Bone healing around implants placed in a jaw defect augmented with Bio-Oss((R)) - An experimental study in dogs

The present experiment was carried out to study some tissue reactions aroun d implants that were placed in an edentulous ridge which had been augmented with deproteinized natural bovine cancellous bone mineral. In 4 male beagl e dogs, the premolars in the right side of the mandible were extracted and a large buccal ridge defect was created by mechanical means. The bone plate at the lingual aspect of the defect was left intact. 5 months later, the d istal 2/3 of the defect area was augmented with Bio-Oss(R) (Geistlich Sons Ltd, Wolhusen, Switzerland) mixed with a fibrin sealer (Tisseel(R), Immune AG, Vienna, Austria). After 3 months of healing, 3 fixtures (Astra Tech AB, Molndal, Sweden; TiO-blast; 8x3.5 mm) were installed in the mandible; 2 we re placed in the augmented portion and 1 was placed in the non-augmented po rtion of the defect. After a healing period of 3 months, abutment connectio n was performed and a plaque control period initiated. 4 months later, the dogs were sacrificed and each implant region was dissected. The tissue samp les were dehydrated, embedded in plastic, sectioned in the bucco-lingual pl ane and examined in the light microscope. It was observed that osseointegra tion failed to occur to implant surfaces within an alveolar ridge portion p reviously augmented with Bio-Oss(R). In the augmented portion of the crest, the graft particles were separated from the host tissue as well as from th e implant by a well-defined connective tissue capsule. Although the lingual aspect of all fixtures (test and control) was in contact with hard tissue at the time of installation, after 4 months of function, a deep vertical bo ne defect frequently had formed at the lingual surface of the implants. It was concluded that in this model (i) Bio-Oss(R) failed to integrate with th e host bone tissue and (ii) no osseointegration occurred to the implants wi thin the augmented portion of the crest.