Pharyngeal airway dimensions in Iranian female young adults with different skeletal patterns using cone-beam computed tomography

OBJECTIVES

To assess the oropharyngeal airway in Iranian female young adults with different skeletal patterns using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This descriptive, cross-sectional study evaluated 105 CBCT scans of female patients between 18 and 35 years retrieved from the archives of a radiology clinic. The images were evaluated in axial, sagittal, and frontal sections. In the axial plane, the maximum and minimum cross-sectional area (CSA) of the airways at the oropharynx, minimum width (anteroposteriorly), and minimum depth (laterally) were measured using Mimics Medical software. The oropharyngeal volume was measured by NemoFAB software. The values were compared among the groups with different sagittal, vertical, and transverse patterns. The correlation of indices with airway measurements was analyzed using Monte Carlo Chi-square and Pearson's correlation coefficient.

RESULTS

No significant difference was noted in oropharyngeal airway dimensions and volume among cases with different skeletal sagittal, vertical, and transverse patterns (P > 0.05) except for class III patients with normal transverse pattern in whom maximum CSA in low-angle group was larger than that in normal-angle group (P < 0.05) and class I normal-angle patients in whom maximum CSA in transverse normal group was smaller than that in constriction group (P < 0.05).

CONCLUSIONS

Oropharyngeal dimensions were not significantly different in Iranian female young adults with different skeletal patterns.

Correlation between the three-dimensional maxillomandibular complex parameters and pharyngeal airway dimensions in different sagittal and vertical malocclusions

OBJECTIVES

This study aimed to determine the three-dimensional (3D) correlation between maxillomandibular complex parameters and pharyngeal airway dimensions in different sagittal and vertical malocclusions.

METHODS

This retrospective cross-sectional study included the CBCT scans of 368 patients with a mean age of 23.81 ± 3.01 years. The patients were classified into three groups (skeletal Class I, II, and III). Each class group was divided into three subgroups based on vertical growth patterns (hypo-, normo-, and hyperdivergent). The maxillomandibular complex was evaluated in the three planes using 16 skeletal measurements. Naso-, oro-, hypo-, and total pharyngeal airway spaces were assessed in terms of width, volume, surface area, and minimum constricted area (MCA). Two-way ANOVA followed by the Bonferroni post-hoc test were used.

RESULTS

The nasopharyngeal airway space was significantly lowest regarding sagittal and lateral widths in the skeletal Class III patients, the lowest volume and surface area were in hyperdivergent patients, and MCA was the highest in Class II and hypodivergent patients. The oro- and hypopharyngeal sagittal width, volume, surface area, and MCA were the lowest in the hyperdivergent patients, and oropharyngeal lateral width and hypopharyngeal sagittal width were the highest in skeletal Class III. The total pharyngeal volume, surface area, and MCA were the lowest in the hyperdivergent patients, and skeletal Class II patients had the lowest MCA.

CONCLUSIONS

The pharyngeal airway dimensions differ with various sagittal and vertical malocclusions. These differences could apply to diagnosis, treatment planning, and possible changes following orthodontic/orthopedic or surgical treatment.

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.

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.

Three-Dimensional Analysis of the Pharyngeal Airway Volume and Craniofacial Morphology in Patients With Bilateral Cleft Lip and Palate

OBJECTIVE

This study aimed to determine the correlations between the craniofacial morphology and pharyngeal airway volume in patients with complete bilateral cleft lip and palate (BCLP).

DESIGN

Retrospective study.

SETTING

Tertiary hospital.

PARTICIPANTS

Twenty-seven patients with complete BCLP and 27 class I control patients, aged 10 to 14 years.

MAIN OUTCOME MEASURE

The pharyngeal airway volume and craniofacial morphology were evaluated using cone-beam computed tomography. Measurements were compared between groups and any correlations were identified.

RESULTS

A significantly smaller total pharyngeal airway volume (TPV), oropharyngeal airway volume, and upper (UOPV) and lower (LOPV) oropharyngeal airway volume were found in patients with BCLP than in class I control patients, with no difference in the nasopharyngeal volume between groups. Furthermore, the craniofacial morphology measurements of N-Me, S-Go, Or-C, Ptm-C, Me-C, Co-Go, Go-Me, Ptm-Or, N-S-Ar, and Ar-Go-Me significantly differed between the BCLP and control groups (all P < .05). Multiple regression analysis indicated that Ptm-C and Me-C; Ptm-C, Or-C, and Me-C; and Me-C explained 20.3%, 38.9%, and 17.1% of the variations in TPV (P = .025), UOPV (P = .002), and LOPV (P = .018), respectively.

