Hegel's dialectics are more fully described as imminent critique, a method where one takes the internal logic of the object of analysis and takes it to its logical conclusion. This is done without bringing in external content or judgement. The point of this excercise is to show whether or not the object in question can stand on its own merit or not. Contradictions are a result of doing imminent critique. We see the internal forces inside an object that will eventually rip it apart. A contradiction is inherently Unstable (or meta-stable at best). No contradiction in the universe can last forever, not even the orbits of the celestial bodies.

Materialism: when hegel first made his imminent critique, it was about ideas evolving through human history. Marx changed it analysing physical and social systems. Mostly the latter, as science is usually more than sufficient to analyse the dynamics of the former.

More broadly speaking, materialism itself has a rich tradition. For most of history, materialist have had to fight against religion and superstition. Today, materialism's basic premises, that reality exists independently of humans, does not sound like it could possibly be used to justify Communism. This is largely because materialist ideas have spread rapidly through the 20th century, although the associated communist impulse that inevitably goes along with it has been suppressed by propaganda.