Abstract
Aim
This study investigated the association between nasal obstruction and its associated factors in young children by quantitatively measuring the nasal airway resistance (NAR).
Methods
A total of 82 children aged 3–6 years (31 boys and 51 girls) were included in the study. Questionnaires were used to collect information about allergies, nasal diseases, stuffy nose, oral habits, and feeding behavior problems from the parents. Furthermore, measurements of the height, body weight, calf circumference, grip strength, tongue pressure, occlusal force, lip-closure strength, mouth rinsing function test, and NAR were taken.
Results
The NAR was negatively correlated with the height and age of the children. Additionally, NAR was associated with feeding behavior problems, as reported by the parents of the children.
Conclusion
The findings of this study suggest that interviewing parents about their children’s feeding behavior problems may prove valuable in diagnosing nasal disorders in young children. Early improvements in nasal obstruction may address feeding behavior problems and contribute to the normal growth and development of oral functions in young children.
1
Introduction
Mouth breathing may have a negative impact on the growth and development of young children due to its association with dental caries, periodontal disease, malocclusion, halitosis, and other conditions [ ]. Previous studies have shown that mouth breathing, a common oral habit, is a symptom of developmental insufficiency of oral function [ ]. Several young children have feeding behavior problems, such as slow eating, taking too long to chew, unbalanced diet, swallowing food without adequate chewing, and picky eating [ ]. Our previous studies showed that these feeding behavior problems in young children are related to oral functions, such as tongue pressure and masseter muscle activity [ , ].
Mouth breathing is caused by nasal obstruction, which can be attributed to nasal inflammation, such as allergic rhinitis, chronic rhinitis, and sinusitis [ , , , ]. Similarly, nasal obstruction can result from morphological deformities of the nose, such as a deviated nasal septum and adenoid hypertrophy [ , , ]. Various methods, such as endoscopy, acoustic rhinometry, and nasal airflow meter, can be used to evaluate nasal obstruction [ ]. However, nasal airway resistance (NAR) is one of the most useful methods for assessment because it is quantitative, simple, and noninvasive; there are several reports on NAR measurements in adults [ , , , ]. According to the otolaryngology guidelines, the average NAR value in Japanese adults is below 0.25 Pa/cm 3 /s [ ]. However, only a few studies have examined NAR in children [ ].
Therefore, this study aimed to investigate the association between nasal obstruction and its associated factors in young children by measuring the NAR, owing to its adaptability.
2
Materials and methods
Ethical approval for the study was obtained from the Ethics Committee of Showa University School of Dentistry (Issue#2018–007 in 2019). After obtaining consent from the Itabashi Ward, the consent forms were sent to the ward nursery schools willing to cooperate in the study. Additionally, consent for participation was obtained from the nursery schools and the parents of the target children.
2.1
Study design and participants
This cross-sectional study was conducted from November to December 2020 initially and included 289 children aged 3–6 years from four nursery schools in the Itabashi Ward in Tokyo, Japan. Among the 289 participants, 112 provided written consent; 30 were excluded from the analysis for the following reasons: absent from school on the test day (n = 5); submitted incomplete questionnaires (n = 5); required special support (n = 2); did not undergo the NAR measurements (n = 6); unable to provide the NAR measurements (n = 11); and unable to provide the tongue pressure measurement (n = 1). Eventually, 82 participants, including 31 boys and 51 girls, were included in the study for further analysis ( Fig. 1 ).
2.2
Calf circumference and grip strength measurements
In our previous study, correlations were observed between the skeletal muscle mass and calf circumference in children; the calf circumferences were measured as indices of the skeletal muscle mass [ ]. Furthermore, previous research has shown a correlation between grip strength and overall muscle strength [ ]. Therefore, grip strength was used as a rapid indicator of the participants’ overall muscle strength.
Therefore, both calf circumference and grip strength were measured in the current study. The children were seated in chairs at a height where the legs could reach the floor comfortably, and the calf circumferences were measured using a measuring tape.
