Two-body wear of resin and ceramic denture teeth

Objectives: To evaluate the two-body wear resistance of denture teeth made from resins or ceramic when opposed to antagonists made from the same material. Materials and methods: Different artificial denture teeth were used in this study. G1: feldspathic ceramic (Bonartic CT, Candulor, Switzerland), G2: nano-filled composite resin (Condyloform II NFC, Candulor), G3: experimental organic-filled acrylic resin (Ivoclar-Vivadent, Liechtenstein) and G4: acrylic resin teeth (Polystar Selection, Merz Dental, Germany). The wear test was performed in a dual-axis chewing simulator (Willytec, Germany). For each group eight maxillary and eight mandibular first premolars were used. The cusps of the maxillary premolars were abraded to a depth of 0.5 mm to achieve a flat area for loading during the wear test. The lower first premolars were used as antagonistic specimens. Wear resistance was analyzed by measuring the total vertical substance loss for the upper und lower premolars and volume loss for the upper premolars using a laser scanner and an optical macroscope after 600,000 chewing cycles. Data were statistically analyzed using one-way analysis of variance (ANOVA) followed by the Games-Howell test (p≤0.05). For qualitative analysis, the specimens were sputter-coated with gold and evaluated at 1000x magnification using a scanning electron microscope. Results: The mean total vertical substance loss and mean volume loss for G3 (59±7µm and 0.011±0.001mm³) and for G4 (73±13µm and 0.019±0.004mm³) were significantly lower than for G1 (127±23µm and 0.068±0.028mm³) and for G2 (160±14µm and 0.135±0.045mm³). The tested teeth showed differences in the wear mechanism. Conclusion: Composite resin teeth showed less attritional wear resistance compared to ceramic teeth, while acrylic resin teeth showed more attritional wear resistance than ceramic teeth when opposite to antagonist from the same material. However, the SEM and Laser scanner observation showed that the tested acrylic resin teeth exhibited deformation of the contact surfaces after the wear test.