Effect of coffee solution on colour stability of various clear aligner attachment composites, does surface sealing make a difference?: An in vitro study

BACKGROUND: In this exploratory study is the first to test the efficacy of a surface sealant in preventing discolouration of orthodontic attachments. It aimed to evaluate the colour stability of four different resin composites used in orthodontic attachments after immersion in a coffee solution and to investigate the effect of surface sealant application on their colour stability. METHODS: A total of 96 specimens were prepared using four resin composites: Aligner Connect, Estelite Sigma Quick, Universal Flo and Transbond XT (n = 24 per group). Each resin composite group was divided into two subgroups (n = 12); one received a surface sealant (Permaseal, Ultradent), and the other served as a control. All specimens were immersed in a coffee solution and colour measurements were recorded at three simulated time intervals: T1 (1 month), T2 (3 months), and T3 (6 months). Colour differences (∆E₀₀) were calculated using the CIEDE2000 formula. Statistical analysis was performed using repeated measures 2-way ANOVA followed by Tukey's post-hoc test (α = 0.05). RESULTS: All resin composites showed a statistically significant increase in discolouration over time (p < 0.05). The Transbond XT group demonstrated the highest ∆E₀₀ (13.57 ± 0.77) values on Day 6, indicating the greatest level of discolouration. All resin composites showed ∆E₀₀ values exceeding the clinically acceptable threshold of 1.8. CONCLUSION: Exposure to coffee solution caused clinically unacceptable discolouration in all tested attachment resin composites. The type of resin composites played a critical role in determining the degree of discolouration in orthodontic attachment fabrication. Application of the surface sealant (Permaseal) did not provide a clinical advantage in improving resistance to discolouration form the coffee solution.