1.Effect of Change Angulation and Material of Mini-screw inserted in Retro Molar Pad Area on Stress Distribution: A Finite Element Simulation Study
Nada Nashee Al-Hafidh ; Saeed AlSamak ; Mohammed T. Sulaiman Al-Abbood ; Ali R. Al-Khatib
Archives of Orofacial Sciences 2024;19(2):173-186
Effect of Change Angulation and Material of Mini-screw inserted in Retro Molar Pad Area on Stress Distribution: A Finite Element Simulation Study
This study evaluated the influence of angulation and material composition on the stress distribution
and displacement of mini-screws placed in the retromolar pad area using finite element analysis; these
mini-screws inserted in the retromolar pad area were referred to as MRM. A 3D mandible model was
generated from CT scan data using Mimics and 3-Matic software, while the mini-screw was modelled
in AutoCAD. Finite element analysis was performed with Inventor Professional software. A 2 N force,
parallel to the occlusal reference line (ORL), was applied to MRM at insertion angles of 0°, 15°, 30°,
45°, and 60° relative to the ORL. Three MRM materials were analysed: stainless steel (SS), titanium
alloy (Ti-6Al-4V), and pure titanium (Ti). Results revealed that the lowest Von Mises stresses occurred
at a 0° insertion angle, while the highest stresses were observed at 60°. Stress levels were comparable
across materials at 0°, 15°, and 30°, but SS MRM generated higher stresses than titanium materials
at 45° and 60°. Displacement analysis indicated that SS MRM had the lowest displacement, while Ti
MRM exhibited the highest across all angles. Importantly, all stress values remained below the bone’s
yield strength, and displacements were clinically insignificant. For optimal stability, a 0° insertion angle
is recommended, with 15° and 30° serving as viable alternatives. These findings provide guidance on
selecting mini-screw angulation and materials for effective orthodontic anchorage in the retromolar pad
area.


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