Abutment screw withdrawal after conical abutment settlement: A pilot study

Area of Science:

• Dental Implantology
• Biomaterials Science
• Mechanical Engineering

Background:

• The stability of the implant-abutment connection is crucial for long-term dental implant success.
• Conical connections are widely used in dental implants due to their favorable mechanical properties.

Purpose of the Study:

• To evaluate the impact of abutment screw withdrawal on the stability of conical implant-abutment connections.
• To compare the performance of different abutment designs with and without screw withdrawal under cyclic loading.

Main Methods:

• Twenty conical connection implants were tested with two abutment designs: cone-only (NI) and cone with an index (I).
• Samples were subjected to cyclic loading (20-200 N, 10^6 cycles) with and without prior abutment screw withdrawal.
• Axial displacement and fatigue cycles were measured; morphology was examined using SEM.

Main Results:

• The group without the index design and without screw withdrawal (Gr NS(NI)) failed the cyclic test, indicating connection instability.
• The indexed design (Gr NS(I)) showed higher axial displacement after settlement and cyclic loading, with SEM revealing antitorsional capability.
• Abutment screw withdrawal was feasible in the indexed conical connection system.

Conclusions:

• The presence of an index design significantly enhances the antitorsional stability of conical implant-abutment connections.
• Abutment screw withdrawal is a viable procedure for conical implant connections that incorporate an index design.
• Further research may be needed to fully understand the long-term implications, despite study limitations.