One year histopathological evaluation of fibrous tissue surrounding TCPL implants using adult rats as a model

Fibrous tissue formation is often used as a screening method to determine the biocompatibility of orthopaedic and dental implanted material. In this investigation, porous implants of tricalcium phosphate-lysine delivery devices were implanted intraperitoneally (IP) using adult male rats as a model. The fibrous tissue surrounding the implant was studied histologically to determine the infiltration of inflammatory cells and other healing components. Fibrous capsular tissues were carefully dissected away from the capsule noting the tissue closest to the implanted material. Evaluation of the sections (5um, H&E) collected from various areas of the implants (n = 5 per group) revealed that: (1) The use of TCPL implants resulted in the formation of three distinct cell layers of fibrous tissue. (2) The fibrous tissue thickness was found to be directly proportional to the duration of the implant. (3) The infiltration of macrophages, polymorphonuclear leukocytes, and fibroblasts were present in all phases studied. (4) Ordered collagen was observed only at the end of the 6, 9, and 12 month phases. (5) Remarkable progression of vascularity was present in the second and third layers of the fibrous tissue. In conclusion, these observations confirm our previous finding using different bioceramic material.