The use of dental implants is a predictable procedure to replace the missing tooth with high rates of success and survival. In addition, placing the abutment on the same day as the implant surgery is a safe and biologically sound procedure to minimize bone loss and peri-implant inflammation. Although citric acid antibacterial coating has never been tested in vivo, recent in vitro data support its clinical use due to its antibacterial effect at the abutment level.

This prospective randomized controlled clinical trial aims to evaluate the microbiological and inflammatory profile of implant abutments coated with citric acid.

The study population will consist on patients referred to the Department of Periodontology at Universitat Internacional de Catalunya for the replacement of missing teeth and who meet the following inclusion criteria will be included consecutively in the study.

5.3.1. Inclusion criteria

• Patients with ≥18 years old.
• Systemically healthy patients.
• Patients with healthy periodontal status with a full mouth plaque index ≤ 20% (O'Leary, 1972) and full mouth bleeding index (Ainamo & Bay, 1975) before implant surgery.
• Need for at least one dental implant in maxillary and mandibular partially posterior edentulous healed sites.

5.3.2. Exclusion criteria

• Patients with some special conditions that could interfere surgical oral procedures.
• Patients with non-treated periodontal disease.
• Patients with uncontrolled systemic disease that could impair wound healing (i.e. Diabetes Mellitus).
• Pregnant women.
• Patients allergic to any metallic component of the materials.
• Need for bone or soft tissue reconstruction simultaneous to implant placement.
• Lack of primary stability during implant placement (i.e., insertion torque < 25 N, ISQ > 60)
• Smokers ≥ 10 cigarettes per day.
• Patients will be excluded from the study if they violate any of the criteria during the trial, as well as if they desire to withdraw the study or have any adverse reactions to the materials employed.

The primary outcome measure will be the reduction of biofilm formation at the test abutments compared with the control abutments at the 12 weeks 6 months, 1 year and 3 year of follow-up. Biofilm formation over abutments will be quantified with Ilumina sequencing analysis.

Inclusion Criteria:

• Patients with ≥18 years old.
• Systemically healthy patients.
• Patients with healthy periodontal status with a full mouth plaque index ≤ 20% (O'Leary, 1972) and full mouth bleeding index (Ainamo & Bay, 1975) before implant surgery.
• Need for at least one dental implant in maxillary and mandibular partially posterior edentulous healed sites.

Exclusion Criteria:

• Patients with some special conditions that could interfere surgical oral procedures.
• Patients with non-treated periodontal disease.
• Patients with uncontrolled systemic disease that could impair wound healing (i.e. Diabetes Mellitus).
• Pregnant women.
• Patients allergic to any metallic component of the materials.
• Need for bone or soft tissue reconstruction simultaneous to implant placement.
• Lack of primary stability during implant placement (i.e., insertion torque < 25 N, ISQ > 60)
• Smokers ≥ 10 cigarettes per day.
• Patients will be excluded from the study if they violate any of the criteria during the trial, as well as those that desire to withdraw the study or have any adverse reactions to the materials employed.