CONCLUSIONS

Total pharyngeal airway volume, TPV, OPV, UOPV, and LOPV were significantly smaller in patients with BCLP than in class I controls. In patients with BCLP, the maxilla showed inhibited sagittal development and a retrograde position; moreover, the pharyngeal airway volume was weakly associated with the position of the maxilla and mandible relative to the coronal plane.

Analysis of the middle region of the pharynx in adolescents with different anteroposterior craniofacial skeletal patterns

Objective:

To assess the volume and morphology of the middle region of the pharynx (MRP) in adolescents with different anteroposterior craniofacial skeletal patterns.

Methods:

One hundred twenty-six patients (56 male and 70 female), who had cone-beam computed tomography (CBCT) within their records, were selected for this cross-sectional study. Participants were classified, according to their ANB angle value, in Class I (1^o ≤ ANB ≤ 3^o), Class II (ANB > 3^o) and Class III (ANB < 1^o). The total volume (tV), minimum axial area (AxMin) and morphology of the MRP and its subdivisions - velopharynx (VP) and oropharynx (OP) - were characterized by CBCT and 3-dimensional image reconstruction software. Intergroup comparisons were performed by ANOVA and Tukey post-hoc tests. Correlations between tV and Axmin with the ANB angle values were tested using linear regression analysis, considering sex as covariable.

Results:

Statistically significant difference between groups were observed in tV only for the VP region; Class II individuals presented significantly lower tV (6863.75 ± 2627.20 mm³) than Class III subjects (9011.62 ± 3442.56 mm³) (p< 0.05). No significant differences were observed between groups for any other variable assessed, neither in MRP nor in the OP region (p> 0.05). A significant negative correlation was evidenced between tV and Axmin and the ANB angle values; sexual dimorphism was observed for some variables.

Conclusions:

Class II subjects have smaller tV in the VP region. tV and Axmin tend to decrease in all evaluated regions when the ANB angle values increase.

Pharyngeal Airway Modifications in Skeletal Class III Patients Undergoing Bimaxillary Advancement Surgery

PURPOSE

The purposes were to study the pharyngeal airway in patients with skeletal Class III malocclusion submitted to surgical orthodontic treatment and to correlate the alterations with bone movements.

MATERIALS AND METHODS

The sample consisted of multislice computed tomography images from 13 patients obtained before and 6 months after maxillomandibular advancement surgery. The following measurements were obtained using Dolphin Imaging software (Dolphin Imaging, Chatsworth, CA): volume and area of the oropharynx, nasopharynx, and total airway, as well as the most constricted area, anteroposterior and lateral dimensions of the narrowest axial cross-sectional area, and airway length. The paired t test was applied at a significance level of 5%.

RESULTS

Sagittal displacement of the maxilla and mandible was correlated with airway alterations using the Pearson correlation test. Alterations in airway measurements were observed in all patients after surgery. We noted a significant increase (P < .05) in total airway area, oropharyngeal area, and anteroposterior dimension of the most constricted area, as well as a significant reduction (P < .05) in airway length. A significant correlation (P < .05) was observed between nasopharyngeal area and maxillary movement and between airway length and mandibular movement (P < .05).

CONCLUSIONS

The results of this study suggest significant alterations in pharyngeal airway measurements when preoperative and postoperative periods of bimaxillary advancement surgery were compared.

Three-dimensional study of the upper airway in different skeletal Class II malocclusion patterns

OBJECTIVES

To characterize upper airway volume and morphology in patients with different skeletal patterns of Class II malocclusion compared to Class I.

MATERIALS AND METHODS

A total of 197 individuals who had cone-beam computed tomography were allocated into groups according to ANB, SNA, and SNB angles (Class I, Class II maxillary protrusion, Class II mandibular retrusion), each subdivided into hypodivergent, normal, and hyperdivergent. Nasopharynx (NP), oropharynx (OP), and hypopharynx (HP) were assessed with three-dimensional image reconstruction software.

RESULTS

Intergroup comparison did not detect significant differences in volume and morphology of NP, OP, and HP. The males displayed larger OP and HP volume than the females. Positive correlations between age and NP, OP, HP volume and between craniocervical angle and OP and HP volume were observed. Linear regression analysis detected a tendency for OP and HP volume to increase as maxillary and mandibular length increased.

CONCLUSIONS

Upper airway volume and morphology were similar in different skeletal patterns of Class II malocclusion. Actual upper and lower jaw lengths were more closely related to upper airway volume and morphology than the angles that reflected their position relative to the cranial base.

Apnea-Hypopnea Index in Healthy Class III Patients Treated With Intraoral Vertical Ramus Osteotomy: A Prospective Cohort Study

PURPOSE

The study purpose was to assess whether mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) induces obstructive apnea and hypopnea in healthy Class III patients without a history of respiratory dysfunction. We hypothesized that the apnea-hypopnea index (AHI) would not exceed 5 events per hour after surgery.

