Cementation Tips for Element-Z Crowns

Element-Z crowns are often used in cases with short clinical preps, reduced vertical dimension, and bruxism. Optimizing adhesive performance in less-than-retentive preparation designs requires both the tooth and indirect substrate be addressed with specific adhesives and primers. Zirconia is a silica-free, acid-resistant, polycrystalline ceramic. It does not contain amorphous silica glass (unlike feldspathic porcelain, leucite-reinforced ceramics, and lithium disilicate ceramics), thus traditional ceramic surface treatments, such as hydrofluoric etching followed by silane application, are ineffective. To overcome this and subsequently increase bond strength we recommend using one of the following ceramic primers:

Clearfil Ceramic Primer
Kuraray 800.879.1676

Z Prime Plus
Bisco 800.247.3368

Apply the primer directly to the internal zirconia crown surface prior to cementation per manufacturers’ instructions. Then fill with a Self Adhesive Resin Cement (ex. SA Cement or RelyX Unicem) or a Resin Modified Glass Ionomer (ex. FujiCem) of your choice.

Utilization of CAD/CAM restorations brings many benefits to dentistry however there are some limitations to what prep designs these systems can tolerate. Preparation undercuts are the main concern when laser scanning for CAD/CAM restorations.

Illusrated on the right in figure 1 is an example of a severe undercut that would cause an open margin in a CAD/CAM restoration. In Figure 1 the undercut actually overhangs the margin; this area must be reduced similiar to the adjacent side in order to avoid an open margin. This is especially critical in bridge preparations.

Figure 2 shows a typical undercut that will not cause a problem. This undercut will be blocked out by hand or within the software and is not an issue of concern.