Characterization of the double bond conversion of acrylic resins is considered critical in the evaluation of dental materials due to the propensity of end-use devices to accumulate residual monomer and degradation products that can cause local and systemic side effects in high doses. In this study, the authors examine two different acrylic-based photopolymers indicated for 3D printing of dental prostheses using Fourier transform infrared spectroscopy: a denture base material comprising ≥75% ethoxylated bisphenol A dimethacrylate, and a crown-and-bridge material composed of >60% proprietary methacrylic oligomer and 15%-25% 2-hydroxyethyl methacrylate. Infrared spectroscopy data showed a conversion rate (240 s) of 52.37 ± 1.05% for the former material and 45.36 ± 1.41% for the latter. Compared to traditional acrylic resins, both materials exhibited a considerably lower degree of conversion. With limited scientific data available on the clinical performance of 3D printing materials in general, additional evidence is needed to ascertain their in vivo performance in the long-term.