Drilling Capability of Orthodontic Miniscrews: In Vitro Study

Area of Science:

• Orthodontics
• Biomaterials Engineering
• Dental Implantology

Background:

• Steel miniscrews are widely used in orthodontics for anchorage.
• Understanding their mechanical properties in different bone densities is crucial for predictable clinical outcomes.
• Assessing insertion torque (IT) and surface integrity provides insights into miniscrew stability and performance.

Purpose of the Study:

• To evaluate the insertion torque (IT) values and mechanical properties of steel miniscrews in artificial bone blocks with varying densities.
• To examine the surface integrity of miniscrews post-insertion using stereomicroscopy and Scanning Electron Microscopy (SEM).

Main Methods:

• Forty self-drilling miniscrews were inserted into artificial bone blocks simulating different densities (20, 40, and 30+50 PCF) and cortical bone thicknesses (2mm, 4mm).
• Insertion torque was measured using an electronic surgical motor.
• Miniscrews were inspected pre- and post-insertion using a 5x stereomicroscope and SEM to detect surface changes.

Main Results:

• Insertion torque (IT) significantly increased with higher bone densities.
• Stereomicroscope and SEM examinations revealed no morphological or surface structural changes in the miniscrews, regardless of bone density.
• Mechanical properties of the self-drilling miniscrews were deemed adequate across all tested artificial bone conditions.

Conclusions:

• Steel miniscrew insertion torque is directly correlated with bone density.
• The tested self-drilling miniscrews exhibit robust mechanical properties and surface integrity, suitable for use in varying bone densities.
• These findings support the predictable use of miniscrews in orthodontic anchorage.