Effect of Twin-block Appliance on Pharyngeal Airway, Sleep Patterns, and Lung Volume in Children with Class II Malocclusion

Abstract

In this study, we sought to evaluate the effect of the twin-block appliance on pharyngeal airway dimensions, sleep patterns, and lung volumes in growing children with class II malocclusion with a retrognathic mandible. Twenty children aged 9-12 years with class II malocclusion with a retrognathic mandible participated in the study. A validated sleep questionnaire assessed the sleep patterns and the sleep problems of the children. The pre-treatment cephalometric variables and the pharyngeal airway passage (PAP) dimensions were analyzed. Spirometry tests were performed to evaluate lung volumes. A custom-made twin-block appliance was fabricated, and children were instructed to wear it for a minimum of 10 months. All variables including sleep problems, cephalometric variables, and pharyngeal airway measurements were evaluated post-treatment. Spirometry tests were re-evaluated at the end of the twin-block treatment. All data were statistically analyzed. Post-twin-block appliance treatment, there was a definite decrease in snoring, noisy breathing, and sleeping with mouth open. The sella-nasion to B point angle (SNB), mandibular length, the depths of oropharynx, nasopharynx, and hypopharynx as well as the height of nasopharynx (HNP) were significantly increased post-treatment (p <0.001). The length and thickness of soft palate (SPI) increased significantly (p <0.001), while its inclination decreased significantly (p <0.001). We found improvements in forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1); however, the changes were statistically not significant (p = 0.88 and p = 0.78). Twin-block appliance significantly increased the pharyngeal airway dimensions and improved the length and thickness of the soft palate in children with class II malocclusion. Post-twin-block treatment showed a considerable reduction in the sleep problems of the children. The lung volume measurements showed improvement; however, it was not statistically significant. Twin block may be used not only to correct the facial disharmony of children with a retrognathic mandible but also to improve the airway dimensions and lung volume as well as to reduce the sleep-disordered symptoms.