Reliability of different composite materials in aligner treatments: a comprehensıve in vitro study

Abstract

Background: Clear aligner therapy has become increasingly prevalent in orthodontics, with composite attachments serving as critical components for achieving predictable tooth movements. Despite their importance, composite material selection remains largely empirical. This double-blind in vitro study assessed four composite materials' performance as aligner attachments under simulated clinical conditions. Methods: Ninety-six extracted human teeth were arranged in upper and lower arch configurations. Four composite systems were evaluated: Omnichroma (79% filler), GC Aligner Connect (orthodontic-specific), G-Aenial Universal Injectable (69% filler, flowable), and Tetric Prime/Evoflow combination (dual-viscosity system). Each underwent aging simulation including 2308 thermal cycles (5–55 °C) and 840 insertion-removal procedures per 12-week period. Digital analysis assessed placement accuracy and volumetric changes at 12, 24, 48, and 96 weeks. Parameters evaluated included operation time, shear bond strength, placement accuracy, and wear resistance. All procedures were performed by a single calibrated operator following double-blind protocols. Polymerization utilized LED curing (1200 mW/cm2, 430–480 nm), verified with radiometry. Results: The Tetric combination required significantly longer placement time (31.08 ± 5.14 versus 5.22 ± 0.74 s for GC Aligner Connect, P < 0.001). Three-dimensional analysis revealed the Tetric combination demonstrated 81.24 ± 19.71% overflow versus 44.62 ± 19.91% for GC Aligner Connect (P < 0.001). After 96 weeks, G-aenial Universal Injectable showed significantly greater volume loss (27.40 ± 18.44%) compared to Omnichroma (18.29 ± 6.78%), GC Aligner Connect (17.56 ± 2.18%), and Tetric combination (14.22 ± 3.70%, all P < 0.001). Bond strength testing revealed no significant differences between groups (18.88–23.23 MPa, P = 0.121), with all materials exceeding clinical requirements. Conclusions: Material viscosity and filler content substantially influence clinical performance during extended treatments. GC Aligner Connect demonstrated optimal balance of placement efficiency, dimensional accuracy, and durability for routine applications. High-viscosity composites showed superior long-term stability despite longer placement times. Injectable composites offered excellent efficiency but demonstrated accelerated wear after 48 weeks. These findings provide evidence-based guidance for material selection in clear aligner therapy, suggesting material choice should align with anticipated treatment duration and clinical requirements.