The clinical signs of peri-implant mucositis include: 1. congestion, redness or hyperplasia of the marginal gingiva, although these features are sometimes not obvious; 2. bleeding and/or pus spillage due to light probing; 3. increased probing depth, with the probe entering the peri-implant gingival sulcus more than 3 mm if unobstructed; 4. usually without significant pain. In addition to the symptoms of peri-implant mucositis, peri-implantitis is accompanied by bone resorption, with a typical crater-like bone defect that surrounds the implant and is well defined. Standard radiographs show V-shaped hypointense translucent areas in the proximal and distal centers. Since the osseointegration from the apical zone to the lesion area is intact, the implant may not show any signs of loosening. Loosening of the implant and radiographs showing translucent areas around the implant indicate complete loss of osseointegration and are a sign of complete failure of the dental implant. Increased clinical probing depth, bleeding on probing (BOP), or peri-implant bone loss alone are not sufficient to support a diagnosis of peri-implantitis. Sites with a probing depth of more than 3 mm do not always suffer from peri-implantitis. The type (shape) of the implant, the attachment component (method) and the superstructure of the restoration affect the structure of the peri-implant tissue. To create a gingival papilla during soft tissue formation in the aesthetic area, the distance from the shoulder of the implant to the gingival margin can be up to 5 mm and the probing depth can be up to 5 mm. Bone resorption can also be caused by implants that are buried too deeply or implants that are placed too close to each other. With deeper implants, there may be both mucositis and marginal bone remodeling, which can be misdiagnosed as peri-implantitis and can be difficult to identify clinically, and the prevalence of peri-implantitis may therefore be overestimated in some studies.