skeletal ages before treatment. The findings may aid RME for young children.

Changes in Cone-Beam Computed Tomography Pediatric Airway Measurements After Adenotonsillectomy in Patients With OSA

Importance

Early intervention using cone-beam computed tomography (CBCT) and adenotonsillectomy for children with obstructive sleep apnea (OSA) may prevent impaired growth, adverse cardiovascular consequences, learning deficits, and poor quality of life.

Objective

To assess changes in CBCT airway measurements and polysomnography (PSG) parameters that occur after adenotonsillectomy in children with OSA and to determine whether CBCT changes are correlated with apnea-hypopnea index (AHI) reduction.

Design, Setting, and Participants

This prospective cohort study was conducted at a tertiary medical center from 2013 to 2016. Children aged 7 to 13 years with PSG-confirmed OSA (ie, AHI ≥1) were recruited. Data analysis was performed from March to July 2021.

Exposures

All participants underwent CBCT and PSG before and after adenotonsillectomy.

Main Outcomes and Measures

Changes in PSG and CBCT parameters after adenotonsillectomy were analyzed.

Results

A total of 49 children (mean [SD] age, 9.5 [1.8] years; 34 boys [69.4%]) were recruited. Eighteen participants (36.7%) had obesity. After adenotonsillectomy, AHI significantly decreased from 11.4 to 1.2 events per hour (mean difference, -10.24 events per hour; 95% CI, -13.84 to -6.64 events per hour). The following CBCT parameters significantly increased: total airway volume (from 11 265 to 15 161 mm3; mean difference, 3896.6 mm3; 95% CI, 2788.0 to 5005.2 mm3), nasopharyngeal volume (from 2366 to 3826 mm3; mean difference, 1459.7 mm3; 95% CI, 1122.9 to 1796.5 mm3), minimal nasopharyngeal airway area (from 128 to 191 mm2; mean difference, 63.1 mm2; 95% CI, 47.4 to 78.8 mm2), mean nasopharyngeal airway area (from 144 to 231 mm2; mean difference, 86.8 mm2; 95% CI, 67.0 to 106.5 mm2), oropharyngeal volume (from 8898 to 11 335 mm3; mean difference, 2436.9 mm3; 95% CI, 1477.0 to 3396.8 mm3), minimal oropharyngeal airway area (from 82 to 158 mm2; mean difference, 76.2 mm2; 95% CI, 57.0 to 95.4 mm2), and mean oropharyngeal airway area (from 182 to 234 mm2; mean difference, 52.5 mm2; 95% CI, 33.6 to 71.4 mm2). Among all parameters, only body mass index percentile showed large effect size between the group with residual OSA (postoperative AHI ≥1) and the group with resolved disease, with the residual OSA group having a higher body mass index percentile (87.8 vs 61.4; mean difference, 26.33; 95% CI, 10.00 to 42.66). A quantile regression model revealed that total airway volume and minimal oropharyngeal airway area were significantly correlated with reductions in AHI.

Conclusions and Relevance

These findings suggest that in children undergoing adenotonsillectomy, improvements in total airway volume and oropharyngeal minimal airway area were correlated with reduction of AHI. Future studies are needed to assess whether CBCT has a role in the evaluation of children with OSA who are being considered for adenotonsillectomy.

Comparison of oropharyngeal airway dimensional changes in patients with skeletal Class II and Class III malocclusions after orthognathic surgery and functional appliance treatment: A systematic review

Objective

To compare the dimensional changes in the oropharyngeal airway in patients with skeletal Class II and Class III malocclusion before and after orthognathic surgery and treatment with a functional appliance.

Methods

The protocol was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) and was registered to the International Prospective Register of Systematic Reviews (PROSPERO) under the registration number CRD42020170901. Furthermore, the reporting of the present SR was performed based on the PRISMA checklist.

Results

The use of removable functional appliances increased the volume of the oropharyngeal airway in patients with skeletal Class II malocclusion. Furthermore, the increase in the volume of the oropharyngeal airway following the removable functional appliance treatment was more than that observed after fixed functional appliance treatment in growing patients. For patients with skeletal Class III malocclusion, who underwent the bimaxillary orthognathic surgery, resulted in no change in the dimensions of the oropharyngeal airway.

Conclusion

Growing patients who receive removable functional appliance treatment have a more favorable long-term prognosis with regard to the oropharyngeal airway when compared with those who receive fixed functional appliance. Alternatively, in patients aged from (18–22) years with skeletal class III malocclusion Bimaxillary orthognathic surgery was found to be the recomended and superior method of treatment.

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.

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.

