Curer et laver, ce n'est pas la même chose
Curer => remove bits of food that were stuck between your teeth, mostly using a toothpick.
Laver => wash, clean, : limpar... with a toothbrush / com a escova de dentes
Comme "se curer les ongles" => remove bits of dirt that are stuck under your nails, if you've been doing some gardening or cooking with your bare hands for examples. You can also use a toothpick or any sharp tool.
Se laver les ongles : with a brush or something...