Related Experiment Video
Updated: Nov 22, 2025

In situ Compressive Loading and Correlative Noninvasive Imaging of the Bone-periodontal Ligament-tooth Fibrous Joint
Published on: March 7, 2014
Change in Pull-Out Force during Resorption of Magnesium Compression Screws for Osteosynthesis of Mandibular Condylar
1Department of Maxillofacial Surgery, Medical University of Lodz, 113th S. Żeromskiego, 90-549 Lodz, Poland.
Background:
Magnesium has been used as degradable fixation material for osteosynthesis, but it seems that mechanical strength is still a current issue in these fixations. The aim of this study was to evaluate the axial pull-out force of compression headless screws made of magnesium alloy during their resorption.
Methods:
The tests included screws made for osteosynthesis of the mandible head: 2.2 mm diameter magnesium alloy MgYREZr (42 screws) and 2.5 mm diameter polylactic-co-glycolic acid (PLGA) (42 pieces, control). The screws were resorbed in Sørensen's buffer for 2, 4, 8, 12, and 16 weeks, and force was measured as the screw was pulled out from the polyurethane block.
Results:
The force needed to pull the screw out was significantly higher for MgYREZr screws than for PLGA ones (p < 0.01). Within eight weeks, the pull-out force for MgYREZr significantly decreased to one third of its initial value (p < 0.01). The dynamics of this decrease were greater than those of the pull-out force for PLGA screws (p < 0.05). After these eight weeks, the values for metal and polymer screws equalized. It seems that the described reduction of force requires taking into account when using magnesium screws. This will provide more stable resorbable metallic osteosynthesis.
Related Concept Videos
Moment of a Force: Problem Solving
Bearings: Problem Solving
Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
Frictional Forces on Screws
A jack with a square-threaded screw is a mechanical device used to lift heavy loads by applying a force at its handle. When the force is applied, the screw turns, raising the load. The screw can...
Machines: Problem Solving I
The toggle clamp system is a machine structure consisting of movable, pin-connected multi-force members that form a stabilized system to transmit forces. The...

