There is another matter to consider - the zinc content of the fixative. A couple of years ago, Poligrip was withdrawn from the market due the zinc content being suspected of causing joint/muscle pain in users. It was reformulated and relaunched without a zinc content some months later, (with the phrase "zinf free" on the tubes) but does not achieve the holding quality of the previous product.
Fixodent still contains zinc, and the cartons/tubes contain advice about excessive usage causing problems referred to above.