Peri-implant diseases are common post-restorative complications in implant rehabilitations and they occur with an incidence of 12-43%. Based on the available data in literature, the surgical therapy for peri-implantitis is effective in disease resolution. Surgical access to peri-implant lesions facilitates the removal of all granulation tissue from the defect area as well as debridement and decontamination of the exposed implant surface defect area. Different techniques have been used for implant surface decontamination during peri-implant surgery, including mechanical, chemical and laser treatments.

Peri-implantitis are defined as inflammatory diseases caused by bacterial biofilm around implant surface characterized by bleeding on probing, probing depth and eventually bone loss; if not successfully treated they may lead to implant loss. Based on the available parameters that have been reported in literature non surgical therapy doesn't seem to be effective on peri-implantitis.

Therefore it is recommended to consider advanced therapies such as surgical interventions when non surgical peri-implant therapy fails to achieve significant improvements in clinical parameters. Numerous approaches have been used for implant surface decontamination during per-implant surgery, including mechanical, chemical and laser treatments. Conventional mechanical means don't seem to be effective on peri-implant diseases. In addition, the rough implant surface is a retentive factor for bacterial colonization and therefore makes implant surface difficult to debride. Another problem in maintaining implant health concerns the presence or absence of keratinised tissue around implant: if present, it seams to help the patient to maintain an optimal level of oral hygiene around implant and therefore the implant survival itself.

The aim of the present randomized controlled clinical trial is to assess the influence of keratinised tissue around implant in improving clinical parameters. In particular, implant surface will be decontaminated mechanically with titanium curettes and chemically using chlorhexidine; after this a CTG around tissue implant will be randomized

Inclusion Criteria:

• presence of at least one screw-type titanium implant exhibiting bleeding and/or suppuration on probing combined with:

  1. PPD ≥ 5 mm and bone loss ≥ 2 mm (compared to crestal bone levels at the time of placement of the reconstruction)
  2. PPD ≥6 and bone loss ≥3 (not compared to crestal bone levels at the time of placement of the reconstruction)

• single tooth and bridgework restorations without overhangs no evidence of occlusal overload (i.e. occlusal contacts revealed appropriate adjustment),

• treated chronic periodontitis and proper periodontal maintenance care FMPS < 20%

• non-smoker or light smoking status in smokers (<10 cigarettes per day) implant function time ≥ 1 year.

Exclusion Criteria:

• Patients with uncontrolled diabetes
• patients with osteoporosis or under bisphosphonate medication,
• pregnant or lactating women
• patients with a history of radiotherapy to the head and neck region hollow implants
• implant mobility
• implants at which no position could be identified where proper probing measurements could be performed;
• previous surgical treatment of the peri-implantitis lesions