An in vitro analysis of two-body wear and three body wear, hardness, and degree of conversion of 3D-printed restorative materials

OBJECTIVES: To compare the two-body wear under thermomechanical loading, three-body wear, degree of conversion and Vickers hardness of three permanent 3D-printed restorative materials with a milled composite control material. METHODS: Three 3D-printed materials (Deltamed 3Delta Crown, Saremco Print Crowntec, Detax Freeprint Crown) and one milled composite (Voco Grandio Disc) were evaluated. For two-body wear, specimens were loaded against 5-mm Al₂O₃ antagonists at 50 N and 1.2 Hz with thermocycling between 5 °C and 55 °C and were scanned after 100,000, 300,000, and 500,000 cycles. For three-body wear, ACTA wear testing was performed in a millet-seed slurry at 15 N and 15% slip, with scanning after 50,000, 100,000, 150,000, and 200,000 cycles. Vickers hardness was measured by microindentation, degree of conversion by Raman spectroscopy, and surface morphology qualitatively by scanning electron microscopy. RESULTS: Wear increased progressively with cycle number in both wear models. In two-body wear, Saremco Print Crowntec showed the highest wear, whereas lower wear values were observed for Deltamed 3Delta Crown, Detax Freeprint Crown, and Grandio Disc. In three-body wear after 200,000 cycles, Grandio Disc showed the lowest wear, followed by Deltamed 3Delta Crown, whereas Saremco Print Crowntec and Detax Freeprint Crown showed the highest values. Grandio Disc showed significantly higher hardness than all 3D-printed materials, whereas no significant differences were detected among the printed materials. The degree of conversion of the 3D-printed materials ranged from 67.53 ± 0.53% to 71.90 ± 1.20%, with no significant differences among groups. SIGNIFICANCE: Volume loss and hardness varied significantly by material. Here was no significant difference in DC. Filler content and distribution were the dominant factor influencing wear, followed by hardness and degree of conversion.