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The Effect of Repeated Closing Torque on Torque Loss and Angular Deviation: An In Vitro Study
Ruoyan Guo1, Yantao Qian2, Guohai Lin2
1Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China.
The Journal of Oral Implantology
|February 20, 2025
Summary
Repetitive tightening and loosening of dental implant screws increase torque loss, especially in narrower implants. Limiting screw retightening cycles is recommended to prevent complications like loosening and fracturing.
Area of Science:
- Biomaterials Science
- Dental Implantology
- Mechanical Engineering
Background:
- Central screw loosening and fracturing are frequent mechanical complications in implant restorations.
- The impact of repeated screw manipulation during fabrication and maintenance on these complications is not well understood.
Purpose of the Study:
- To investigate torque loss after repeated tightening and loosening of central screws in dental implants of varying diameters.
- To assess changes in the angular deviation of the central screw relative to the implant.
Main Methods:
- Twenty dental implants (3.7mm and 4.5mm diameters) were subjected to 10 cycles of tightening and loosening at 15 N.cm or 35 N.cm closing torque.
- Reverse torque measurements and angular deviation were recorded.
- Surface wear was analyzed using scanning electron microscopy.
Main Results:
- Torque loss significantly increased with each tightening cycle across all groups.
- Smaller implant diameters (3.7mm) exhibited greater torque loss compared to larger diameters (4.5mm).
- Angular deviation was influenced by closing torque and the number of cycles, but not implant diameter.
Conclusions:
- Repeated screw manipulation leads to increased torque loss and angular deviation, particularly in narrow-diameter implants.
- Implant diameter is a critical factor influencing torque loss.
- Limiting retightening cycles for narrow implants is advised to mitigate mechanical complications.
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