Variation of patterns of malocclusion by site of pharyngeal obstruction in children.

Objective: To correlate the type of dental occlusion and the type of pharyngeal lymphoid tissue obstruction in children.

Design: Cross-sectional study.

Setting: Ambulatory ear, nose, and throat clinic of Faculdade de Medicina da Universidade de São Paulo.

Patients: One hundred fourteen children aged 3 to 12 years presenting with mouth breathing and snoring due to tonsil and/or adenoid enlargement.

Interventions: Oroscopy and nasal fiber pharyngoscopy complemented by lateral head radiography to diagnose the type of obstruction, and clinical examination to evaluate the dental occlusion.

Main Outcome Measures: Tonsil and adenoid obstruction (classified from grades 1-4) and sagittal, transverse, and vertical evaluation of dental occlusion.

Results: Obstructive enlargement of both tonsils and adenoids was detected in 64.9% of the sample; isolated enlargement of the adenoids, in 21.9%; isolated enlargement of the palatine tonsils, in 7.0%; and nonobstructive tonsils and adenoids, in 6.1%. All types of pharyngeal obstruction were related to a high prevalence of posterior crossbite (36.8%). Statistically significant association was found between sagittal dental occlusion and the site of lymphoid tissue obstruction (P = .02). A higher rate of class II relationship (43.2%) was detected in the group with combined adenoid and tonsil obstructive enlargement. Isolated tonsil obstruction showed a higher rate of class III relationship (37.5%).

Conclusions: Different sites of obstruction of the upper airway due to enlarged lymphoid tissue are associated with different types of dental malocclusion. Findings are relevant to orthodontic and surgical decision making in these mouth-breathing patients.