As zirconia restorations continue to grow in popularity, so do the questions about zirconia bonding. With the right knowledge and materials, zirconia crowns can last a long time.
Here are three tips to help you make sure all your crowns stay bonded for your patients.
1. Sandblast and Clean
Phosphate contaminants from saliva can weaken bond strength and cause debonding if they aren’t removed before cementation. We recommend the following procedure: Try-in the restoration. Thoroughly rinse the restoration with water spray and dry with oil-free air. Sandblast the restoration (unless the restoration has previously been sandblasted by the lab). Clean the internal surface with a cleaning agent such as ZirClean® to decontaminate the restoration completely. Rinse thoroughly with water spray and dry with oil-free air. Then, apply a zirconia primer and seat the crown with the cement.
2. Use a Primer that Contains MDP
MDP is an organophosphate, which is an adhesion promoting monomer that allows chemical bonding between the cement and zirconia restoration; it has affinity for metal ions, so it will work with zirconia (remember, zirconia is not a metal but it does have metal ions). Look to make sure that either the primer or the cement you’re using contains MDP; likewise, if you use a dedicated zirconia primer, such as Z-PRIME™ Plus then the resin cement you use doesn’t have to contain the monomer. Some resin cements contain MDP already (TheraCem® is an example), and therefore an additional primer won’t be necessary.
3. Consider the Retention
When deciding which cement and bonding procedure to use, you must consider the retention of the prep. If the prep has less than ideal retention, then using a bonding procedure on the tooth is necessary. BISCO recommends using All-Bond Universal® on the tooth, and then using Z-PRIME Plus on the restoration and cementing with Duo-Link Universal™. If the prep has ideal retention, then a self-adhesive resin cement that contains MDP is enough to bond the restoration to the tooth. BISCO recommends cementing with TheraCem.