Effects of postpolymerization time and temperature on the flexural properties and hardness profile of three-dimensional printed provisional resin

Background/purpose: Three-dimensional (3D) printing technique was widely used for provisional restorations in clinical use. However, the effects of post-polymerization temperature and time on the flexural properties and hardness profile were not fully elucidated yet. The purpose of this study is to investigate the effects of post-polymerization temperature and time on the flexural properties and hardness profile of the provisional restoration. Materials and methods: 3D-printing provisional resin was printed and post-polymerized at various temperatures (room temperature, 40 degrees C, 60 degrees C and 80 degrees C) and periods (0, 15, 30, 60, 90 and 120 min of photopolymerization). Afterwards, the flexural strength, flexural modulus, surface hardness, and internal hardness at different depth were evaluated. Results: The group post-polymerized without concurrent heating had significantly shallow depth of cure comparing to the heating counterparts. The surface hardness of the groups post-polymerized at different temperatures did not show any difference. All groups with post-polymerization temperature at 40 degrees C, 60 degrees C and 80 degrees C and post-polymerization time ranged between 15 and 90 min, had curing depth between 3 and 4 mm. Group post-polymerized without concurrent heating has significantly shallow depth of cure comparing to the heating counterparts. Conclusion: Post-polymerization at an elevated temperature, preferably 60 degrees C, is suggested. The wall thickness of the 3D-printing provisional prosthesis thinner than 3e4 mm is recommended. (c) 2023 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).