I have heard that sunflower seeds damage the teeth and causes them to decay. is that right?

Perhaps in excess: Interesting question. If you eat shelled seeds and crack the shells in your mouth too frequently it might break down the enamel. See http://vegetarian.lovetoknow.com/Can_You_Eat_Too_Many_Sunflower_Seeds There's not much research on this. One study found "dried-roasted seeds" could lead to "tooth surface loss" but I could not find out if sunflower seeds were studied. See http://tinyurl.com/hxe6hwv