Effect of the anatomical patterns of maxillary sinus floor on the endodontic microsurgery plan of maxillary sinusitis of endodontic origin.

[BACKGROUND] Due to the close relationship between maxillary posterior teeth and maxillary sinus floor (MSF), infection from teeth with endodontic disease may spread into maxillary sinus and cause the occurrence of maxillary sinusitis of endodontic origin (MSEO). Endodontic microsurgical intervention in infected teeth causing MSEO requires careful assessment and planning. This study evaluated the anatomical patterns of MSF using cone-beam computed tomography (CBCT), and further explored their influence on the endodontic microsurgery of MSEO.

[METHODS] A total of 333 CBCT scans were collected between August and December 2023. The classification of MSEO, the degree of mucosal thickening, and the shortest distance from the root apex to MSF were recorded. An improved classification of the anatomical relationships between the teeth and MSF was proposed based on CBCT images. Additionally, the angle at the nadir of MSF, and the divergence angle between the roots and maxillary sinus septa were recorded. Analysis of variance was used to analyze the differences among different groups. A significance level of P < 0.05 was employed.

[RESULTS] The anatomical relationship between the root apex and MSF affected the endodontic microsurgery plan of MSEO. Maxillary sinus elevation is needed when MSF is below the line between the buccal and palatal roots, when the root apices contact or protrude into MSF, or when apical lesion is directly connected to the maxillary sinus mucosa. In addition, maxillary sinus mucosal thickening may be more severe when the root apex or apical lesion is close to the maxillary sinus.

[CONCLUSION] The anatomical relationship between maxillary posterior teeth and MSF is an important factor in evaluating and designing endodontic microsurgery for MSEO.