There are still rumblings in some quarters about how composite resin restorations don't work very well, don't last very long, and get all kinds of recurrent cavities underneath them.
First of all, it's dental amalgam (which dates from at least 1833 in the U.S.) which fails from the inside out. Composite resins usually have the excellent feature that if they fail, it's from the outside in. They give us notice.
More on dental amalgam here, if interested:
Composite resins can be extraordinarily successful if the enamel and dentin are treated properly. For back teeth, this requires the use of self-etching primers, careful placement of flowable composites as first layers that intimately adapt to the dentin, placing increments of the main composite so as not to let curing stresses pull the materials away from the surrounding tooth structure, and finally a great wedging and contouring system.
Let's look at a practical example.
These three restorations were placed six years ago, in 2007. For various reasons my patient has not elected to restore the center tooth with a crown, which, speaking ideally, is indicated. The support pins show at the surface intentionally, because the material is less likely to break that way, at least according to one study.
Six years. No recurrent decay, no symptoms, no root canal necessary, reasonable wear of the restoration surface. And yes, a sample size of one is merely anecdotal evidence. So I read the literature and also watch hundreds, perhaps thousands, of these restorations year after year in my practice and can never blame problems directly on the materials themselves. It's either me, or the patient if they have poor oral hygiene and excessive sugar intake in their diet. Even then, if there are new cavities, they form beyond the composite resin restoration, on the root surface.
The materials we used were:
Bonding agent: SE Bond
Flowable composite Resin: Flow-It
Composite Resin: Heliomolar
Matrix: Bitine Ring
This system works because the best self-etching primers work. I'd only use two brands as of 2012: SE Bond from Kuraray and Prelude SE from Danville Engineering. These two products minimize problems including transudation issues, which means water moving up from the dentin in the tooth and pushing bubbles into the resin-tooth interface, weakening the bond. This is kept to an absolute minimum with these two products.
Thus, so far as I can tell, in practical terms, this restoration is as fine at the five year point as it was when I placed it.