Metal Nanoparticles Released from Dental Implant Surfaces: Potential Contribution to Chronic Inflammation and Peri-Implant Bone Loss.

David Penarrocha,Cristian Taccioli,Eitan Mijiritsky,Chiara Gardin,Eriberto Bressan,Giulia Brunello,Letizia Ferroni,Miguel Penarrocha,Gloria Bellin,Luca Sbricoli,Marco Tatullo,Barbara Zavan,Devorah Schwartz-Arad,Adriano Piattelli,Stefano Sivolella

doi:10.3390/ma12122036

Abstract

Peri-implantitis is an inflammatory disease affecting tissues surrounding dental implants. Although it represents a common complication of dental implant treatments, the underlying mechanisms have not yet been fully described. The aim of this study is to identify the role of titanium nanoparticles released form the implants on the chronic inflammation and bone lysis in the surrounding tissue. We analyzed the in vitro effect of titanium (Ti) particle exposure on mesenchymal stem cells (MSCs) and fibroblasts (FU), evaluating cell proliferation by MTT test and the generation of reactive oxygen species (ROS). Subsequently, in vivo analysis of peri-implant Ti particle distribution, histological, and molecular analyses were performed. Ti particles led to a time-dependent decrease in cell viability and increase in ROS production in both MSCs and FU. Tissue analyses revealed presence of oxidative stress, high extracellular and intracellular Ti levels and imbalanced bone turnover. High expression of ZFP467 and the presence of adipose-like tissue suggested dysregulation of the MSC population; alterations in vessel morphology were identified. The results suggest that Ti particles may induce the production of high ROS levels, recruiting abnormal quantity of neutrophils able to produce high level of metalloproteinase. This induces the degradation of collagen fibers. These events may influence MSC commitment, with an imbalance of bone regeneration.

Highlights

Several publications have indicated that dental implants are a predictable option for the replacement of missing teeth, due to their high survival and success rates [1]
The results showed the activation of the osteoclasts activity in presence of metal particles and ions, the presence of macrophages that phagocytosed Ti microparticles and mutations in human cells cultured in medium containing
In order to test if Ti nanoparticles could affect the main cells presents around the implants, i.e., fibroblasts and mesenchymal stem cells (MSCs), cells were in vitro treated with a defined concentration of these nanoparticles

Summary

Introduction

Several publications have indicated that dental implants are a predictable option for the replacement of missing teeth, due to their high survival and success rates [1]. In vitro tests confirmed that micro-movements occurring at the implant-abutment connection can increase the wear of the inner surfaces of the connection and, subsequently, the release of metal ions and micro- and nanoparticles into the surrounding tissues [8,9,10,11]. In this view, the main question is if these degradation products released from dental implants could affect peri-implant tissue, inducing pathologic bone resorption [8]

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