Changes of epiglottis and hyoid bone position after orthodontic treatment with cast splint fixed functional appliances

OBJECTIVES

Angle Class II malocclusions including a retrognathic mandible are the most frequent orthodontic problems. Both removable and fixed functional appliances can be used for mandibular advancement. Mandibular advancement after treatment with any fixed functional appliance has numerous therapeutic effects, such as stretching of masticatory muscles, ligaments, membranes and surrounding soft tissues, thus causing positional changes of the hyoid bone and epiglottis. This retrospective study investigates and compares treatment effects upon epiglottis- and hyoid bone position and posterior airway space in class II patients who received mandibular advancement through two different cast splint fixed functional appliances.

MATERIAL AND METHODS

Two groups of 21 patients each ('Functional Mandibular Advancer' (FMA) and Herbst appliance) were investigated. The same experienced orthodontist performed the treatment in all patients, employing a single-step advancement protocol. The mandible always received initial protrusion into an edge-to-edge position. Conventional lateral cephalograms were available pre-treatment (T1) and immediately after appliance removal (T2) for all patients. The measurements comprised (I) hyoid bone, (II) epiglottis or (III) posterior airway space. Treatment-related changes were analysed with one-sample Student's t tests for intragroup comparisons and independent Student's t tests for intergroup comparisons. Statistical significance was set at p < 0.05.

RESULTS

Measurements of the hyoid bone showed mostly increases for both appliances after treatment. Intergroup comparisons were not significant for FMA patients but significant for selected measurements in Herbst appliance patients. Intergroup comparisons showed insignificant changes. The posterior airway space was always insignificantly increased after treatment. The greatest increase was found caudally. Intergroup comparisons showed insignificant changes.

CONCLUSIONS

Both fixed functional appliances cause an anterior and caudal displacement of epiglottis and hyoid bone and enlarge the posterior airway space. The therapeutic effects of the Herbst appliance are slightly larger, although not significantly.

CLINICAL RELEVANCE

Treatment with either Herbst appliance of FMA alters the hyoid bone position and enlarges the posterior airway space. Still, long-term data are as yet unavailable; it remains unknown if the effects upon posterior airway space remain stable, and if a resulting posterior airway space enlargement may have clinical influence upon obstructive sleep apnoea syndrome.

Changes in the upper airway, hyoid bone and craniofacial morphology between patients treated with headgear activator and Herbst appliance: A retrospective study on lateral cephalometry

Background

The present study compared the treatment changes in the upper airway, hyoid bone position and craniofacial morphology between two groups of children with skeletal class II malocclusion treated with the headgear activator (HGA) and Herbst appliance (Herbst).

Setting and sample population

Orthodontic population from the Faculty of Dentistry of the University of Hong Kong.

Methods

Thirty‐four skeletal class II patients treated with the HGA (17 patients, mean age 10.6 ± 1.5 years) and the Herbst (17 patients, mean age 11.0 ± 1.4 years) were matched for sex, age, overjet, skeletal class and mandibular divergence. The patients received lateral cephalometric radiographs (LCRs) at the beginning of treatment (T₁), after treatment (T₂) and at follow‐up (T₃). In the HGA group, patients underwent LCRs 7 months before the beginning of treatment (T₀), which were used as growth reference for intra‐group comparison. Paired Student's t tests were used for intra‐ and inter‐group comparisons (α = .05).

Results

Treatment changes (T₂‐T₁) did not differ significantly between the groups. However, at follow‐up (T₃‐T₁) the Herbst group showed a smaller increase than the HGA group in the vertical position of the hyoid bone relative to the Frankfort plane (P = .013) and mandibular plane (P = .013).

Conclusions

There were no significant differences in the upper airway, hyoid bone position and craniofacial morphology between the groups at the end of treatment. However, the Herbst may provide better long‐term control of the vertical position of the hyoid bone than the HGA in children with skeletal class II malocclusion.

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.

Evaluation of the upper airway dimensions following Herbst appliance treatment in adolescents: A retrospective study

Objectives:

This retrospective study investigated dimensional changes in the upper airway following Herbst appliance therapy in adolescents with Class II malocclusion and compared those changes with growth data.

Materials and Methods:

Lateral cephalograms from 44 Herbst-treated adolescents (23 boys, mean age = 13.3 ± 1.1 years, and 21 girls, mean age = 12.6 ± 1.1 years) were analyzed for the changes in the upper airway and craniofacial variables. Longitudinal cephalometric data of 34 untreated adolescents (15 boys, mean age = 12.6 ± 0.3 years, and 19 girls, mean age = 12.9 ± 0.4 years) were used as growth data for comparison.

Results:

Following treatment, significant changes were noted in most of the variables. Boys displayed greater downward movement of the hyoid bone than girls did (P = 0.021). Compared with the growth data, a greater increase in retroglossal oropharyngeal depth and hypopharyngeal depth was observed in boys and girls, respectively. Both displayed a decrease in the inclination of the soft palate and a smaller change in nasopharyngeal depth.

