Multi-material DLP printing for denture materials: Investigation of surface characteristics, physico-mechanical...

This study aimed to investigate the use of multi-material digital light processing (DLP) printing in denture materials, evaluating surface characteristics, water sorption and solubility, mechanical properties, and cytotoxicity.

Four types of specimens were fabricated using DLP printing: artificial denture teeth resin (PT), denture base resin (PB), artificial denture teeth bonded with base resin (PT-PB), and multi-material printed denture teeth and base resin (MPT-B), respectively. Surface characteristics were assessed. Water sorption and solubility were determined as per ISO 20795-1: 2013. Biaxial flexural strength (BFS) was measured in accordance with ISO 6872: 2015. Shear bond strength (SBS) and failure modes were examined. Cytotoxicity was evaluated according to ISO 10993-5/-12.

The highest surface roughness was observed in PB (S_a = 2.47 ± 0.61 µm, p < 0.05). Lower water absorption was found in the MPT-B group (5.86 ± 0.68 µg/mm³) compared to the PT-PB group (9.81 ± 2.99 µg/mm³, p = 0.0163). Higher solubility was exhibited by PT-PB (0.78 ± 0.37 µg/mm³) than MPT-B (-4.07 ± 0.81 µg/mm³, p < 0.0001). A lower BFS value was observed in the PB group compared to the other groups. In contrast, no significant differences were observed among the PT, PT-PB, and MPT-B groups (p > 0.05). Higher SBS was achieved by MPT-B (17.78 ± 3.22 MPa) compared to PT-PB (7.96 ± 2.03 MPa, p < 0.0001), with cohesive fracture being predominant. No cytotoxic effects were observed in the tested groups.

Multi-material DLP printing technology improves interfacial integrity and mechanical reliability without compromising biocompatibility. This approach provides an efficient alternative for the fabrication of digital dentures.