Abstract:To assess the relationship between the maxillary sinus floor (MSF) and the maxillary posterior roots using Multi-slice computed tomography (MSCT) in Indian population. Materials and Methods: MSCT images of about 604 maxillary sinuses from 302 patients were studied. The relationship of 2416 teeth and 5926 root tips consisting of first premolar, second premolar, first and second molar to the maxillary sinus were examined. Image analysis was done separately by an endodontist, a postgraduate student and a radiologist trained in MSCT. The observers has to assess the vertical relationship between the MSF and the roots of molar and premolar teeth which were noted as “g” for gap between root tip and MSF; “t” for root tip touching the MSF; “p” for root projecting into the sinus and the length of projection into the sinus was measured in millimeters. Data were recorded and statistical analysis was done.