Uvulo-glosso-pharyngeal dimensions in different anteroposterior skeletal patterns

Evaluation of the influence of hyoid bone position, volume, and types on pharyngeal airway volume and cephalometric measurements

OBJECTIVES

We aimed to explore the position, morphological, and morphometric properties of the hyoid bone (HB) and to investigate the effect of HB on the pharyngeal airway (PA) volume and cephalometric measurements.

METHODS

A total of 305 patients with CT images were included in the study. DICOM images were transferred to the InVivoDental three-dimensional imaging software. The position of the HB was determined based on the cervical vertebra level and in volume render tab, the bone was classified into six types after all structures around the HB were removed. Also, final bone volume was recorded. In the same tab, the pharyngeal airway volume was divided and measured in three groups (nasopharynx-oropharynx-hypopharynx). The linear and angular measurements were performed on the 3D cephalometric analysis tab.

RESULTS

HB was most commonly located in C3 vertebra level (80.3%). While B-type was found to be the most frequent (34%), V-type was the least frequent (8%). The volume of the HB was found to be significantly higher in male (3205 mm3) than female (2606 mm3) patients. Also, it was significantly higher in the C4 vertebra group. The vertical height of the face was positively correlated with the HB volume, C4 level position, and increased oro-nasopharyngeal airway volume.

CONCLUSION

The volume of the HB is found to differ significantly between genders and can potentially serve as a valuable diagnostic tool for understanding respiratory disorders. Its morphometric features are associated with increased face height and airway volume; however, are not related with the skeletal malocclusion classes.

Assessment of Posterior Pharyngeal Airway Changes After Orthognathic Surgery Using Barium Sulfate

INTRODUCTION

 Obstructive sleep apnea (OSA), caused by airway narrowing, is likely to occur if the mandibular plane to hyoid distance is greater than 15.4 mm and the posterior airway space (PAS) is less than 11 mm. OSA may be caused by mandibular deficit, bimaxillary retrusion, increased lower facial height, extended soft palate, a large tongue base, and a posteroinferiorly positioned hyoid bone. Snoring and drowsiness during exercise are symptoms of OSA, which is a risk factor for high blood pressure, heart disease, and stroke, and these can result in car crashes. However, orthognathic surgery can improve dental occlusion and aesthetics by adjusting facial bone position, shape, and size. When bones move, the position and tension of soft tissues change. These novel soft tissue interactions, especially when anteroposterior, change the face's appearance and PAS dimensions. This study uses barium sulfate paste to enhance lateral cephalograms before and after orthognathic surgery to assess posterior pharyngeal airway changes.

MATERIALS AND METHODS

 Barium sulfate was mixed with water to make a paste for the tongue's dorsum. A preoperative digital lateral cephalogram was obtained, and a postoperative evaluation was conducted six weeks after the procedure. In the cephalostat, the Frankfort horizontal and median planes were aligned parallel to the floor, and a radiograph was taken after the breathing cycle to standardize the hyoid bone location. Preoperative lateral cephalogram analysis using Burstone's hard tissue landmarks confirmed skeletal class II or III deformities. First, the narrowest part of the posterior pharyngeal airway was measured. Second, the narrowest portion between the soft palate and posterior pharyngeal wall parallel to the Frankfort horizontal plane was measured preoperatively, and the procedure was repeated six weeks postop.

RESULTS

 Complexity characterizes the pharyngeal airway, which, along with the surrounding structures, facilitates the bodily functions of eating, talking, and breathing. The pharyngeal airway is located behind the nose, mouth, and larynx, and adjusting the jaws changes the size and structure of the pharyngeal airway and surrounding soft tissues, which may affect breathing. A statistically significant change is detected in the posterior palatal and posterior lingual airways after different orthognathic operations. After the mandible is moved forward, both the posterior palatal and posterior lingual airways enlarge. Furthermore, the soft palate exhibits slight decreases in length, thickness, and angle. Additionally, there is an anterosuperior displacement of the hyoid bone. Following maxillary superior impaction, mandibular autorotation is seen in a counterclockwise direction, which has the same result as that of mandibular advancement.

CONCLUSION

 It is essential to consider these soft tissue changes when planning orthognathic procedures, as alterations in the pharyngeal airway may impact the patient's postoperative breathing and overall health. Patients with OSA or those at risk of developing it should be closely evaluated and managed appropriately during the surgical planning process.

