But, did you know that MILK is good for teeth as well? Not just growing teeth, but in dental trauma, it is best to STORE a tooth in a sealed baggie of milk when a tooth is knocked out of its socket (an avulsion injury). Why milk? Milk is a good medium for teeth because cells from the root surface don’t swell up and burst. This CAN occur when placed in water. The proteins in milk keep a constant acid-to-alkaline ratio, anti-bacterial substances, as well as sugars to keep cells growing.