Nasorespiratory characteristics and craniofacial morphology.

The relationship between respiration and craniofacial morphology has been debated for many years. Despite numerous studies, the term 'mouth breathing' remains ill-defined. Still, medical and surgical treatments are performed in order to modify respiration and 'improve' facial growth. This clinical belief continues, in the absence of conclusive evidence, that a causal relationship exists between oral respiration and facial growth, or that such treatment modalities and their associated risks actually modify respiratory mode. Moreover, diagnostic indicators have been postulated for the identification of patients for whom such therapy would be beneficial. The purpose of this study was to investigate the strength of association between mode of respiration and craniofacial morphology. In addition, the precision level was calculated for two popular cephalometric tests for possible nasal impairment. The results suggest that: (1) cephalometric analyses are poor indicators of nasal impairment and should not be used in clinical decision making, and (2) facial morphology and respiratory mode are unrelated.