Impact of Two Implant-Abutment Connection Types on Crestal Bone Stability: A 3-Year Comparative Split-Mouth Clinical Trial

This prospective, preliminary controlled clinical trial investigates the comparative effectiveness of platform-switching (PS) versus traditional butt-joint or platform-matching (PM) implant-abutment connections on peri-implant crestal bone stability. Utilizing a split mouth design, 10 systemically healthy patients (n= 20 implants) had adjacent non-restorable maxillary anterior teeth replaced with two different implants (butt-joint connections and platform-switching interfaces). Patients underwent alveolar ridge preservation, followed by implant placement: platform-matching implants were inserted at crestal bone level, and platform-switching implants were placed 1mm subcrestally. Customized Zirconia crowns were then fabricated for both systems. Outcome measures included bleeding on probing (BOP), probing pocket depth (PPD), and marginal bone loss (MBL), which were evaluated through standardized periapical radiographs over 3-year timeframe. Results showed significantly higher initial MBL in the PM group (0.86 ± 0.13 mm) compared to the PS group (0.34±0.29 mm) [p value: p<0.01]. Moreover, at the three-year follow-up, the crestal bone levels remained above the implant shoulder until the third year of the study for the PS subcrestal group (PS: -0.15±0.39 mm) and slightly below the implant platform in the PM crestal group (PM: 0.55±0.19). After 3 years, the PS group also exhibited lower mean BOP percentages (12%) than the butt-joint group (17%). This study suggests that subcrestal placement with PS and internal connections can provide better long-term peri- implant bone preservation, thereby potentially improving implant success and aesthetic outcomes in the anterior maxillary region.