Wear resistance of additive-manufactured denture teeth following mastication simulation

Denture teeth have traditionally been made from polymethyl methacrylate (PMMA) material. The introduction of subtractive manufacturing enabled the milling of denture teeth, and the advent of additive manufacturing (AM) enabled the 3-dimensional (3D) printing of denture teeth. However, the wear resistance of 3D printed denture teeth is unknown.

The purpose of this in vitro study was to compare the linear and volumetric wear of AM resins of different compositions with conventional double cross-linked (DCL) PMMA denture teeth and natural enamel.

DCL PMMA second mandibular premolar denture teeth (Ivoclar Ortholingual conventional DCL PMMA resin teeth) and natural human enamel specimens were used as controls (n=8). The DCL teeth were scanned and printed in 3 different AM resin materials. The specimens DCL PMMA resin teeth (DCL), natural human enamel (enamel), VarseoSmile Crown Plus (AM-CFH), DENTCA Denture Teeth (AM-MPR), a diurethane dimethacrylate (DUDMA) photopolymerizable resin, and OnX Tough (AM-NCH), labeled a hybrid ceramic resin, underwent mastication simulation in a biaxial fatigue testing machine. The mastication simulator was set at 1.53 Hz, thermocycling between 5 °C and 55 °C, and 49 N against a Ø6-mm steatite antagonist following the International Organization for Standardization Technical Specification (ISO/TS) 14569-2. After 250 000 cycles, the linear and volumetric changes on the occlusal surfaces of the specimens were analyzed with a 2-way analysis of variance (ANOVA), followed by a Tukey comparison test (α=.05).

A statistically significant difference in linear and volumetric wear was found between enamel, DCL, and AM denture teeth (P<.001). Enamel had the lowest mean values for linear (0.183 mm) and volumetric wear (0.224 mm³). Within AM materials, AM-CFH linear wear (0.265 mm) did not significantly differ from that of DCL (P=.707). AM-NCH resulted in the highest linear wear (0.515 mm) and largest wear volume (1.841 mm³).

AM denture teeth exhibited varying degrees of wear resistance. The wear rate was contingent upon the material, with AM-CFH resin and increased filler content exhibiting wear comparable with that of DCL denture teeth. Both types of denture teeth had a higher rate of wear than enamel.