3D-printed crowns show high fracture strength after aging

A new laboratory study with NIOM as a significant contributor, has investigated how crown thickness and simulated long-term use affect the fracture strength of permanent 3D-printed dental crowns.

The study shows that all tested crowns withstood artificial aging corresponding to approximately five years of clinical function, while several of the 3D-printed materials demonstrated higher fracture strength than the reference material.

The study was carried out in collaboration between several research institutions, with Mina Aker Sagen and Magnus Anderson from NIOM contributing extensively to the laboratory investigations and mechanical testing procedures.

What is this about?

Additive manufacturing, commonly known as 3D-printing, is becoming increasingly relevant in restorative dentistry. New resin-based materials developed for permanent crowns may offer advantages such as reduced material waste, lower production costs and greater design flexibility compared with traditional milling techniques.

However, questions remain regarding how these materials perform over time and whether thinner restorations can maintain sufficient strength under functional loading.

In this study, researchers evaluated crowns manufactured from three different 3D-printed resin materials and compared them with a clinically established CAD/CAM material based on a polymer-infiltrated ceramic network.

What did the researchers find out?

The results showed that all crowns survived thermomechanical aging, a testing protocol designed to simulate approximately five years of clinical service.

The 3D-printed crowns generally demonstrated higher fracture loads than the reference material. At the same time, aging reduced the fracture strength of all 3D-printed crowns, while the reference material was not significantly affected by aging.

Even after aging, however, all tested crowns showed fracture loads exceeding previously reported chewing forces in the molar region.

The study also found that crown thickness influenced fracture strength, although the relationship varied depending on whether the crowns had been aged.

What are the key results?

The findings suggest that modern 3D-printed crown materials show potential for use in permanent restorations.

Although thermomechanical aging reduced the strength of the 3D-printed materials, all crowns remained mechanically stable throughout the testing period and maintained fracture loads above clinically relevant chewing forces.

The researchers conclude that material selection and crown thickness influence mechanical performance and should be considered when designing permanent restorations.