The objective of this human randomized, double blind, placebo-control (RDBPC) study is to evaluate the efficacy of a 0.2% chlorhexidine (CHX) gel on reducing bacterial load and peri-implant inflammation at implant-abutment interface during the early healing stage.Thirty-six healthy patients (mean age 52,28 years; range 29-75 years) without a significant past medical anamnesis, all non-smokers, will be recruited as candidates for single implant placement and prosthetic rehabilitation.Patients will be randomly divided in group A (control) and group B (test) as indicated by the randomization chart. All Implants (Cortex classic, Shalomi, Israel)would be inserted by two skilled operators who followed a two-stage protocol and placed them according to the manufacturer's instructions.Eventually, all patients will be rehabilitated with a single implant-supported crown. During all the stages either a gel containing 0.20% CHX (Plak ®Gel; Polifarma Wellness Srl, Rome, Italy) or a placebo gel (Placebo, Polifarma Wellness Srl, Rome, Italy) will be used. The two gels are perfectly alike in packaging, color and smell and nobody knew the exact location of placebo or test gel, which will be revealed, only after data collection would be performed, by the person who prepared them. A or B gel will be placed on the internal connection abutments and then a cover screw would be inserted. Finally, the site would be sutured with non-absorbable nylon sutures. Cone Beam Computed Tomography evaluation (CBCT) (VatechIpax 3D PCH-6500, Fort Lee, NJ USA) would be performed both for pre-operative and post-surgical implant placement. Both gels will be given to the patients, according to the protocol, and applied 2 times/day until suture removal after 7 days. Soft tissue biopsies would be performed by means of a circular scalpel (5.5 mm in diameter) at the implant insertion (T0) and after two months of healing (second stage surgery)(T1) to analyze the peri-implant inflammatory infiltrate and the micro-vessel density (MVD) in both groups. All the radiographs taken during the study time points would be analysed to measure the bone resorption after 1 year or on other studt time points.

The objective of this human randomized, double blind, placebo-control (RDBPC) study is to evaluate the efficacy of a 0.2% chlorhexidine (CHX) gel on reducing bacterial load and peri-implant inflammation at implant-abutment interface during the early healing stage. Thirty-six healthy patients (mean age 52,28 years; range 29-75 years) without a significant past medical anamnesis, all non-smokers, will be recruited as candidates for single implant placement and prosthetic rehabilitation.Patients will be randomly divided in group A (control) and group B (test) as indicated by the randomization chart. The randomization of this prospective, randomized-controlled, double blind study was obtained using computer generated random numbers, centralized with sequentially sealed opaque envelopes provided by the study adviser.The surgeon will open the sealed envelope containing the randomized group only after having inserted the implant.During the first evaluation, all subjects will be clinically examined: radiographs, plaque and bleeding scores would be carried out for diagnostic evaluation; then the patients would be scheduled for surgery procedures. All Implants (Cortex classic, Shalomi, Israel) would be inserted by two skilled operators who will follow a two-stage protocol and would place them according to the manufacturer's instructions. Before surgery all the patients would be subject to applications of chlorhexidine digluconate solution 0.2% for 2 minutes to obtain lower bacterial load and local anesthesia would be given with Articaine® (Ubistesin 4% - Espe Dental AG Seefeld, Germany) associated with epinephrine (1:100.000). Eventually, all patients would be rehabilitated with a single implant-supported crown. During all the stages either a gel containing 0.20% CHX (Plak ®Gel; Polifarma Wellness Srl, Rome, Italy) or a placebo gel (Placebo, Polifarma Wellness Srl, Rome, Italy) would be used. The two gels are perfectly alike in packaging, colour and smell and nobody knows the exact location of placebo or test gel, which would be revealed, only after data collection would be performed, by the person who prepared them. A or B gel would be placed on the internal connection abutments and then a cover screw would be inserted. Finally, the site would be sutured with non-absorbable nylon sutures. Cone Beam Computed Tomography evaluation (CBCT) (VatechIpax 3D PCH-6500, Fort Lee, NJ USA) would be performed both for pre-operative and post-surgical implant placement. All patients will recieve antibiotic therapy, 2g/day for 6 days (Augumentin®; Glaxo-Smithkline Beecham, Brentford, UK).The post-operative pain would be controlled with NSAIDs, and oral hygiene instructions would be given. Both gels would be given to the patients, according to the protocol, and applied 2 times/day until suture removal after 7 days. Soft tissue biopsies would be performed by means of a circular scalpel (5.5 mm in diameter) at the implant insertion (T0) and after two months of healing (second stage surgery)(T1) to analyze the peri-implant inflammatory infiltrate and the micro-vessel density (MVD) in both groups.

Inclusion Criteria:

• patients of both sex between 18 and 75 years,
• good systemic and oral health,
• need of single crown implant supported restoration,
• at least six months of healing after tooth extraction,
• cortical bone thickness > 5 mm measured by means of a cone beam computed tomography (CBCT).

Exclusion Criteria:

• poor oral hygiene,
• active periodontal disease or other oral disorders,
• insufficient bone thickness for implant insertion,
• bone augmentation procedures,
• immediate loading protocols,
• uncontrolled diabetes mellitus,
• immune diseases,
• smoking
• bruxism.