To avoid complications, the intimate relation between the maxillary sinus and dental roots deserves attention during surgical procedures. Accidental introduction of foreign bodies, such as dental implants, may irritate the maxillary sinus mucosa, causing sinusitis. Cone beam computed tomography (CBCT) has been proven to be suitable for diagnosis in these cases by providing the exact location of the foreign body. The present article reports 3 cases of foreign bodies inside the maxillary sinus associated with inflammatory processes. Imaging examinations, such as CBCT, are an important tool to assist dentists in diagnosing the presence of foreign bodies in the interior of the maxillary sinus.