Trueness, precision, and internal fit of additively and subtractively manufactured definitive resin-based crowns.

Purpose
To assess the fabrication trueness, precision, and internal fit of additively manufactured (AM) and subtractively manufactured (SM) resin-based definitive crowns.
Materials And Methods
A maxillary right first molar complete-coverage crown was designed and fabricated using 2 additively manufactured [Pro Resins Crown X (AM-S); Straumann USA LLC and Flexcera Smile Ultra+ (AM-F); Desktop Health] and 2 subtractively manufactured [Shofu HC (SM-S); SHOFU Dental Corp and Brilliant Crios (SM-C); Coltene/Whaledent AG] resins (n = 15). The crowns were scanned using an intraoral scanner (IOS) and then seated onto the abutment tooth and rescanned. Fabrication trueness was evaluated by superimposing test data (TD) over the reference crown and computing the root mean square (RMS, µm) error for overall, intaglio, and margin surfaces. Internal fit was evaluated by measuring the average gap distance between the crown and abutment tooth (µm) using a modified triple scan protocol (TSP) for overall, occlusal, and axial surfaces. One-way ANOVA followed by post hoc Tukey's comparison tests was used to analyze the data (α = 0.05).
Results
Significant differences were observed among the resin-based crown materials for trueness (RMS), precision deviation, and internal fit (p < 0.001). AM-F had the lowest intaglio RMS value. Margin RMS values for AM-F and AM-S were significantly lower than those for SM-C and SM-S (p < 0.001). SM-C and SM-S showed superior occlusal fit compared to AM-F and AM-S (p < 0.001).
Conclusions
The type of CAD-CAM manufacturing method-additive or subtractive-significantly influenced the trueness and internal fit of resin-based definitive crowns.