Roles of a new drug-delivery healing abutment in the prevention and treatment of peri-implant infections: a preliminary study

In this study we modified the common healing abutment into a specifically designed drug-delivery abutment (DDA), which is a hollow columnar system with drug-distribution holes in peripheral wall. The objective of this study was to investigate the possibility of the prevention and treatment of peri-implant diseases with this drug-delivery system. Minocycline hydrochloride was added to DDAs with different hole diameters, and then subjected to bacteria-inhibition tests in vitro with three oral bacterial strains, namely, Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis. The implants were placed into the mandible of beagle dogs. DDAs with or without minocycline and normal healing abutments were installed. One week after surgery, the plaques on all the abutments were analyzed by plaque stain. Following this, both abutments and adjacent teeth received oral hygiene to maintain a healing environment. Eleven weeks later, the ligature-induced experimental peri-implantitis model was set up for eight weeks. Periapical radiographs and clinical measurements were performed during the process. We found that inhibition zones were observed surrounding all the tested drug-delivery abutments in all three bacterial strains. One week after implant installation, oral plaque formed on the DDAs with minocycline was significantly less than that on normal abutments and DDAs without drugs. DDA with the minocycline group showed a relatively slower rate of deterioration of the mucosal inflammation and probing depth in the experimental peri-implant lesions. We suggest that this drug-delivery abutment could effectively deliver medications into peri-implant tissues to minimize plaque formation and relieve peri-implant inflammation in the experimental peri-implantitis model.