TNF and periodontitis: Likewise, it has also been shown that patients with periodontitis and with Cr-Co or nickel-chromium (Ni-Cr)-based metal restorations show a more pronounced inflammatory reaction with increased levels of MMP-8, IL-1β, IL-6 and TNF-α compared to patients with periodontal involvement but without prosthetic restorations demonstrating once again that metal ceramic prosthetic restorations could induce a more marked deterioration of periodontal tissues [35].