Comparison of craniofacial morphology, head posture and hyoid bone position with different breathing patterns

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Influences of Adenoid Hypertrophy on Children's Maxillofacial Development

This study aims to investigate the association between adenoid hypertrophy and facial development. A total of 388 children aged 1-13 years old who had undergone head MRI in Foshan Maternal and Child Health Hospital were collected, including 196 hypertrophic cases and 192 normal cases. The maxillofacial soft tissue indicators were measured and compared. The A/N ratio and adenoid thickness consistently increased with age in the hypertrophic group and the A/N ratio reached a maximum value three years earlier than the normal group. The pharyngeal airway space, vallecula of epiglottis to anterior plane distance of the third/fourth cervical vertebrae, angle of convexity, total angle of convexity, and the nasolabial angle in the hypertrophy group were smaller than those in the control group (p < 0.05). The thickness of adenoids, palate height, palate length, and tongue length in the hypertrophy group exceeded that of the control group (p < 0.05). To conclude, adenoid hypertrophy was associated with craniofacial features such as a convex facial profile, a narrowed nasopharyngeal airway, an elongated and heightened palate, a lengthened tongue or a lower tongue position. These findings emphasize the importance of early intervention for children with adenoid hypertrophy to mitigate potential adverse effects on maxillofacial development.

Investigation on the Effect of Oral Breathing on Cognitive Activity Using Functional Brain Imaging

Oral breathing directly affects behavioral performance and dental health. Various relationships between oral breathing and periodontal disease have been well-described. However, the effect of oral breathing on cognitive performance remains unclear. This study aimed to investigate the effects of oral breathing on cognitive function using functional magnetic resonance imaging (fMRI). Twenty-two healthy participants (mean age, 22.27 ± 1.42 years) performed a two-back (2B) working memory fMRI task using a 3T MRI scanner while breathing through their oral or nasal passage. Functional activity analysis was performed using a statistical parametric mapping software package. One-sample group analyses were performed in 2B > Rest contrast. Functional connectivity analysis was conducted using MATLAB-based imaging software. Mixed ANOVA analysis was performed. The results showed more brain activation and connection during nasal breathing than during oral breathing. For Nasal > Oral contrast, various functional connections are known to have a significant relationship with working memory, including the left cerebellum, left and right inferior parietal gyrus. This can be significant evidence to demonstrate that oral breathing is an inappropriate method for intellectual activity using brain imaging techniques. Therefore, this study suggests that changing various habits related to oral breathing is important for cognitive function.

Investigation of Functional Connectivity Differences between Voluntary Respirations via Mouth and Nose Using Resting State fMRI

The problems of mouth breathing have been well-studied, but the neural correlates of functional connectivity (FC) still remain unclear. We examined the difference in FC between the two types of breathing. For our study, 21 healthy subjects performed voluntary mouth and nasal breathing conditions during a resting state functional magnetic resonance imaging (fMRI). The region of interest (ROI) analysis of FC in fMRI was conducted using a MATLAB-based imaging software. The resulting analysis showed that mouth breathing had widespread connections and more left lateralization. Left inferior temporal gyrus had the most left lateralized connections in mouth breathing condition. Furthermore, the central opercular cortex FC showed a significant relationship with mouth breathing. For nasal breathing, the sensorimotor area had symmetry FC pattern. These findings suggest that various FCs difference appeared between two breathing conditions. The impacts of these differences need to be more investigated to find out potential link with cognitive decline in mouth breathing syndrome.

Facial morphological characteristics of mouth breathers vs. nasal breathers: A systematic review and meta-analysis of lateral cephalometric data

The present systematic review and meta-analysis was performed to assess the association between mouth breathing and facial morphological characteristics in children and adolescents. PubMed, Medline, Scopus and Google Scholar databases were searched for cross-sectional case-control studies published between 1^st January 1980 and 1^st April 2019. Studies comparing cephalometric data of mouth breathers and nasal breathers were included, while studies on adults were excluded. Meta-analysis was performed regarding 11 angular and 4 linear measurements. A total of 19 studies were included in the systematic review and data from 18 studies were extracted for the meta-analysis. The results indicated statistically significant decreases in Sella-Nasion-Point A (SNA) angle [mean difference (MD)=-1.33; 95% CI -2.03 to -0.63; P=0.0002] and Sella-Nasion-Point B (SNB) angle of mouth breathers as compared to nasal breathers (MD=-1.33; 95% CI -2.18 to -0.49; P=0.002). There was no difference in Point A-Nasion-Point B (ANB) angle between the two groups (MD=0.25; 95% CI -0.26 to 0.75; P=0.34). Mouth breathers demonstrated an increased mandibular plane angle, total and lower anterior facial height and decreased posterior facial height. Within the limitations of the study, the results indicated that mouth breathers tended to have a retrognathic maxilla and mandible, vertical growth pattern with high mandibular plane angle, downward and backward rotation of the mandible and an increase in total and lower anterior facial height and decrease in posterior facial height. Further high-quality studies are required to strengthen the evidence on this subject.

