The use of titanium dental implants has become a common modern treatment to restore teeth. Although the success rate of dental implants is high, inflammation around the dental implant still occurs. The current study will investigate if the inflammation around the implant is due to bacterial infection, hypersensitivity or both.

The goal of this cross-sectional study is to (1) Establish the levels of cytokines in peri-implant crevicular fluid associated with bacterial infection and hypersensitivity reaction; (2) Compare the levels of cytokines associated with hypersensitivity and bacterial infection between healthy implants and inflamed implants (peri-mucositis and peri-implantitis); (3) Determine whether the difference in the levels of cytokines, if they exist, reflects the clinical diagnosis of healthy implants and inflamed implants.

The main objective of this study is to:

1. Establish the levels of cytokines in peri-implant crevicular fluid associated with bacterial infection (Type 1 and 3: IL-1, IL-6, IL-12, IL-17, IL-23, GM-CSF, IFN-γ, TNF-α), hypersensitivity reaction (Type 2: IL-4, IL-5, and IL-13) and the level of MMPs and including MMP-1, MMP-2, MMP-3, MMP-9 and MMP-13.
2. Compare the levels of cytokines associated with hypersensitivity and bacterial infection between healthy implants and inflamed implants (peri-mucositis and peri-implantitis).
3. Determine whether the difference in the levels of cytokines, if they exist, reflects the clinical diagnosis of healthy implants and inflamed implants.

Secondary objectives includes:

1. Measure the volume of peri-implant crevicular fluid and compare it between healthy implants and inflamed implants (peri-mucositis and peri-implantitis).
2. Investigate the association between the levels of cytokines and the severity of inflammatory responses.
3. Show how levels of cytokines influence the severity of inflammatory responses.

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.

This cross-sectional study is carried out at McGill University Health Center (MUHC) - Montreal General Hospital Oral and Maxillofacial Clinic. The electronic dental records database at the MUHC Montreal General Hospital Oral and Maxillofacial clinic were screened to identify potentially eligible participants. Individuals who had a functional implant (implant restored with a prosthesis) placed between year 2010 and year 2016 were reviewed. Eligible individuals are contacted and invited to participate.

There is no plan to make individual participant data (IPD) available to other researchers.