Role of pharyngeal length in patients with a lack of overbite

Abstract

Anterior open bites may be localized dental manifestations, which are caused by habits or skeletal disharmony, with or without functional aberration. Previous studies suggest various associations between open bites and underlying etiologic factors. We hypothesize that respiratory efficiency may be associated with anterior open bites. Under the assumption that breathing efficiency of the oropharynx and hypopharynx may be related to pharyngeal airway length, a cephalometric variable, vertical airway length (VAL), was measured on lateral cephalograms obtained from a total of 58 subjects with, so called, “open bite tendencies” (hereafter, open bite tendency). By means of the variable VAL, the association between pharyngeal length and open bite was investigated. In addition, the difference between actual open bite and open bite tendencies was also examined. The samples were randomly collected under stringent selection criteria from an existing database. A series of statistical analyses, such as unpaired t test, multiple regression, and discriminant analysis, was used to test the proposed hypothesis. The study found that none of the open bite tendency indicators used can segregate open bite subjects from nonopen bite subjects. The obtained discriminant function clearly divides the samples into two groups, i.e., open bite group and nonopen bite group, which were based on VAL and lower facial height. The study concludes that, first, an open bite tendency may be a different entity from an actual open bite or may be a misconceptualized term. Second, pharyngeal length may be a convenient indicator to diagnose open bite. We speculate that open bite may be different from an open bite tendency in pharyngeal length.