Teeth and oral hygiene! I've already written a huge piece on fluoride (and how we should avoid it like the plague!), and I always repeat that the health of your teeth is directly linked to the health of your gut and your microbiome. Because the mouth is an integral part of your GI system. So the bad and good bacteria in your intestines affect the bacteria residing in your mouth and your teeth.
Obviously, your diet is key as well, that's self-explanatory - processed sugars, sparkling sodas, preservatives, toxic substances, etc, all upset your oral flora and your teeth's enamel, apart from defining your gut's flora.
Amalgam ("silver") fillings emit mercury vapors every time you chew or ingest hot/cold substances, I have also written on that topic before, but in this case oral health is the least of your worries, unfortunately.
So when it comes to things that are useful for maintenance and remineralisation, the right toothpaste and mouthwash are a big deal. Both need to have ONLY natural preferably organic ingredients, and a good option are products based on activated charcoal as they are not only mineral but also whiten your teeth naturally. Yes, BLACK charcoal WHITENS your teeth.
Coconut oil is amazing both for toothpastes and mouthwashes, and oil pulling, for its antibacterial and antiinflamatorios properties.
Cinnamon is also a strong anti-inflammation spice, and so is clove.
Things like SLS, parabens and glycerine. Have no place in your mouth, the latter being a direct cause of increase in cavity formation.
A note of warning must be given to the use of sodium bicarbonate and hydrogen peroxide. In principle - they can be ok for use on teeth, BUT not if you have amalgams. These substances react with mercury in the filling and increase the rate of its release causing a stronger intoxication of the body.