Position of the Hyoid Bone in Anteroposterior Skeletal Patterns

Introduction

Hyoid bone plays a vital role in the craniofacial dynamics. From the maintenance of pharyngeal airway to phonation, deglutition, and mandibular movements, it has multifactorial roles to fulfill. The hyoid bone has a spatial relationship with cranial base, mandible, and cervical vertebrae. This study was performed to determine the position of the hyoid bone in different anteroposterior growth patterns.

Materials and Methods

75 lateral cephalograms belonging to all three sagittal skeletal patterns were evaluated in the study. The angular and linear measurements using 10 variables were made to determine the relationship of the hyoid bone with different craniofacial structures. SPSS was used to calculate the descriptive statistics, mean, and standard deviation of all the linear and angular variables. The analysis of variance (ANOVA) and post hoc test were used to compare the means of linear and angular measurement and multiple comparisons, respectively, at p < 0.05 significance level.

Results

There was no significant difference in the mean angular measurements (NSH and MPH) between the 3 groups (p > 0.05). Also, the multiple comparisons showed no significant difference between the linear measurements (H-FH, H-MP, H-H', and H-N). However, there was a significant difference in three linear measurements: H-Rgn, RGN-C3, and C3-H. The values were more in class III subjects, compared to class I and class II.

Conclusion

The linear millimetric distance between points H-RGN, RGN-C3, and C3-H which determine the relationship and spatial position of the hyoid bone with the mandible and third cervical vertebrae was statistically significant among groups. The values were more in class III subjects inferring the anterior position of the hyoid bone.

Pharyngeal Airway and Craniocervical Angle among Different Skeletal Patterns

Purpose

The aim of the present study was to investigate the pharyngeal airway dimensions and their correlations among the craniocervical angle and skeletal patterns.

Materials and Methods

Cephalometric radiographs were obtained from 300 patients (≥15 years of age), of whom 150 were male patients and 150 were female patients. The patients were divided into three groups according to their skeletal patterns. The following dimensions were measured: NP: nasopharyngeal airway; PS: shortest distance from the soft palate to the pharyngeal wall; MP: Me-Go line intersecting the pharyngeal airway; TS: shortest distance from posterior tongue to pharyngeal wall; LP: laryngopharyngeal airway; UE length: shortest distance from the uvula to the epiglottis; PW: width of soft palate; PL: length of soft palate; ANB angle; palatal angle; and craniocervical angle. Paired t-test, one-way analysis of variance (ANOVA), and Pearson correlation were applied for statistical analysis. The null hypothesis was that there were no differences among skeletal patterns in terms of pharyngeal airway dimensions.

Results

The C4C2-SN angle of the Class II pattern (108.1°) was significantly greater than that of the Class III pattern (104.4°). The Class II PL was significantly longer than the Class III PL in the all patients and female patients groups. The ANB angle exhibited moderate positive correlation with palatal angle (r: 0.462) and moderate negative correlation with TS (r: -0.400) and MP (r: -0.415) length. No significant differences were found in vertical hyoid lengths among all skeletal patterns. Class III (PS, TS, and MP) lengths were significantly greater than Class I and Class II in the all patients group. Regarding the LP length, no significant difference was found in the all patients group. Therefore, the null hypothesis was rejected.

Conclusion

Class III had significantly greater pharyngeal airway dimensions (PS, TS, and MP) than Class I and Class II. In all skeletal patterns, NP length was moderately correlated with the palatal angle. The PS was weakly negatively correlated with the ANB and PL. The TS and MP were moderately negatively correlated with the ANB angle.

Study of Upper Pharyngeal Airway Dimension in Young Adults Visiting Orthodontic Department of a Dental College: A Descriptive Cross-sectional Study

Introduction:

Orthodontic treatment may affect the size and position of oropharyngeal structures altering the airway dimension. Airway dimension is considered as one of the parameter of orthodontic diagnosis and treatment planning. Narrow airway passage is associated with sleep disordered breathing. This aims to study about the measurement of upper pharyngeal airway dimension of young Nepalese adults visiting orthodontic department of a dental college.

Methods:

This descriptive cross-sectional study conducted at Department of Orthodontics, People's Dental College and Hospital, Kathmandu. Data was collected from 8^th December 2020 to 28^th February 2021. Ethical clearance (Reference number. 1, CH100 06, 2077/2076) was taken from Institutional Review Committee of Peoples Dental College and Hospital, Kathmandu, Nepal. Convenient Sampling technique was done. Data was collected and analysis was done using Statistical Package of Social Sciences 16.

