Abstract
Nasal cavity is well fitted for respiratory function. Habitual mouth breathing, however, is not only unphysiological, but also quite hazardous to maintain oral health condition. Clinically, severe gum-disease, multiple tooth decay and bad mouth odor may be associated with mouth breathing, but their cause has not yet been clarified sufficiently. To estimate the flow pattern associated with mouth breathing, equipotential points in and out side oral cavity were measured on a jaw model made of cupper plate. Following to this experiment, Uranin and aluminum powder was introduced in water flow to visualize the flow patterns of inspiration and expiration. As the results of these experiments, the followings were observed; (1) Main inhalation flow goes into the oral cavity along the lower lip as well as in front of the mouth; (2) Direction and speed of flow were mainly affected by angulations and opening widths of upper and lower teeth; (3) After entering into the mouth, main flow clashed against the palatal gingiva margin and then ran into the throat alongside hard palate; (4) Air flow visualization technic using oral model is effective to analyze mouth breathing.
