STATEMENT OF PROBLEM: A ceramic composite concentrate that can be incorporated into resins used in additive manufacturing to improve their mechanical properties has been recently marketed. However, knowledge on whether this modification enhances the mechanical properties of such resins is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the mechanical properties and reliability of a dental resin used for additive manufacturing incorporated with a commercially available ceramic composite concentrate. MATERIAL AND METHODS: Specimens for flexural strength (17×4×1.5 mm, n=12), Vickers hardness (Ø10×1.5 mm, n=16), and fracture toughness (25×5×2.2 mm, n=15) tests were additively manufactured from an urethane acrylate-based resin with no fillers intended for definitive use (AM-D), a composite resin with ceramic fillers intended for definitive use (AM-DC), a resin with no fillers intended for interim use (AM-I), and the AM-I resin reinforced with a commercially available ceramic composite concentrate (AM-IR). The AM-IR resin was obtained by mechanically mixing 30 wt% of the ceramic composite concentrate with 70 wt% of the AM-I resin for 3 hours at 50 °C. Flexural strength and Vickers hardness data were analyzed with the Kruskal-Wallis and Dunn tests, while 1-way analysis of variance and the Tukey honestly significant difference tests were used for the fracture toughness data. Weibull modulus and characteristic strength were evaluated with the chi-squared test (α=.05). RESULTS: Resin type affected tested outcomes (P<
.001). AM-DC and AM-IR had significantly higher flexural strength than the other groups (P≤.004). AM-DC also had the highest Vickers hardness among tested resins (P<
.001). In terms of fracture toughness, AM-IR had the highest values followed by AM-DC (P≤.010). AM-IR had the highest Weibull modulus, and AM-DC had the highest characteristic strength among tested resins (P≤.019). CONCLUSIONS: The resin modified with the ceramic composite concentrate had similar biaxial flexural strength to that of the composite resin with ceramic fillers intended for definitive use along with the highest Weibull modulus and fracture toughness. However, its Vickers hardness was similar to that of resins indicated for interim use.