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 primed zirconia and to assess the bond stability before and after aging.Materials and methods: Zirconia samples (n=50) 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. The groups of comparison were, silica coating (gp 1&6)/ silica coating + MDP primer "Z-prime plus" (gp2&7)/ silica coating + MDP + heat ttt (gp 3&8)/ silica coating + MDP + hydrophobic coating (gp 4&9)/ silica coating + MDP+ hydrophobic coating + heat treatment X2 (gp 5&10). The μSBS of the groups was tested using an INSTRON® universal testing machine and the bonding surfaces were scanned with an electronic microscope under magnification of X40 pre and post aging (5000 cycles at 5-50˚C). Results:The study showed that there is a significant difference between the mean SBS of the groups pre and post aging (P=0.001). There was a positive correlation (with no significance) between applying heat treatment to the MDP treated groups and achieving higher SBS both pre and post aging. The heat treated groups came superior pre and post aging followed by the MDP treated group with no heat treatment. 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 in comparison to the non-treated samples (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 as the heat treated groups had the highest numbers of samples with mixed failure in the post aging groups. Applying a hydrophobic coating didn't improve the SBS.