DIS Comment: Packable composites were introduced to the market as substitutes for amalgam in
the posterior dentition. They were claimed to handle more like amalgam and to be packable, which
made it easier to establish an acceptable proximal contact. The manufacturers of these products
claim that their physical properties and handling characteristics are better than those of
traditional hybrids and microfills. They purportedly have larger filler particles, higher filler loading,
and different shapes and types of filler particles. If true, one would expert that their fracture
toughness (their ability to resist failure from crack propagation) should be better than that of
traditional composites because their filler particles should make it harder for cracks to move
through the resin. This was not the consistent finding of this study, however. The packable
composite with chopped microfibers as fillers, Alert, did perform significantly better than the
others, but Solitaire performed worse. This shows that at least this physical property varies widely
across the class of packables. Perhaps most surprisingly is that the indirect composite,
Belleglass, did not perform better. One would expect that it would because it is processed using
heat and pressure, which should make it more highly cured. DIS has found, and others have
confirmed, that the physical properties of packables are generally no better than those of hybrid
resin composites. It is also important to note that none can be cured to the 5-mm depth that their
manufacturers claim, and they tend to be more expensive than traditional resin composites.
Perhaps the main reason to use one is because they tend to resist packing better than traditional
composites, so it is easier to establish a good proximal contact.