There is increasing concern about particles generated from wear-prone implants that are placed in body tissues. including artificial hip, knee, and jaw joints. Although phagocytes and foreign body giant cells are associated with inhaled or embedded particulate debris, some particles also induce bone digestion by eliciting the differentiation and proliferation of highly specialized osteoclastic cells. This report describes the differential phagocytic cellular responses to four implant-related types of ground. model wear particles in a live-egg cell-response model, as implants to the chick chorioallantoic membrane (CAM): polymethylmethacrylate (PMMA). a main constituent of some temporomandibular joint (TMJ) implants and orthopedic cements used to retain artificial hips and knees: Proplast-HA, an implantable composite of polytetrafluoroethylene (PTFE) and degradable mineral (hydroxyapatite) that has been associated with bone erosion around failed TMJ implants: talc, a nondegradable mineral sometimes found in tissues as a contaminant from talc-coated surgical gloves, and authentic bone, known to induce the formation of osteoclastic cells. tight and electron microscopy of CAM tissues harvested, sectioned and stained with special reagents for the enzymes tartrate-resistant acid phosphatase (TRAP) and tartrate-resistant adenosine triphosphatase (TrATPase). and for the osteoclast-specific antigen 121F. showed that only authentic bone and the degradable HA-rich particles induced osteoclast formation. From these results. and supporting data with polypropylene particles, it is concluded that nonbiodegradable polymer particles, alone. do not induce bone dissolution. inert polymers do induce foreign body giant cells without the external mineral digestion qualities unique to osteoclasts. however. The chick embryo model system allows quick and affordable examination of material-dependent differences in phagocytic cellular responses to implant wear debris and particles from various occupational environments.