Effect of septal deviation on nasomaxillary shape: A geometric morphometric study

Nasal cavities in their primitive stage communicate with the oral cavity until the 8th week of intrauterine life where the posterior palate initiates its development. Hence, starting from the initial growth phases, a significant connection lays between the nasal structures and the maxillary bone and witnessing key functional roles, among which the respiration. Proper nasal breathing has been proven to be a crucial factor for the maturity of the craniofacial complex, and obstruction of the respiratory airway due to nasal septum deviation can generate clinically significant reduction of the nasal airflow. This situation will imply irreversible repercussions that hinders the harmonious development of the craniofacial complex. In order to understand such potential impacts of septal deviation, our first objective was to materialize the relation between septum deviation, and both nasal cavity and maxillary structures. For the second objective, we used Procrustes analysis to assess the shape variation of these two anatomical regions, the bivariate plots of Principal Components to evaluate their shape space, and a two-block Partial Least Square (PLS) to explore their covariation. We analysed, in this cross-sectional study, 62 posteroanterior cephalometric radiographs of adult subjects from both sexes (23 males, 39 females; mean age 25.3 years) collected from the database of the Department of Orthodontics at Lebanese University. Landmarks were plotted and variables were calculated and divided into nasal septum, nasal cavity and maxillary ones. The sample was further divided into two groups based on septal deviation severity (a septal deviation is considered minor if <6). The results suggested that nasal septum deviation was correlated to reduced nasal cavity area and a reduced maxillary area. Moreover, the comparison of the two groups concluded that the difference between all variables was statistically significant with higher scores in the minor septal deviation group. These findings were corroborated with the shape analysis where the mean centroid size of nasal cavity and that of the maxilla in the group of reduced septal deviation were significantly greater than those of the group with increased angle of deviation. Results of PLS analysis concluded to a strong covariation between nasal septum and nasomaxillary complex. These conclusions support the early septoplasty in growing patients as a solution to redirect the normal course of growth and re-establish a good function of the nasomaxillary complex.