As mentioned in Part I and Part II of this series, an easy way to transfer the esthetics and occlusion from the diagnostic wax-up to the mouth is to use the "eggshell" provisional technique. In Part II I discussed trimming the provisional to ensure it is seated correctly.
Once you have confirmed that the shell seats properly, it can now be prepared for relining. First, the exterior of the shell should be air abraded. This will help assure that you will not see the junction between the original shell and the reline material when completed.
Prior to relining, paint the entire internal and external 1/3 with your dentin adhesive of choice and light cure. Next, paint another light layer of dentin adhesive, but leave this second coat uncured. This will act as a "wetting agent" and will be cured after relining to help bond the materials together.
The shell is now ready to be re-lined over the preps. Apply a light layer of Vaseline over the preparations to help prevent sticking to the teeth, load the provisional shell, and seat it over the preps. If you are only doing one arch, the opposing occlusion can also be used to help seat the provisional in the re-line process. As the reline material goes through it's initial set, you can start to cure the intermediate layer of adhesive. In addition, you'll want to use hemostats to unseat and reseat the provisional to assure you don't lock it on. Once the material has set adequately, the shell can be removed from the mouth. Prior to trimming I will place the shell in a light cure oven to fully polymerize the dentin adhesive and help complete the cross polymerization. After this step, the shell is thoroughly cleaned with alcohol to remove the air-inhibited layer followed by trimming.
Although this technique does take some time in the lab to fabricate the shell, the amount of time you save in the clinic will more than outweigh the time and cost associated with the initial fabrication.