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

Abstract

Reducing marginal bone resorption is a challenge in implant dentistry. Sub-gingival implant placement has been suggested as a suitable strategy to avoid long-term esthetic and biological complications. A total of 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 and classified as bone loss (BL) if it occurred below the implant neck and bone remodeling (BR) if above. Pocket-probing depth (PPD), Bleeding on probing (BoP), and Plaque Index (PI) were collected. At 12 months, the mean MBM was 0.61 mm in the test group and 0.52 mm in the control group. In all the cases of the test group (SCG), MBM occurred only above the implant neck, therefore being classified as BR, and no BL was observed. In the control group (BLG), MBM occurred below the implant neck, thus corresponding entirely to BL. The test group had an average PPD of 2.38 mm compared to 3.04 mm in the control group, with BoP at 50% and 43%, and PI at 33% and 19.44%, respectively. 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.