Repair of Cerec porcelain with seven different systems

Intra-oral repair of fractured porcelain is a challenging clinical necessity, because time, economics, as well as possible trauma to teeth, often contra-indicate replacement of the original restoration. The purpose of this study was to evaluate the bond strength of seven different porcelain repair systems used in combination with Cerec Vitablocs Mark II porcelain. The systems were Scotchbond Multi-Purpose (SMP), All-Bond 2 (AB), Optibond (OB), C&B Metabond (CB), Imperva Bond (IB), Silistor (S) and Mirage Bond (MB). When Mirage Bond was used, the porcelain was either etched with 9.6 percent hydrofluoric acid for 2 min (10 specimens = MB1) or with 4 percent APF gel for 2 min (10 specimens = MB2). The shear bond strengths (SBS) of all the products were determined using an Instron. The effects of the pretreatments on the porcelain with different systems were also examined in a SEM. Data were statistically analysed (Wilcoxon Sum of Rank Test). The mean SBS (MPa) of the products were: SMP = 22.6 +/- 6.5; AB = 17.1 +/- 4.1; OB = 17.1 +/- 2.3; CB = 25.8 +/- 4.2; IB = 18.3 +/- 5.2; S = 16.4 +/- 3.7; MB1 = 13.1 +/- 3.9 and MB2 = 6 +/- 2.1. CB and SMP were significantly stronger (p < 0.05) than all other products, with MB2 statistically weaker (p < 0.01) than the other groups. Most specimens showed cohesive fractures in the porcelain, except when MB was used with 4 percent APF gel, where all samples fractured at the adhesive interface. It can be concluded that all seven systems can be used to repair Cerec Porcelain, except possibly MB when used in conjunction with 4 percent APF etchant.