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OBJECTIVE: To determine if the duration between 3D printing indirect bonding materials and initiation of post-processing steps (lag time) affects the flexibility or radiant energy penetration properties of 3D-printed indirect bonding jigs.
MATERIALS AND METHODS: The flexural modulus and radiant energy penetrance of three 3D-printed resins (Formlabs IBT Resin, SprintRay IDB 2, Pro3dure GR-18.1 IB) were assessed at three time intervals post-printing (0 hours, 16 hours, 64 hours), representing common delays in post-print processing in clinical workflows. Cylindrical disks (2 mm thickness, 18.9 mm diameter) were printed, totaling 90 samples (30 per resin type). Radiant energy penetration was measured using an Ortholux luminous curing light and a Molectron PowerMax 500D power meter. Indirect evaluation was conducted using a custom device with BracePaste composite resin cured through the 3D-printed resin samples. Cured composite samples were subjected to Vickers Hardness testing. Ten rectangular samples (25 x 15 x 2 mm) for each of the nine groups were also printed and subjected to flexural modulus testing. The flexibility of the samples was assessed using Young’s Modulus, derived from Instron tensile testing and 3-point bending rheometry.
RESULTS: Both the resin type and lag time duration had a statistically significant effect on the radiant energy penetration of the samples and the microhardness of the composite cured through the samples. A temporal effect of lag time duration was observed, but it was dependent on the resin type. Young’s Modulus data from Instron testing showed that lag time duration had a statistically significant effect on the flexibility of samples only for the Pro3dure group. In contrast, Young’s Modulus data from linear drive rheometry demonstrated a statistically significant effect on the flexibility of samples only for the SprintRay IDB 2 group.
CONCLUSIONS: Direct and indirect radiant energy penetration qualities as well as the flexibility of a 3D-printed indirect bonding jig are affected by both resin material and duration of lag time between printing and initiation of post-processing steps.