Bone-To-Implant Contact At 4- And 6-Week Healing Stages in Implants With Different Surfaces.

Inclusion Criteria: * • Height of the residual bone crest in the programmed implant site ≥ 9 mm and thickness ≥ 7mm. * Availability, in each sector, of sufficient mesio-distal space allowing placement of 2 standard-sized implants and at least 2 mini-implants (3.5x8.5mm) for retrieval. * Healed bone crest (≥ 3 months elapsed after extraction or tooth loss). * Age \> 18 years. * Ability to examine and fully understand the study protocol. Exclusion Criteria: * • Myocardial infarction within the past 6 months. * Poorly controlled diabetes (HBA1c \> 7.5%). * Coagulation disorders. * Radiotherapy to the head/neck area within the past two years. * Present or past treatment with intravenous bisphosphonates. * Immunocompromised patients. * Psychological or psychiatric problems. * Alcohol or drug abuse. * Poor oral hygiene and motivation (full mouth plaque score \> 30% and/or full mouth bleeding score \> 20%). * Uncontrolled periodontal disease.