Alveolar Ridge Augmentation Around Exposed Mandibular Dental Implant With Histomorphometric Analysis

Alveolar ridge augmentation either before or during implant placement is a predictable procedure under certain conditions. A major complication during the healing phase is incision line opening and membrane exposure, which may result in reduced bone gain and reduced implant survival. This case report describes alveolar bone regeneration around three dental implants despite membrane exposure that developed during healing post-surgically.

A 72-year-old female presented requesting dental implants to replace tooth numbers 18, 19, and 20. A cone-beam computed tomography (CBCT) scan showed loss of horizontal and vertical ridge dimensions. All implants were placed with a variable degree of implant thread exposure on their buccal surfaces, ranging from 3 to 4.5 mm. Simultaneous bone grafting was performed using freeze dried bone allograft and deproteinized bovine bone mineral that was covered by a d-PTFE membrane that was secured with tacking screws. Primary closure was obtained, and flaps were sutured. Three weeks post-surgically, membrane exposure occurred. Exposure was monitored and patient was instructed to follow strict oral hygiene instructions around the exposed membrane. Membrane exposure gradually increased without infection and was removed at 16 weeks. Membrane removal revealed dense fibrous tissues covering all implant surfaces. At the second stage surgery, new bone was seen covering all the implants coronal to the cover screws. A trephine core biopsy specimen revealed significant new bone formation and connective tissue around any residual grafted bone.

d-PTFE membrane exposure does not necessarily lead to adverse healing outcomes for alveolar ridge augmentation if handled properly with close patient follow-up.