Effect of Acidic Environment on the Mechanical Strength and Surface Properties of Three-Dimensional-Printed Denture Base Resin

INTRODUCTION AND AIMS: This study evaluated the effects of acidic immersion conditions on the mechanical properties, colour stability, microhardness, and surface roughness of a three-dimensional (3D) printed denture base resin compared with a conventional autopolymerized resin. METHODS: Specimens of both materials were immersed for 24 hours at 36°C in solutions with pH values of 1, 3, 5, or 7. Flexural strength and modulus were measured using a three-point bending test, and Vickers hardness, colour stability, surface roughness, and contact angle were evaluated using established laboratory protocols. Surface morphology was examined using scanning electron microscopy to assess microstructural changes under different pH conditions. RESULTS: Two-way ANOVA showed that material type and pH level significantly affected flexural strength, flexural modulus, and Vickers hardness (P < .05), with significant material × pH interactions for flexural modulus and Vickers hardness. The tested 3D-printed resin generally showed higher mechanical properties than the autopolymerized resin under the tested pH conditions. Surface roughness was significantly affected by pH level and increased under lower pH conditions, while scanning electron microscopy qualitatively showed more visible surface irregularities at lower pH values. Colour stability and contact angle were not significantly affected by material type, pH level, or their interaction (P > .05). CONCLUSION: The tested 3D-printed denture base resin showed more favourable mechanical behaviour than the tested autopolymerized resin under the present acidic conditions. Further studies using broader material formulations and clinically relevant ageing models are needed to validate these findings.