I take excellent care of my teeth. I floss daily, brush 2 -3x daily, change my toothbrush often, avoid dark colas and coffee and staining foods like blueberries, and I use Biotene mouthwash (the label says it "brings out the natural whiteness of teeth.") but still my teeth looking super dull lately and not nearly as white as they used to be. I am 35 now, but is there anything other than age that could be contributing to the "aging" look to my teeth? I can't afford in-office whitening; even though it's much cheaper than it used to be it still costs hundreds of dollars. Do any of those over the counter products really work? I've tried Crest Whitestrips before and they didn't really make any noticeable change.