Results:

Mean upper pharyngeal airway dimension was 11.40±1.84mm and 11.68±1.96mm for male and female respectively. Upper pharyngeal airway dimension was found to be almost similar for male and female.

Conclusions:

Gender diversity regarding upper pharyngeal airway dimesnion was not observed in this study while other studies also revealed similarities in upper pharyngeal airway dimension between male and female, inspite of larger craniofacial dimension in males than females.

Relationship between hyoid bone and pharyngeal airway in different skeletal patterns

Background/purpose

The hyoid bone and its attached muscles play an important role in the maintenance of the pharyngeal airway space. The aim of the present study was to investigate the correlations between hyoid bone and pharyngeal airway spaces among three skeletal patterns.

Materials and methods

Cephalograms of 90 male and 90 female were divided into skeletal patterns: Class I, Class II, and Class III. The following pharyngeal airway spaces were measured: SP, soft palate related pharyngeal airway; BP, B point related pharyngeal airway; C2P, second cervical vertebra related pharyngeal airway; and LP, laryngopharyngeal airway. The paired t-test, one-way analysis of variance, and Pearson correlation analysis were used in the statistical analyses.

Results

SP was significantly longer in Class III (12.4 mm) than in Class I (10.7 mm) and Class II (9.5 mm), and BP was significantly greater in Class III (16.3 mm) than in Class II (12.4 mm). The hyoid bone had a significantly anterior location in Class III compared to Class II, whereas vertical positions of the hyoid bone showed no significant differences among the three skeletal patterns. Among female with a Class III skeletal pattern, the horizontal position of the hyoid bone had a positive moderate, significant correlation with the C2P, whereas among male, this was not observed.

Conclusion

The location of the maxilla (SNA) was not significantly correlated with the pharyngeal airway space. However, the more protruding the mandible (SNB) is, the more anterior the hyoid bone and the longer the pharyngeal airway will be.

Evaluation of pharyngeal airway volume for different dentofacial skeletal patterns using cone-beam computed tomography

Background/purpose

Understanding of the three-dimensional airway space in three skeletal patterns is important in orthodontic treatment. This study investigated differences between the volume of pharyngeal airway sections and the smallest cross-sectional area in three skeletal patterns by using cone-beam computed tomography (CBCT).

Materials and methods

The 90 patients were collected to measure total pharyngeal airway volume (TP), velopharyngeal airway volume (VP), glossopharyngeal airway volume (GP), oropharyngeal airway volume (OP), hypopharyngeal airway volume (HP), and the smallest cross-sectional areas (SCA) of the upper respiratory tract as well as other relevant anatomical structures. The mean values differences between classes were analyzed using ANOVA. Pearson's test was used to compare classes in terms of the correlations between different factors.

Results

Patients in skeletal classes I and III exhibited significantly higher SCA values (322.6 mm²and 344.5 mm² respectively) than those in skeletal class II (240.8 mm²). Subjects from skeletal classes I and III exhibited significantly higher values of VP, HP, and OP than those in skeletal class II. Skeletal classes I and III exhibited significantly higher TP values (31190.1 mm³ and 30696.2 mm³, respectively) than those in skeletal class II (22386.0 mm³). Non-significant relationships were discovered between pharyngeal airway and skeletal pattern. Conversely, significant relationships were found between TP and gender, ANB, SNB, hyoid and pogonion positions.

Conclusion

The skeletal class II has smaller airway volume than those in skeletal class I and III. The pharyngeal airway volumes could serve as a guide in differentiating the different skeletal classes in clinical settings.

Craniofacial characteristics of Syrian adolescents with Class II division 1 malocclusion: a retrospective study

Background

Malocclusion characteristics vary across different ethnic groups and populations. Limited data are available regarding the characteristics of Syrian adolescents with Class II division 1 (Class II-1) malocclusion, and the recent inflow of Syrian refugees and immigrants into Europe and many areas worldwide demonstrate the need for updated studies to discover the craniofacial characteristics of these new immigrants.

Objectives

The present compound cephalometric and tooth-size study sought to assess the dentofacial morphology, upper-airway dimensions, and tooth-size characteristics of Syrian adolescents with Class II-1 malocclusion and compare the results with established Syrian population norms.