A Jamar® Smart Hand Dynamometer (Patterson Medical Ltd., Sutton-in-Ashfield, UK) was used to assess the maximum grip strength. Two consecutive measurements were taken, and the maximum value was recorded.
2.3
Oral function and examination
Various aspects of oral function, such as tongue pressure, occlusal force, lip-closure strength, and mouth rinsing function, were assessed.
Tongue pressure was measured using the JMS Tongue Pressure Measuring Device® (GC Co., Ltd., Tokyo, Japan). The children were seated in chairs with postures such that the Frankfurt plane was parallel to the floor, and the larger of two consecutively measured tongue pressure values were recorded [ ].
The occlusal force was measured using an occlusal pressure measurement film (Dental Prescale II® S size; GC Co., Ltd., Tokyo, Japan). The children were seated in chairs as described earlier and asked to bite the film with maximum force; two consecutive measurements were taken. The films were analyzed on the same day using the Bite Force Analyzer® (GC Co., Ltd., Tokyo, Japan), and the larger of the two values were recorded [ , ].
The lip-closure strength was measured using the Lipplekun® device (Shofu Corporation, Kyoto, Japan). The children were seated in chairs in a manner that the eye–ear plane was parallel to the floor. The lip-closure strength was measured three times consecutively, and the intermediate values were recorded [ ].
The coordinated movements of oral functions were measured using the mouth rinsing function test [ ]. The children were asked to sit in chairs and gargle water (10 mL) from cups. They were required to gargle softly while keeping their head from bending backward. The evaluation was based on the movement of water from its initial position in the mouth to where it was discharged.
Finally, the oral cavities of the children were examined for the number of teeth and the presence of dental caries and occlusal abnormalities.
2.4
Nasal airway resistance
The children cleared their nasal airways by blowing their noses before the NAR measurements. The nasal airway resistance was measured via rhinomanometry (NR6 Executive; GM Instruments Ltd., UK; Fig. 2 ) using the nozzle anterior method. The bilateral resistance during inhalation was measured at 100 Pa. The NAR measurements were conducted three times per child, and the average value was recorded [ , , , , ].
2.5
Questionnaires
The children’s parents were asked to complete the questionnaires before the main survey. Information about the children’s age, gender, mouth breathing habits, nasal diseases, and feeding behavior problems were collected and recorded in survey forms.
2.6
Statistical analysis
The correlations between the NAR and age, body weight, height, and the Kaup index were examined using Spearman’s correlation coefficients. The NAR data among the various questionnaire items were compared using Mann–Whitney U test. Data analysis was performed using the SPSS Statistics software (version 27.0, IBM Japan, Tokyo, Japan), and a p-value of <0.05 was considered significant.
3
Results
3.1
Demographic and anthropometric characteristics of the children
The median age of the children was 5 years and 4 months (interquartile range, 4 years and 6 months–6 years and 1.8 months). Table 1 shows the median and mean measurements, ranges, average values, and standard deviation based on age. Older participants tended to be taller and heavier. Survey results were based on the age group.
