In Vitro Analysis of Bonding and Wear Properties of 3D Printed Denture Tooth Materials

While additive manufacturing (3D printing) has recently enhanced removable prosthodontics, the properties of new 3D printed materials are not well understood. This study aims to elucidate the physical properties of these materials, focusing on bonding to a 3D printed denture base material and wear resistance.

For denture tooth-denture base bonding analyses, the same denture tooth material (Premium Teeth, Formlabs) was used with three denture base-bonding group assignments (n=6 each group) bonded using three protocols: Group A1 was bonded with Lucitone Digital Print-3D Denture Base using the Lucitone Fuse System (Dentsply), Group A2 with Formlabs Denture Base using the Formlabs Denture Base Bonding System, and Group A3 with Formlabs Denture Base using the Ivoclar Ivotion Bonding System (Ivoclar). Specimens were made according to the ISO-TS-19736-2027 standard. A 3D printed tooth mimicking a central incisor was bonded to the denture base and subjected to a palatal load at the incisal region at 90° from the long axis of the tooth until failure. The fracture surface was examined at 10× magnification. ANOVA with α=0.05 was used to determine statistically significant differences. For wear analysis, the same denture base material and bonding system (Lucitone Digital Print-3D Denture Base/Lucitone Fuse System, Dentsply) was used with four denture tooth material group assignments (n=8 each group): Group B1 used Formlabs Premium Teeth, Group B2 used SprintRay High Impact Denture Teeth, Group B3 used Lucitone Digital IPN Premium Tooth, and Group B4 used Ivotion Polymethyl Methacrylate (PMMA) Milled Teeth (Ivoclar). A premolar denture tooth bonded with the denture base was subjected to a chewing simulation cyclic loading of 1,200,000 cycles. Sample failures, vertical wear, and volume loss were documented. ANOVA with α=0.05 was used to determine statistically significant differences.

The fracture load to failure values for A1, A2, and A3 were 175±106 N, 167±46.3 N, and 183±48.9 N, respectively (p=0.95). Most failure characteristics were mixed, except one of A2 was cohesive and half of A3 was cohesive. For cyclic loading, B4 was the only group where all specimens failed within 1,200,000 cycles, while B1, B2, and B3 had four, three, and five sample failures, respectively. Vertical wear was 0.93±0.34 mm, 1.22±0.37 mm, 1.05±0.27 mm, and 0.37±0.02 mm for B1, B2, B3, and B4, respectively (p<0.01). Abrasion volumes were 9.5±3.7 mm³, 12.2±4.7 mm³, 10.6±3.5 mm³, and 2.2±1.3 mm³ for B1, B2, B3, and B4, respectively. Vertical height loss per chewing cycle (μm/cycle) was 0.0022±0.0019, 0.0030±0.0029, 0.0012±0.00005, and 0.0080±0.0050 for B1, B2, B3, and B4, respectively (p<0.01). Abrasion volume per chewing cycle (μm³/cycle) was 17650.8±9682.9, 27263.4±24746.8, 11836.5±4200.8, and 70436.8±73602.5 for B1, B2, B3, and B4, respectively (p=0.02).

The bonding strength and wear resistance of 3D printed denture materials vary by manufacturer. Formlabs Denture Base with Ivoclar Ivotion showed the highest fracture load, indicating superior bonding strength. In wear analysis, Ivoclar Ivotion PMMA Milled Teeth exhibited the least vertical wear and abrasion volume but had the highest failure rate under cyclic loading. While printed denture materials excel in bonding strength, their wear resistance may not be as good as milled denture teeth, highlighting the need to balance these properties in clinical applications.