Tooth polishing This outermost fluoride rich layer of enamel is removed when tooth polishing is provided. The mineral components of saliva and polishing pastes containing fluoride can assist in remineralizing this outer layer. The enamel surface is strong enough to withstand repeated tooth polishing, but it should be avoided on newly erupted teeth, exposed root surfaces and areas of demineralization. If polishing does occur on these surfaces, fluoride therapy can minimize the risk of dental caries. Excessive pressure can lead to frictional heat that may cause pulpal discomfort or necrosis of the dental pulp. Surfaces of restorations may be damaged by conventional
Development of the nervous system intellectual disability. The mammalian central nervous system (CNS) is derived from the ectoderm—the outermost tissue layer—of the embryo. In the third week of human development the neuroectoderm appears and forms the neural plate along the dorsal side of the embryo. The neural plate is the source of the majority of neurons and glial cells of the CNS. A groove forms along the long axis of the neural plate and, by week four of development, the neural plate wraps in on itself to give rise to the neural tube, which is filled with cerebrospinal fluid (CSF). As the embryo develops, the