Effects of modifying the post-curing protocol on transparency and the fit capacity of directly printed expanders for pediatric patients

This study investigates the impact of post-curing protocol modifications on the transparency of directly printed expanders and evaluates the adaptive capacity of Shape Memory Aligners® for pediatric palatal expansion. Two encapsulated expanders were fabricated using Tera Harz TC-85 resin, based on digital models from a 6-year-old patient with skeletal maxillary atresia. One expander followed the recommended post-curing protocol, while the other underwent a 12-hour delay before post-curing. Transparency testing revealed significant opacity and yellowing in the delayed sample. Adaptation tests were conducted by applying a 2.4 mm transverse expansion and assessing fit under oral-simulated conditions. Results showed that the expanders maintained adaptation without attachments, suggesting that Tera Harz TC-85 aligners can accommodate clinically relevant expansions. The findings underscore the critical role of timely post-curing for optimal esthetics and support the clinical feasibility of using shape-memory aligners for progressive palatal expansion. Future clinical studies are recommended to explore different expansion magnitudes and the use of attachments to enhance retention.