Study of Hard and Soft Tissue Behavior Around Abutments on Implants: Randomized Clinical Trial.

All patients volunteered will be selected from the Clinica Universitaria de Odontología (CUO) of the Universitat Internacional de Catalunya (Spain) and also from the Clinica Dental Crooke & Laguna to participate in the study must sign an informed consent form based on the Helsinki Declaration of 1975, as revised in 2013. The patients must required implants for implant-supported restorations and will be thoroughly informed regarding the nature of the study. This study will include 60 patients. The sample number required for the study was determined with an alpha risk of 0.05, a power of 80%, a standard deviation of 1.1mm and estimating a loss rate to follow-up of 20%.

In this prospective cohort multi-centric clinical study all implants of the same brand will be tested. The study will be conducted in the Clinica Universitaria de Odontologia from the Universitat Internacional de Catalunya located in C/ Josep Trueta, s/n, 08195 Sant Cugat del Vallès and also in the Clinica Dental Crooke Marbella located in Calle Mediterráneo, 1. 29602 Marbella (Málaga)

On the surgical and prosthetic protocols will be performed by experienced clinicians in accordance to the manufacturer's recommendations. All surgical procedures will be conducted under local anesthesia (Ultracain; Aventis Inc., Frankfurt, Germany). Sinus augmentation procedures will be performed in patients with inadequate bone availability, applying the bone scraper technique as described elsewhere. All sinus cavities will be grafted using autologous cortical bone in combination (approximate ratio of 1:1) with anorganic bovine bone particles (250-1000 lm in size, Bio-Oss; Geistlich Pharma AG, Wolhusen, Switzerland) and a healing period of six to nine months is required for implant placement.

A conventional implant placement protocol using only Nobel Parallel Implants will be followed in patients not requiring maxillary sinus augmentation. The maxilla or mandible will be surgically exposed. Any resining compromise teeth will be removed either before or after flap elevation based on the surgeon's preference. The bony platform of the residual mandible will be surgically levelled parallel to the opposing occlusal plane to create a space for the restoration and/or soft tissue. Analog drill guides and templates will be used to ensure precise placement of implants in the correct location while accommodating the position of the dentition.

All patients will be prescribed a pharmacologic regimen of amoxicillin/clavulanic acid tablets (875/125 mg, TID for 7 days) or, if allergic to penicillin, clindamycin tablets (300 mg, TID for 7 days), and anti-inflammatory medication (Ibuprofen 600 mg every 4 to 6 hours as needed to a maximum of 3600 mg/ day). Six implant pure titanium (grade IV) dental implants with an acid-etched surface will be used.