Materials and Methods

The study sample consisted of 43 Syrian patients including 24 females and 19 males with Class II-1 malocclusion (age: 14.3 (±1.5) years, mean (±SD)). Cephalometric radiographs and orthodontic casts were analyzed using special orthodontic software (OnyxCeph3^™) and a universal digital caliper, respectively. Statistics were calculated using the SPSS software.

Results

In Syrian adolescents with Class II-1 malocclusion, the position of the mandible relative to the nasion perpendicular (mean (95% confidence interval)) was −11.01 (−12.45, −9.57) mm. Facial axis angle showed a negative value: −6.25 (−7.65, −4.85) degrees. An obtuse nasolabial angle was observed: 104.05 (101.77, 106.33) degrees. The average width of the upper pharynx was 11.50 (10.53, 12.47) mm; however, there was no prevalence of an upper-pharyngeal width of 5 mm or less. The average value of the anterior tooth-size ratio was 80.69 (79.85, 81.53) percent. In total, 39.5% of the investigated subjects had anterior ratios outside two standard deviations from Bolton’s norm, while 25.6% of the investigated subjects had anterior ratios outside two standard deviations from Syrian population norm.

Conclusions

In this study, the inter-maxillary discrepancy of Class II-1 Syrian adolescents was a consequence of their hyperdivergent facial pattern. The observed small pharyngeal widths were not clinically significant, while the anterior tooth-size discrepancy might be clinically relevant.

Evaluation of the airway space changes after extraction of four second premolars and orthodontic space closure in adult female patients with bimaxillary protrusion - A retrospective study

Background & objectives

Previous studies have found that first premolar extractions during orthodontic treatment may alter the upper airway dimensions. The objective of this study is to investigate the effects of second premolar extraction during orthodontic treatment on the dimensions of the upper airway in a sample of female adults.

Methods

Twenty-nine female adult patients with ages between 18 and 30 years old and incisor bimaxillary protrusion were included in this study. They were treated with comprehensive orthodontic treatment which included the extraction of four second premolars. Pre and post cephalometric radiographs were analyzed using Dolphin imaging software for changes in tongue length and height, soft palate thickness and length, the superior, middle, and inferior airway space, and vertical airway length. Descriptive statistics were used to characterize measurements. Student’s paired t-test was preformed to compare the pre- and post-test mean values of the dimensions.

Results

A significant increase in the vertical airway length was observed after the extraction of the second premolars (p = 0.02). The soft palate length showed a tendency towards an increase that did not reach statistical significance (p = 0.053). No other significant changes in the airway soft tissue measurements were observed. The proclination and protrusion of the upper and lower incisors were significantly decreased compared to pre-treatment measurements.

Interpretation & conclusions.

Orthodontic treatment involving the extraction of all four second premolars in females with bimaxillary protrusion increases the vertical airway length, which is the amount of distance between base of the tongue and posterior nasal spine. No other significant alterations in the upper airway measurements were observed.

Change of the upper airway after mandibular setback surgery in patients with mandibular prognathism and anterior open bite

Purpose

It has been reported before that the amount of pharyngeal airway space (PAS) significantly decreases following mandibular setback (MS) surgery in patients with mandibular prognathism (MP). Further, MP patients with an anterior open-bite (AOB) presentation may show a larger decrease in PAS compared with those without AOB. However, studies on postoperative PAS changes in MP patients with AOB remain rare. This study sought to evaluate changes in PAS and hyoid bone positioning following MS surgery in MP patients with and without AOB.

Patients and methods

Twenty patients who underwent two jaw surgery involving MS movement were included. Patients were divided into a non-AOB group (n = 10; overbite > 2 mm) and an AOB group (n = 10; overbite < - 4 mm). Three-dimensional changes in PAS and hyoid bone positioning were compared and statistically evaluated pre- and postoperatively using computed tomography (CT).

Results

The mean magnitude of MS was 6.0 ± 2.8 mm and 5.6 ± 3.2 mm in the non-AOB group and AOB group, respectively. The oropharyngeal volume and upper hypopharyngeal volume were significantly reduced after surgery in both the groups (p = 0.006 and p = 0.003), while the retroglossal cross-sectional area was significantly reduced only in the AOB group (p = 0.028). Although the AOB group showed a larger decrease in PAS, the difference was not statistically significant between the groups. The position of the hyoid bone showed significant posterior and inferior displacement only in the AOB group, while the vertical displacement of the hyoid bone showed a statistically significant difference between the two groups.

