Effect of Access Channel Sealing and Superstructure Material on Abutment-Implant Screw Stability After Cyclic...

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Screw loosening is a frequent mechanical issue in implant restorations.
• The interplay between sealing agents and superstructure materials on screw stability needs more research.

Purpose of the Study:

• To investigate how access channel sealing materials and superstructure materials affect abutment-implant screw stability.
• To analyze screw stability after subjecting restorations to thermomechanical cyclic loading.

Main Methods:

• Forty-eight implant-abutment assemblies with monolithic zirconia or Cerasmart crowns were tested.
• Two sealing protocols were used: Polytetrafluoroethylene (PTFE) + composite or polyvinyl siloxane (PVS) putty.
• Assemblies underwent 750,000 cycles of off-axis loading, and reverse torque values (RTV) were measured.

Main Results:

• A significant interaction was found between restorative material and sealing protocol (p=0.0170).
• Sealing protocol significantly affected RTV (p=0.0499), but superstructure material did not (p=0.8368).
• Zirconia crowns with PVS putty showed higher RTV (36.33 ± 4.53 Ncm) than those with PTFE (29.32 ± 6.30 Ncm).

Conclusions:

• Access channel sealing materials influence abutment screw stability in a material-dependent manner.
• Silicone-based sealing (PVS) enhanced torque maintenance in zirconia restorations.
• Resilient materials like Cerasmart may be less affected by sealing material choice regarding preload maintenance.