Objectives <p>Biofilm accumulation is considered the primary cause of peri-implant inflammation. Still, metallosis caused by an increased concentration of titanium ions at the site of peri-implantitis site cannot be ignored. Whether titanium ions alone or in concert with bacterial biofilm trigger inflammation and bone destruction in peri-implant tissues remains unproven.</p> Materials and methods <p>Articles were retrieved from PubMed/Medline, Web of Science. All studies focusing on titanium ions release in peri-implant reactions were included and evaluated.</p> Results <p>Titanium implants are considered non-inert and may release titanium ions in the intraoral microenvironment, the most important of which is the acidic environment created by bacterial biofilms. Although the correlation between titanium ion release and the incidence or progression of peri-implantitis is controversial, several studies have confirmed the potential role of titanium ions. Diffusion or entry of titanium ions into the circulation may be a scavenging effect on local titanium ions but can cause systemic adverse effects. However, existing measures are not yet able to balance reducing biocorrosion and maintaining osteogenic results, and the exploration of new materials requires long-term clinical data.</p> Conclusions <p>Titanium ions have potential impacts on peri-implant tissue and systemic circulation. Titanium ions are closely associated with bacterial biofilms in the occurrence and development of periimplantitis. The preventive strategies for the release and action of titanium ions remain to be explored.</p> Clinical relevance <p>Our findings may provide the hope of shedding light on the pathogenesis of peri-implantitis and its treatment.</p>