If you want to show the data in the drop down based on the material provided in the edit box you must make an online request to get the data based on the material right. For that what I am suggesting is going for a menu item or button to pass the material entered as an input.
The other solution will be writing your own custom code in custom.js file. In that case I haven't seen any example on automatically triggering online request our user completes his text in edit box. But you can try it.
- Midhun VP