A New Geometric Intersection Point (Ms) to Determine the Spatial Position of Maxillary Sinus

Introduction: Cephalometeric landmark detection, is a knowledge intensive activity to identify on standardized lateral x-rays of the skull, to perform measurements needed for medical diagnosis, treatment planning and evaluation. For computation of analysis of steps and for determination of underlying structures, provided landmarks should be correctly localized. Due to the complexity of human anatomy sensed in a cephalometric x-ray, the landmarks are localized and constructed. Maxillary sinus has an important role to play in the formation of facial contours. Objective: Our aim is to check the validity of new geometric intersection point Ms, evaluating cephalometerically the spatial position of maxillary sinus and to find any correlation between the spatial position of maxillary sinus and sagittal dysplasias. Study design: A single-institution prospective analysis. Subjects and methods: A total of 20 lateral cephalograms were used, of both sexes, ranging in age from 18-25 years. These radiographs were from subjects, classified into class I and class II on the bases of ANB and Ao-Bo. Maxillary sinus was carefully analyzed and measured in linear dimensions of length and width and its spatial position was calculated by using a new geometric intersection point Ms, created by the intersection of the linear measurements, in relation to the anterior cranial base. The spatial position of maxillary sinus was calculated from the position of the intersection point Ms. The length and height of maxillary sinus was measured and compared in both the groups. Results: The mean of maxillary sinus length (MSL) and height (MSH) was 43.2±SD 3.2mm and 41.2±SD 3.8mm , respectively for class I (p value=0.595) and 44.2±SD 4.9mm and 43.0±SD 3.4mm, respectively for class II (p value=0.283). The intersection point Ms depicting centre of maxillary sinus from x-axis (Ms-Msx) was same for both the groups. Mean for Ms-Msy, was 37.3±SD 5.7 for class I and 37.8±SD 1.9 for class II (p value=0.796). No statistical significance was found among the results in both the groups. Conclusion: The length and height of maxillary sinus was calculated and the centre of maxillary sinus was calculated by the intersection of the two. This new point can contribute in calculating the spatial position of sinus and be an effective measure to study the convexity and concavity of the midface. In the present study, the length and height of the sinus did not alter with the increased or decreased ANB and Ao-Bo. There was no significant spatial position change of maxillary sinus with variation in ANB and Ao-Bo (sagittal). Regarding vertical parameters, Ms may have significant correlation with the various malocclusions.