Comparative In-vitro Analysis of Fracture Strength in 3D-printed VarseoSmile TriniQ Resin Versus Milled Monolithic Zirconia Endocrowns: Advancing Restorative Material Performance

Introduction: Restoring endodontically treated teeth requires materials that balance mechanical strength and tooth preservation. Endocrowns provide a conservative approach compared to conventional post-and-core restorations. While monolithic zirconia is widely used for its superior fracture resistance, novel 3D-printed materials like VarseoSmile TriniQ offer potential advantages in digital workflows and restorability. This study compares the fracture resistance and failure patterns of monolithic zirconia and VarseoSmile TriniQ endocrowns to evaluate their suitability for clinical application. Methods: Eighteen extracted human molars were randomly assigned to two groups (n = 9 per group). Standardized endodontic treatment was performed, followed by endocrown preparation. Monolithic zirconia endocrowns were milled using CAD/CAM technology, while VarseoSmile TriniQ endocrowns were fabricated using highprecision 3D printing. All restorations were cemented with dual-cure resin cement. Fracture resistance was tested using a universal testing machine, applying a compressive load until failure. Failure patterns were classified as favorable, unfavorable simple, or unfavorable complex based on whether fractures were confined to the restoration, extended into the tooth structure, or severely compromised both. Data were analyzed using the Mann–Whitney U test to determine statistical significance. Results: Zirconia endocrowns exhibited significantly higher fracture resistance (median = 3746.70 N, IQR = 1362.32 N) compared to VarseoSmile TriniQ (median = 1114.73 N, IQR = 180.66 N) (P < 0.001). Fracture patterns varied: 67% of zirconia failures were complex or destructive, compromising the natural tooth structure, whereas 60% of VarseoSmile TriniQ fractures remained confined to the restoration, sparing the tooth structure. Conclusion: Monolithic zirconia endocrowns demonstrate superior fracture resistance, making them ideal for high-load-bearing applications. However, VarseoSmile TriniQ offers a more favorable failure pattern, reducing the risk of catastrophic tooth damage. These findings suggest that while zirconia remains the preferred choice for durability, 3D-printed materials like VarseoSmile TriniQ could serve as viable alternatives in cases, prioritizing tooth preservation and digital efficiency.