Conclusion

PAS was significantly decreased after MS in both the groups, while only the AOB group presented a statistically significant reduction in the retroglossal cross-sectional area. Vertical displacement of the hyoid bone showed a statistically significant difference between the groups, while the PAS change was not. Surgeons should be aware of potential postoperative airway problems that may arise when performing MS surgeries.

Comparison of Pharyngeal Airway between Mandibular Setback Surgery Patients (Skeletal Class III) and Nonsurgery Patients (Skeletal Classes I and II)

Purpose

We investigated the pharyngeal airway dimensions and their correlations in patients who underwent mandibular setback surgery versus those who did not.

Materials and Methods

One hundred and sixty cephalometric radiographs (120 patients) were obtained from patients with three skeletal malocclusion classifications: Class I and Class II in the nonsurgery group and Class III in the surgery group (preoperative and postoperative cephalograms). The following dimensions were measured: nasopharyngeal airway (NOP), uvulopharyngeal airway (UOP), shortest distance from the posterior tongue to the pharyngeal wall (TOP), and distance from the epiglottis to the pharyngeal wall (EOP). Paired t test, one-way analysis of variance, and Pearson correlation coefficients were used for statistical analysis.

Results

Preoperatively, UOP and TOP of skeletal Class III patients (15.2 mm and 16.6 mm) were significantly larger than those of skeletal Class II (11.5 mm and 12 mm) and Class II (12.3 mm and 12.9 mm) patients, respectively. No differences were observed in EOP between the three skeletal patterns. The hyoid bone of Class III patients was significantly anterior to that of Class I/II patients. Furthermore, UOP had a moderate negative correlation with soft palate length. Postoperatively, no significant difference (UOP, TOP, EOP, soft palate width, and hyoid bone) was found between the skeletal classes.

Conclusion

Preoperatively, UOP and TOP of skeletal Class III patients were significantly wider than those of skeletal Class I/II patients. Pre- and postoperatively, EOP did not exhibit significant differences among the three skeletal classifications. No differences were found in all postoperative pharyngeal airway dimensions between Class III patients and nonsurgery patients (Class I and Class II).

Hyoid bone position in different facial skeletal patterns

Background

Hyoid bone plays a significant role in physiological functions of craniofacial region and it’s position adapts to changes of the head. The purpose of this study was to determine the position of the hyoid bone among subjects with class I, class II and class III skeletal patterns and evaluate the gender differences.

Material and Methods

One hundred and ten lateral cephalograms (59 females and 51 males) from different skeletal patterns (class I, II and III) were selected. The skeletal patterns were determined according to ANB angle. Using MicroDicom software, different linear and angular measurements (6 variables) was carried out to determine the position of hyoid bone. Intraclass correlation coefficient was used to verify reliability. Descriptive statistics of the variables were calculated and analyzed using two-way ANOVA and Bonferroni statistical methods.

Results

The mean distance from the hyoid bone (H) to mandibular plane (MP), to palatal plane (PP), as well as to a third cervical vertebra (C3) was more in males than females (p=0.023, p<0.001, p<0.001 respectively). The mean H to PP distance was significantly more in skeletal class I compared to class III (P=0.01). The mean H to C3 distance was significantly more in skeletal class I compared to class II (P=0.008). The mean angle between H-MP and H-PP did not show any statistical difference among three skeletal classes (p=0.102, P=0.213) and among male and female groups (P=0.172, P=0.904).

Conclusions

The hyoid bone is positioned more superior and posterior in females than males and its location differs among different skeletal classes. It is placed more posterior in skeletal class II patterns and more inferior and anterior in skeletal class I patterns.

Key words:Hyoid bone, Lateral cephalometry, Class III, Class II, skeletal pattern, Orthodontics.

An Evaluation of Upper and Lower Pharyngeal Airway Width, Tongue Posture and Hyoid Bone Position in Subjects with Different Growth Patterns

INTRODUCTION

It is important to evaluate the position of the hyoid bone in relation to the tongue at the beginning of orthodontic treatment so that during the treatment, its position may be directed hence overall impact on airway could be assessed.

AIM

The aim of this study was to evaluate the upper and lower pharyngeal airway dimensions, posture of tongue and hyoid bone position in young adults with different growth patterns.

MATERIALS AND METHODS

Sample size of the study included 90 post-adolescent subjects, within the age range of 18-32 years. Based on the different growth pattern of the face, subjects were divided into Group I (n=30; average growth pattern), Group II (n=30; horizontal growth pattern) and Group III (n=30; vertical growth pattern). Lateral cephalogram were traced and analysed manually by the same investigator for evaluation of upper and lower pharyngeal airway, tongue posture and hyoid bone position. The intergroup comparison of upper and lower pharyngeal airway dimensions, posture of tongue and hyoid bone was performed with one-way ANOVA test.

