Why Buddhists generally uses OM?

In [wikipedia](https://en.wikipedia.org/wiki/Chandogya_Upanishad) i read: > The Chandogya Upanishad is ... one of the oldest Upanishads of Hinduism. > [It] opens with the recommendation that "let a man meditate on Om". It calls the syllable Om as udgitha (उद्गीथ, song, chant), and asserts that the significance of the syllable is thus: the essence of all beings is earth, the essence of earth is water, the essence of water are the plants, the essence of plants is man, the essence of man is speech, the essence of speech is the Rig Veda, the essence of the Rig Veda is the Sama Veda, and the essence of Sama Veda is the udgitha (song, Om). Its date is given as "8th to 6th century BCE" i.e. at least 100 years before Gautama. Now "Om" is also used in Buddhism. Is its use the same as in Hinduism? If you recite the OM, do you (or not) think it is connected to a Super Consciousness as described in the Vedanta? Is it difficult to describe the philosophical basis, if the practice is somehow derived from concepts and knowledge from a text whose date is from before Gautama?