Torque loss of different abutment sizes before and after cyclic loading

Area of Science:

• Dental implantology
• Biomaterials science
• Prosthodontics

Background:

• Abutment diameter and crown retention method are critical factors in dental implant stability.
• Understanding torque loss is essential for predicting the long-term success of implant-supported restorations.

Purpose of the Study:

• To compare torque loss in 3.8-mm and 4.8-mm abutments under simulated masticatory loads.
• To evaluate the influence of cemented versus screw-retained crowns on abutment and crown torque loss.

Main Methods:

• Forty implant/abutment sets were divided into four groups based on abutment diameter (3.8-mm or 4.8-mm) and crown retention (cemented or screw-retained).
• Abutments were subjected to 300,000 simulated masticatory cycles after initial torque application.
• Torque loss was measured before and after cyclic loading.

Main Results:

• Screw-retained crowns showed significantly increased torque loss after cycling, particularly with 3.8-mm abutments.
• While initial abutment torque loss showed no difference, 3.8-mm abutments exhibited greater loss post-cycling.
• Significant changes in abutment torque loss were only observed in the 3.8-mm cemented crown group.

Conclusions:

• Abutment diameter influences torque loss in screw-retained crowns, potentially leading to mechanical failure.
• Mechanical cycling exacerbates torque loss in both abutment screws and screw-retained crowns.