Enamel Structure Clinical Considerations

Basic units of enamel, extending from the dentino-enamel junction (DEJ) to the enamel surface.

Boundary where enamel and dentin meet.

Enamel's structural units arranged in a pattern

Material surrounding enamel rods with crystals oriented differently.

Organic material separating enamel rods.

Enamel rods have a keyhole shape in transverse section, with a head directed towards the incisal or occlusal aspect and a tail towards the cervical region.

Each enamel rod is formed by four ameloblasts, each contributing to four different rods.

Enamel rods are built from long, ribbon-like apatite crystals that are closely packed.

Enamel rods have a length of 0.05-1 micrometer, an average thickness of 30 nanometers, and a width of 90 micrometers.

The hexagonal shape of enamel rods is due to the hexagonal symmetry of the calcium phosphate unit cell.

Enamel rods run in a tortuous course from the DEJ to the enamel surface. This course is oblique and wavy, with rods being longer than the enamel thickness.

Enamel rods are longer in the cusp region compared to the cervical region.

Each enamel rod is composed of segments separated by dark lines, giving it a striated appearance. The segments are about 4 micrometers in length.

An optical appearance of enamel characterized by irregular twists and intertwining, potentially associated with increased enamel strength.

Alternating zones of slightly different permeability and organic material content within enamel, extending from the dentino-enamel junction (DEJ) towards the outer enamel surface.

Growth lines within enamel representing rhythmic enamel deposition, appearing as dark lines extending from the DEJ towards the tooth surface.

Most Striae of Retzius form every 6-11 days. Some are believed to be caused by stress.

An accentuated incremental line of Retzius marking the boundary between prenatal and postnatal enamel development.

The DEJ is a unique interface where two distinct tissues with different properties meet, with enamel projections fitting into dentin depressions.

In sections, the DEJ appears as a scalloped line with the convexities directed towards the dentin.

Growth lines in enamel marking daily deposition cycles, visible as thin, dark lines.

Prominent growth lines in enamel marking the transition from pre-natal to post-natal development.

Grooves on the surface of the enamel that correspond to the incremental lines of Retzius.

A thin, protective layer covering newly erupted enamel, also called Nasmyth's membrane.

Leaf-like structures extending from the enamel surface towards the DEJ, often containing organic matter.

Small, spindle-shaped structures extending from the DEJ into the enamel, remnants of odontoblast processes.

Narrow, ribbon-like structures extending from the DEJ into enamel, often seen as tufts of grass in ground sections.

Enamel undergoes changes with age, including attrition, loss of perikymata, and reduced permeability.

The wearing down of tooth structure due to tooth-to-tooth contact during chewing.

The ability of fluids to pass through enamel.

Acidic substances like food, drinks, or swimming pool water can erode enamel.

Loss of enamel structure due to wear or erosion makes teeth more susceptible to cavities.

A technique used in dentistry to roughen enamel surfaces, allowing better bonding of dental materials.