Effects of adenoid hypertrophy on nasopharyngeal airway ventilation: A computational fluid dynamics study.

OBJECTIVES

Adenoid hypertrophy causes impaired nasopharyngeal airways (NA) ventilation. However, it is difficult to evaluate the ventilatory conditions of NA. Therefore, this study aimed to analyze the nasopharyngeal airway resistance (NA) based on computational fluid dynamics simulations and the nasopharyngeal airway depth (NA) and adenoid hypertrophy grade measured on cephalometric cone-beam computed tomography images and determine the relationship between NA and grade and NA to ultimately assess using cephalometric measurements whether NA has airway obstruction defects.

METHODS

Cephalogram images were generated from cone-beam computed tomography data of 102 children (41 boys; mean age: 9.14 ± 1.43 years) who received orthodontic examinations at an orthodontic clinic from September 2012 to March 2023, and NA and adenoid grade and NA values were measured based on computational fluid dynamics analyses using a 3D NA model. Nonlinear regression analyses were used to evaluate the relationship between NA and NA and correlation coefficients to evaluate the relationship between grade and NA.

RESULTS

NA was inversely proportional to the cube of NA (R = 0.786, P < 0.001), indicating a significant relationship between these variables. The resistance NA increased substantially when the distance NA was less than 5 mm. However, adenoid Grade 4 (75 % hypertrophy) was widely distributed.

CONCLUSIONS

These study findings demonstrate that the ventilatory conditions of NA can be determined based on a simple evaluation of cephalogram images. An NA of less than 5 mm on cephalometric images results in NA obstruction with substantially increased airflow resistance.