RESULTS

The results showed that upper oropharyngeal widths were significantly different in different facial skeletal patterns (p=0.00). Subjects with vertical skeletal pattern have significantly narrower upper airways than those with horizontal skeletal pattern (p= 0.025). There was significantly higher difference in position of dorsum of the tongue in vertical growth pattern group (p=0.00). The hyoid bone was positioned farther from the mandibular symphysis in brachyfacial subjects, reflected by the larger H-RGN (Hyoid- retrognathion) values compared with the dolichofacial and normal subjects (p=0.044).

CONCLUSION

The upper oropharyngeal width was found to be narrower in subjects with vertical growth pattern. The dorsum of the tongue is seen to be placed higher in subjects with vertical growth pattern. The hyoid bone was more inferiorly and posteriorly positioned in subjects with horizontal growth pattern. Variations are seen in upper and lower oropharyngeal widths, posture of the tongue and hyoid bone position in all the growth patterns.

Comparison of pharyngeal airway dimension, tongue and hyoid bone position based on ANB angle

OBJECTIVE

This study was undertaken to cephalometrically evaluate the pharyngeal airway dimension, tongue and hyoid position in subjects with normal nasorespiratory functions having different dentofacial patterns (A-point-nasion-B-point [ANB] >40 and ANB <40) and to find if a correlation existed.

MATERIALS AND METHODS

Class I and Class II Division I patients were selected randomly. Lateral head cephalograms were taken in normal head position within a lead foil attached to the tongue tip and a barium coating on the dorsal surface of tongue. The lateral cephalograms obtained were traced using lead acetate paper and measurements were taken. Different analyses were done for the pharyngeal airways, hyoid bone, and tongue.

RESULTS

The ANB angle is a significant predictor for Class I and Class II Division I malocclusion, and the mean ANB angle of Class II Division I was different and higher. The overall mean pharynx and hyoid parameters were different and lower in Class II Division I patients than in Class I patients. The mean tongue parameter almost remained the same except for the tongue position (TT-LOP), which was higher in Class II Division I.

CONCLUSION

In general, there was no difference either in the pharyngeal airway anterioposterior dimension or in the position and relationship of the hyoid bone and tongue, between Class I and Class II Division I patients. These findings are consistent with the findings in studies. Anterioposterior dimension of the upper airway is usually maintained by adaptation of both the tongue and the hyoid bone. The result should be viewed in the light of the fact that only anterioposterior dimensions were taken into consideration; the vertical and transverse dimensions of these complex anatomical structures need to have newer three-dimensional (3-D) imaging technique to find if a correlation existed between them, making future studies more comprehensive.

Pycnodysostosis with Special Emphasis on Dentofacial Characteristics

Pycnodysostosis is an autosomal recessive disorder that manifests as osteosclerosis of the skeleton due to the defective osteoclasts mediated bone turnover. The diagnosis of this disorder is established on the basis of its characteristic features and must be differentially diagnosed with other bone disorders. Dental surgeons should be aware of the limitations and possible adverse oral complications such as osteomyelitis of bone in these patients. This will guide them in planning realistic treatment goals. This paper reports the clinical and radiographic features of pycnodysostosis with the great emphasis on its dentofacial characteristics. The aim of this case report is to give an insight into the etiology, pathogenesis, and differential diagnosis of this disorder and to prepare the dentists and maxillofacial surgeons to overcome the challenges in treating these patients.

Airway in Class I and Class II skeletal pattern: A computed tomography study

BACKGROUND AND OBJECTIVES

A normal airway is required for the normal growth of the craniofacial structures. The present study was designed to evaluate and compare the airway in Class I and Class II skeletal pattern and to see if there is any association between the airway and maxillomandibular relationship.

MATERIALS AND METHODS

Peripheral nervous system computed tomography scans of 30 patients were divided into two groups as Class I (ANB ≤ 4.5°), Class II (ANB ≥ 4.5°). The Dolphin three-dimensional version 11 was used to assess the airway.

STATISTICAL ANALYSIS

Correlations between the variables were tested with the Pearson correlation coefficient. Independent sample t-test was performed to compare the averages between the two groups. P < 0.05 was considered as statistically significant.

