The present report describes the case of a patient who underwent maxillary sinusitis right after dental implant installation with sinus lifting. Computed tomography scan revealed a dental implant (#16) was protruded inside the right maxillary sinus and confirmed the obstruction of ostium. A symptom remission was gained with the dual approaches combined by functional endoscopic sinus surgery and an intra-oral approach. Fully recovered function and healing of sinus were identified after 10 months follow-up. We report the case of sinusitis caused by protrusion of implants with sinus floor lift procedures and propose that practitioners should be aware of the possible its complications and management.