This is a question that frequently comes up in car forums. At first, it makes sense, toothpaste is supposed to clean away yellowing on your teeth, so it makes sense it might work on your headlights. While this is never something I have tried myself, most people who try this find that the results are only temporary. The toothpaste does not provide as much cutting power as sandpaper or polishing compound, nor does it provide any UV protection. Using toothpaste will probably improve the look of severely clouded headlights but remember this isn’t a full solution. Some people have found that adding a small amount of baking powder to toothpaste give more cutting power.