Conclusion:

Herbst appliance therapy enlarges the upper airway dimensions at two dissimilar sites in girls (oropharynx) and boys (hypopharynx). Boys display a greater increase in anterior and posterior facial heights than girls do, potentially accounting for the site dissimilarities. Moreover, a Herbst appliance improves the inclination of the soft palate and restricts the growth of the nasopharynx in both boys and girls.

A cross-sectional retrospective study of normal changes in the pharyngeal airway volume in white children with 3 different skeletal patterns from age 9 to 15 years: Part 1

INTRODUCTION

This study investigated correlations between airway size and age, sex, and skeletal patterns; identified airway change trends; and measured volumetric norms in children via cone-beam computed tomography.

METHODS

Four hundred twenty nontreated white patients were stratified by age, sex, and anteroposterior skeletal pattern. The nasopharyngeal airway (NPA), oropharyngeal airway (OPA), and total pharyngeal airway (TPA) volumes were delineated on 3-dimensional digital cephalograms. SPSS (SPSS, Chicago, Ill) was used to run an analysis of variance and post-hoc analyses.

RESULTS

The Class III group had significantly larger OPA volumes than Class I and II groups. Male subjects had considerably larger NPA volumes than female subjects. Age was significantly associated with all 3 airway volumes (P <0.05). The young cohort (ages, 9-10 years) had a mean TPA of 11,435.34 ± 484.45 mm³, the middle cohort (ages, 11-13 years) had a mean TPA of 14,152.07 ± 395.46 mm³, and the older cohort (ages, 14-15 years) had a mean TPA of 18,057.99 ± 484.25 mm³.

CONCLUSIONS

An effect of skeletal classification on OPA and a sex effect on NPA were observed. The annual change in the mean of TPA volume decreased in subjects aged 10-12 years, then rebounded until 14 years. TPA change peaked in female subjects 1 year before male subjects.

Changes in pharyngeal airway dimensions following incremental and maximum bite advancement during Herbst-rapid palatal expander appliance therapy in late adolescent and young adult patients: a randomized non-controlled prospective clinical study

OBJECTIVES

This was a parallel, assessor-blinded, randomized, non-controlled prospective trial with the objective to evaluate and compare the effects of maximum advancement (MA) and incremental advancement (IA) of mandible with cast-splint-type Herbst-rapid palatal expander (RPE) appliance on pharyngeal airway dimensions and hyoid bone position in skeletal Class II late adolescents and young adults.

MATERIALS AND METHODS

A total of 48 patients (19 male and 29 female, mean age: 15.45 ± 1.42 years) with skeletal Class II malocclusion were treated with cast-splint Herbst-RPE appliance. Inclusion criteria were skeletal Class II malocclusion, mandibular retrognathia, bilateral Class II molar and canine relationship, increased overjet, normal or decreased vertical dimensions, minimal crowding, and no missing teeth. Enrolled subjects were randomly allocated into two groups according to mandibular advancement type: IA and MA Herbst-RPE therapy. The outcome assessor was blinded. Advancement in MA group was adjusted until tête-à-tête incisor relationship or super Class I molar relationship was obtained. Initial forward movement in IA group was 4-5 mm and followed by bimonthly 2 mm of subsequent advancements. Skeletal, pharyngeal airway, and hyoid measurements were performed using lateral cephalometric films. Statistical significance was set at P value of less than 0.05.

RESULTS

Hypopharyngeal airway dimensions (P < 0.000), oropharyngeal airway dimensions (P < 0.001, P < 0.007), and PASmin values (P < 0.010, P < 0.009) were increased and soft palate angle (P < 0.018, P < 0.007) was decreased in MA and IA groups significantly. Hyoid bone measurements revealed a significant difference in H-Cv2 distance (MA: P < 0.002-P < 0.002; IA: P < 0.001-P < 0.043) and H-Cv3 distance (P < 0.005, P < 0.001) for both groups. However, all these changes did not differ among the MA and IA activation groups. ANB°, Wits, overjet, and overbite measurements decreased and SNB°, Co-Gn, Na-Me, ANS-Me, and S-Go increased with the treatment significantly in both mandibular advancement groups (P < 0.000-P < 0.040).

CONCLUSIONS

Herbst-RPE appliance provided a similar improvement in the oropharyngeal and hypopharyngeal airway dimensions and similar changes in sagittal and vertical hyoid position for both maximum and IA protocols in patients with skeletal Class II malocclusion.

TRIAL REGISTRATION

ISRCTN69743543.

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.

Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study

OBJECTIVES

This study aimed to determine the anteroposterior depth (APD) of the pharyngeal airway (PA) where post-operative PA obstruction was predicted, using computer fluid dynamics (CFD), in order to prevent obstructive sleep apnoea after mandibular setback surgery.

SETTINGS AND SAMPLE POPULATION

Nineteen skeletal Class III patients (8 men; mean age, 26.7 years) who required mandibular setback surgery had computed tomography images taken before and 6 months after surgery.

METHODS

The APD of each site of the four cross-sectional reference planes (retropalatal airway [RA], second cervical vertebral airway, oropharyngeal airway and third cervical vertebral airway) were measured. The Maximum negative pressure (Pmax) of the PA was measured at inspiration using CFD, based on a three-dimensional PA model. Intersite differences were determined using analysis of variance and the Friedman test with Bonferroni correction. The relationship between APD and Pmax was evaluated by Spearman correlation coefficients and non-linear regression analysis.

RESULTS

The smallest PA site was the RA. Pmax was significantly correlated with the APD of the RA (r_s  = .628, P < .001). The relationship between Pmax and the APD-RA was fitted to a curve, which showed an inversely proportional relationship of Pmax to the square of the APD-RA. Pmax substantially increased even with a slight reduction of the APD-RA. In particular, when the APD-RA was 7 mm or less, Pmax increased greatly, suggesting that PA obstruction was more likely to occur.

CONCLUSIONS

The results of this study suggest that APD-RA is a useful predictor of good PA ventilation after surgery.

[Obstructive sleep disordered breathing and orthodontics: primum non nocere]

Obstructive sleep apnoea syndrome is a widespread and under-diagnosed condition, making it a major public health and safety issue. The objective of this article was to clarify some of the evidence-based elements of therapeutic decision-making and the information provided to the patient and family on the benefit-cost-security ratio of several of his therapeutic options. Published data on the effectiveness of oral appliances and functional orthopaedic appliances for obstructive sleep apnea (OSA) in children, the durability of their effects, the therapeutic possibilities of maxillary or bimaxillary expansion, and the interrelationships between permanent teeth extractions and obstructive sleep disordered breathing, were researched and analyzed. Based on available evidence, in growing patients with Class II malocclusion, treatment with functional orthopedic devices can increase the volume of the pharyngeal airway and thus hopefully reduce the risk of developing OSA. An improvement in the apnea-hypopnea index and lower oxygen saturation was observed in children treated with rapid maxillary expansion. Permanent teeth extractions prescribed for the treatment of teeth crowding in an orthodontic age patient do not result in any significant change in the upper airway. The role of the orthodontist in the multidisciplinary team in the screening and management of Obstructive Sleep Disordered Breathing (OSDB) is essential. By combining clinical experience with published data on various therapeutic approaches, the orthodontist helps the patient to benefit from better adapted care and a more sustainable outcome, while taking into account his or her preferences.

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.

Upper airway in children with unilateral cleft lip and palate evaluated with computational fluid dynamics

INTRODUCTION

Children with unilateral cleft lip and palate (UCLP) exhibit snoring and mouth breathing. They are also reported to show obstructive sleep apnea syndrome. However, their upper airway ventilation condition is not clearly understood. Therefore, this study was performed to evaluate upper airway ventilation condition in children with UCLP with the use of computational fluid dynamics.

METHODS

Twenty-one children (12 boys, 9 girls; mean age 9.1 years) with UCLP and 25 children (13 boys, 12 girls; mean age 9.2 years) without UCLP who required orthodontic treatment underwent cone-beam computed tomography (CBCT). Nasal resistance and upper airway ventilation condition were evaluated with the use of computational fluid dynamics from CBCT data. The groups were compared with the use of Mann-Whitney U tests and Student t tests.

RESULTS

Nasal resistance of the UCLP group (0.97 Pa/cm³/s) was significantly higher than that of the control group (0.26 Pa/cm³/s; P < 0.001). Maximal pressure of the upper airway (335.02 Pa) was significantly higher in the UCLP group than in the control group (67.57 Pa; P < 0.001). Pharyngeal airway (from choanae to base of epiglottis) pressure in the UCLP group (140.46 Pa) was significantly higher than in the control group (15.92 Pa; P < 0.02).

CONCLUSIONS

Upper airway obstruction in children with UCLP resulted from both nasal and pharyngeal airway effects.

