Histomorphometric observations of bone integration from cadaveric subperiosteal mandibular implants

Objective:

Overall comparisons were made between two human cadaveric mandibles restored with subperiosteal implants to determine the relative magnitude of bone integrated to the implant alloy/coating and hydroxyapatite (HA) grafting particulates.

Methods:

Two cadaveric (10-11 year in vivo times) mandibular specimens were obtained with subperiosteal implants fabricated from cobalt alloy coated with plasma sprayed HA. Surgically, HA particulate was placed along the implant struts and bone surfaces.

The explanted mandibles* fixed in 10% buffered formalin were cross-sectioned at six locations at the transcutaneous posterior posts plus two sections at the anterior posts. Histomorphometric measurements of ground sections stained with Sanderson's Rapid Bone Stain were analyzed with a Bioquant Nova system to determine the bone integration on both the implant surface and the HA particulates.

Results:

Mandible 1 histomorphometry showed that 65% of the HA coating remained on the alloy. A greater amount of bone was integrated to the HA coating and bone was integrated along parts of the alloy surface. There was a noticeable lack of cortical bone under the implant and the HA particulate apparently migrated within the bone.

Mandible 2 implant was placed without particulate HA and retained more of the HA coating compared to the first mandible (86 Vs 65%). Overall, more integration (coated and non-coated regions) existed compared to the mandible one (58%).

Conclusions:

Plasma sprayed HA coating on these 11 year in vivo cobalt subperiosteal implants was integrated and was partially resorbed over time.

Bone was integrated along the non HA coated cobalt alloy surfaces.

Some cortical bone remodeled along the implant framework, and the HA particulate apparently repositioned over time and function.

Studies are continuing for parametric and statistical comparisons including another cadaveric specimen.

*IRB number: X050823001