Effects of post-curing level and phosphorylcholine modification on a 3D-printable resin for definitive crowns

This in vitro study evaluated the effects of 2 wt% 2-methacryloyloxyethyl phosphorylcholine (MPC) and post-curing level on degree of conversion, water sorption, and Bis-EMA release from a 3D-printable resin for definitive crowns.

VarseoSmile Crown plus and its 2 wt% MPC-modified formulation were fabricated by digital light processing and post-cured with 2 × 2000, 4 × 2000, or 8 × 2000 flashes. Degree of conversion and water sorption were evaluated in 10 specimens per group, and Bis-EMA release in 5. Degree of conversion was measured before and after 10,000 thermocycles by FTIR-ATR, water sorption after thermocycling, and Bis-EMA release at 24 h and 14 days by HPLC-UV. Statistical significance was set at α = 0.05.

Higher post-curing levels increased degree of conversion and reduced Bis-EMA release (P < 0.05), but did not affect water sorption (P = 0.294). MPC reduced degree of conversion and increased water sorption (P < 0.05), but did not affect 24-hour or cumulative 14-day Bis-EMA release (P = 0.130 and P = 0.083, respectively). Bis-EMA release from Lava Ultimate remained below the detection limit.

Increasing post-curing improved polymerization and reduced Bis-EMA release. MPC reduced degree of conversion and increased water sorption without significantly affecting Bis-EMA release. After thermocycling, degree of conversion increased only at the lowest post-curing level.

Appropriate post-curing may limit Bis-EMA release from definitive 3D-printed crowns. Although MPC modification was associated with lower degree of conversion and greater water sorption, the magnitude of the observed difference in degree of conversion may be of limited clinical relevance.