Subcrestal versus Bone-Level One-Stage Implants: Early Bone and Soft Tissues Modification: One-Year Randomized Clinical Trial

Objectives: To compare early bone changes around conical connection, platform-switched implants placed at bone level or 2 mm sub-crestally, distinguishing between bone remodeling (above implant neck) and bone loss (below implant neck). Material and Methods: 38 healthy patients received bone-level (BLG-Control) or 2 mm sub-crestal (SCG-Test) conical connection, platform-switched implants. The test group received an immediate tissue-level abutment following the one-time abutment (OTA) concept. Marginal bone modification (MBM) was calculated on standardized radiographs at surgery (T0), loading (T1), and 6 (T2) and 12 (T3) months after loading. Pocket-probing depth (PPD), Bleeding on probing (BoP), and Plaque Index (PI) were collected. Results: At 12 months, mean MBM was 0.61 mm in test group and 0.52 mm in control group. In all test group cases (SCG), MBM occurred only above the implant neck (bone remodeling), with no bone loss observed. In the control group (BLG), MBM occurred below the implant neck, corresponding entirely to bone loss. Test group had average PPD of 2.38 mm vs 3.04 mm in control group (p<0.05). Conclusions: At one year after loading, sub-crestal conical connection, platform-switched implants show comparable MBM to bone level implants; however, no bone loss was observed in the subcrestal group.