The emergence of zirconia has advanced dentistry. A crystalline ceramic, zirconia can give great esthetic qualities to the patient. In addition, with its high metal oxide concentration, zirconia shows great mechanical strength. However, bonding to zirconia is known to be particularly troublesome. Sand blasting with alumina, silanization, glass infiltration and zirconia primers have all emerged as different methods to aid in bonding to zirconia. Many of these procedures involve complex laboratory work and don’t allow for intraoral repair work (other than zirconia primers).
Here come universal adhesive systems. These systems have phosphate functional monomers, similar to zirconia primers, and are said to be able to bond to different materials, such as ceramics and metals. So, can these universal systems give bond strength to zirconia comparable to that of zirconia primers? And if they do, does the zirconia surface need to be polished or sandblasted to achieve functional bonding?
To answer this question, Scotchbond Universal (3M ESPE), All Bond Universal (Bisco) and Z-Prime Plus (Bisco zirconia primer) were all tested for their bond strength on polished and sandblasted zirconia.
It was shown that universal adhesive systems (Scotchbond and All Bond Universal) gave bond strengths similar to or even greater than that of zirconia primers (Z-prime plus).
Bond strength between 15 to 25MPa is considered sufficient for clinical use. Whether using sandblasted or polished zirconia, the universal adhesive systems and z-prime all showed acceptable bond strengths.
Sandblasting the zirconia surfaces before treatment with any bonding system provided even better bonding strength. Sandblasting was shown to promote mechanical retention, by interlocking the adhesive system and the surface irregularities of zirconia.
Therefore, universal-bonding systems containing phosphate functional monomer, can give clinically acceptable bond strength to zirconia. You can achieve even great bond strength, if you sandblast the zirconia. This can give incredible flexibility in cementation and repair of zirconia restorations.