The histopathology of different foreign-body reactions in oral soft tissue and bone tissue.

Foreign bodies may be endogenous or exogenous and provoke chronic inflammation of the foreign-body type. The reaction provides a mechanism for elimination of the foreign body and the reaction pattern depends on the kind of tissue involved. In soft tissues there is cellular inflammation and fibrous encapsulation with macrophages. In bone, during the healing period, biomechanical factors determine whether a fibrous encapsulation or a bony covering develops demarcating the foreign material. The particular characteristics of the foreign-body reaction in bone explain the success of dental and orthopaedic implants.