Are microhybrid composites the best for posterior restorations in terms of strength?

Microhybrids are strong, but nano-filled composites are also very strong. Because they are smaller, nano-particles are able to be more densely packed, thus making the resin matrix, which is the weaker link, less dense lower in volume. Also, microhybrid filler particles, and  nano-particles are silanated, which enhances the bond between the filler and the resin matrix. These features all add to the strength of the final restorative material. Nano-filled composites often attain a smoother finish and higher gloss when polished.