Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The identification of the primary site of OSA is essential to determine treatment ...strategy. This study aimed to establish computational fluid dynamics (CFD) analysis for determining the clinical severity of OSA and the primary site of OSA.
Twenty children (mean age, 6 years) were divided into OSA and control groups according to their apnea-hypopnea index. Three-dimensional airways were constructed from computed tomography data. The pharyngeal airway morphology and the pressure and velocity of the upper airway were evaluated using CFD analysis.
The maximum velocity and negative pressure of the upper airway in the OSA group were significantly correlated with the severity of OSA (r
= .741, P < .001; r
= -.653, P = .002). A velocity higher than 12 m/s indicated the primary site of OSA. In addition, we found that the primary site of OSA is not necessarily the same as the collapsible conduit site.
CFD analysis allows both the evaluation of the disease severity of OSA and the identification of the primary site of OSA in children. The primary site of OSA is not necessarily the same as the collapsible conduit site; therefore, CFD analysis can be used to identify the appropriate intervention for treating OSA.
(1R)-trans-Norchrysanthemic acid fluorobenzyl esters are synthesized and their structure-activity relationships are discussed. These esters show outstanding insecticidal activity against mosquitoes. ...In particular, the 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl analog (metofluthrin) exhibits the highest potency, being approximately forty times as potent as d-allethrin in a mosquito coil formulation when tested against southern house mosquitoes (Culex quinquefasciatus). Metofluthrin also exhibits a significant vapor action at room temperature.
Spatial repellency of metofluthrin-impregnated polyethylene latticework plastic strips against Aedes aegypti mosquitoes was evaluated. Analysis of environmental factors affecting the efficacy of ...these strips, such as room temperature, humidity, and house structure, was performed in a residential area in My Tho City, Tien Giang Province, Vietnam. Treatment with the strips at the rate of 1 strip per 2.6-5.52 m(2) (approximately 600 mg per 2.6-5.52 m(2)) reduced the collection of Ae. aegypti resting inside the houses for at least eight weeks. Multiple regression analysis indicated that both increase in the average room temperature and decrease in the area of openings in the rooms that were treated with the strips positively affected the spatial repellency of metofluthrin.
Introduction Rapid maxillary expansion (RME) is known to improve nasal airway ventilation. Recent evidence suggests that RME is an effective treatment for obstructive sleep apnea in children with ...maxillary constriction. However, the effect of RME on tongue posture and pharyngeal airway volume in children with nasal airway obstruction is not clear. In this study, we evaluated these effects using cone-beam computed tomography. Methods Twenty-eight treatment subjects (mean age 9.96 ± 1.21 years) who required RME treatment had cone-beam computed tomography images taken before and after RME. Twenty control subjects (mean age 9.68 ± 1.02 years) received regular orthodontic treatment. Nasal airway ventilation was analyzed by using computational fluid dynamics, and intraoral airway (the low tongue space between tongue and palate) and pharyngeal airway volumes were measured. Results Intraoral airway volume decreased significantly in the RME group from 1212.9 ± 1370.9 mm3 before RME to 279.7 ± 472.0 mm3 after RME. Nasal airway ventilation was significantly correlated with intraoral airway volume. The increase of pharyngeal airway volume in the control group (1226.3 ± 1782.5 mm3 ) was only 41% that of the RME group (3015.4 ± 1297.6 mm3 ). Conclusions In children with nasal obstruction, RME not only reduces nasal obstruction but also raises tongue posture and enlarges the pharyngeal airway.
A number of previous studies have reported the effects of breathing on maxillofacial morphology in childhood. However, accurate findings for evaluating the airway are difficult to acquire because it ...analysis of upper airway ventilation condition can be problematic. To improve this situation, we developed a three-dimensional upper airway model using cone beam CT data for highly precise analysis of the upper airway with computational fluid dynamics used to assesses the flow of air. As a result,we found that the pharyngeal airway morphology in Class III children showed that the long diameter type of pharyngeal airway and wide diameter type of pharyngeal airway with low tongue posture were shown. On the other hand, in Class II children, upper airway obstruction can be a cause of excessive vertical maxillofacial growth, and that this may be attributed to various parts of the upper airway, such as the nasal, nasopharyngeal, oropharyngeal, and hypopharyngeal airway. It was also revealed that when nasal obstruction is improved by rapid maxillary expansion, the volume of the pharyngeal airway increases and low tongue posture is improved. Thus, we succeeded in clarifying the mechanism by which rapid maxillary expansion improves upper airway obstruction. Pediatric obstructive sleep apnea syndrome occurs at a high frequency, with a prevalence of 2% in otherwise health children. With use of available medical treatment, the success rate is 70%. In the future, we hope to examine the efficacy of application of orthodontic procedures for treatment, such as rapid maxillary expansion or mandibular forward induction, for social contributions from the field of pediatric dentistry.
Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The most common cause of pediatric OSA is adenotonsillar hypertrophy. ...Adenotonsillectomy is the first-line treatment for pediatric OSA; however, OSA persists in a significant number of patients due, in part, to the method of evaluating enlarged adenoids and tonsil tissue. The reason for these effects on OSA severity is not clear. This study aimed to establish a method to diagnose the need for adenoidectomy or tonsillectomy.
Twenty-seven Japanese children (mean age 6.6 years) participated in this study, undergoing polysomnography and computed tomography examination. Pharyngeal airway morphology (adenoids and tonsil tissue size, volume, and cross-sectional area CSA) and pressure on the upper airway were evaluated at each site using computational fluid dynamic analysis.
