Comparative study of alloplastic materials for temporomandibular joint disc replacement in rabbits.

Young adult, white New Zealand rabbits underwent either sham surgical procedures or discectomy. In the animals that underwent discectomy, either reinforced silicone or polytetrafluoroethylene-aluminum oxide (PTFE-Al2O3) implants were placed in the glenoid fossa. During gross sectioning, the silicone implants could be easily displaced from the specimen, while the PTFE-Al2O3 implants were firmly anchored. Histologically, fragmentation of the implants was seen in the silicone group; 21.4% of the implants placed were torn. Foreign body giant cell reactions reached a peak after eight weeks. Associated fibrosis and foreign body giant cell reactions were seen, resulting in a thickened capsule and resorption of the condyle and articular fossa. In the PTFE-Al2O3 group there was marked osteoclastic activity, with resorption and severe degenerative changes in both the condyle and glenoid fossa. The foreign body giant cell reaction was severe at all time intervals and increased with time. Tearing of the implant was observed in 46.2% of the joints. These results indicate a need for further evaluation of these materials as disc replacements in humans.