**3. Diagnosis of peri-implantitis**

The advanced case of peri-implantitis can be identifiable with the evidence of radiographic bone loss, mobility, and clinical signs of infection. The challenge is to diagnose the early stage of peri-implantitis that will aid in the prevention of further bone resorption and subsequent loss of the implant. Diagnosing peri-implant diseases using periodontal probing and radiographs may be inaccurate and only provides a historical record of past disease rather than current disease activity (**Figure 1**).

**Figure 1.** *The clinical and radiographic appearance of peri-implantitis.*

Some of the clinical parameters used for the diagnosis are as follows [7]:


Developing biomarker technologies may offer possibilities in the diagnostic application. Although more research is needed, the assessment of proinflammatory cytokines (IL-1β, TNFα, MMP-8) in the peri-implant crevicular fluid may be of value to diagnose peri-implantitis and peri-implant mucositis but are, at this time, inappropriate to predict peri-implantitis because of the limited evidence of controlled longitudinal clinical trials. MMP-8 is a promising biomarker as an early signal of peri-implant inflammation [8]. Commercially available chair-side diagnostic tests for MMP-8 to detect peri-implant diseases are promising. Elevated levels of MMP-8 in peri-implant crevicular fluid (PICF) are associated with peri-implant inflammation, while low MMP-8 levels (<20 ng/mL) indicate healthy peri-implant tissues. Pathologically elevated levels of MMP-8 (>20 ng/mL) can be detected by a quantitative MMP-8 chair-side device, ImplantSafe® [9].
