Are bio-based resins suitable alternatives for additively manufactured removable dies? An in vitro study on dimensional and positional trueness and stability.

Purpose This study aimed to compare the dimensional and positional deviations of additively manufactured removable dies fabricated using two bio-based resins and one conventional dental cast resin, while also evaluating these outcomes over a 4-week period.Materials And Methods A right mandibular first molar preparation on a typodont was scanned to digitally design removable dies and hollow partial arch casts. Based on a priori power analysis, a total of 30 dies (n = 10) and three hollow casts (n = 1) were fabricated using additive manufacturing (AM) from three different dental cast resins: DentaMODEL (DM), FotoDent bio-based model (CB), and soy-based resin (SB). The dies and their seated positions in casts were digitized 1 day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4) after fabrication. Dies' dimensional deviations (crown, root, base of the root, and overall) and positional deviations in casts (crown region surface and point-based) at T0 were defined as trueness, while deviations measured over 4 weeks (T0-T4) were defined as stability. The deviations measured at T0 were analyzed either using a generalized linear model (dimensional deviations) or one-way analysis of variance (crown region and point-based deviations). The deviations measured over the 4-week period were analyzed with generalized linear model analysis and Bonferroni-corrected post hoc tests (α = 0.05).Results CB dies mostly had the lowest and SB dies mostly had the highest dimensional deviations (p ≤ 0.001). The crown region had the lowest dimensional deviations, while the dimensional deviations measured at T3 were higher than those at T2 and T4 (p ≤ 0.003). SB dies had the highest and CB dies had the lowest positional deviations, while crown region deviations were lower at T0 and T1 than at T4, and point-based deviations were lower at T0 than at T4 (p ≤ 0.049).Conclusions CB dies mostly had better dimensional and positional trueness and stability over 4 weeks. The changes in tested outcomes for all dies over time were small.