Evaluation of the fatigue behavior of implant-supported 3D-printed and milled resins for definitive crowns.

OBJECTIVES

To evaluate the reliability and failure modes of 3D-printed crowns fabricated from different resin composites compared to a milled resin composite block, all indicated as definitive restorations.

METHODS

Four 3D-printing resins were evaluated: 1) CeramicCrown (CC; SprintRay), 2)VarseoSmile-Crown (VSC, Bego), 3) Crowntec (CRO, Saremco), and 4) Ceramage 3D-Printed (C3D, Shofu), along a milled resin-composite block: Shofu Block HC Super-Hard (SSH, Shofu). Eighteen implant-supported maxillary first-molar crowns were manufactured per group and tested under step-stress accelerated life testing. Weibull statistics were applied, and reliability was calculated for 100,000 cycles at different loads. Fractographic analysis was performed under scanning electron microscopy.

RESULTS

All 3D-printed samples failed during fatigue testing, whereas SSH samples survived both the initial protocol and the extended cycling, in which the load profiles were modified to increase the number of cycles (up to 2400,000). Failures were related to material strength (C3D, CC, VSC) or fatigue damage accumulation (CRO). At a mission of 100,000 cycles at 300 N, all 3D printed groups presented high reliability (>99 %). Under higher loads (800-1000 N), CRO and VSC had lower reliability compared to C3D and CC. Characteristic fracture load was highest for C3D and CC, intermediate for CRO, and lowest for VSC. CRO showed the lowest Weibull modulus. Fractographic analysis indicated fracture initiation at the occlusal surface in printed crowns, propagating toward the margins and abutment. SSH crowns exhibited wear marks with no crack formation.

SIGNIFICANCE: While the milled composite demonstrated superior fatigue resistance, 3D-printed definitive crowns exhibited material-dependent fatigue behavior. Among printed groups, CC and C3D presented higher characteristic fracture load and reliability under higher loads compared to CRO and VSC.