Soft Tissue and Microbiological Outcomes of Platform-Switching vs. Platform-Matching Single Implants: A Split-Mouth Randomized Controlled Trial

ABSTRACT Objectives: This study aimed to evaluate the soft-tissue and microbiological characteristics of single implants with platform-switched (PS) and platform-matched (PM) abutments. Methods: A randomized, controlled, split-mouth trial was conducted on 22 patients with bilaterally symmetrical mandibular molar loss. Patients were randomly assigned to the PM (platform matching) or PS (platform switching) group. Implants were placed using a one-stage protocol without bone grafting, and final screw-retained restorations were placed after three months of osseointegration. Peri-implant parameters – including plaque index (PI), gingival index (GI), probing depth (PD), and bleeding on probing (BOP) – were assessed at 3, 6, and 12 months post loading. Bacterial DNA copies (log10 copies/DU/ml) of 7 types of bacteria in peri-implant subgingival plaque were quantified using real-time PCR at 6 and 12 months. Results: The dropout rate was 9.1%, with 20 patients completing the study. No implant or prosthesis complications were observed. Within each group, PI, GI, PD, and BOP showed no statistically significant differences between follow-ups (p > 0.05). Similarly, no significant differences were found between the PM and PS groups in any soft tissue parameters (p > 0.05). Microbiological analysis revealed no significant differences in bacterial composition between groups at different time points (p > 0.05). Conclusions: Peri-implant soft tissue remained healthy in both groups, with no cases of peri implantitis. No statistically significant differences were observed in soft tissue and microbiological characteristics between PS and PM implants over the study period.