ROLE OF PHARYNGEAL LENGTH IN PATIENTS WITH A LACK OF OVERBITE

Anterior open bites may be localized dental manifestations, which are caused by habits or skeletal disharmony, with or without functional ab erration. Previous studies suggest various associations between open b ites and underlying etiologic factors. We hypothesize that respiratory efficiency may be associated with anterior open bites. Under the assu mption that breathing efficiency of the oropharynx and hypopharynx may be related to pharyngeal airway length, a cephalometric variable, ver tical airway length (VAL), was measured on lateral cephatograms obtain ed 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 ten dencies was also examined. The samples were randomly collected under s tringent selection criteria from an existing database. A series of sta tistical analyses, such as unpaired t test, multiple regression, and d iscriminant analysis, was used to test the proposed hypothesis. The st udy found that none of the open bite tendency indicators used can segr egate open bite subjects from nonopen bite subjects. The obtained disc riminant function clearly divides the samples into two groups, i.e., o pen bite group and nonopen bite group, which were based on VAL and low er facial height. The study concludes that, first, an open bite tenden cy may be a different entity from an actual open bite or may be a misc onceptualized term. Second, pharyngeal length may be a convenient indi cator to diagnose open bite. We speculate that open bite may be differ ent from an open bite tendency in pharyngeal length.