Board Thread:The Panopticon/@comment-4028641-20151008023030/@comment-6032121-20191108161226

Nah, I don't think so. The very fact that a Time Lord doesn't understand it, combined with the description of what the Fountain does as "invigorating properties", make it clear that the Fountain isn't literally turning back time in any fashion, it's just healing magic/life-force/what-have-you.