There are two schools of thought about dentin adhesive when seating indirect restorations. One school of thought treats the technique much like a direct resin and places and cures the dentin adhesive prior to placing the final restoration. The other group leaves the dentin adhesive uncured until after the restoration is placed and the resin cement is in place. Most manufacturers recommend curing the dentin adhesive layer, so why did the other technique develop?
All dentin adhesives have a film thickness when cured, and in some of the fourth generation total etch systems even with air drying the resin and thinning it is a significant thickness. The technique came about of leaving the dentin adhesive uncured until after placement of the restoration to avoid open margins and a resin interface that was larger and could stain and break down more easily. Many of today’s dentin adhesives have much lower film thicknesses, however even with air drying and thinning a small amount of pooling could create an open margin. Unless you know the film thickness of the particular material you are using, and are willing to confirm this if you decide to switch dentin adhesives it is most predictable to leave the material uncured. In this technique you are now depending on the penetration of light all the way to the dentin adhesive layer for adequate curing.
In posterior restorations such as inlays and onlays light penetration to the depth of the restoration can be a concern so utilizing a dual cure resin cement system will be required. One note is that when you utilize a dual cure resin cement you either need to make sure that the dentin adhesive system is compatible.
Hi Lee. I agree totally that we have to worry about film thickness of the adhesive, especially with 4th generation systems (which are still the gold standard by which other systems are measured). However, curing the resin cement and adhesive can come at a price. It may not be a big deal and should work fine to cure both concomitantly when the prep is mostly in enamel. BUT, when a large part of the prep is in dentin (not the ideal situation), if we don’t pre-cure the adhesive then we risk a significant drop off of bond strength if we just cure everything all at once.
Barry,
I have heard that before and would love to read more about it, any references or authors you could direct me to?
Lee
Lee,
Thank you so much for your wonderful posts.
There is a third school of thought (Immediate Dentin Sealing), which advocates placing the dentin bonding agent/adhesive at the prep appointment before the final impression. Placing bonding agent on freshly cut tooth provides the best bond strengths, any pooling of DBA is captured in the impression so it won’t prevent complete seating of the restoration, and the final restoration can be seated before curing, provided there is adequate translucency. As Barry mentioned, 4th generation bonding systems should have a THIN film of adhesive resin cured over the primed dentin, so as to fully impregnate the collagen/tubule network with resin before stressing them with the higher contraction forces that happen with a thick layer of composite or adhering a restoration. There is a great article about this somewhere.. It’s probably because I used to do it totally wrong I remember it as well as I do.
Challenges to IDS include how to NOT bond your provisionals in place, and polyether impression material reportedly bonds to tooth structure even after removing the oxygen inhibited layer…
Pascal Magne has several great articles and a book about this.
Warm Regards,
Michael E Martin DDS
Seattle
Michael,
Thanks for addressing this immediate dentin sealing is a viable alternative technique. I wrote a ost on it a few months back and addressed some of the challenges you mentioned.
https://leeannbrady.com/restorative-dentistry/immediate-dentin-sealing
Lee