The effect of post-ultraviolet light curing on the accuracy of direct-printed aligners: an in vitro study

Abstract

Abstract Background/Objectives Direct-printed aligners have proven to be more cost effective and accurate. However, the post-curing process might affect their dimensional accuracy, leading to unwanted tooth movement. The present study aimed to investigate the effect of different post-curing durations on the location specific accuracy of direct-printed aligners. Method A stereolithography printer was used to produce 30 aligners using Dental LT V2 resin. The aligners were randomly assigned into 3 groups (n = 10 each) according to different post-ultraviolet light-curing durations: 0 min (No cure); 40 min or 60 min. The aligners in each group were then scanned and superimposed on certain landmarks to check for location specific deviations using a best fit algorithm. Discrepancies were assessed at 10 different points by one examiner at two different time intervals (0.25 mm was the clinically acceptable threshold limit). One way ANOVA and repeated measures ANOVA were applied for statistical analysis. Results Deviations were maximum in the ‘No cure’ group but were statistically insignificant (p-value > 0.05). The deviation values in the ‘40 and 60 min cure’ groups were comparable and statistically significant (p-value < 0.05), with maximum deviation noted in the anterior region. All values in the ‘40 and 60 min cure’ groups were within the clinically acceptable range. Conclusion Post-print ultraviolet light curing is a crucial step to ensure the rigidity of the direct-printed aligner. However, increasing the duration of light curing has little effect on aligner accuracy.