We all know the sure way to creating an ultralight backpack is to start light with minimalist pack, mat, bag and tent (under 10 pounds). Beyond that, the little things can add up; an ounce here and an ounce there can quickly become pounds on your back.
One of my recent finds for good trail oral hygiene and pack weight reduction, which eliminates the need for a tube of toothpaste, is the Archtech Toothpaste Tablet. See photo for size of a single tablet. You can buy 60 tablets from Amazon for $6.74. Maybe you even leave behind the brush and use your finger, further cutting your weight.
I bought a pack and tried them. They taste good. And, they seem to work.
Be light. Be safe. Be one with the pack.