There are two major approaches when cleaning resin cement as part of seating indirect all ceramic restorations. Each method has pros and cons and places where we can introduce challenges or encounter issues. As a foundation to bonding restorations we etch the tooth and apply a dentin adhesive. Despite the fact that many of our new dentin adhesives have very low values for film thickness I am still hesitant to cure prior to placing the restoration. Leaving the dentin adhesive uncured reduces the surface tension and increases the ability of the resin cement to flow when seated. It also eliminates the possibility of the thickness of the dentin adhesive preventing the restoration from seating and a resulting wide resin interface.
e.max by Ivoclar ( lithium Disilicate) has rapidly become one of my favorite materials over the last five years. Not only do I use it for about 95% of the posterior restorations in my practice, but I lecture on it quite a bit. With this I get asked quite often about the protocol for placing these restorations, and it always occurs like there is a “should”. So what is the “right” answer for placing e.max restorations. One of the incredible advantages to e.max is it’s versatility and when it comes to placing the material, this is both a bonus and the basis of some confusion. I like to think of the options based on the type of restoration.
Self-Etching Self-Priming resin cements, better known as “cem’s”, are a very popular option for placing indirect restorations. Dentists have jumped on board with this category of cement because of it’s many advantages. One of the major advantages is ease of use. The original packaging is a capsule that is activated and then mixed in an automatic mixer similar to a triturator. Newer versions of these cements come in syringe like dispenser with automixing tips. These cements are known for low post operative sensitivity, and their translucency makes them perfect for seating all ceramic crowns where esthetics are paramount. Clean up can be accomplished easily if we get the cement in the early stages prior to final set.
I love to let my patients have the opportunity to see their final restorations prior to final cementation, In addition to evaluating the esthetics it is important to floss the contacts and adjust the occlusion if the material allows. These can be difficult and awkward procedures with multiple restorations prior to cementation. My gut flips over when one drops off and I have to struggle to retrieve it from the back of the patient’s mouth. A quick and easy solution when working with full coverage restorations is to use Mach II die silicone as a try-in cement. Place a tiny drop of the Mach II in the crown and then seat on the teeth. The die silicone sets very quickly and holds the crowns in place so you can sit the patient up and they can admire their new smile in a mirror.
I often use Fynal, a temporary cement by Caulk, to place my full coverage provisionals. One of the challenges with the material is the bright white color. When the provisionals are of adequate thickness or they are posterior and esthetics is less critical this can be easily overlooked. In the anterior patients have been bothered by the white line at the margins, and show through at the cervical where the material is thin. I have also had situations where in a 1mm reduction prep on maxillary anterior teeth the white color can make the provisionals too high in value.
Recently I learned a way to correct for this in clinical situations where it is an issue.