Multiparametric performance comparison of dental composites for clear aligner attachments

Abstract

Background: As clear aligner technology (CAT) gains prominence, the performance of composite attachments - critical devices for optimizing aligner retention and tooth movement control - require systematic evaluation. This study assesses three light-cured composites (Filtek™ Z250 XT, Z350 XT, and P60; 3 M ESPE) regarding color stability, shear bond strength (SBS), and durability to establish evidence-based selection criteria. Methods: Attachments were bonded to mandibular premolars, simulating the clinical process, and materials were tested for color changes (after immersion in coffee, cola, or iced tea), SBS, and durability (wear volume, surface roughness, morphology, post-aging SBS). The data obtained from the study were statistically evaluated via the Shapiro-Wilk test, the Levene test, t-tests, one-way analysis of variance and chi-square test. A p-value < 0.05 was considered statistically significant. Results: Z250 showed significantly higher coffee - induced discoloration than Z350 (p < 0.05) and P60 (p < 0.01), exceeding clinical acceptability (ΔE00 ≥ 3.3). Z250 also emerged similar trends with cola and iced tea. Z350 exhibited the highest immediate SBS (p < 0.05 vs. Z250) that may cause enamel damage. P60 demonstrated superior wear resistance, with significantly lower surface roughness (Sq / Sa) than Z250 (p < 0.001) and Z350 (p < 0.01), and the smallest post-wear defect volume (p < 0.01 vs. Z250). The SBS differences in immediate groups were eliminated through aging treatment. Conclusions: Z250 underperformed in color stability, SBS, and durability versus Z350/P60, though demonstrated cost-effectiveness. Z350 offers outstanding color durability and higher SBS but risks enamel damage from interfacial delamination. P60 excels with color stability, acceptable adhesive remnants, and exceptional wear resistance, serving diverse clinical needs. Clinical decisions could prioritize P60 for function-aesthetic balance, with targeted Z350/Z250 use in special scenarios.