Clinical, Radiological and Microbiological Outcomes of Implants With Two Different Connection Configurations, a Split-mouth RCT.

Inclusion Criteria: * able to sign an informed consent form * aged 25 years or more * Any patient requiring two implant-supported crowns in the lower or upper jaw * Kennedy class I, II, and III; * teeth extracted at least 6 months before implant placement; * sufficient bone volumes to accommodate dental implants without augmentation procedure Exclusion Criteria: * General medical and/or psychiatric contraindications to implant surgery, * Pregnancy or nursing, * Heavy smoking (more than 10 cigarettes/day), * Treatment with anticoagulant drugs (International Normalized Ratio under 1.8), bisphosphonates, steroid therapy or anticonvulsants drugs. * No regenerated bone * Untreated Periodontal disease and inability of the patient to maintain reasonable oral hygiene according to study requirements. * Patients with history of alcohol, narcotics or drug abuse. (Alcoholism: more than two bottles of beer per day) * Patients receiving radiotherapy, chemotherapy or any other immunosuppressive treatment, or who have been administered radiotherapy in the last 5 years. (Patients through at any time received radiotherapy to the head and neck region should be excluded anyway.) * Metabolic bone disorders * Uncontrolled bleeding disorders such as: hemophilia, thrombocytopenia, granulocytopenia. * Degenerative diseases. * Osteoradionecrosis. * Renal failure. * Organ transplant recipients. * HIV positive. * Malignant diseases. * Diseases that compromise the immune system. * Unbalanced diabetes mellitus. (HbA1c above 6.5), Uncontrolled endocrine diseases * Psychotic diseases. * Hypersensitivity to one of the components of the implant in general and titanium in particular. * Women who are pregnant or lactating. * Lack of patient cooperation. * Parafunctional habits, such as Bruxism or Temporomandibular joint disease. * Various pathologies of the oral mucosa for example: Benign mucous pemphigoid, desquamative ginigivitis, erosive lichen planus, malignancy of oral cavity, bolus erosive diseases of the oral mucosa.