The aim is to compare the adhesion between zirconia and cements attained with melt-etching with potassium hydrogen difluoride, KHF2, with that found when such traditional surface treatments as sandblasting and ceramic stone grinding are employed.

Materials and methods:
Groups of zirconia crowns where treated by sandblasting (n=6), grinding with carbide bur (n=6) or melt-etching with KHF2 (n=6) of the surface before cementation with a resin cement to an implant substitute made by Selective Laser Melting of a cobaltchromium alloy. Tensile testing was performed to rupture, while measured increasing load at the zirconia-cement interface. The strength was calculated by dividing the rupture load with the contact area. The three groups were compared using one-way ANOVA.

The adhesion strength between the zirconia crowns and the cement resulted in significant differences between all groups (p<.05). The sandblasted group had the lowest strength (5.2 ± 0.95MPa), the ground group significantly higher (7.3 ± 1.49MPa) and the melt-etched group the highest values (9.8 ± 1.37MPa).

The adhesive strength of resin cement to zirconia can be ranked according to the surface preparation with surfaces melt-etched with KHF2 stronger than ground which is stronger than sandblasted.

Comparison of sandblasted, ground and melt-etched zirconia crowns regarding adhesion strength to resin cement
Kvam K, Irkayek A, Vangaeva E, El-Homsi F
Biomaterial Investigations in Dentistry 2019, VOL. 6, NO. 1, 1–5