The Role of Mechanical Properties in 3D-Printed Dental Models

In the field of dental 3D printing, printer resolution often receives the most attention. However, it is only one part of what determines the quality and reliability of a printed dental model. The true performance drivers are the mechanical properties of the material, specifically flexural strength, flexural modulus, biaxial strength, and surface hardness. When these properties are optimized, models remain stable and accurate throughout every stage of use, from printing and trimming to scanning, mounting, and thermoforming without losing precision.

Why Mechanical Properties Are the Real Deal

For 3D printed dental models, mechanical performance plays a critical role in ensuring both accuracy and long-term stability. While layer resolution influences surface detail, the model’s resistance to stress, heat, and handling determines how well it performs in real clinical workflows. Four essential properties define this performance and directly influence reliability across a wide range of applications.

Breaking Down the Four Core Properties

• Three-Point Flexural Strength (MPa): Indicates how well a model withstands bending forces without fracturing. High flexural strength is essential for maintaining the integrity of dies during margin trimming, crown seating, and sectioning procedures.

• Flexural Modulus (GPa): Represents the stiffness of the material. A higher modulus reduces unwanted deformation during occlusal adjustments, articulator mounting, or thermoforming, helping the model maintain its intended geometry.

• Biaxial Strength (MPa): Measures resistance to forces applied from multiple directions. This is particularly important during thermoforming, appliance assembly, or implant-related procedures where models are subjected to complex stress patterns.

• Vickers Hardness (VH): Defines surface hardness, which supports scratch resistance, accurate marking, and predictable scanning behavior. A harder surface ensures the model withstands repeated handling without degrading.

When you've got a good balance of these, dimensional accuracy and surface quality stick around from start to finish. No surprises, just consistent results.

How They Compare: Independent Testing from October 2025

We conducted practical evaluations to measure how leading model resins perform under real workflow conditions. The results provide a clear view of material stability and strength.

Three-Point Flexural Strength

• Pac-Dent TruModel: Shows the highest performance with an average of 113.8 ± 16.6 MPa in the as-printed state, followed by 104.1 ± 14.3 MPa after an aging cycle of three days at 55°C.

• Formlabs Fast Model: Delivers a solid result at 106 MPa in the as-printed condition.

• Other resins: Most competing materials fall within the range of 61 to 85 MPa, with Formlabs Model V2 at the lower end of the group.

Flexural Modulus

• Pac-Dent TruModel: The strongest performer in this category reached an average of 3.1 ± 0.6 GPa. 

• Shows a modulus of 2.74 GPa, placing it in the upper tier of this group.

• Keystone & Carbon: Both fall within the range of 1.85 to 2.2 GPa.

A higher modulus indicates greater stiffness, which reduces distortion during thermoforming and during any mechanical adjustments made to the model.

Biaxial Strength & Hardness

• Pac-Dent TruModel: Impressive at 131.0 ± 26.5 MPa (as-printed) and 122.5 ± 21.4 MPa (aged).

• Vickers hardness: Still in testing, but early signs are promising.

• Note: We didn't have comparable data for other resins in this roundup. "Aged" here mimics thermo-mechanical stress over 3 days at 55°C.

Introducing Rodin TruModel: Built for the Clinic

This is a next-gen model resin designed from the ground up—biocompatible, zero VOCs, and optimized for speedy DLP/LCD printing (385–405 nm wavelength). It's all about reliability without the headaches.

Shades and What They're For

• TruModel Prime (Stone Tan): Perfect for restorative and diagnostic models—gives that classic gypsum vibe.

• TruModel Gray (Light Gray): Ideal for thermoforming and inspection, with great contrast for spotting issues.

Early Validation Data (Q4 2025)

Both versions take pencil marks like a champ, shrug off chalking or discoloration, and often skip the need for reflective sprays during scans.

Applications and Picking the Right One

Study & Diagnostic Models

These models are frequently handled, scanned, marked, and shared across teams, so material durability is essential. Strong surface hardness helps prevent wear from pins, trays, and repeated handling, while long-term stability protects the arch from distortion during storage or transport. A matte surface also reduces glare, which supports faster and more accurate scans. TruModel Prime in Stone Tan is well-suited for this category because it delivers a gypsum-like appearance combined with dependable mechanical performance, making it a consistent and reliable reference in any clinical or laboratory workflow.

Healing & Prosthodontic Models

Dies in this category undergo frequent sectioning, trimming, and seating, so margin stability is essential. A flexural strength of at least 100 MPa helps prevent chipping, while a modulus above 2.8 GPa limits deformation during adjustments. Strong biaxial performance also supports multi-unit frameworks. TruModel Prime offers the stiffness and precision needed for accurate and reliable verification.

Orthodontic & Thermoforming Models

Heat and vacuum pressure during forming can distort arches or alter tooth positions. A higher modulus helps preserve vertical dimension and overall shape, while strong flexural performance reduces the risk of cracking around delicate embrasures. A smooth matte gray surface also makes imperfections easier to identify before forming. TruModel Gray is designed for this category, offering thermal stability and clear visual contrast for consistent and accurate results.

Implant Verification & Surgical Models

These models must withstand analog placement, torque in the range of fifteen to twenty N cm, and repeated scanning without distortion. Strong biaxial performance counters compression and shear forces, while a high modulus prevents flexing when verification jigs are tightened. Materials with biaxial strength above 120 MPa deliver the stability required for accurate implant verification.

Educational & Demonstration Models

Focus on looks and longevity. Hard surfaces resist scratches from constant handling, and anti-yellowing keeps them looking sharp over time.

Practical Tips to Get the Most Out of It

• For any model that requires die sectioning, target a flexural strength of at least 100 MPa.

• For thermoforming, aim for a modulus above 2.8 GPa to reduce the risk of distortion.

• Models with a matte, durable surface finish scan faster and reduce the risk of remakes.

• For post-curing, around twenty minutes at sixty degrees Celsius can significantly improve mechanical performance.

• For high-volume orthodontic work, a 75 µm layer height paired with a thermally stable resin offers an ideal balance of speed and accuracy.

Conclusion

Mechanical properties directly influence the reliability and precision of 3D printed dental models in clinical and laboratory workflows. Strong flexural and biaxial performance helps prevent distortion, while higher modulus values and durable surfaces support long-term stability and consistent scanning. Pac-Dent's Rodin TruModel, available in Stone Tan and Light Gray, is formulated to meet these demands across restorative, diagnostic, and thermoforming applications. When paired with a well-optimized printing process, it delivers consistent and highly accurate results from planning to chairside use.