Delayed Foreign Body Granuloma Following Sinus Augmentation With Deproteinized Bovine Bone: A Case Report.

This report describes an uncommon granulomatous foreign body reaction that developed after lateral sinus augmentation with deproteinized bovine bone mineral (DBBM). The patient presented 5 months postoperatively with an extraoral draining fistula and intraoral swelling that failed to resolve with multiple courses of antibiotics and was initially misdiagnosed as a chronic infection. Early surgical exploration with subsequent histopathological analysis identified multinucleated giant cells enclosing residual graft particles, establishing a diagnosis of a noninfectious foreign body granuloma. Following thorough debridement and a 12-month recovery period, implant placement was carried out successfully, with clinically stable results maintained at 30 months of follow-up. This case illustrates the importance of considering foreign body reactions when evaluating persistent postoperative complications after sinus augmentation and emphasizes the essential role of tissue biopsy in reaching an accurate diagnosis.