Walk into any dental conference today, and you'll likely hear the same prediction—3D printing is set to transform restorative dentistry. While printers have already become commonplace for models, surgical guides and temporary restorations, one question still lingers: can a 3D-printed crown really withstand the forces of everyday chewing?
A recent laboratory study set out to answer that question by evaluating the mechanical performance and marginal adaptation of 3D-printed resin-based composite molar crowns.
Researchers compared nine different groups of additively manufactured resin crowns intended for either temporary or permanent use with conventionally milled resin composite crowns, which served as the reference standard. Each crown was adhesively bonded to prepared extracted human molars before being subjected to thermal cycling and mechanical loading to simulate oral aging.
The results were encouraging.
None of the 3D-printed crowns failed during the chewing simulation, suggesting that all tested materials were able to withstand the aging protocol without catastrophic fractures or debonding.
When fracture resistance was measured, the printed crowns demonstrated fracture forces ranging from approximately 1,700 N to 2,840 N. Although the conventionally milled crowns recorded the highest average fracture strength at just over 3,100 N, several of the printed materials performed remarkably close to the reference.
Equally important was how well the crowns maintained their fit over time.
Before artificial aging, the proportion of perfectly adapted margins ranged from 97.8% to 100%. Even after thermal cycling and mechanical loading, marginal integrity remained high, ranging between 92.3% and 99%. Researchers also observed only moderate wear at the contact points, with no cracks or defects developing along the crown margins after simulated function.
Most fractures, when they occurred during strength testing, involved the crown itself and were sometimes accompanied by fracture of the underlying tooth, reflecting the high forces required to reach failure.
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