Micro-computed tomography evaluation of aligner fitting on anchorage attachments

Area of Science:

• Orthodontics
• Biomaterials Science
• Dental Technology

Background:

• Clear aligners (CAs) are increasingly used in orthodontic treatment.
• Accurate fit of CAs to anchorage attachments is crucial for effective tooth movement.
• Material properties and thickness of CAs can influence their adaptation to dental models.

Purpose of the Study:

• To evaluate the fit of clear aligners (CAs) made from different materials and thicknesses to anchorage attachments.
• To compare three-dimensional (3D) and two-dimensional (2D) analyses of air gaps between CAs and attachments.

Main Methods:

• Forty CAs of varying materials (PET-G, ABA) and thicknesses (0.50 mm, 0.625 mm, 0.75 mm) were tested.
• Micro-computed tomography (Micro-CT) was used to scan CAs fitted onto a master model with attachments.
• 3D volumetric analysis and 2D sectional analysis were performed to quantify air gaps, with a 20 μm threshold for practical relevance.

Main Results:

• No statistically significant differences in overall 3D air-gap volume were found among the tested CA groups.
• 2D analysis revealed significant localized fit differences, particularly in palatal and gingival sections.
• PET-G aligners showed greater gap widths than CA PRO-Hard in critical areas, exceeding the 20 μm threshold.

Conclusions:

• Micro-CT provides detailed assessment of CA fit to attachments.
• While volumetric analysis showed no significant differences, sectional analysis highlighted material-dependent variations in fit.
• CA PRO-Hard exhibited superior adaptation in specific regions, suggesting material choice impacts precision in clear aligner therapy.