NASAL OBSTRUCTION AND FACIAL GROWTH - THE STRENGTH OF EVIDENCE FOR CLINICAL ASSUMPTIONS

The orthodontic relevance of nasorespiratory obstruction and its effec t on facial growth continues to be debated after almost a century of c ontroversy. The continuing interest in nasal obstruction is fueled by strong convictions, weak evidence, and the prevailing uncertainty of c ause and effect relationships that exist. The essence of any debate is to provide opposing evidence from which a majority vote is obtained. Political issues may be appropriately resolved by such means as a majo rity vote. Scientific issues, however, can only be resolved by data an d appropriately structured hypotheses put to the test. One of the prob lems in debating nasorespiratory obstruction and facial growth is the inability to provide unequivocal answers to such issues as: How much n asal obstruction is clinically significant? At what age is the onset c ritical and for how long does it have to exist before an effect on fac ial growth can be expected? To provide unequivocal answers, clinical s tudies need to be designed to identify and quantify the degree of naso respiratory obstruction and compare individuals for any clinically rel evant differences. The purpose of this article is to review the availa ble evidence. If both data and untested popular beliefs are subjected to the same rigorous criteria, indications for the orthodontic managem ent of patients with nasorespiratory obstruction may gain a more ratio nal approach to treatment recommendations.