Retention characteristics of porous rooted Co-Cr-Mo alloy dental implants.

The interface characteristics of porous rooted cobalt-chromium-molybdenum alloy (Co-Cr-Mo) dental implants which had been in free standing function in canine mandibles for a period of two years were investigated. The displacement of the implants and of points on the adjacent mandibular cortex were determined by mechanical testing. Bone ingrowth was quantified, and the structure of the bone-implant interface and mandibular cortex were characterized using histologic and microradiographic analyses. Displacement characteristics were correlated with determinations of the tissue structure adjacent to and growth within the implant to provide information about the biological attachment. A correlation was found between the thickness of the buccal and lingual cortical plates and implant displacements; implants having the greatest displacement response were in mandibles with the thinnest cortical plates. A relationship could not be established between the implant displacement response and the quantitative tissue structure data. Differences observed in the displacement response of the implant by mechanical testing were not observed by clinical measurements of mobility. It was concluded that implant retention mechanical behavior results from both interfacial displacement and deflection of the adjacent mandibular structures.