When Clearfil Protect Bond first came out, I wrote a review of the product. At the time, it was released as a product to stand alongside its gold-standard predecessor, Clearfil SE Bond. Early in 2010, Kuraray essentially combined the two names, and in doing so, "updated" both products to create Clearfil SE Protect.
Along with the name change, Kuraray's been releasing a ton of research about the product, supporting why they believe that Clearfil SE Protect is the new gold standard. Below are some of the highlights from scientific symposium I attended in Los Angeles with some of the top clinical researchers from Kuraray: Drs. Franklin Tay, Satoshi Imazato, and Junji Tagami. (All referenced articles are available from your Kuraray representative.)
The first point they covered was that most composite- based restorations last just under six years on average. They noted that after only 14 months, there was degradation of the collagen in the hybrid layer, essentially resulting in complete elimination of the dentin bond. This degradation is usually subclinical, since the enamel bond is what maintains the restoration. Dr. Tay's research discovered that there are actually enzymes in the dentin, call Matrix Metaloproteinase's, or MMP's. These enzymes are released when dentin is etched with phosphoric acid. Minerals are stripped from the collagen, and over time, MMP's chew the collagen into a gelatin. There are several things that can inhibit MMP's from causing that destruction, including the MDPB monomer present in Clearfil SE Protect . Plus, because it is a self-etching system and not washed away, the monomer itself is trapped in the hybrid layer to allow for long term suppression of MMP's.
The MDPB monomer is also antibacterial. Even with use of rubber dam, there will always be bacteria left in the preparation of the tooth. It works as a very rapid, wide-spectrum antibiotic. In other words, the simple step of brushing on the primer is disinfecting your cavity prep. This also helps to reduce inflammation in the pulp, even on deeper restorations.
The adhesive half of the Clearfil SE Protect system contains fluoride. This, combined with the more mild demineralization of a self-etching system, have had some interesting effects. Dr. Tagami has done some studies in which he takes a tooth with a restoration bonded in place with Clearfil SE Protect , sections it, and then tries to dissolve the tooth with a strong acid, and a strong base. What he was able to demonstrate is that the tooth structure below the bonded hybrid layer was resistant to acid/base attack. This means that the tooth structure below the restoration was actually harder than the original natural tooth. Dr. Tagami has research of this happening in dentin, and in enamel. How did other adhesive systems match up? There was some formation of the acid/base resistant layer with the classic Clearfil SE Bond, but not as deep as with Clearfil SE Protect. And for total-etch systems? There was no observation of this layer at all.
Six years later, I am happy that research has only further confirmed why I use this dental adhesive. I simply cannot remember the last time I had a patient with sensitivity after placing a composite. We even have used it successfully to eliminate root surface sensitivity. Kuraray has definitely done its homework, and continues to do so now. Check back here on Dentalcompare for updates as new research is completed from Kuraray.