Dashicons and my old wordpress icons are conflicts

Hello,

Before there are are was no dash icons I was able to replace default wordpress icons with mine like the one on top right of adminbar. On 3.8 dashicons are not allows me to make such modifications. I can`t rewrite default CSS of wordpress because it in not image but text.

So please explain me how can I replace default wordpress admin bar dashicons.

Thanks in advance.
Regards,
Turkel.