Fracture toughness of 3D printed denture teeth

Advances in digital dentistry lead to use of three-dimensional (3D) printed resin denture teeth. Fracture toughness of these teeth must be assessed.

This study aimed to compare the chipping and indirect tensile fracture resistance of denture teeth fabricated by 3D printing technique with traditionally fabricated resin denture teeth.

Four groups (Gr) were made (n= 50/group): Gr-1 3D printed denture teeth (denture teeth; Formlabs Inc., Somerville, MA, USA), Gr-2 SR-Orthosit-PE (Ivoclar Vivadent AG), Gr-3 Portrait IPN (Dentsply Sirona), Gr-4 Pala Premium 8 (Heraeus Kulzer GmbH). Stereolithography 3D printing was used to create the methacrylate-based photopolymerized resin teeth models and remaining group teeth were collected commercially. A 1 mm/min chipping and indirect tensile fracture speed tests were carried out till fracture occurred. The data so obtained were statistically analysed using one-way analysis of variance with Tukey's honestly significant difference multiple comparisons test (p< 0.05). At the end of the test, the fractured areas of the specimens were evaluated by the chief researcher to assess the fracture pattern of the teeth.

The indirect tensile fracture values of the 3D printed teeth were more than that of Pala Premium-8 and SR-Orthosit-PE but it was lower than that of Portrait IPN teeth. In chipping test, buccal chipping of the loaded cusp was seen in 3D printed resin without distortion and in indirect tensile test in 3D printed resin teeth, line of fracture emerges near the loading point propagates from the inner incline of both cusps and extends cervically, unlike in other groups where first deformation occurs then fracture.

Prosthetic teeth fabricated by the 3D printing technique using printable resin material provide adequate fracture resistance as denture teeth.