RESULTS

The ANB angle was negatively correlated with all the airway parameters. The airway area and volume was significantly reduced in Class II subjects compared to Class I.

CONCLUSION

The results suggest a strong association between the airway and skeletal pattern showing a reduced airway in Class II patients with a high ANB angle.

Correlation between the Pharyngeal Airway Space and Head Posture after Surgery for Mandibular Prognathism

Purpose. The aim of this study was to determine the correlation between the pharyngeal airway space and head posture after mandibular setback surgery for mandibular prognathism. Materials and Methods. Serial lateral cephalograms of 37 patients with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) were evaluated before (T1) and immediately (T2), between 6 weeks and 3 months (T3), and more than 1 year (T4) after surgery. Paired t-tests and Pearson's correlation analysis were used to evaluate the postoperative changes in all cephalometric parameters, including the mandible, hyoid, head posture (craniocervical angle), and pharyngeal airway space. Results. The mandible and hyoid were set back by 12.8 mm and 4.9 mm, respectively, at T2. Furthermore, the hyoid showed significant inferior movement of 10.7 mm, with an 8 mm increase in the tongue depth. The upper oropharyngeal airway (UOP) shortened by 4.1 mm, the lower oropharyngeal airway (LOP) by 1.7 mm, and the laryngopharyngeal airway by 2 mm. The craniocervical angle showed a significant increase of 2.8°. UOP and LOP showed a significant correlation with the craniocervical angle at T2 and T4. Conclusions. Our findings conclude that the oropharyngeal airway space is significantly decreased and correlated with a change in the head posture after mandibular setback surgery.

Effects of first premolar extraction on airway dimensions in young adolescents: A retrospective cephalometric appraisal

OBJECTIVE

To evaluate the upper airway dimensions in adolescents treated for bimaxillary proclination with first premolar extraction.

MATERIALS AND METHODS

A retrospective cephalometric evaluation was carried out on the available pre and post orthodontic treatment records of 150 patients (12-18 years of age) who had bimaxillary proclination and were treated with fixed orthodontic therapy. Cephalometric landmarks for sagittal airway measurements and hyoid bone were identified; linear and angular measurements were obtained. Descriptive statistics using paired t-test was used to assess changes in pre and post treatment values and Pearson's correlation coefficient was calculated to evaluate the reliability of observations. The method error calculations were performed using the Dahlberg formula.

RESULTS

It was observed that the mean values of nasopharyngeal dimension and Total Airway Length (TAL) showed no statistically significant difference in pre and post treatment groups. All other airway and hyoid parameters showed statistically significant difference. Pearson's correlation coefficient showed statistically significant correlations in all the airway and hyoid parameters.

CONCLUSIONS

In the present study, the nasopharyngeal dimension and TAL were not found to be directly affected by the retraction of anterior teeth, This can be attributed to the fact that nasopharyngeal dimension and TAL are not under direct influence of tongue position. The other findings also indicated direct correlation of tongue position to oropharynx and hypopharynx. Consequently, we emphasize clinically relevant anatomic risk factors that should be given prime importance and serious consideration on the decision whether to extract or not in growing patients.

Long-term pharyngeal airway changes after bionator treatment in adolescents with skeletal Class II malocclusions

Objective

The aim of this study was to evaluate long-term changes in the pharyngeal airway dimensions after functional appliance treatment in adolescents with skeletal Class II malocclusions.

Methods

Pharyngeal airway dimensions were compared between subjects with skeletal Class II malocclusions (n = 24; mean age: 11.6 ± 1.29 years) treated with a Class II bionator and age-matched control subjects with skeletal Class I occlusions (n = 24; mean age: 11.0 ± 1.21 years) using a series of lateral cephalograms obtained at the initial visit (T0), after treatment (T1), and at the completion of growth (T2).

Results

The length of the nasopharyngeal region was similar between adolescents with skeletal Class I and Class II malocclusions at all time points, while the lengths of the upper and lower oropharyngeal regions and the pharyngeal airway areas were significantly smaller in the skeletal Class II adolescents before treatment when compared to the control adolescents (p < 0.05). However, following treatment with a functional appliance, the skeletal Class II adolescents had increased pharyngeal airway dimensions, which became similar to those of the control subjects.

Conclusions

Functional appliance therapy can increase the pharyngeal airway dimensions in growing adolescents with skeletal Class II malocclusions, and this effect is maintained until the completion of growth.

