<p>Preoperative maxillary cone-beam computed tomography for dental implant planning frequently reveals incidental pathologic findings of the maxillary sinus. As such findings may be associated with an increased risk of implant failure, they are of great significance. While asymptomatic patients with mucosal thickening only at the floor of the maxillary sinus may directly proceed to implantation, symptomatic patients with concentric mucosal thickening and an obstructed ostiomeatal unit should undergo functional endoscopic sinus surgery (FESS) in advance. In the case of odontogenic sinusitis after implantation, the implants must be ruled out as a&#xa0;cause. Perforation of the implant tip into the maxillary sinus is not a&#xa0;source of infection in an otherwise well-integrated implant. In case of implant-related sinusitis, treatment ranges from antibiotic therapy to functional surgery. The success rate of dental implants is, however, high, even in the case of pathologic findings in the maxillary sinus.</p>