A retrospective study on the relationship between maxillary posterior teeth and maxillary sinus floor using cone-beam computed tomographic images

Introduction: The aims of this study were to evaluate the distance and relationship between the root apex of maxillary posterior teeth and the maxillary sinus floor (MSF) and whether they varied with age. Cone-beam computed tomographic (CBCT) images covering maxillary sinus taken in our department from December 2015 to December 2016 were retrospectively analyzed. Material and Methods: Totally 221 CBCT images of maxillary posterior teeth were analyzed. The distance and relationship between the root apex and the MSF was measured and categorized into four types. The data were correlated with age. ANOVA, Fisher's exact test, Cochran-Armitage trend test, Pearson's Chi-square test were used. Results: For the second premolar, the distance from the apex to the MSF was the furthest compared to first and second molars. The majority of apices were located below the MSF. For the first molar, the palatal root owned the shortest distance (2.79 mm) (P < 0.05) and highest frequency (11.8%) in Type IV (root protruded into the MSF) in all teeth. For second molar, the mesiobuccal root had the minimum distance (2.08 mm) (P < 0.05) in all teeth and the second highest frequency (11.0%) in Type IV. In young people (20-40 years), the shorter distance and higher frequency in Type IV differed significantly compared to other age groups (P < 0.05). Discussion and Conclusion: The data verified the close relationship between the root apex of maxillary posterior teeth and the MSF. Age was a key factor to correlate the relation. Special care should be taken when dealing with maxillary posterior teeth, especially for young people.