IMMEDIATE IMPLANT PLACEMENT USING A BIODEGRADABLE BARRIER, POLYHYDROXYBUTYRATE-HYDROXYVALERATE REINFORCED WITH POLYGALACTIN-910 - AN EXPERIMENTAL-STUDY IN DOGS

The purpose of this study was to evaluate the use of a biodegradable m embrane of polyhydroxybutyrate-hydroxyvalerate copolymer reinforced wi th polyglactin 910 fibers, as an occlusive barrier over implants place d into fresh extraction sockets. Ten dogs had the 3rd and 4th mandibul ar premolars extracted bilaterally. Each dog had 4 Astra Dental Implan ts(R) placed directly into the fresh extraction sockets. The top of th e fixtures was placed at the same level as the top of the buccal corti cal bone. The two implants in the right side were covered with the hyd rolyzable polyester material (polyhydroxybutyrate-hydroxyvalerate rein forced with polyglactin 910 fibers; PHB-HV/PG), and the 2 implants in the left side were controls without occlusive membranes. Soft tissue d ehiscences were registered for half of the implants in the test side b ut were not noted in the control side. The histomorphological measurem ents after 12 weeks showed that the mean distance from the top of the fixtures to the first bone-to-implant contact was significantly greate r than for the control side. The membrane-covered implants without deh iscences showed also significantly less bone fill compared with the co ntrol side. Inflammatory cell infiltrates were seen adjacent to all PH B-HV/PG membranes, and frequently the membrane material was surrounded by a fibrous tissue capsule. The polyester membranes used in this stu dy interfered with the marginal bone healing adjacent to the immediate ly placed implants. An increased inflammatory reaction and significant ly less marginal bone healing was registered in the membrane side comp ared with the control side.