Digital fabrication accuracy and fit analysis of additively and subtractively manufactured zirconia fixed dental prostheses

To compare the fabrication accuracy and fit of three-unit fixed dental prostheses (FDPs) manufactured additively from a 3Y-TZP slurry with those manufactured subtractively from a translucent or a strength-gradient zirconia. Forty-five three-unit posterior FDPs were fabricated either additively from a 3Y-TZP slurry (Cera-P, AM) or subtractively from a translucent (4Y-TZP, n!ce Zirconia HT, SM-HT) or a strength-gradient zirconia (3/5 Y-TZP, IPS e.max ZirCAD Prime, SM-SG) (n = 15). Surface deviations (external, intaglio, marginal, and overall) and average gaps (fit) of the FDPs were digitally analyzed. Data were analyzed with one-way analysis of variance and Tukey (surface deviations) or Tamhane tests (average gaps). Precision was defined as the average of measured values from the mean value, and analyzed similar to each outcome (α = 0.05). AM FDPs exhibited the highest deviations across all surfaces but the lowest gaps ( P < .001) and no significant differences were detected between SM-HT and SM-SG ( P ≥ 0.360). There was no difference in the precision of measured deviations ( P ≥ 0.057). When the precision of average gap values was considered, AM FDPs had higher values than SM-SG FDPs ( P = 0.024). AM FDPs demonstrated the lowest fabrication trueness, while SM-SG and SM-HT FDPs had similar fabrication accuracy. Although AM FDPs exhibited improved fit, their fit precision was inferior to SM-SG FDPs, whereas SM-SG and SM-HT FDPs had similar fit accuracy. The fit of all FDPs remained within clinically acceptable limits.