Simple post-curing methods to optimize the depth of cure and physicochemical properties of 3D printed resin.

Objectives: This in vitro study evaluated the effect of different post-curing methods on the degree of conversion, mechanical properties, and color change of a 3D printing resin.

Methods: Specimens of a 3D printing resin were subjected to different post-curing processes: CONo post-curing; PCC-Post-curing in a violet light chamber; VA-Post-curing with VALO; HC-Post-curing in an oven; HP-Post-curing in an autoclave; PCC+HC-Post-curing in a violet light chamber associated with an oven; PCC+HP-Post-curing in a light chamber associated with an autoclave. The 3D printing accuracy, flexural strength, flexural modulus, Knoop microhardness and degree of depth conversion, surface hardness before and after immersion in solvent, gloss and roughness before and after brushing cycles, and color change after aging in UV light were evaluated.

Results: PCC+HC showed a significant reduction in length and no significant difference was detected in width. CO and VA showed higher distortion in thickness and PCC, HC and PCC+HP were statistically similar. PCC+HP had greater flexural strength and flexural modulus. All groups showed significantly decreased hardness after immersion in the solvent. The groups that associated PCC and heat had greater depth curing efficiency. PCC showed the lowest color change followed by PCC+HC and PCC+HP.

Conclusions: 3D printed resins require additional polymerization methods for optimal physicochemical properties. Post-curing combining violet light and a heat source, oven, or autoclave significantly enhances the depth of cure and improves the optical and physicochemical properties of a 3D resin for indirect restoration.

Clinical Significance: Post-curing methods that combine violet light and a heat source can increase the durability and performance of 3D printed resins for indirect restorations, potentially improving clinical outcomes by providing more reliable and durable restorations.