I found Dr. Gordon Christensen’s article "Resin Cements and Postoperative Sensitivity" (August JADA) very interesting, as usual. I noticed that several cement types expand as they set. Apparently, zinc phosphate cement is not worth mentioning, as no one seems to know why it worked so well for years. Only one lecturer I have heard still uses it.
What concerns me is the use of "die spacers," an enamellike red or blue (usually) hard "paint" used by labs to cover dies. I know a smooth die makes waxing easier, but how significant is its use? Have any studies been done to determine the optimal thickness to be used for today’s cements? To me, its use seems to decrease crown retention.
I get tired of seeing cementation kits continue to rise in cost, but I also question just how much better they really are in reducing sensitivity and keeping crowns retained. Is this "die spacer" necessary? Thank you.
