Effect of Soft Tissue Augmentation With an Acellular Dermal Matrix in Marginal Bone Levels Around Implants

Inclusion Criteria: * Systemically healthy * Periodontally healthy or with stable treated periodontitis and good oral hygiene (Full Mouth Plaque Score (FMPS) and Full Mouth Bleeding Score (FMBS) ≤ 15%, measured at six sites per tooth) * Need for one or two implants in the posterior mandible (maximum of three missing teeth). * Enough bone availability to place an implant with a minimum diameter of 3.8 mm and at least 7 mm length. * Non-smoker or smokers \< 10 cig/day (self-reported). * Ability to understand the study procedures and to comply with them to the entire length of the study. Exclusion Criteria: * Subjects with uncontrolled systemic diseases (ASA type III). * Subjects taking medications with immunosuppressors, bisphosphonates or high doses of corticosteroids; current drug or alcohol use or dependence that could interfere with adherence to study requirements. * Pregnant or lactating women. * Allergy to collagen or analgesics/anti-inflammatory non-steroid drugs. * History of cancer requiring radiotherapy or chemotherapy during the last 5 years. * Local inflammation (including untreated periodontitis) * Severe bruxism or clenching habits. * Any kind of bone augmentation performed on the implant site, with a healing period \<6 months * Less than 4 mm of keratinized mucosa * Post-extraction sites with \<12 weeks of healing * Lack of primary implant stability assessed intrasurgically.