Upper Airway Changes following Functional Treatment with the Headgear Herbst or Headgear Twin Block Appliance Assessed on Lateral Cephalograms and Magnetic Resonance Imaging

OBJECTIVE

The present study compared the changes in the upper airway dimensions and sleep-related breathing disorder (SRBD) condition between functional treatment with the headgear Herbst (HG-Herbst) and headgear Twin Block (HG-TB) appliance. Soft tissues were assessed on lateral cephalometric X-ray and magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Consecutive patients who sought orthodontic treatment at the Faculty of Dentistry of The University of Hong Kong were screened. Adolescents (12-17 year sold for boys and 10-15 years old for girls), with class II molar relationship and overjet >5 mm, with no severe transverse maxillary deficiency, were recruited. Patients were assigned either to the HG-Herbst or to the HG-TB treatment by stratified block randomisation, with sex as the stratification factor. Lateral cephalograms, magnetic resonance imaging (MRI), and the Paediatric Sleep Questionnaire (PSQ) were obtained at baseline and after treatment.

RESULTS

28 patients were enrolled, and 26 patients (13 in each group) completed the treatment. Following 1 year of functional appliance treatment, a significantly lower increase of the lower anterior facial height was observed in the HG-Herbst group compared to the HG-TB group (p = 0.024). However, no significant differences were observed in the upper airway structures or SRBD between the two groups.

CONCLUSION

The changes in upper airway dimensions and SRBD condition were not significantly different between the HG-Herbst and the HG-TB appliance treatment. Additional studies with larger sample size are warranted.

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.

Effects of rapid maxillary expansion on upper airway volume: A three-dimensional cone-beam computed tomography study

OBJECTIVE

To compare changes in pharyngeal airway volume and minimal cross-sectional area (MCA) between patients undergoing rapid maxillary expansion (RME) and a matched control group and to identify markers for predicting airway changes using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Pre- and posttreatment CBCT scans were selected of children who had RME (14 girls and 12 boys; mean age, 12.4 years) along with scans of a control group (matched for chronological age, skeletal age, gender, mandibular inclination) who underwent orthodontic treatment for minor malocclusions without RME. Changes in airway volume and MCA were evaluated using a standardized, previously validated method and analyzed by a mixed-effects linear regression model.

RESULTS

Upper airway volume and MCA increased significantly over time for both the RME and matched control groups (P < .01 and P = .05, respectively). Although the RME group showed a greater increase when compared with the matched controls, this difference was not statistically significant. A reduced skeletal age before treatment was a significant marker for a positive effect on the upper airway volume and MCA changes (P < .01).

CONCLUSIONS

Tooth-borne RME is not associated with a significant change in upper airway volume or MCA in children when compared with controls. The younger the skeletal age before treatment, the more positive the effect on the upper airway changes. The results may prove valuable, especially in RME of young children.

Long-term effects of Class II Herbst treatment on the pharyngeal airway width

Objective

The aim was to assess the long-term effects of Class II malocclusion treatment with the Herbst appliance on the pharyngeal airway (PA) width in comparison to untreated individuals with Classes I and II malocclusion.

Methods

Lateral cephalometric radiographs of 13 male Class II patients from before (T1) and after (T2) treatment with the Herbst appliance as well as after the end of growth (T3) were retrospectively analyzed and compared to two untreated age- and gender-matched samples with Class I (n = 13) or Class II (n = 13) malocclusion. The PA dimensions were measured using the parameters p (narrowest distance between the soft palate and the posterior pharyngeal wall) and t (narrowest distance between the base of the tongue and the posterior pharyngeal wall). In addition, standard cephalometric measurements were performed.

Results

Relevant changes in PA dimensions were only seen for the post-treatment period, during which the distances p and t showed a significant increase in the Herbst group only (∆p: 2.3 mm, ∆t: 3.3 mm) while remaining similar in both untreated groups (∆p: 0.5 mm, ∆t: 0.5 mm, respectively, ∆p: 0.7 mm, ∆t: 1.6 mm). During the same period, posterior face height showed a significantly larger increase in the Herbst group than in both control groups (8.2 versus 5.8 mm, respectively, 5.4 mm), whereas anterior face height (NL-Me) showed a similar development in all groups (4.6 versus 4.4 mm, respectively 3.2 mm).

Conclusion

In the long term, Herbst treatment resulted in a significant post-treatment increase of PA width, possibly due to an increased lower posterior facial height development compared to untreated individuals.

