Cellular inflammatory responses to implanted dental materials

Cellular inflammatory responses to subcutaneous implantation of amalgam and composite resins were assessed in rats by use of histologic and immunocytochemical methods 2 days to 8 weeks after implantation. Frozen and paraffin sections were obtained from subcutaneous tissues associated with amalgam and composite resin suspensions. The amalgam induced mild inflammation with proliferation of few resident macrophages, but implantation of composite resins was associated with an influx of monocytes, increased numbers of resident connective tissue macrophages, and abnormal major histocompatibility antigen class II (Ia antigen) expression. The data suggest that composite resins may produce a more pronounced inflammatory response than dental amalgams do when incorporated in soft tissues.