Embrasure aligner fit and thickness in 3D-printed and thermoformed aligners: a microcomputed tomography study

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Orthodontic Technology

Background:

• Evaluating the clinical performance of orthodontic aligners is crucial for treatment efficacy.
• Tooth embrasure fit and material thickness are key parameters influencing aligner effectiveness.
• Comparing three-dimensional (3D)-printed and thermoformed aligners provides insights into evolving fabrication methods.

Purpose of the Study:

• To compare the embrasure fit and material thickness of 3D-printed and thermoformed aligners.
• To assess the impact of offset variations in 3D-printed aligner fabrication.
• To determine the dimensional stability of different aligner types post-fabrication.

Main Methods:

• Fabrication of 30 aligners: 3D-printed (no-offset and 0.05 mm offset) and thermoformed.
• Microcomputed tomography scanning of mounted aligners on a dental model.
• Measurement of embrasure gap distance and thickness at coronal and cervical levels.
• Statistical analysis using Kruskal-Wallis and Mann-Whitney U tests.

Main Results:

• The 0.05 mm offset 3D-printed aligners showed significantly smaller embrasure gaps (73-93% fit ratio).
• No significant fit differences were observed between coronal and cervical levels for the 0.05 mm offset 3D-printed group.
• Thermoformed aligners experienced significant thickness reduction (36.5-88.5%), while 3D-printed aligners showed thickness increases (197-470%).

Conclusions:

• 0.05 mm offset 3D-printed aligners provide superior embrasure fit over no-offset 3D-printed and thermoformed types.
• 3D-printed aligners exhibit increased thickness at embrasures, unlike thermoformed aligners which decrease in thickness.