Features and Structure of Tooth Enamel - Enamel is the hardest substance in the human body, composed of 96% minerals. - The primary mineral in enamel is hydroxyapatite, a crystalline calcium phosphate. - Enamel is formed on the tooth during development and does not contain blood vessels or nerves. - Remineralisation can repair some damage to enamel, but beyond a certain point, it cannot be repaired by the body. - Enamel varies in thickness and color, with yellowish teeth having a thin, translucent enamel and grayish teeth having a more opaque enamel. - Enamel is made up of tightly packed enamel rods, which are organised in a keyhole pattern. - The arrangement of crystallites within each enamel rod is complex, with different orientations in the head and tail of the rod. - Enamel rods are found in rows along the tooth, generally perpendicular to the underlying dentin. - Interrod enamel surrounds the enamel rods and has a similar composition. - Incremental lines called Striae of Retzius and Perikymata can be observed in mature enamel, indicating growth patterns.

Enamel Development and Composition - Enamel formation is part of the overall process of tooth development. - Enamel formation occurs after the establishment of dentin, through cells called ameloblasts. - Enamel forms at a rate of around 4μm per day, starting at the future location of cusps. - Enamel formation can be divided into the secretory stage and the maturation stage. - The secretory stage involves the formation of a partially mineralised enamel, while the maturation stage completes enamel mineralization. - Enamel is composed primarily of minerals, with water and organic material making up the rest. - Enamel does not contain collagen like other hard tissues. - Enamel contains unique classes of proteins called amelogenins and enamelins, which aid in enamel development. - Once mature, enamel is almost entirely without organic matter. - Enamel is avascular and does not have a nerve supply.

Strength and Properties of Enamel - Enamel is the hardest substance in the human body, ranking 5 on Mohs hardness scale. - Enamel is brittle due to its high mineral content. - Dentin, less mineralised and less brittle than enamel, provides support. - Enamel appears lighter than dentin or pulp on radiographs due to its higher density. - Enamel undergoes mineralization changes but is not renewed.

Enamel Destruction and Factors Affecting Enamel Destruction - Enamel cannot regenerate itself. - Enamel can be affected by decay or injury. - Enamel is covered by structures such as the Nasmyth membrane and acquired pellicle. - Enamel demineralizes in a process known as dental caries or cavities. - Tooth decay is caused by acids dissolving tooth enamel. - Fermentable carbohydrates are the main cause of tooth decay. - Bacteria in the mouth interact with sugars to form lactic acid, decreasing the pH. - Critical pH for enamel demineralization is generally accepted to be pH 5.5. - Tooth morphology makes deep grooves, pits, and fissures susceptible to decay. - Bruxism, tooth wear, and enamel fractures also contribute to enamel destruction.

Prevention, Maintenance, and Dental Procedures Related to Enamel - Oral hygiene is crucial for preventing tooth decay and maintaining enamel health. - Toothbrushes reduce dental biofilm and food particles on enamel. - In isolated societies without toothbrushes, alternative objects like sticks are used for teeth cleaning. - Regular dental check-ups and professional cleanings help maintain enamel health. - Proper diet and limiting sugar intake can also prevent enamel destruction. - Fluoride catalyzes diffusion of calcium and phosphate into tooth surface, aiding in remineralization. - Dental restorations involve removal of enamel. - Dental sealants prevent decay by 55% over 7 years. - Acid-etching techniques are used to bond restorations to teeth. - Tooth whitening attempts to lighten tooth color chemically or mechanically.