Comparison of Accuracy of Fit of Different Thermoformed Clear Aligner Thicknesses to Orthodontic Study Models with Different Attachment Shapes: An in-vitro Study

Objective: Clear aligner therapy (CAT) has gained significant popularity in orthodontics. However, the accuracy of fit between aligners and teeth is crucial for treatment success. This study aimed to investigate the influence of aligner thickness (0.6 mm and 0.8 mm) on the gap width between the aligner and the tooth at different anatomical sites and different attachment shapes.Material and methods: Passive aligners of two aligner sheet thicknesses were fitted to a resin cast prototyped from an STL file from a single patient. The samples were sprayed with an opaque scanning spray, scanned, imported to Geomagic® Control X™ metrology software, and superimposed on the scanned model STL file using the “Best Fit Alignment” algorithm. Distances between the aligner meshes and the reference STL file were measured at different anatomical landmarks. The average measurements and standard deviations between aligners and reference models at each anatomical landmark were examined to compare the accuracy of fit between the two different aligner thicknesses. Results: The study found significant differences in gap width between the two aligner thicknesses. Thinner aligners (0.6 mm) exhibited smaller gap widths compared to thicker aligners (0.8 mm). Additionally, the gap width varied across different tooth types and regions, and different attachment shapes and levels.Conclusions: Aligner thickness significantly influences the fit between the aligner and the tooth. Thinner aligners may provide a closer fit, which could potentially impact force delivery and treatment outcomes. Further research is warranted to investigate the clinical implications of these findings.