My blog on removing the air inhibited layer that occurs when resin sets, created a number of questions regarding a technique called immediate dentin sealing. This technique, which is more prevalent in Europe then the US, can be incorporated as part of every indirect restorative procedure. The concept is to seal all of the freshly cut dentin as soon as you have the preparation complete. This sealing of the dentin prevents continued bacterial contamination or chemical intrusion from the temporary cement into the dentinal tubules. In addition formation of a hybrid layer and bond strengths are more effective prior to the dentin being contaminated, or the collagen matrix collapses as part of the impression process. Additionally, immediately sealing the dentin decreases the incidence of post operative sensitivity between the prep and cementation appointments. The theory behind immediate dentin sealing is to increase patient comfort by minimizing post op sensitivity, decrease the risk of post operative pulpal inflammation and death by minimizing contamination into the tubules, and increase bond strengths by creating the hybrid layer on freshly cut dentin.
Prepare the teeth as you would for any indirect restoration. If you need to place a core do so, and then refine and finish the prep. At this point you will follow the steps for your dentin adhesive, etching, priming and applying the resin. This process can be done with either total etch or self etch adhesives. Cure the dentin adhesive completely. The enamel margins need to be free of adhesive, so after curing, go back and refine and finish the margins. The entire prep will have a thin layer of uncured resin, the air inhibited layer, present. If left it can prevent the set of certain impression materials, and also cause bisacryl provisionals made directly in the mouth to bond to the adhesive layer. Remove this air inhibited layer with rubbing alcohol. Now impress and provisionalize as you normally would.
Impressions should be taken in this technique after the dentin is sealed, both so that the film thickness of the resin will not alter the fit of the restoration, and the physical effect of the impression hasn’t altered the dentin. When the patient returns for placement of the final restoration, remove the temporary and thoroughly clean the prep. This can be done with a prophy cup and pumice or a very light application of air abrasion with 50 micron aluminum oxide. Once the prep is clean follow your regular process for bonding or cementation.
Thanks for posting this.
I agree that open tubules is a potential hazard at the prep stage. I’ve dabbled with using dentin primer/bond at the prep stage with a few products and ended up settling on Super Seal, which seems to work quite well. Instead of a bond, it produces a calcium oxalate precipitate to occlude the tubules. No fussing with an air-inhibited layer, though using a bonded layer is probably more of a sure thing.
Do you use isopropyl alcohol or ethanol to remove that air-inhibited layer? The thought of using isopropyl intraorally concerns me.
Joe :)
Question? If when seating you want to bond the restoration into place (all-ceramic, etc)…Do you then follow the same bonding steps again? I would assume you do.
I have been using isopropyl alcohol to remove the oxygen-inhibited layer as well as powder from my CEREC preps for over a year now and have had absolutely no issue. I put the alcohol in a syringe and use a disposable (screw on) brush tip. I can control the amount of alcohol and I have the brush tip there to scrub the preparation as well.
Thanks again, Lee, for another great tip.
I have used both isopropyl and ethanol. I have found they work equally well, and I have not had any problems with either.
How about first ozone treating the tooth – this sterilises the dentine AND reduces sensitivity, then paint over either your resin bonding or a re-mineralising solution to kick start the re-mineralisation process (tooth serum, http://www.enlightensmiles.com) then go from there. I’ve been doing this for the past 15+ years. Results are live healthy teeth, zero sensitivity and no 2ndry decay almost irrespective of OH 4-5 years later. Also you can leave softened (read leathery here) decayed dentine as once ozone treated, it will re-mineralise so you maintain the strength of the stubs.. The published research is on http://www.the-o-zone.cc. regards, Julian Holmes
Thanks for this information. I have not used ozone treatment, and in truth don’t know much about it but will check it out.
Hi,
You’re absolutely correct to want to not leave the sticky oxygen inhibited layer BUT, if you use a thin layer of adhesive then further thin it by removing the inhibited layer (about 40 microns) you risk not sealing the hybrid layer adequately. This has led to the resin coating technique where either an additional layer of adhesive or aflowable composite are placed and cured before taking impressions. The other approach is to tack cure your adhesive, then place glycerin and cure through the glycerin. Use vaseline or chlorhexidine to prevent your temporaries adhering. At fit stage re-activate the adhesive as described, I don’t know of any resaearch about using pumice for that – Magne originally used airabrasion or a slow coarse diamond bur.
At the fit stage you can consider the adhesive as if it were enamel – so etch and adhesive only are required. The great benefit here is that you can then simultaneously cure your adhesive and the luting agent ensuring perfect seating. If you have a dentine margin then you need to use a dentine bonding agent but you really don’t want to cure it and risk the restoration not seating so use a dual cure such as all bond 3.