I lacked proper dental hygiene when I was young, so I paid for it (in pain and money) in my 20s. I now have dental PTSD, and cannot STAND the thought of a dentist, so I take immaculate care of my teeth. Brush 3-4 times per day, and floss at least twice. But my secret weapon is h2o2; I dilute it myself from 29% down to about 5-6%, and swish it around in my mouth for at least 3 minutes. Then I use an electric toothbrush to brush while the peroxide is still in my mouth. There is not a millimeter of space even between my teeth, that doesn't get power-washed this way. I smoke and drink coffee, but my teeth are blazingly white, people always do a double-take. If I could apply this neurotic obsession to anything else productive, I'd be a fucking millionaire by now...