Characterizing the Inflammation Around Dental Implants: Bacterial Infection, Hypersensitivity or Both?

Inclusion Criteria: * Received at least one functional implant (implant restored with a prothesis); * Did not receive peri-implant mucositis and peri-implantitis treatment in the past three months. Exclusion criteria: * Dental records with incomplete information; * Individuals with a weak immune system or chronic disease such as diabetes, heart, lung or kidney disease; * Pregnant women; * Individuals undergoing orthodontic therapy and those who have oral piercing. * History of diseases that modify or suppress the immune and inflammatory response, including rheumatoid arthritis, diabetes, lupus, and inflammatory bowel disease and metastatic cancer; * Taking medications that cause antiresorptive osteonecrosis of the jaw (including any dose of intravenous bisphosphonates, oral bisphosphonate intake for more than three years, receptor activator of nuclear factor kappa-B ligand inhibitors, or antiangiogenic medications); * Taking medications known to induce gingival hyperplasia including anticonvulsants, immunosuppressants, or calcium channel blockers; * Taking steroid medications, systemic or local antibiotics in the last three months (as this may affect the interleukins activity); * Received radiation therapy to the head and neck or chemotherapy; * Received treatment to manage an inflamed implant, including management of peri-implantitis and peri-implant mucositis in the last three months.