Why scrub? Apply toothpaste, leave it overnight to give it time to work properly.
It's the 'grit" in the WHITE toothpaste that removes the silicone residue in the mask. Gently scrubbing the toothpaste with your fingers which acts as a mild abrasive is supposed to be the key to removing manufacturer residue. I'm not sure why leaving it overnight will do anything else but perhaps improve the aroma of the mask. Do your brush your teeth or leave the toothpaste in your mouth overnight?
I am going to do the toothpaste scrub 5-7 times more and see if that helps. I do appreciate the advice regarding lighters but I imagine that a careless mistake may rend the manufacturers warranty void. And this is one EXPENSIVE mask.