Mechanical Constriction of the Maxilla Alters Nasal Architecture

Introduction: We investigated the effect of transverse maxillary constriction on nasal septal deviation (NSD) and nasal floor slanting. Methods: 60 growing Wistar rats (21 days old) were divided into four groups: (1) Experimental Group 1 received active constriction force (100cN), (2) Experimental Group 2 received active expansion force (100cN), (3) Sham received the same spring as Experimental Groups without receiving any active force, and (4) Control group did not receive any appliance. Samples were collected after 28 days for microcomputed tomography (μCT) analysis. Results: Experimental Group 1 demonstrated maxillary constriction (both skeletal and dental), accompanied by mandibular shift on closure, clockwise mandibular rotation, and increased mandibular plane angle and facial height. Constriction was also associated with severe nasal floor slanting in the molar area that extended posteriorly. Nasal floor canting was accompanied by a slanted vomer and a C-shaped NSD. The direction of nasal floor canting and mandibular shift was always similar. Experimental Group 2, on the other hand, was not associated with nasal deviation, and a slight slanting of the nasal floor was observed only when there was a mandibular shift. Conclusions: Our study suggests that the constricting transverse forces applied to the maxilla can be associated with nasal septal deviation. One possible mechanism by which constriction contributes to nasal septal deviation is by promoting mandibular shift. Mandibular shift, in turn, dictates the direction of slanting of the nasal floor and, consequently, the vomer, which may, in turn, lead to nasal septal deviation.