الفهرس 
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Abstract
compare between two types of self-drilling orthodontic miniscrews biomechanically and by using bone density measurements.
The study was conducted on six dogs, where 12 miniscrews of both types (6 cylindrical and 6 tapered) were inserted in the same buccal area of the maxilla in each dog between the roots of M1 and P3 respectively.
• Radiographs were taken pre-insertion of the miniscrews and post-insertion at time of insertion T0, after 4 weeks T1, after 8 weeks T2, and after 12 weeks T3.
• Bone density was measured using special software to estimate the amount of grey-colour in all radiographs.
• The amount of extrusion of miniscrews was measured using Digora software for both groups after 12 weeks period.
• Removal torque measurements were recorded during the removal of both types of miniscrews using special device and after 12 weeks period.
The following conclusions could be drawn from the current study:
1-Cylinderical miniscrews showed significantly higher peri-implant bone density in comparison with the tapered miniscrews immediately at insertion and after 8 weeks post-insertion.
2-Both cylindrical and Tapered miniscrews showed no significance difference regarding peri-implant bone density after 4 weeks and 12 weeks post-insertion.
3-Tapered miniscrews extruded more than the cylindrical miniscrews during the 12 weeks period.
4- Cylindrical miniscrews showed higher resistance to removal compared to tapered miniscews after 12 weeks loading period.
6- Both types of miniscrews showed stability during the whole 12 weeks period inspite of the immediate loading and extrusion of the miniscrews.