Orthopaedic treatment effects of functional therapy on the sagittal pharyngeal dimensions in subjects with sleep-disordered breathing and Class II malocclusion

The purpose of this cephalometric study was to evaluate the craniofacial changes induced by functional treatment of mandibular advancement with special regard to pharyngeal sagittal airway dimensions, tongue and hyoid bone position in subjects with sleep-disordered breathing (SDB) and dentoskeletal Class II malocclusions compared with an untreated Class II control group. 51 subjects (24 female, 27 male; mean age 9.9 ± 1.3 years) with Class II malocclusion and SDB consecutively treated with a functional appliance (Modify Monobloc, MM) were compared with a control group of 31 subjects (15 males, 16 females; mean age 10.1 ± 1.1) with untreated Class II malocclusion. For the study group, mode of breathing was defined by an otorhinolaryngologist according to complete physical examination. The parents of all participants completed a modified version of the paediatric sleep questionnaire, PSQ-SRBD Scale, by Ronald Chervin (the Italian version in 22 items form) before and after the trial. Lateral cephalograms were available at the start and end of treatment with the MM. Descriptive statistics were used for all cephalometric measurements in the two groups for active treatment changes. Significant, favourable skeletal changes in the mandible were observed in the treated group after T2. Significant short-term changes in sagittal airway dimensions, hyoid position and tongue position were induced by functional therapy of mandibular advancement in subjects with Class II malocclusion and SDB compared with untreated controls. After orthodontic treatment, a significant reduction in diurnal symptoms was observed in 45 of the 51 participants who had received an oral appliance. Orthodontic treatment is considered to be a potential therapeutic approach for SDB in children. Orthodontists are playing an increasingly important role in managing snoring and respiratory problems by oral mandibular advancement devices and rapid maxillary expansion.

Three-dimensional evaluation of changes in upper airway volume in growing skeletal Class II patients following mandibular advancement treatment with functional orthopedic appliances

OBJECTIVES

The aim of this study was to assess three-dimensionally the upper airway changes following functional appliance treatment in growing Class II patients.

MATERIALS AND METHODS

Pre-and post-treatment Cone beam computed tomography scans of 20 patients (age range: 9 to 12; mean: 11.4 ± 1.0 years) were retrieved from the list of patients previously treated with functional appliances in the Postgraduate Clinic at the Section of Orthodontics, Aarhus University, Denmark. Total and partial volumes of the upper airway (ie, lower nasopharynx, velopharynx, and oropharynx) were calculated. To rule out the effect of growth, the changes in the functional appliance group were compared to an age-matched Class I group of 18 patients (age range: 8 to 14; mean: 11.8 ± 1.4 years).

RESULTS

In the functional appliance group, all the partial and total volumes were significantly larger at the end of treatment when compared to the start of treatment ( P < .003). On the other hand, when comparing the changes for the total and partial volumes of the upper airway in the functional appliance group with the Class I group, a statistical difference was seen only for the oropharynx ( P = .022) and total volume ( P = .025), with the functional appliance group showing a larger volume increment.

CONCLUSIONS

An increase in the upper airway volume was found after treatment with functional appliances. This difference was mainly related to the changes at the oropharynx level, which differed significantly from what was observed in the Class I group.

[A change of paradigm in the treatment of Class II malocclusions in children and adolescents: the benefits of the Class II Corrector]

INTRODUCTION

The treatment of class II malocclusions is the core of our clinical activity. What elements can clinician rely on to offer their patients, whether children or adolescents, a treatment of their class II malocclusion that is not only effective but also the most appropriate for each individual case? Which schedule and what therapeutic device should be used?

MATERIALS AND METHODS

Evidence-based orthodontics, along with a search for the best data on two-phase treatments, were used to judge the validity of the main objectives sought when correcting a Class II malocclusion in children or adolescents, including treatment of mandibular retrognathy.

RESULTS

Published data show that the long-term effects of a first phase of treatment on the amount of mandibular growth are at best weak and clinically insignificant. This observation triggers a paradigm shift by refocusing patient treatment on the achievement of other therapeutic objectives. A new orthodontic appliance, the Clas II Corrector, is presented. Its advantages and its use are described and illustrated by means of clinical cases.

CONCLUSIONS

Class II Corrector allows distalization of maxillary lateral areas, effectively limits undesirable dentoalveolar compensations and facilitates the rehabilitation of orofacial functions. In addition to its clinical efficacy, patients appreciate its small footprint, ease of wearing, and lack of impact on phonation.

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.

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.

Three-dimensional Evaluation of Nasal Surgery in Patients with Obstructive Sleep Apnea

Background:

Obstructive sleep apnea (OSA) is a common sleep disorder and is characterized by airway collapse at multiple levels of upper airway. The effectiveness of nasal surgery has been discussed in several studies and shows a promising growing interest. In this study, we intended to evaluate the effects of nasal surgery on the upper airway dimensions in patients with OSA using three-dimensional (3D) reconstruction of cone-beam computed tomography (CT).

Methods:

Twelve patients with moderate to severe OSA who underwent nasal surgery were included in this study. All patients were diagnosed with OSA using polysomnography (PSG) in multi sleep health centers associated with Massachusetts General Hospital, Massachusetts Eye and Ear Infirmary and the Partners Health Care from May 31, 2011 to December 14, 2013. The effect of nasal surgery was evaluated by the examination of PSG, subjective complains, and 3D reconstructed CT scan. Cross-sectional area was measured in eleven coronal levels, and nasal cavity volume was evaluated from anterior nasal spine to posterior nasal spine. The thickness of soft tissue in oral pharynx region was also measured.

