Morphometric analysis of the relationships between the maxillary first molar and maxillary sinus floor

Objectives: To assess the relationships between the maxillary first molar and the maxillary sinus floor in a group of patients referred to a dental clinic. Methods: Ninety-seven patients were recruited for this study. The distances between the examined roots (mesio-buccal, disto-buccal and palatal) as well as furcations, and the sinus floor, were evaluated using cone beam computed tomography, and grouped as follows: class 0: distance = 0 mm; class 1: 0 mm < distance < 2 mm; class 2: 2 mm ≤ distance < 4 mm; class 3: 4 mm ≤ distance < 6 mm; class 4: 6 mm ≤ distance. The Spearman’s Rank Correlation coefficient was used to test the univariate associations between furcation-sinus floor distance and each root class. Results: The prevalence of class 0 was the highest for the palatal root (44.33%), followed in descending order by mesio-buccal (40.21%), and disto-buccal (38.14%) roots. The highest correlation coefficient was recorded when assessing the relationship between furcation-sinus floor distance and palatal root classes (rho = 0.66, p < 0.001, n = 97). Conclusions: Altogether, the results suggest that the palatal root of the maxillary first molar not only had the closest relationship with the sinus floor, but also proved to be the best predictor for the furcation-sinus floor distance. The clinician should be aware of the anatomical and morphological details of this root, especially when taking surgical decisions.