Many of us have a routine of making the provisional prior to taking the final impression. It's a sequencing zone of comfort for some, while others like to check their reduction by looking for thin areas on their provisional. I routinely prefer to do it this way when prepping a veneer case.

There is an inherent problem with this IF you use bisacryl provisional material. This type of material leaves behind an uncured resin coating that will stick to your preps. When you impress, this coating interacts with the VPS material and doesn't allow for an accurate set of the material.

If you ever had an impression or working cast look like this and wondered why, it's most likely that there was a contaminant on your preps.

It's really easy to clean this off and I routinely clean my preps before impressing with either hydrogen peroxide in a syringe with an infusa-tip or with 91 percent isopropyl alcohol in the same kind of syringe. I use the alcohol when I want to clean any remaining uncured resin on preps.

After cleaning the preps with this, I rinse with water and blot dry. It is an extra step in the process but beats having to re-impress—by a mile.

Mary Anne Salcetti, DDS, PC, Spear Education Visiting Faculty. [ ]