TNF and Peri-Implantitis: In a similar study, but with prosthetic implants, Duarte, et al.11(2009) evaluated TNF-α expression in sites exhibiting different peri-implant inflammation severities using RT-PCR and found higher TNF-α expression in implants with severe peri-implantitis, followed by initial peri-implantitis and mucositis, which did not differ from each other.