This will be a prospective, randomized, controlled, single center clinical trial with

1 year enrollment period, surgical and prosthetic rehabilitation with 1-year post-loading follow-up. A total of 2.0 years of study duration The primary objective is to compare peri-implant hard and soft tissue changes between single implants placed in the posterior mandible and immediately loaded either with definitive (one-time) or provisional abutment.

Hard tissue contour changes will be assessed using standardized two-dimensional intra-oral radiographs and partial small field of view three-dimensional cone beam CT scans. Soft tissue contour changes will be assessed using superimposition of dental digital models. Inflammatory soft tissue reactions will be evaluated by measurement of respective cytokines' levels.A quantitative evaluation of total bacteria amount of the peri-implant samples.

Secondary objectives of this study will be to estimate total bacterial amount (quantitative real-time polymerase chain reaction - qRT-PCR).

Bleeding on probing (BoP), full mouth oral hygiene index, periodontal pocket depth (PPD) and keratinized tissue width will also be evaluated.

Indication: Patients with need of at least two implants (one per side) in the premolar or molar region in the mandible, bilaterally.

Inclusion Criteria:

• Minimum age of 25 years
• In need of a one or two implants.
• Healed site (healed site defined by restored gingiva, free of inflammation and scar tissue , with a keratinized band of 3mm from crest to muco-gingival junction, and sufficient osseous architecture to receive an implant with a minimal diameter of 3.5 mm).
• Mandible second premolar or molar region.
• At least one neighboring tooth to be present.
• Absence of visible active periapical or periodontal inflammation.
• Adequate oral hygiene: PI< 20%, BoP< 20%.
• Sufficient occlusal units mesial or distal and antagonizing, including the diastema to be restored: 4 occlusal units.

Exclusion Criteria:

• Medical condition that contraindicates surgery: ASA -score ≥ III
• History of radiotherapy in the head and neck region.
• History of Bisphosphonate medication.
• Medium smokers ≥ 10 cigarettes per day.
• Patients unwilling or incapable of understanding and signing the informed consent.
• Active caries.
• Presence of inflammation expressed by PPD >4mm and BoP on adjacent teeth.
• Active periapical radiolucency or root canal treatment performed < 4 months previous to planned implant insertion on a neighboring tooth to future implant.
• Insufficient restorative space.
• Interocclusal plane distance < 20mm at planed implant position.