The goal of this randomized clinical study is to investigate the impact of soft tissue phenotype modification following free gingival grafting (FGG) in addition to the non-surgical mechanical therapy of peri-implant mucositis (PM) with keratinized mucosa width (KMW) < 2 mm over a 6-month follow-up period. Therefore, the following questions related to the study are raised:

• Does soft tissue modification following free gingival grafting around the implants with KMW < 2 mm, in addition to non-surgical mechanical therapy of PM, affect the change in bleeding on probing and the rate of complete disease resolution?

Patients who apply to the Department of Periodontology, Faculty of Dentistry, Gazi University, are systemically healthy, have implant-supported restorations installed at least one year prior to their enrollment, and are diagnosed with PM on these implants will be selected for the study. Patients with KMW < 2 mm at the respective implant sites will be treated with non-surgical mechanical treatment combined with soft tissue augmentation with FGG or non-surgical mechanical treatment alone.

The primary goal of treating peri-implant mucositis (PM) is to disturb the dental implant biofilm and resolve inflammatory conditions. This aims to achieve treatment success or complete disease resolution, preventing its progression to peri-implantitis. Indeed, regardless of the non-surgical mechanical/physical instrumentation approaches and despite noticeable clinical improvements, none of the existing procedures would result in complete disease resolution [i.e., absence of bleeding on probing (BOP)] in peri-implant mucositis. Taking this into account, the execution of interventions targeted at managing modifiable risk factors plays a pivotal role in maintaining peri-implant health.

Despite the increasing evidence documenting that implant sites exhibiting either a lacking or a reduced keratinized mucosa (KM) of ≤2 mm demonstrate difficulties in eliminating bacterial biofilm, leading to inflammation around the soft tissue, the requirement for a minimum peri-implant KM width (KMW) to avoid peri-implant diseases has been a highly debated topic. Indeed, KM augmentation at implant sites with a reduced KMW has been reported to be associated with statistically significant lower plaque and gingival scores as well as peri-implant probing depths (PPD) when compared with non-augmented sites. However, there is no study evaluating primarily the effect of KM augmentation on maintaining peri-implant health and preventing peri-implant diseases.

Therefore, the aim of this study is to investigate the impact of soft tissue phenotype modification following free gingival grafting in addition to the non-surgical submarginal instrumentation of peri-implant mucositis over a 6-month follow-up period.

Inclusion Criteria:

Peri-implant Mucositis

• Adult (>18 years old), systemically healthy patients,
• Presence of at least one implant affected by peri-implant mucositis characterized by the presence of bleeding on probing and/or suppuration (BoP/SoP) and the absence of bone loss beyond crestal bone level changes that occur as a result of initial bone remodeling,
• Presence of buccal peri-implant keratinized mucosa width (KMW) < 2 mm around the implants diagnosed with peri-implant mucositis,
• Patients who have implant-supported restorations installed at least one year prior to their enrollment.

Exclusion Criteria:

• Systemic diseases that could influence the outcomes of dental and surgical treatments such as uncontrolled diabetes (HbA1c > 7), active treatment phase for cancer, autoimmune diseases, osteoporosis, medications such as steroids, bisphosphonates, selective serotonin reuptake inhibitors (SSRIs), proton pump inhibitors (PPIs), and antihypertensives,
• Consumption of anti-coagulants, anti-aggregation agents, antibiotics, or corticosteroid medications during the past three months,
• Pregnancy or lactation,
• History of soft tissue grafting at the respective implant sites,
• Current untreated periodontal diseases,
• Smokers (≥ 10 cigarettes per day),
• Malpositioned implants.