Effect of different ceramic surface treatments on resin microtensile bond strength

The objective of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (micro-tbs) of composite bonded to hot-pressed ceramic. The null hypothesis tested was that neither of the surface treatments (silanization or fluoric acid etching) would produce greater bond strength of composite resin to the ceramic.

Four 7 x 7 x 5 mm hot-pressed ceramic blocks of IPS Empress 2 were fabricated and polished to 600 grit followed by sandblasting with 50 microm alumina. The ceramic blocks were then divided into four groups and submitted to the following surface treatments: Group 1: 9.5% hydrofluoric (HF) acid for 20 seconds and silane (S) for 3 minutes; Group 2: silane for 3 minutes; Group 3: 9.5% HF acid for 20 seconds; Group 4: no treatment. Scotchbond adhesive was applied to the treated ceramic surfaces and covered with Filtek Z250 composite resin. The composite-ceramic blocks were cut with an Isomet low speed diamond saw machine producing sticks (n = 25), which were loaded to failure under tension in an Instron Universal testing machine. The mean micro-tbs was analyzed with one-way ANOVA and Bonferroni "t" test.

All specimens of Group 4 experienced adhesive failure during the cutting of the block and were eliminated. The mean micro-tbs and standard deviations (SD) in megaPascals were: Group 1 = 56.8 (+/-10.4), Group 2 = 44.8 (+/-11.6), Group 3 = 35.1 (+/-7.7). Statistical analysis showed that the bond strength was significantly affected by surface treatment (p < 0.0001). Group 1 (HF + S) had the highest micro-tbs, and Group 2 (S) had higher micro-tbs than Group 3 (HF). The mode of fracture of the specimens was examined using scanning electron microscopy (SEM), and all fractures occurred within the adhesion zone.

The results show that surface treatment is important for resin adhesion to ceramic and suggestthat silane treatment was the main factor responsible for resin bonding to ceramic.