Polymerization behavior, filler weight, mechanical properties, and Weibull parameters of additively manufactured resins for definitive short-span fixed dental prostheses

To evaluate the polymerization behavior among commercially available and experimental additively manufactured (AM) resins intended for definitive short-span fixed dental prostheses, while comparing their inorganic filler weight, mechanical properties, and reliability with a subtractively manufactured resin. Disk- and bar-shaped were fabricated from three AM resins (Tera Harz BR-23, AM-TH; Bridgetec, AM-BT; and VarseoSmile Triniq; AM-VT) and a subtractively manufactured resin (breCAM.HIPC; SM-BR). Degree of conversion (DC) and filler weight were evaluated using the disk-shaped specimens (n = 3 per analysis), whereas bar-shaped specimens (n = 15) were analyzed for flexural strength and elastic modulus. The DC and filler weight data were analyzed using one-way analysis of variance (ANOVA) and Tukey tests and flexural strength and elastic modulus data were analyzed using Welch's ANOVA and Games-Howell tests. The maximum likelihood estimation method was used for the Weibull analysis of the flexural strength data and the resultant Weibull parameters were compared using chi-squared tests (α = 0.05). AM-VT exhibited the highest DC (P ≤ 0.040). Filler weight decreased in the order of AM-BT, AM-VT, and AM-TH (P < 0.001), while SM-BR was excluded from the statistical analysis due to the absence of detectable fillers. Elastic moduli were highest for AM-TH and AM-BT (P < 0.001). SM-BR demonstrated higher characteristic strength than AM-TH (P = 0.001). Despite varying filler contents, all AM resins achieved favorable conversion, with flexural strength values and Weibull moduli comparable to the SM-BR resin. While AM-TH and AM-BT resins demonstrated greater stiffness, the SM-BR resin yielded similar or higher characteristic strength. Combining tested additively manufactured resins with the printing and post-polymerization protocol used in this study may provide a reliable workflow for achieving high conversion and adequate flexural strength for polymer-based restorations. However, given demanding mechanical requirements of multi-unit restorations, further studies are required before recommending tested resins for short-span FDPs.