Immunohistochemical characterization of local tissue reactions to the implantation of highly porous implants based on polyetheretherketone and polymethylmethacrylate

The development of biocompatible implant materials remains a key priority in modern maxillofacial surgery and dental practice. This study presents an evaluation of tissue responses to subcutaneous implantation of 3D-printed constructs made from polyetheretherketone (PEEK) and polymethylmethacrylate (PMMA). A morphological and immunohistochemical analysis was performed at various time points after implantation, using markers such as CD3, CD20, VEGF, and Collagen I. The findings revealed differences in inflammatory response, angiogenesis, and fibrosis depending on the material composition. The results confirm the high biocompatibility of PEEK and highlight its potential for use in reconstructive surgery. Objective: To assess the immunohistochemical response of local tissues following subcutaneous implantation of PEEK and PMMA-based materials, and to determine their biocompatibility for clinical applications. Materials and methods. Soft tissue samples were obtained from experimental animals after subcutaneous implantation of implants made from four different polymers. Morphological and immunohistochemical analyses were conducted using antibodies to CD3, CD20, VEGF, and Collagen I. Quantitative assessment was performed within standardized microscopic fields. Results. The study revealed differences in the inflammatory response, angiogenesis, and fibrosis depending on the material composition. The findings confirm the high biocompatibility of PEEK and demonstrate its potential for use in reconstructive surgery. Mild inflammatory reaction was observed near all implant types; however, the PEEK group exhibited the most stable tissue response, with CD3+ cell density corresponding to 1—2 scores and stable VEGF levels (2—3 scores) throughout the observation period. In contrast, the PMMA group showed a more pronounced immune response, particularly on day 7, where CD3+ lymphocyte density reached 3 scores, exceeding the PEEK group by 2.8-fold (p<0.05); increased expression of VEGF and Collagen I (up to 3 scores) was also observed, followed by a decrease by day 60. Conclusion. The results demonstrate the high biocompatibility and low immunogenicity of PEEK, supporting its use as a preferred implant material. PMMA-based materials may elicit stronger tissue reactions and warrant further investigation and surface optimization.