The Effect of Heat Treatment and Surface Energy Alteration on Controlling the Long Term Stability of the Zirconia-Resin Bond

Abstract

Purpose: To evaluate the proper curing and surface energy alteration protocol for the MDP zirconia primer and to assess the bond stability before and after aging. Materials and methods: 50 Zirconia samples were cut using an Isomet 4000® and sintered into a standardized dimension of (8x8x4mm), then they were divided into 10 groups of 5 and assorted according to the surface treatment they received. All samples were silica-coated, the surface ttt they received were, No ttt, MDP primer , MDP+ heat ttt, MDP+ hydrophobic bonding agent, MDP+ hydrophobic bonding agent+2 step heat ttt. The μSBS of the groups was tested and the bonding surfaces were scanned with an electronic microscope under magnification of X40 pre and post aging (5000 cycles at 5-50ᵒC). Results: Aging of zirconia decreased the SBS of the Zr-resin bond (P=0.001). There was a positive correlation (with no significance) between applying heat to the MDP treated groups and achieving higher SBS both pre and post aging. After aging the groups with the highest number of (mixed failure) were the ones that received heat treatment. Conclusions: Aging affects the SBS of the zr-resin bond negatively. Applying an MDP primer significantly improved the SBS of the bond (pre and post aging). Exposing the MDP treated samples to heat treatment had a positive correlation to improving the SBS pre and post aging. Heat treatment protected the bond from water degradation. Applying a hydrophobic coating didn’t improve the SBS.