The long-term success of dental implants depends not only on osseointegration but also on the stability and health of the surrounding peri-implant soft tissues. Inadequate keratinized mucosa width and reduced soft tissue thickness have been associated with increased plaque accumulation, mucosal inflammation, discomfort during oral hygiene, and compromised aesthetic outcomes. Therefore, peri-implant soft tissue augmentation has become an important component of modern implant therapy. This thesis aimed to evaluate the role of peri-implant soft tissue phenotype-specifically keratinized mucosa width, mucosal thickness, and supracrestal tissue height—in maintaining peri-implant health and long-term implant stability.