In this study genomic, proteomic and histological technologies for the search and characterization of epigenetic modifications and molecular or protein markers, useful in the diagnosis and progression of peri-implant diseases and prevention of implant failure will be used.

Samples stored at the Biomedical Research Institute of A Coruña, Xerencia Integrated Management of A Coruña (University Hospital Center of A Coruña), belonging to the collection of the line of research "Oral Health and Systemic Relationship" with registration nº 2017/104 will be used for the realization of the present study.

Nucleic acid extraction and histological analysis of the samples will be performed to evaluate the functional epigenetic modifications associated with peri-implant diseases, in an exploratory manner.

Inclusion Criteria:

• The subjects must have read, understood and signed an informed consent regarding the obtaining of biological samples and participation in the research line of "Oral Health and Systemic Relationship" existing in the Pardiñas Dental Medical Clinic and approved by the ethical committee.
• The subjects must be between 20-90 years of age.
• Subjects must be non-smokers or former smokers who have quit smoking for at least one year prior to enrollment in the study.

In addition to the general criteria listed, samples of a healthy periodontal subject must meet the following criteria when reviewing their medical and dental history :

-Subjects do not have or have had a history of periodontal disease, as described in the " 2017 World Workshop on the Classification of Periodontal and Peri- Implant Diseases and Conditions "

Samples from a subject with peri-implant disease must meet the following criteria:

-Samples of subjects who have at least one implant - supported prosthesis for at least 12 months and affected by peri- implant disease according to the " 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions "

Exclusion Criteria:

• Samples of pregnant or lactating women at the time of collection.
• Samples of subjects who were taking antibiotics within 1 month before collection of the sample.
• Samples of subjects with chronic use of non-steroidal anti-inflammatory drugs for more than 3 weeks at the time of sample collection. The use of aspirin in low doses (≤81 mg / day) will be allowed .
• Samples from subjects with disease in the mucosa in the area located around the site of sample collection.
• Samples of subjects with a systemic disease that would exclude the analysis (for example, severe medical problems, bone metabolism disorders, uncontrolled bleeding disorders, depressed immune system, diseases that require the periodic use of steroids, uncontrolled endocrine disorders) .
• Samples of subjects with a history of local irradiation therapy in the head / neck area.
• Samples of subjects with a history of having received treatment with intravenous or subcutaneous antiresorptive agents associated with osteonecrosis of the jaw, such as bisphosphonates.

Samples of subjects assigned to the healthy group that meet any of the following criteria will be excluded from participation in this study:

• Root fragments, pericoronaritis, endo-perio lesions, dental abscesses at the site of the biopsy.
• Presence of BOP in the sample collection site.

Peri- implant disease samples / Exclusion of Subjects

The samples of the subjects assigned to the peri- implant diseases group that meet any of the following criteria will be excluded from participation in this study if the implants were removed due to:

• Inadequate position of the implant.
• Subjects with implants previously treated surgically for peri- implant disease with antibiotics.

• Periodontally Healthy Subjects
• Peri-implantitis Subjects