[Adhesive property and flexural strength of patterned microstructured zirconia posts fabricated by 3D printing]

This study aims to design surface patterns using integrated programming software on zirconia posts fabricated through 3D printing.

A type 3 3M fiber post was built as a research model, and HyperMill 2021 software was applied to design linear overflow grooves extending from the apex to the base on the post surface. The design parameters included the number, depth, and width of the overflow grooves. Five groups of patterned microstructured zirconia posts were designed, with the 3M fiber post as the control group. Micro-push-out and three-point bending tests were used to measure the bon-ding and flexural strengths of the patterned microstructured zirconia posts. The failure mode of bonding was analyzed by using a stereomicroscope.

The patterned microstructure significantly increased the bond strength of zirconia posts (P<0.05). Bonding strength ranged from 9.80 MPa±0.64 MPa to 26.49 MPa±0.94 MPa at the base of the root, from 9.26 MPa±1.08 MPa to 18.51 MPa±0.93 MPa at the center of the root, and from 6.74 MPa±0.31 MPa to 13.00 MPa±0.71 MPa at the apex of the root. The implementation of patterned microstructures reduced the flexural strength of the zirconia post (P<0.05), and flexural strength ranged from 378.3 MPa±24.18 MPa to 587.4 MPa±36.60 MPa. The failure mode of zirconia post adhesions treated with patterned microstructures was mainly mixed failure.

Patterned microstructured zirconia posts with improved flexural strength and adhesive properties could be produced by using 3D printing. The bonding and flexural strengths of the patterned zirconia posts can meet the clinical requirements for custom post-and-core design.