The shape and sagittal position of the mandible is under stronger genetic control, than is its size and vertical relationship to cranial base.

BackgroundMalocclusion, body posture, and breathing pattern may be correlated, but this issue is still controversial. The aim of the study was to examine the relationship between the type of malocclusion, body posture, and nasopharyngeal obstruction in children aged 7–14 years.Material/MethodsThe study group comprised 94 patients aged 7–14 years (mean±SD: 11.9±2.1 years); 44 (46.8%) males and 50 (53.2%) females. All patients passed an examination performed by the same orthodontist (study model and cephalometric radiograph analysis), orthopedic surgeon (body posture examined from the front, side, and back), and otorhinolaryngologist (anterior and posterior rhinoscopy and pharyngoscopy) in a blind manner.ResultsPostural disorders were observed in 72 (76.6%) patients. Hypertrophy of the adenoids was diagnosed in 54 (57.4%) patients, hypertrophy of the tonsils in 85 (90.3%), nasal septum deviation in 51 (54.3%), and allergic rhinitis in 19 (20.2%) patients. There was a statistically significant correlation between presence of kyphotic posture and a reduction in the SNB angle, representing sagittal position of the mandible. Also, there was a statistically significant association between kyphotic posture and nasopharyngeal obstruction (54.1% of patients with nasopharyngeal obstruction were kyphotic, compared with 25% of patients with no nasopharyngeal obstruction; p=0.02). Kyphotic posture and reduced SNB angle were more common among males.ConclusionsWe concluded that: 1) there was a significant association between the sagittal position of the mandible (SNB angle) and a kyphotic posture; 2) kyphotic posture was significantly more common among patients with nasopharyngeal obstruction.

Background and Objective. Malocclusion, the body posture, and the breathing pat- tern may correlate, but this issue is still controversial. The aim of the study was to examine the relationship between the type of malocclusion, the body posture, and the nasopharyngeal obstruction in 12-14-year-old children. Material and Methods. The study group consisted of 76 orthodontic patients (35 boys, 41 girls) aged 12-14 years (mean age, 12.79 years {SD, 0.98J). All the patients were examined by the same orthodontist (study model and cephalometric radiograph analysis), the same orthopedic surgeon (body posture examined from the front, the side, and the back), and the same otorhinolaryngologist (anterior and posterior rhinoscopy and pharyngoscopy) in a blind manner. Results. The prevalence of a poor body posture and a nasopharyngeal pathology was high in the present study. In total, 48.7% of the orthodontic patients had a kyphotic posture and 55.3% a rib hump in the thoracic region. The nasopharyngeal pathology was diagnosed in 78.9% of the patients. The patients with the kyphotic posture had a higher mandibular plane angle (MP-SN) and a lower sagittal position of the mandible SNB angle. A deeper overbite correlated with shoulder and scapular asymmetry. The kyphotic posture was diagnosed in 55.0% of the patients with the naso- pharyngeal pathology. Conclusions. The sagittal body posture was related to the vertical craniofacial parameters and hypertrophy of the tonsils and/or the adenoids. The study showed no relationship between the degree of crowding, the presence of a posterior cross bite, orthopedic parameters, and a breathing pattern.

Background: To evaluate the genetic and environmental influences on craniofacial and airway dimensions using cephalometric analysis and deoxyribonucleic acid (DNA) based zygosity determination in a group of post-pubertal twins. Materials and methods: 22 cephalometric variables of 94 pairs of twins with completed growth were analysed. Zygosity was determined using 15 specific DNA markers. A genetic analysis was performed using maximum likelihood genetic structural equation modelling (GSEM). Results: The genetic heritability estimates of cephalometric variables describing upper airway dimensions, skeletal variables, soft palate size, maxilla relationship with hyoid bone, sagittal position of mandible. The lower airway parameters were determined by environmental factors. Conclusions: The upper airway dimensions are strongly determined by genes while the lower airway parameters are affected by environmental factors. Trial registration: The protocol has been approved by the Kaunas Regional Ethical Committee No BE – 2-41., 2020 May 13.

Background The interplay between genetic and environmental impacts on dental and facial morphology has been widely analyzed, but little is known about their relative contributions to airway morphology. The aim of this study was to evaluate the genetic and environmental influences on the cephalometric variables of airway morphology in a group of postpubertal twins with completed craniofacial growth. Materials and methods The materials comprised lateral head cephalograms of 94 pairs of twins (50 monozygotic, 44 dizygotic) with completed craniofacial growth. Zygosity was determined using 15 specific DNA markers. The computerized cephalometric analysis included 22 craniofacial, hyoideal, pharyngeal structural linear and angular variables. Genetic analysis and heritability estimation were performed using maximum likelihood genetic structural equation modeling (GSEM). Principal component analysis (PCA) was used to assess the correlations between cephalometric measurement variables. Results Upper airway dimensions showed moderate to high genetic determination (SPPW-SPP and U-MPW: a2 = 0.64 and 0.5, respectively). Lower airway parameters showed only common and specific environmental determination (PPW-TPP a2 = 0.24, e2 = 0.38; LPW-V c2 = 0.2, e2 = 0.63; PCV-AH c2 = 0.47, e2 = 0.28). The relationship between the maxilla and the hyoid bone (for variables PNS-AH, ANS-AH d2 = 0.9, 0.92, respectively) showed very strong additive genetic determination. The size of the soft palate was affected by additive and dominant genes. Its length (SPL) was strongly influenced by dominant genes, while its width (SPW) showed a moderate additive genetic influence. Owing to correlations in the behavior of variables, the data could be expressed in 5 principal components that jointly explained 36.8% of the total variance. Conclusions The dimensions of the upper airway are strongly determined by genes, while the parameters of the lower airway depend mainly on environmental factors. Trial registration The protocol has been approved by the Kaunas Regional Ethical Committee (No. BE – 2–41., May 13, 2020).