Gravitational forces, negative pressure and facial structure in the genesis of airway dysfunction during sleep: a review of the paradigm

The recent and distant literature has extensive discussion of how sleep apnea, adeno-tonsillar growth, and facial structural deformity are related. Conventionally, the order of cause and effect is as follows: (1) Inflammatory/infectious process→tonsillar/adenoid tissue growth→(2) airway obstruction and mouth breathing/Obstructive Sleep Apnea (OSA)→(3) altered facial structure (adenoid facies). Using this same reasoning, adenotonsillectomy is the first line of treatment in the prevention of structural abnormalities. However, through a lifetime of clinical research Christian Guilleminault and his colleagues have challenged this paradigm. Through multiple articles and studies, Guilleminault et al., teach that even slight (subclinical) facial structure/muscle tone variations may be the inciting event triggering mouth-breathing and the eventual adenotonsillar growth in most patients. Essentially, this is the reverse of the conventional paradigms. Initial treatments therefore shift from simplified removal of inflammatory tissue to limiting mouth-breathing via musculo-skeletal modification. The purpose of this paper is to synthesize and analyze the recent (and distant) relevant literature to provide support for, and provide a potential anatomic mechanism for Guilleminault et al.'s paradigm-questioning clinical observations.

Breathing mode influence on craniofacial development and head posture

OBJECTIVE

The incidence of abnormal breathing and its consequences on craniofacial development is increasing, and is not limited to children with adenoid faces. The objective of this study was to evaluate the cephalometric differences in craniofacial structures and head posture between nasal breathing and oral breathing children and teenagers with a normal facial growth pattern.

METHOD

Ninety-eight 7-16 year-old patients with a normal facial growth pattern were clinically and radiographically evaluated. They were classified as either nasal breathing or oral breathing patients according to the predominant mode of breathing through clinical and historical evaluation, and breathing respiratory rate predomination as quantified by an airflow sensor. They were divided in two age groups (G1: 7-9) (G2: 10-16) to account for normal age-related facial growth.

RESULTS

Oral breathing children (8.0±0.7 years) showed less nasopharyngeal cross-sectional dimension (MPP) (p=0.030), whereas other structures were similar to their nasal breathing counterparts (7.6±0.9 years). However, oral breathing teenagers (12.3±2.0 years) exhibited a greater palate length (ANS-PNS) (p=0.049), a higher vertical dimension in the lower anterior face (Xi-ANS-Pm) (p=0.015), and a lower position of the hyoid bone with respect to the mandibular plane (H-MP) (p=0.017) than their nasal breathing counterparts (12.5±1.9 years). No statistically significant differences were found in head posture.

CONCLUSION

Even in individuals with a normal facial growth pattern, when compared with nasal breathing individuals, oral breathing children present differences in airway dimensions. Among adolescents, these dissimilarities include structures in the facial development and hyoid bone position.

Craniofacial morphology of HIV-positive children and adolescents undergoing antiretroviral therapy: A pilot study

INTRODUCTION

In this study, we aimed to analyze craniofacial morphology by assessing the skeletal cephalometric profiles of HIV-positive patients receiving antiretroviral therapy.

METHODS

For this study, 21 HIV-positive patients aged between 6 and 17 years (study group) were selected and compared with 21 normoreactive patients (control group), paired by sex and age. The patients were also divided into 3 age ranges (6-8, 9-12, and 13-17 years) considering the pubertal growth spurt as the central event. Eighteen (linear and angular) measurements were traced on teleradiographs by using 2 methodologies. The mean values of each measurement were compared between the study and control groups by age range.

RESULTS

The majority of the measurements checked in the HIV-positive children and adolescents for the 13-to-17 year age range were diminished, but not enough to generate a statistically significant difference in craniofacial growth. Statistically significant differences (P <0.05) were found only in the inclination of the palatal plane (6-8 years) and the position of the maxilla in the anteroposterior direction (13-17 years).

CONCLUSIONS

These results led us to conclude that some cephalometric measurements of HIV-positive children and adolescents may be similar to those of normoreactive subjects.

Correlation between forward head posture, respiratory functions, and respiratory accessory muscles in young adults

BACKGROUND

Forward head posture (FHP) causes changes in the strengths and rigidities of cervical muscles.

OBJECTIVE

The aim of this study was to investigate correlations between FHP and respiratory functions and the muscle activities of respiratory accessory muscles in young adults in their 20s.

METHODS

A volunteer sample of 33 healthy young adults participated in this study. Craniovertebral angle (CVA), cranial rotational angle (CRA), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume at 1 second (FEV1), peak expiratory flow (PEF), maximal voluntary ventilation (MVV), and sternocleidomastoid (SCM) and upper trapezius activity ratios were measured.

RESULTS

Significant positive correlations were found between CVA and VC, FVC, FEV1, PEF, and MVV, and a significant negative correlation was found between CVA and SCM activity ratio. Significant negative correlations existed between CRA and VC and FVC, and significant positive correlations between CRA and SCM and upper trapezius activity ratios.

CONCLUSION

FHP may act to lower respiratory functions, and thus, the maintenance of correct head posture is required to prevent such functional reductions.