Dimensional stability of additively manufactured dental casts in bio-based resins: Influence of cast base design and storage conditions

To compare the dimensional stability of dentate, maxillary, bio-based resin casts with various base designs and storage conditions to that of casts in a dental resin. Dentate maxillary casts with either solid or hollow bases were additively manufactured using liquid crystal display technology from reference design files using a soy-based (EX), a corn-based (FD), and a dental cast (KM) resin (N = 20). Each set of casts was divided into two subgroups based on storage conditions (exposed to light or stored in light-proof boxes) (n = 10). Casts were digitized with a laboratory scanner the day after fabrication and weekly for the following four weeks. The scans were superimposed over their respective reference file to calculate region-based (anterior, posterior, entire arch, soft tissue, and entire cast) root mean square (RMS) values. Data were analyzed using a generalized linear model (α = 0.05). The RMS values were affected from the interactions among resin type, base design, and storage condition (P ≤ 0.018). Hollow-based KM casts stored in a light-proof box had the lowest anterior, posterior, and entire arch RMS, and mostly had lower overall RMS (P < 0.001). Hollow-based FD casts exposed to light mostly had lower soft tissue RMS (P ≤ 0.019). Hollow-based KM casts stored in a light-proof box mostly had higher dimensional stability. However, the deviations observed across all casts remained within previously reported clinically acceptable thresholds for diagnostic and orthodontic applications.