Human tooth development the low levels of fluoride incorporation and very mild fluorosis makes the tooth more resistant to demineralization and subsequent decay. Deficiencies of nutrients can have a wide range of effects on tooth development. In situations where calcium, phosphorus, and vitamin D are deficient, the hard structures of a tooth may be less mineralized. A lack of vitamin A can cause a reduction in the amount of enamel formation. Fluoride ingestion has been noted to delay eruption of teeth for as much as a year or more from the accepted eruption dates since the initial 1940s fluoridation trials. Researchers theorize that
Eggshell the uterus. The egg can take up fluids and grow in size during this process, and the final, most rigid layer is not added until the egg is full-size. Hatching birds, amphibian and egg-laying reptiles have an egg-tooth used to start an exit hole in the hard eggshell. Eggshell waste is fundamentally composed of calcium carbonate, and has the potential to be used as raw material in the production of lime. Eggshell An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats. Insects and other arthropods lay a variety of