Put simply, it is a way of dealing with deep subgingival margins. It is not so much revolutionary in its technique, more mould-breaking in the approach it takes. Basically it involves placing a deep (usually metal) matrix onto the subgingival margin to control the material being used and the moisture from bleeding and crevicular exudates. Purpose-made bands are starting to appear but any band which creates a tight seal can be used. I tend to use a Tofflemire band with a “bulge” to reach the deepest part of the margin.
This is where things get uncomfortable (for those as old as me anyway!). The margin is restored with bonded composite to above gingival level then the rest of the cavity is temporised and the patient sent away for a couple of weeks. When they return, the temporary is removed and the cavity prepped for the definitive restoration (possibly an E-max inlay) with a supragingival margin. So effectively there are 2 margins, one on top of the other.
I have found this to be a very effective approach but the devil is in the detail. You have to have plenty of time because time is the best haemostatic I have found. I place the band, very tight and wedged if possible, though there is no point wedging if you can’t get the edge of the wedge down below marginal level. Then I put a pledget of cotton wool into the deep area of the cavity, flood it with water and wait. The moisture avoids clotted blood sticking to the margin which then has to be blasted away with the 3-in-1 starting the bleeding again. When I remove the cotton wool, if there is any sign of bleeding, I replace it, and wait again. Once I am sure the bleeding is stopped, it is just a matter of GENTLY irrigating and drying the cavity. Then I use a universal bonding agent, usually All-Bond Universal from Bisco (no connection, no freebies!!) and restore up to supragingival level with a low-shrinkage flowable composite, SDR from Dentsply (still no freebies!!!).
This simplifies technique works well by cutting out steps which can lead to errors and by using the technology we have available. I usually restore the resulting “shallower” cavity with direct composite using a sectional matrix to provide a better contact point and contour.
The 2-step approach may seem time-consuming but I find it a much calmer and controlled process. Restoring subgingival restorations are always going to be close to the edge of what we can achieve with any predictability but this method cuts out some of the uncertainty.