PATIENTS AND METHODS

A prospective cohort study was conducted. The sample was composed of healthy Class III patients without a history of obstructive sleep apnea treated with isolated mandibular setback surgery by the IVRO procedure at a university hospital. In-home respiratory sleep recordings (Nox T3; Nox Medical, Reykjavik, Iceland) and self-administered questionnaires were obtained before and at least 3 months after surgery. The AHI was the primary outcome variable. Other study variables were as follows: peripheral capillary oxygen saturation, oxygen desaturation index, snore index, body mass index, Epworth Sleepiness Scale, and Oral Impact on Daily Performance index. Descriptive and bivariate statistics were computed, and the significance level was set at .05.

RESULTS

The sample was composed of 8 patients. The mean age at surgery was 23.2 years (range, 18.2 to 33.4 years). The mean amount of surgical setback was 4.3 mm (range, 2.5 to 7.4 mm). The mean body mass index was 24.2 kg/m² (standard error [SE], 1.3 kg/m²) and 23.9 kg/m² (SE, 1.4 kg/m²) at the presurgical and postsurgical sleep recordings, respectively. The mean AHI was 1.3 events per hour (SE, 0.3; range, 0.1 to 2.5) before surgery and 1.8 events per hour (SE, 0.4; range, 0.3 to 3.3) after surgery. No statistically significant changes in AHI (P = .412), peripheral capillary oxygen saturation (P = .443), oxygen desaturation index (P = .194), snore index (P = .363), or Epworth Sleepiness Scale (P = .812) were observed. The patients' self-reported oral health-related quality of life was statistically significantly improved after surgery (P = .034).

CONCLUSIONS

Mandibular setback surgery with the IVRO procedure in the range of 2.5 to 7.4 mm did not induce obstructive sleep apnea, measured as an AHI above 5 events per hour, in the 8 healthy, young adult Class III patients presented in this study. More studies including larger patient samples are needed.

Guideline Values for Minimum Nasal Cross-Sectional Area in Children

OBJECTIVE

The purpose was to determine age-specific values of the minimum cross-sectional area of the nasal airway in children without cleft lip or palate and to assess whether gender differences occur with growth in order to develop guidelines for assessment in children with clefts.

PARTICIPANTS

All schoolchildren aged 8 to 17 years who met the research criteria were studied during rest breathing using the pressure-flow technique. The children came from a rural area of 3800 inhabitants. Consecutive age cohorts were used for comparisons.

RESULTS

Nasal cross-sectional area increased in females from 0.38 cm² in 8-year-olds to 0.58 cm² in 17-year-olds. There was a decrease in size at ages 10 to 11 and 14 to 15 years. In males, the area increased from 0.40 to 0.68 cm² and decreased slightly from 9 to 10 and 14 to 15 years. The annual changes were statistically significant in females between 8 and 9 and 11 to 13 years of age, and in males from 11 to 12, 13 to 14, and 15 to 17 years of age. Across gender, the only significant difference occurred at age 16.

CONCLUSIONS

Our results indicate that the increase in nasal airway size is not consistent during growth. Nasal airway size showed almost equal values for both genders in young children but was systematically larger in boys from 14 years of age on. The results refer that by 17 years of age nasal airway may not have reached adult size in males.

Upper airway asymmetry in skeletal Class III malocclusions with mandibular deviation

The purpose of this study was to investigate the relationship between bilateral differences of upper airway and mandibular morphologic patterns in subjects with skeletal Class III mandibular deviation. 47 skeletal Class III (ANB < 0°) adult patients with and without mandibular deviation were divided into 2 groups. Bilateral differences of minimum cross-sectional area, mean cross-sectional area, volume of subdivisions (nasopharynx, palatopharynx, glossopharynx, hypopharynx) were assessed paired t test. Stepwise linear regression analysis and Pearson correlation coefficients were computed between a significant pair of upper airway variables and a pair of mandibular deviation variables to examine the quantitative relationship between the upper airway asymmetry and mandibular deviation. The mean cross-sectional area and the volume of palatopharynx on the deviated side in mandibular deviated group was significantly smaller than non-deviated side. The asymmetry index of the palatopharyngeal volume showed significant correlations with CRA asymmetry (r = 0.49) and Ramus asymmetry (r = 0.54). However, in the glossopharyngeal and hypopharyngeal segment, the mandibular deviated group showed significant asymmetry, characterized by larger mean cross-sectional area and volume in deviated side. The asymmetry index of the glossopharyngeal volume and hypopharyngeal volume showed significant correlations with CRA asymmetry (r = 0.42), Me-s (r = 0.72) and Me-s (r = 0.67) respectively.

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.