Effect of mixed adhesive-silane coupling agent on the repair of hydrofluoric acid-etched ceramic restoration

Objectives: It is well known that the application of silane coupling agent (S) is essential for enhancing the bonding ability of composite-resin to the ceramic restoration before the application of adhesive (A). This study was planned to find out whether the application of different mixting ratio of A and S could gain a bond strength similar to that of the respective application of these two materials during the ceramic repair procedure.
Methods: Ceramic blocks (8x8x6mm, n=20) were prepared and divided into four groups. Each ceramic block was etched (10%HF), washed (5m) and applied with one of the different mixing ratio of S (Ceramic primer) and A (G-Premio Bond) as the following: 1) Group 1: 1S5A; 2) Group 2: 5S1A; 3) Group 3: 1S1A. Another group (Group 4) treated with S and A separately was served as control. Composite-resin was piled onto each ceramic block with each 2mm/40s light-curing successively to 4mm in thickness. After water immersion (37°C, 24h), each resin-ceramic block was sectioned into non-trimming microtensile test specimens tested with observation of the fractured surface and statistically analyzed (Bonferroni, p<0.05).
Results: The bond strength showed a decreasing order from Group 3, Group 4, Group 1 to Group 2. The bond strength showed no significance between Group 3 and 4. Group 2 presented was significantly lower than other groups with the largest number of pre-test dislodgement specimen during sectioning procedure.
Conclusions: A mixture of less than 50 vol% ratio of silane coupling agent in adhesive-silane coupling agent might have a potential of maintaining bond strength similar to that of the conventional application method.