 [ Symptoms ] is it safe to be out in the sun all day if i am pregnant [ Disease ] the link between calcium as a child and the strength of adult teeth is not proven if your teeth are cracking it is probably the result of failing fillings the most important nutritional advice i can give you is to reduce the ph or acid content in your mouth and avoid soda which leaches the calcium from your body xylitol gum anti caries rinses and fluoride supplements will all harden your teeth and make them less susceptible to cavities