Changes on the Interproximal Bone Level on Direct Prostheses or With Intermediate Abutments

Study Title: Changes on the Interproximal marginal bone level after CAD-CAM designed bridges directly placed on bone-level implants, or with intermediate abutments. A Randomized Clinical Trial. * Objectives: To evaluate differences on changes on the interproximal marginal bone level 12 months after the connection of CAD/CAM designed prosthesis with an intermediate abutment (3mm long) or directly placed to bonelevel implants. Secondary objectives will be evaluate changes on the soft tissues and implant survival, as well as patients' satisfaction 3, 6 and 12 months after the connection of the definitive prosthesis. * Design and Outcomes: Randomized double-blinded clinical trial with parallel design to asses the effect of CADCAM designed bridges directly placed * Interventions and Duration: Patients will be selected according to the inclusion/exclusion criteria among those who attend the Unit of Periodontology of the University of Santiago de Compostela. After clinical and radiological implant planning, implant surgical placement will be scheduled. 2 MOZO GRAU® INHEX ST implants, with 3.75 mm or 4.25 mm of diameter and 8mm, 10mm or 11.5mm length will be placed on each patient, according to the bone availability. After 8 weeks of submerged healing, second stage surgery will be performed and definitive impression will be taken. All groups patients will keep a heeling abutment until the definitive prosthesis is placed, 3 weeks later (test group: direct to implant / control group: abutment 3 mm long). Clinical and radiological assessment after 1, 3, 6 and 12 months will be performed. Each participant will be on study about 15 months since the recruitment visit until the end of the study. * Sample Size and Population: Based on previous studies, a sample size calculation determined that a group of 32 subjects, considering possible dropouts, will provide 80% power to detect a true radiographic difference of 0.80mm between groups after 12 months of observation since the defin