Short-term pharyngeal airway changes after mandibular advancement surgery in adult Class II-Patients--a three-dimensional retrospective study

The purpose of this study was to investigate volume changes in posterior airway space (PAS) after bilateral mandibular advancement surgery. Measurements were taken based on three-dimensional (3D) records available for a large and homogeneous cohort of patients. Pre- and postoperative CBCT scans of 102 adult patients with Class II dysgnathia were visualized and analyzed using 3D software (Mimics® Innovation Suite 14.1; Materialise, Leuven, Belgium). The PAS was divided into three segments by three planes parallel and one plane perpendicular to the Frankfort horizontal plane. Total volume, partial volumes, and cross-sectional areas were calculated from the pre- and postoperative scans. Dahlberg coefficients were obtained to verify each parameter for the measurements' reliability. The statistical significance of the changes observed was analyzed by Wilcoxon's rank-sum test. Highly significant (p=0.000) increases in total posterior airway volume (+32.0%) were noted as an effect of mandibular advancement surgery, amounting to 45.6% in the lower PAS third compared to 38.8% in the middle and 12.5% in the upper PAS third. We also obtained highly significant (p=0.000) increases in all the cross-sectional areas investigated, amounting to 48.5% on the soft-palate level compared to 21.6% on the level of the epiglottis tip, and 14.6% on the hard-palate level. These results demonstrate that bilateral mandibular advancement surgery in Class II-Patients leads to significant increases in PAS volume and significant widening of the narrower sites inside the pharynx.

Correlation analysis of the hyoid bone position in relation to the cranial base, mandible and cervical part of vertebra with particular reference to bimaxillary relations / teleroentgenogram analysis

Introduction:

The relationship among the orofacial system and the rest of the body ,both in functional and anatomical terms was the subject of numerous scientific studies. The optimum position of the bone structures of orofacial system provides performance of intact vital functions, such as breathing or swallowing. Hyoid bone represents a link between the head and neck. Although located in the neck, hyoid bone due to its brachial origin belongs to the visceral skeleton.

The purpose of the research:

a) To determine the position of the hyoid bone, in relation to the cranial base, mandible and cervical part of the vertebra; b) To determine the linear measures of hyoid bone and its constituents and c) to Identify on the profile teleroengen image, whether there are differences in the position of hyoid bone depending on the saggital maxillo-mandibular relationship.

The examinees and methods:

30 profile teleroengen images of patients aged 17-18 years of both sexes were used for this study. To study the position of hyoid bone depending on the saggital maxillo-mandibular relationship respondents were divided into groups based on the ANB-angle values. The first group is ortognat patients with ANBangle values, from 1 to 4°. The second group included patients with distal jaw relationship, that is, whose values of ANB-angle were greater than / or 5°. The third group consists of patients with ANB-angle value of 0 or negative.

Results and Conclusion:

The position of hyoid bone is not constant, but depends on the maxillo-mandibular anterior posterior relationships. Length of hyoid bones and greater horns of hyoid bone differs with respect to the sagittal malocclusion. In relation to the cranial base and maxillary bones flat position of the hyoid bone is highly correlated. A positive correlation was found with relation to the cervical vertebra, while the dependence is determined in relation to the steep mandibular plane.

Interaction between otorhinolaryngology and orthodontics: correlation between the nasopharyngeal airway and the craniofacial complex

In terms of pathophysiology, an anatomically narrow airway is a predisposing factor for obstruction of the upper respiratory tract. The correlation between the nasopharyngeal airway and the craniofacial structures is discussed in this context. Thus a mutual interaction between the pharynx and the mandibular position was demonstrated, whereby the transverse dimension of the nasopharynx was significantly larger in patients with prognathism than in patients with retrognathism. The influence of chronic obstruction of the nasal airway on craniofacial development was also discussed. The form-and-function interaction, which ought to explain the causal relationship between nasal obstruction and craniofacial growth, appears to be of a multifactorial rather than a one-dimensional, linear nature. It is not disputed, however, that expanding the maxilla improves not only nasal volume and nasal flow, but also the subjective sensation of patients, although it is not possible to make a prognostic statement about the extent of this improvement because of the differing reactions of individuals. Orthodontic appliances for advancing the mandible can also be successfully used in the treatment of mild obstructive sleep apnea syndrome. This treatment method should be considered particularly for patients who are unwilling to undergo or cannot tolerate CPAP (continuous positive airway pressure) treatment.