| 3 years (n = 9) | 4 years (n = 24) | 5 years (n = 20) | 6 years (n = 29) | Total (n = 82) | |
|---|---|---|---|---|---|
| boys | 3 | 7 | 10 | 11 | 31 |
| girls | 6 | 17 | 10 | 18 | 51 |
| Height (cm) | 99.0 (96.8–103.0) | 102.6 (99.9–103.9) | 110.0 (107.4–113.8) | 115.0 (113.0–120.0) | 108.6 (103.0–114.9) |
| 98.9 ± 3.8 | 101.6 ± 5.1 | 109.8 ± 4.5 | 116.0 ± 4.9 | 108.4 ± 8.2 | |
| Body weight (kg) | 14.2 (14.0–16.0) | 15.7 (14.5–17.4) | 18.3 (17.0–19.3) | 20.4 (18.8–22.0) | 18.0 (15.6–20.0) |
| 14.8 ± 1.2 | 15.9 ± 2.1 | 18.3 ± 2.1 | 21.4 ± 4.1 | 18.3 ± 3.9 | |
| Kaup index | 14.9 (14.6–15.4) | 15.4 (14.6–16.2) | 14.7 (14.3–16.0) | 14.8 (14.6–16.0) | 15.0 (14.4–16.1) |
| 15.1 ± 0.7 | 15.3 ± 1.2 | 15.1 ± 1.3 | 15.9 ± 2.4 | 24.7 ± 2.1 | |
| Calf Circumference (cm) | 22.8 (22.6–23.4) | 23.2 (22.6–24.3) | 24.4 (23.6–25.7) | 26.1 (24.9–27.2) | 24.6 (23.3–25.8) |
| 22.8 ± 1.0 | 23.4 ± 1.3 | 24.6 ± 1.3 | 26.3 ± 2.1 | 24.7 ± 2.1 | |
| Maximum grip strength (kg) | 4.0 (3.2–4.7) | 4.5 (2.8–5.6) | 5.4 (4.8–6.7) | 8.3 (5.6–9.3) | 5.3 (4.2–7.4) |
| 3.9 ± 1.1 | 4.3 ± 1.7 | 5.6 ± 1.3 | 7.5 ± 2.2 | 5.7 ± 2.3 | |
| Maximum tongue pressure (kPa) | 13.2 (12.3–20.0) | 18.4 (14.0–26.0) | 21.1 (14.9–24.3) | 22.8 (17.6–28.6) | 20.6 (13.9–26.0) |
| 16.0 ± 6.1 | 18.8 ± 9.4 | 19.7 ± 8.6 | 23.3 ± 8.4 | 20.3 ± 8.9 | |
| Maximum occlusal force (N) | 551.6 (525.6–700.6) | 428.0 (372.8–593.3) | 468.9 (324.8–541.7) | 511.0 (383.7–681.0) | 492.7 (368.6–667.3) |
| 566.3 ± 123.2 | 481.6 ± 192.4 | 494.7 ± 276.7 | 535.2 ± 190.9 | 513.0 ± 212.0 | |
| Median Lip-closure strength (N) | 4.4 (3.7–7.5) | 5.5 (3.6–8.1) | 6.7 (5.4–8.8) | 8.9 (7.1–10.2) | 7.1 (5.0–9.8) |
| 5.6 ± 2.5 | 6.4 ± 3.7 | 7.4 ± 2.6 | 8.8 ± 2.5 | 7.4 ± 3.1 | |
| Mouth Rinsing Function Test | 5.0 (4.0–5.0) | 5.0 (4.0–5.0) | 5.0 (4.0–5.0) | 5.0 (5.0–5.0) | 5.0 (4.0–5.0) |
| 4.4 ± 0.7 | 4.3 ± 1.1 | 4.6 ± 0.7 | 4.8 ± 0.5 | 4.5 ± 0.8 | |
| Number of present tooth | 20.0 (20.0–20.0) | 20.0 (20.0–20.0) | 20.0 (20.0–20.0) | 22.0 (20.0–24.0) | 20.0 (20.0–20.0) |
| 20.0 ± 0.0 | 20.0 ± 0.0 | 20.2 ± 0.8 | 21.5 ± 2.0 | 20.6 ± 1.5 | |
| Number of “dmf” tooth | 0.0 (0.0–0.0) | 0.0 (0.0–1.0) | 0.0 (0.0–0.0) | 0.0 (0.0–1.0) | 0.0 (0.0–1.0) |
| 0.0 ± 0.0 | 0.4 ± 0.7 | 1.1 ± 2.9 | 1.3 ± 2.7 | 0.8 ± 2.2 | |
| Nasal pain airway degree (Pa/㎤/sec) | 0.554 (0.477–0.674) | 0.555 (0.517–0.638) | 0.527 (0.452–0.660) | 0.455 (0.407–0.676) | 0.532 (0.443–0.676) |
| 0.575 ± 0.106 | 0.693 ± 0.513 | 0.643 ± 0.374 | 0.693 ± 0.680 | 0.668 ± 0.527 |
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