Caesar never says "hegel" used it. It is called as Hegelian dialectics. "Hegelian Triad" to be more specific. Hegel's own dialectics can be described as "synthesis of opposites". Dialectics go back to Plato, and Hegel studied Kant as well.

"synthesis of opposites" or "synthesis of contradictions" is a characteristic of Hegel. He didn't use the traditional triad, because he thought it was very mathematical. A formula. "thesis-antithesis-synthesis" was too robotic and was a literal formula for Hegel. He argued against it, and criticized Fichte. Still, he was influenced by Fichte in his works, and Fichte helped him to move beyond Kantian dialectics. Still, this is called as "Hegelian Dialectics.", and the triad is associated with him. I am sorry for anyone who opens "Dialectics" wikipedia page, and read the paragraph of "Hegel never used thesis-antithesis-synthesis". Sorry guys, you are not philosophy major after reading it.

After Hegel, people studied Hegel's Dialectics, and it became "Hegelian Dialectic", not "Hegel's dialectic". There are many Marxists in the world right now that are for example "neo marxists". They take Marx as basis, but don't accept it as a whole, or they take it totally different. Still, those ideas are considered and coined as Marxist ideas. There were Caesarians after Jul Caesar's death, but they were a faction defending Jul Caesar and his legacy. The examples can go on. "-ian" often means influenced by. It is like an "-ism".