In Vitro Analysis of Structural Integrity and Surface Alterations of Reused Healing Abutments

Abstract

Purpose: This study aimed to investigate the changes in healing abutments (HAs) after use based on an in vitro comparison with unused HAs and to evaluate the effectiveness and clinical implications of reusing HAs. Materials and Methods: Fifty used HAs were collected from affiliated clinics of the Department of Dentistry at Hanyang University Hospital and analyzed for surface damage, protein contamination, and microgap formation using three-dimensional laser microscopy and microcomputed tomography. The interfacial microgap between the implant and the abutment was measured at different tightening torques (5 N·cm, 10 N·cm, and 15 N·cm). Additionally, bacterial leakage and growth at various tightening torques were assessed by incubating reused HAs over different time periods. Results: Reused HAs exhibited significant surface roughness, protein contamination, and larger microgap compared to unused HAs. The average microgap for reused HAs was 43 μm, whereas unused HAs showed no detectable gap. Bacterial leakage was significantly higher with reused HAs, particularly in those subjected to more than two tightening cycles. Tightening torques of 15 N·cm effectively eliminated the microgap and minimized bacterial leakage, whereas lower torques (5 N·cm and 10 N·cm) resulted in considerable bacterial growth. Conclusion: Reusing HAs increases the risk of surface damage, protein contamination, microgap formation, and bacterial leakage, potentially compromising implant treatment outcomes. Higher tightening torque, (15 N·cm) significantly reduces microgap and bacterial leakage at the implant - HA imterface. Clinicians are advised to limit the reuse of HAs. However, if reuse is necessary, an appropriate tightening torque should be applied following a careful assessment of the clinical conditions of each HA.