Immunological and tissue reactions to titanium particles generated by the mechanical decontamination of dental implants: In vitro and in vivo study

Abstract

Background: Mechanical decontamination of biofilm, or implantoplasty, is a commonly employed technique for managing peri-implantitis. However, the inflammatory response and in vivo behavior of titanium (Ti) particles released during this procedure remain underexplored. This study aimed to evaluate the cytotoxic, inflammatory, and osteogenic effects of Ti particles released during implantoplasty, as well as their in vivo behavior Material and Methods: Titanium particles were generated by following a standardized protocol using drills on 150 commercially pure Ti implants. Cytotoxicity thresholds were determined using THP-1 macrophages and bone marrow-derived mesenchymal stem cells (BM-MSCs). These cells were subsequently cultured with Ti particle-conditioned medium, and inflammatory responses were analyzed using RT-qPCR for markers such as CCR7, TNF-alpha, IL-1 beta (pro-inflammatory), and CD206, TGF-beta, IL-10 (anti-inflammatory). Cytokine levels were quantified using ELISA. Osteogenic responses in BM-MSCs were assessed by analyzing Runx2, alkaline phosphatase (ALP), and osteocalcin (OC) expression, and ALP activity was measured colorimetrically. In vivo, Ti particles were introduced into mandibular defects in 20 Wistar rats, with histological analysis performed 20 days post-implantation Results: Ti particles elicited a pro-inflammatory response in macrophages, with increased expression of TNF-alpha and reduced expression of TGF-beta and CD206. Cytokine analysis confirmed elevated IL-1 beta and reduced IL-10 levels. No significant changes in ALP activity were observed. Conclusions: Titanium particles released during implantoplasty induce pro-inflammatory responses.