Influence of Vertical Soft Tissue Thickness and Keratinized Mucosa Width on Marginal Bone Loss Around Platform-Matched and Platform-Switched Implants: A Split-Mouth Randomized Controlled Trial.

Aims: To evaluate marginal bone loss (MBL) around implants restored with platform-matched (PM) or platform-switched (PS) abutments after loading and to examine the influence of vertical soft tissue thickness (STT) and keratinized mucosa width (KMW) on MBL. Materials and Methods: In a split-mouth randomized controlled design of total 22 patients (44 implants), patients received one PM and one PS restoration in contralateral posterior mandibular sites. Standardized periapical radiographs were obtained immediately after restoration, at 3, 6, and 12 months to measure MBL. STT (thin, <2 mm vs thick, and ≥2 mm) and KMW (narrow, <2 mm vs wide, and ≥2 mm) were recorded. A linear multiple regression analysis was conducted with dependent variable (MBL) and independent variables (STT and KMW). Results: MBL did not differ significantly between PM and PS across follow-up. In contrast, thin STT and narrow KMW were associated with greater bone loss over time. Multivariable analysis revealed that the soft tissue phenotype significantly influenced MBL, whereas the abutment design showed no significant effect (β = -0.43 for STT and β = -0.36 for KMW). Conclusion: Establishing a STT and KMW of ≥2 mm may be beneficial for bone preservation around implants, although further long-term studies are needed for clinical practice.