Long-term bond of glass ceramic and resin cement: evaluation of titanium tetrafluoride as an alternative etching agent for lithium disilicate ceramics.

Abstract

To evaluate in vitro the effect of using titanium tetrafluoride as an alternative etchant prior to the silanization of the bonding surface on the long-term resin bond strength to lithium disilicate ceramic. Disk-shaped specimens made of lithium disilicate ceramic were ground with abrasive paper, then etched with aqueous solutions (2.5% and 5%) of titanium tetrafluoride for 60 s, 120 s and 240 s. Positive control specimens were etched with 5% hydrofluoric acid for 20 s and negative control specimens were not etched. Afterwards, bonding surfaces of all specimens were silanized. Plexiglas tubes filled with a composite resin were bonded to the specimens using an alignment apparatus and a composite luting resin. After storage in 37°C tap water for three days (n = 8) and after storage in 37°C tap water for 150 days interrupted by 5 x 7500 thermal cycles (n = 8), tensile bond strength (TBS) was measured in a universal testing machine at a crosshead speed of 2 mm/min. After artificial aging, all specimens etched with titanium tetrafluoride debonded spontaneously resulting in a TBS of 0 MPa. Therefore, statistical analysis revealed a highly significant difference between the positive control and the test groups after 150 days storage. Etching the bonding surface of lithium disilicate ceramic restorations with hydrofluoric acid is still a "gold standard" and cannot be replaced by titanium tetrafluoride.