Apnea-hypopnea index (AHI) showed a strong linear association with maximum negative pressure (P
) (AHI = -0.055* events/h P
-1.326, R² = .805). The relationship between minimum CSA (CSA
) and P
was represented by an inversely proportional fitted curve (P
= -4797/CSA
-5.1, R² = .507). The relationship between CSA
and AHI was also represented by an inversely proportional fitted curve (AHI = 301.6 events/h/CSA
, R² = .680). P
greatly increased if CSA
became ≤ 30 mm². The negative pressure of each site increased when CSA measured ≤ 50 mm².
In children, when the CSA for each site is ≤ 50 mm², AHI is likely to be elevated, and the patient may require tonsillectomy or adenoidectomy.
The purpose of the study was to test the hypothesis that condylar shape varies based upon the condition of anterior disk displacement in young adolescent patients with temporomandibular disorder ...(TMD). The study design consisted of 96 juvenile female patients (aged 9 to 20; 15.1±2.3 yrs.) with clinical signs and/or symptoms of TMD. Bilateral high-resolution magnetic resonance imaging scans were performed in frontal and horizontal views with the mandible in the closed position. Disk positions were evaluated to classify the patients into three diagnostic groups. The results of the study, using ANOVA and Bonferroni tests, demonstrated significant differences among the groups. The conclusion drawn from the study was that condylar shape and size vary based on anterior disk position in juvenile females with TMD. The study's results suggest that disk displacement results in a smaller condyle.
Introduction Upper airway size is increasingly recognized as an important factor in malocclusion. However, children with Class III malocclusion are somewhat neglected compared with those with a Class ...II skeletal pattern. Therefore, the purpose of this study was to establish the characteristic shape of the oropharyngeal airway (OA) in children with Class III malocclusion. Methods The sample comprised 45 children (average age, 8.6 ± 1.0 years) divided into 2 groups: 25 with Class I and 20 with Class III malocclusions. OA size of each group was evaluated by cone-beam computed tomography. Cluster analysis, based on OA shape, redivided the subjects into wide, square, and long types. The distributions of Class I and Class III subjects were compared among the types. Results The Class III group showed statistically larger OA area and width compared with the Class I group. Area was positively correlated with Class III severity. The square type included 84% of the Class I malocclusions but only 30% of the Class III malocclusions, indicating that the OA in Class III malocclusion tends to be flat. Conclusions The Class III malocclusion is associated with a large and flat OA compared with the Class I malocclusion.
Introduction The purpose of this study was to clarify the relationships between upper airway factors (nasal resistance, adenoids, tonsils, and tongue posture) and maxillofacial forms in Class II and ...III children. Methods Sixty-four subjects (mean age, 9.3 years) with malocclusion were divided into Class II and Class III groups by ANB angles. Nasal resistance was calculated using computational fluid dynamics from cone-beam computed tomography data. Adenoids, tonsils, and tongue posture were evaluated in the cone-beam computed tomography images. The groups were compared using Mann-Whitney U tests and Student t tests. The Spearman rank correlations test assessed the relationships between the upper airway factors and maxillofacial form. Results Nasal resistance of the Class II group was significantly larger than that of the Class III group ( P = 0.005). Nasal resistance of the Class II group was significantly correlated with inferior tongue posture ( P <0.001) and negatively correlated with intermolar width ( P = 0.028). Tonsil size of the Class III group was significantly correlated with anterior tongue posture ( P <0.001) and mandibular incisor anterior position ( P = 0.007). Anterior tongue posture of the Class III group was significantly correlated with mandibular protrusion. Conclusions The relationships of upper airway factors differ between Class II and Class III children.
Rapid maxillary expansion (RME) expands the maxillary dentition laterally and improves nasal airway obstruction. However, the incidence of nasal airway obstruction improvement after RME is ...approximately 60%. This study aimed to clarify the beneficial effects of RME on nasal airway obstruction in specific pathologic nasal airway diseases (nasal mucosa hypertrophy and obstructive adenoids) using computer fluid dynamics.
Sixty subjects (21 boys; mean age 9.1 years) were divided into 3 groups according to their nasal airway condition (control, nasal mucosa hypertrophy, and obstructive adenoids), and those requiring RME had cone-beam computed tomography images taken before and after RME. These data were used to evaluate the nasal airway ventilation condition (pressure) using computer fluid dynamics and measure the cross-sectional area of the nasal airway.
The cross-sectional area of the nasal airway significantly increased after RME in all 3 groups. The pressures in the control and nasal mucosa groups significantly reduced after RME but did not change significantly in the adenoid group. The incidence of improvement in nasal airway obstruction in the control, nasal mucosa, and adenoid groups was 90.0%, 31.6%, and 23.1%, respectively.
The incidence of improvement in nasal airway obstruction after RME depends on the nasal airway condition (nasal mucosa hypertrophy and obstructive adenoids). In patients with nonpathologic nasal airway conditions, the obstruction may be sufficiently improved with RME. Furthermore, to some extent, RME may be effective in treating nasal mucosa hypertrophy. However, because of obstructive adenoids, RME was ineffective in patients with nasal airway obstruction.
•In normal children, nasal airway obstruction improves after rapid maxillary expansion (RME).•In nasal mucosa hypertrophy children, RME improves nasal airway obstruction to some extent.•RME is not effective in addressing obstruction among children with adenoids.
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