Adenoid hypertrophy and open bite

Aim: To evaluate if the constricted airway passage, measured by the nasopharyngeal (NP) and oropharyngeal (OP) width, has a correlation to anterior open bite.
Methods: Lateral cephalometric radiographs of 43 patients with anterior open bite (26 with mixed dentition and 17 with permanent dentition) and 30 patients with overbite (15 with mixed dentition and 15 with permanent dentition) were obtained from de Department of Pediatric Dentistry and Orthodontics of the Federal University of Rio de Janeiro for examination. Eight patients with syndromes were excluded from study. Cephalometric measurements were carried out using Dolphin Imaging Management SolutionsTM software (Chatsworth, CA, USA). Measures of NP and OP were evaluated according to the McNamara's soft tissue analysis and were correlated with the presence of open bite or overbite. Student's t test and chi-square were used to assess statistical differences in continuous and dichotomic variables, respectively. Kruskal-Wallis test was employed to compare multiple variables.
Results: Open bite patients showed significant decreased mean NP and OP values compared to overbite patients. Lack of labial seal was observed in all open bite patients. When patients with mixed and permanent dentitions were analyzed separately, the mean NP value was still significantly smaller in the open bite group. However, the mean OP values were smaller in the open bite group in both dentitions analysis, but were not statistically different.
Conclusions: All patients with anterior open bite had reduced NP and OP measures compared to overbite patients, in spite of dentition.

Keywords
anterior open bite, adenoid hypertrophy; nasopharyngeal width; oropharyngeal width