Formation of the primary teeth begins in utero.
The mixed dentition, when primary teeth are being exfoliated and permanent teeth move in to take their places, occurs between the ages of 6 and 12 years. The average child has 20 primary teeth in place, and root resorption of the incisors has started as the developing permanent incisors move into position. The first permanent molars are partially erupted.
Mineralization of the permanent teeth starts at birth and continues into adolescence. Roots normally are completed by 3 years after eruption.
is a defect that occurs as a result of a disturbance in the formation of the organic enamel matrix.
Types and etiology for Enamel Hypoplasia:
- Hereditary. Enamel is partly or wholly missing. An example is amelogenesis imperfecta.
- Systemic (environmental). Factors that may contribute to enamel hypoplasia during tooth development include severe nutritional deficiency, particularly rickets; fever-producing diseases, such as measles, chickenpox, and scarlet fever; congenital syphilis; hypoparathyroidism; birth injury; prematurity; Rh hemolytic disease; fluorosis.
- Local. A single tooth can be affected; trauma or periapical inflammation about a primary tooth can injure the adjacent developing permanent tooth.
usually in the form of grooves or pits, appears in the enamel at a level corresponding with the stage of development of the teeth
______ and ______ are typical crown forms that result from congenital syphilis. The central incisors are narrowed at the incisal third, and the lateral incisors may be conical or peg-shaped.
Hutchinson’s incisors and mulberry molars (Crown forms of enamel hypoplasia)
- is the wearing away of a tooth as a result of tooth-to-tooth contact
- Location; May be found on occlusal, incisal, and proximal surfaces. Age factor. Increases with age (but not because of age) as bruxism continues over time. More attrition is seen in men than in women of comparable age.
- Etiology: Bruxism. Predisposing factors may be psychological, tension, or occlusal interferences. Usage. Wear of surfaces on each other. Predisposing factors may be coarse foods, chewing tobacco, or abrasive dusts associated with certain occupations.
- is the loss of tooth substance by a chemical process that does not involve known bacterial action.
- Occurrence: Location. Facial or lingual surfaces, depending on cause. Usually involves several teeth.
- Etiology: the lesions are caused by some form of chemical dissolution. Chronic vomiting. Acid of chronic vomiting affects lingual surfaces, particularly anterior teeth. Pregnancy. Eating disorder, such as bulimia. Extrinsic. Industrial: workers’ teeth can be exposed to atmospheric acids. Dietary: facial surfaces are most frequently affected. Carbonated beverages. Lemons or other citrus fruit sucked frequently. May be idiopathic (unknown).
- Appearance: smooth, shallow, hard, shiny (in contrast to dental caries, in which appearance is soft and discolored). Shape varies from shallow saucer-like depressions to deep wedge-shaped grooves; margins are not sharply demarcated. May progress to involve the dentin and stimulate secondary dentin. May occur in combination with dental caries, calculus, or dental restorations.