Abstract
Three cases in whom dental implants had migrated into the maxillary sinus were admitted to our hospital. General dentists at another private clinic had previously performed dental implant placement in combination with socket lift procedures in the posterior maxillae. In case 1, an implant had migrated into the maxillary sinus 7 months after placement. In case 2, an implant had migrated three months after the first surgery. In case 3, three implants had migrated into the maxillary sinuses at or immediately after the first surgery. All implants were removed through the access window on the lateral maxillary sinus wall under local anesthesia. Waters radiographs of cases 1 and 2 revealed signs of inflammation of the maxillary sinus at the first visit. Additional surgical intervention for removal of bone substitute was needed in case 1, because pain and nasal symptoms did not improve after removal of the implant. Case 3 was admitted to our hospital 2 years after implant displacement; the delay was because his previous dentist had told him not to worry about the implants in the sinus cavities, and no signs of inflammation presented in the maxillofacial region.
Two migrated implants of these three cases had been placed in the non-submerged condition and these three patients had minimum residual bone height of the posterior maxillae. Therefore, non-submerged implant placement and minimum residual bone height are the main risk factors for migration of implants into the maxillary sinus, because of insufficient primary stability and occlusal load on the healing abutments of the implants postoperatively.