Results:

Five out of the 12 patients were successfully treated by nasal surgery, with more than 50% drop of apnea–hypopnea index. All the 12 patients showed significant increase of cross-sectional area and volume postoperatively. The thickness of soft tissue in oral pharynx region revealed significant decrease postoperatively, which decreased from 19.14 ± 2.40 cm² and 6.11 ± 1.76 cm² to 17.13 ± 1.91 cm² and 5.22 ± 1.20 cm².

Conclusions:

Nasal surgery improved OSA severity as measured by PSG, subjective complaints, and 3D reconstructed CT scan. 3D assessment of upper airway can play an important role in the evaluation of treatment outcome.

Herbst appliance effects on pharyngeal airway ventilation evaluated using computational fluid dynamics

OBJECTIVE

To evaluate the effect of a Herbst appliance on ventilation of the pharyngeal airway (PA) using computational fluid dynamics (CFD).

MATERIALS AND METHODS

Twenty-one Class II patients (10 boys; mean age, 11.7 years) who required Herbst therapy with edgewise treatment underwent cone-beam computed tomography (CBCT) before and after treatment. Nineteen Class I control patients (8 boys; mean age, 11.9 years) received edgewise treatment alone. The pressure and velocity of the PA were compared between the groups using CFD based on three-dimensional CBCT images of the PA.

RESULTS

The change in oropharyngeal airway velocity in the Herbst group (1.95 m/s) was significantly larger than that in the control group (0.67 m/s). Similarly, the decrease in laryngopharyngeal airway velocity in the Herbst group (1.37 m/s) was significantly larger than that in the control group (0.57 m/s).

CONCLUSION

The Herbst appliance improves ventilation of the oropharyngeal and laryngopharyngeal airways. These results may provide a useful assessment of obstructive sleep apnea treatment during growth.

Effect of Treatment with Twin-Block Appliances on Body Posture in Class II Malocclusion Subjects: A Prospective Clinical Study

Background

There is strong evidence that malocclusion and body posture are interdependent. The relationship between improvement of nasopharyngeal airway, correction of malocclusion by orthodontic treatment or orthognathic surgery, and changes in body posture were evaluated in several studies. The purpose of the present study was to analyze the effect of the orthodontic treatment with Twin-block appliance on body posture.

Material/Methods

The study group consisted of 23 children (mean age 12.45 (1.06) years). They were orthopedically (back shape analysis) and orthodontically (cephalometric radiograph analysis) examined before the treatment with Twin-block appliance and 10–14 months after the beginning of treatment.

Results

Treatment with Twin-block appliance caused mandibular protrusion as SNB increased by 0.91°, distance Ar-B increased by 4.9 mm, ANB decreased by 0.15°; and increase of face height. Oropharynx airway increased by 1.54 mm and deep pharynx airway by 1.08 mm. The decrease in kyphotic, lordotic, craniocervical angles, upper thoracic, pelvic, and trunk inclinations was found to be statistically significant. When comparing orthopedic measurements between study and control groups, no differences were detected. The control group also showed reduction of all measured angles. Although the decrease of kyphotic angle, upper thoracic inclination, trunk inclination, and craniocervical angle were more pronounced in the study group, the differences were not significant.

Conclusions

Based on these results, the body posture changes during treatment with Twin-block appliance were an expression of the physiological growth, not a response to improvement in occlusion.

Pharyngeal airway effects of Herbst and skeletal anchored Forsus FRD EZ appliances

BACKGROUND AND OBJECTIVE

To evaluate the skeletal and pharyngeal airway effects of skeletal anchored Forsus FRD EZ appliance using bilateral miniplates inserted on mandibular symphyses and to compare the findings with a well matched control group treated using a Herbst appliance.

METHODS

Thirty patients with skeletal Class II malocclusion due to mandibular retrusion were divided into two groups. Group 1 consisted of 15 patients (8 females and 7 males; mean age: 13.11 ± 1.29 years) treated using the Herbst appliance and Group 2 consisted of 15 patients (9 females and 7 males; 12.84 ± 1.27 years) treated using the skeletal anchored Forsus FRD EZ appliance. Treatment changes were assessed by means of linear, angular, and area measurements.

