We use Xyliwhite, which is not specifically a kids' toothpaste, but my kids like it. Here are the ingredients:
Functional Ingredients: Xylitol (25%), Papain (whitening). Other Ingredients: Water, Hydrated Silica, Sorbitol, Glycerin, Sodium Bicarbonate, Cocamidopropyl Betaine, Carrageenan Gum (Chondrus crispus), Cassia Oil (Cinnamomum cassia) (Leaf), Tea Tree Oil (Melaleuca alternifolia) (Leaf), and Potassium Sorbate. Contains no: Fluoride.
So, it doesn't have sodium lauroyl sarcosinate (not that I know what that does or what it is).