Manufacturing Accuracy, Intaglio Surface Adaptation, and Survival of Additively and Subtractively Manufactured Definitive Resin Crowns After Cyclic Loading: An In Vitro Study

Purpose: To assess the manufacturing accuracy, intaglio surface adaptation, and survival of resin-based CAD/CAM definitive crowns created via additive manufacturing (AM) or subtractive manufacturing (SM). Materials and Methods: A maxillary right first molar crown was digitally designed and manufactured using AM hybrid resin composite (VarseoSmile Crown Plus, Bego [AM-HRC]), AM glass filler–reinforced resin composite (Crowntec, Saremco Dental [AM-RC]), and SM polymer-infiltrated ceramic (Vita Enamic, VITA Zahnfabrik [SM-PICN]). Manufacturing accuracy (trueness and precision) was assessed by computing the root mean square (RMS) error (in μm; n = 15 per material). Intaglio surface adaptation was assessed by calculating the average gap distance (μm). Ten crowns from each group were cemented on fiberglass-reinforced epoxy resin dies and cyclically loaded to simulate 5 years of functional loading. One-way ANOVA, post hoc Bonferron comparison tests, and Levene’s test were used to analyze the data (α =.05). Results: AM-RC had higher overall trueness than AM-HRC and SM-PICN (P ≤.05), whereas the trueness of AM-RC on the external surface was similar to that of SM-PICN (P =.99) and higher than AM-HRC (P =.001) SM-PICN had lower precision than AM-RC and AM-HRC overall and at internal occlusal surfaces (P ≤.05). Overall intaglio surface adaptation was similar between all groups (P =.531). However, for the axial intaglio surface, AM-RC and AM-HRC had higher adaptation than SM-PICN (P ≤.05). Al tested crowns survived the cyclic loading simulation of 5 years clinical use. Conclusions: AM-RC showed high manufacturing accuracy and adaptation. The tested resin-based CAD/CAM materials demonstrated clinically acceptable manufacturing accuracy and simulated medium-term durability justifying the initiation of clinical investigations to determine their potential implementation in daily clinical practice.