RESULTS

The groups were well matched regarding to the chronological ages, gender distribution and initial cephalometric values (P > 0.05). In both groups, skeletal Class II malocclusion was corrected by decrease in SNA and increase in SNB, Co-Gn, VRL-B and VRL-Pog measurements. Those changes caused a significant correction in the maxillo-mandibular relationship. Upper and lower pharyngeal airway dimensions were increased in both group, while the increase in the lower pharyngeal dimension was found to be statistically significant in the skeletal anchored Forsus FRD EZ group (P < 0.05). Oropharyngeal area measurements significantly increased in both groups (P < 0.001 and P < 0.01, respectively). Comparison of the groups showed that both groups had similar changes with no statistically significant differences (P > 0.05).

CONCLUSION

Skeletal changes produced by both appliances caused significant pharyngeal airway changes.

[Pediatric obstructive sleep apnea syndrome: Treatment strategy]

Pediatric obstructive sleep apnea syndrome (OSAS) has a multifactorial origin. For the child with no dysmorphic disorders or comorbidities, its main etiology is pharyngeal soft tissue hypertrophy, a dimensional reduction of the facial skeletal frame restricting the airway, an anomaly of muscular tone, or a combination of these factors. Consequently, proper diagnosis and treatment planning for these children can require several medical specialties, according to the complexity, severity, and persistence of OSAS: ear-nose-throat specialists (ENT), pneumologists/allergologists, dentofacial orthopedists/orthodontists, and physical therapists/speech therapists. A workshop was organized so as to establish the treatment strategy for these young patients, the majority of whom cannot access multidisciplinary teams (as very few exist in France), and to create guidelines for specialists in the field. The workshop comprised an orthodontist, a pediatric ENT specialist, and a physical therapist, who led a working group of about 50 physicians. They exchanged experience, discussed publications, and established decision trees about pediatric OSAS. Three main areas were studied, and conclusions are presented in this article: (1) multidisciplinary diagnosis strategy, (2) therapy according to the patient's age, and (3) treatment modality for patients combining adenotonsillar hypertrophy and maxillary transverse deficiency.

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.

A retrospective cephalometric study on pharyngeal airway space changes after rapid palatal expansion and Herbst appliance with or without skeletal anchorage

Background

The aim of this study is to investigate the pharyngeal airway space changes in patients treated with rapid palatal expansion (RPE) and Herbst appliance with or without skeletal anchorage.

Methods

A 40-patient study group treated with the Herbst RME combination was included; moreover, a comparison between two subgroups based on whether miniscrews were used was evaluated. A subgroup 1 included 20 patients who were treated with RPE and an acrylic splint Herbst with miniscrews, and subgroup 2 included 20 patients who were treated with RPE and an acrylic splint Herbst. A cephalometric analysis was performed before (T1) and after (T2) treatment. The skeletal parameters of the sagittal occlusion analysis of Pancherz were utilized together with some extra measurements to evaluate the airways.

Results

An increased nasopharyngeal airway space was observed in group 1 (p < 0.05) from T1 to T2. Furthermore, the increase in nasopharyngeal airway space was significantly higher in subgroup 1 (p < 0.05) in comparison to the subgroup 2. Oropharyngeal (OA) and laryngopharyngeal (LA) dimensions were significantly increased in the subgroup 1 at the end of the treatment. In the subgroup 1, a significant decrease in SNA, a significant increase in SNB, and a significant decrease in ANB were observed from T1 to T2. In the subgroup 2, the treatment resulted in a significant decrease in ANB. In both groups, Pogonion increased significantly from T1 to T2.

Conclusions

The results suggest that the RPE and the Herbst appliance allow a slight improvement of the sagittal dimensions of the airways. The oropharyngeal dimension increased significantly more in the skeletal anchorage group.

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.

Changes in the oropharyngeal airway of Class II patients treated with the mandibular anterior repositioning appliance

OBJECTIVE

 To evaluate the effects of functional appliance treatment on the oropharyngeal airway volume, airway dimensions, and anteroposterior hyoid bone position of growing Class II patients.

MATERIALS AND METHODS

 Twenty Class II white patients (mean age, 11.7 ± 1.75 years) treated with the MARA followed by fixed appliances were matched to an untreated control sample by cervical vertebrae maturation stage at pretreatment (T1) and posttreatment (T2) time points. Cone beam computed tomography scans were taken at T1 and T2. Dolphin3D imaging software was used to determine oropharyngeal airway volume, dimensions, and anteroposterior hyoid bone position.

RESULTS

 Multivariate ANOVA was used to evaluate changes between T1 and T2. Oropharyngeal airway volume, airway dimensions, and A-P position of the hyoid bone increased significantly with functional appliance treatment. SNA and ANB decreased significantly in the experimental group (P ≤ .05). Changes in SNB and Sn-GoGn failed to reach statistical significance.

CONCLUSIONS

 Functional appliance therapy increases oropharyngeal airway volume, airway dimensions, and anteroposterior hyoid bone position in growing patients.