Enamel Flashcards
Color of enamel?
White to grayish white
Translucent
% of mineralization of enamel?
96-98%
True or false. After eruption, enamel increases density?
True
True or false. After eruption, enamel becomes less permeable?
True
Substances that enamel allow to flow through? (2)
- Water
- Alcohol
Texture of enamel?
Smooth and glossy
Specific gravity of enamel?
2.8
Chemical formula of hydroxyapatite?
CaPO4
Fluorine and chlorine can be substituted for OH groups
Organic content of enamel?
Enamel proteins (2-4%)
Enamel proteins are collagenous or non-collagenous?
Non-collagenous
Loss of function of amelogenin would cause?
Thin enamel without enamel rods
It inhibits lateral growth of hydroxyapatite?
%?
Amelogenins; 90%
Hydrophobic proteins rich in proline, histidine and glutamine?
Amelogenin
Enamel protein found mostly in newly formed enamel?
Ameloblastin
Loss of ameloblastin would cause?
- Terminal branching
- Detachment of ameloblast from dentin
- Amelogenesis aborts
Largest but least abundant enamel protein?
Enamelin
Fundamental organizational unit of enamel?
Enamel rods
Shape of immature enamel rods?
Hexagonal
General direction of enamel rods?
Perpendicular to DEJ
Direction of enamel rods under pits and fissure?
Tentlike
Direction of enamel rods in proximal?
Horizontal
Direction of enamel rods in cervical of deciduous teeth?

Coronally oblique
Direction of enamel rods cervical of permanent teeth?

Apically oblique
Its crystals are oriented in a different direction from enamel rod?
Interrod enamel
Accounts for the fish scale appearance?

Enamel rod sheath
True or false. Enamel rod sheath contains more inorganic material than enamel rod and interrod enamel?
False.
Enamel rod sheath is more organic
True or false. Enamel rod sheath are more acid resistant.
True
True or false. Enamel rod sheath covers the entire rod.

False
Incremental lines of enamel?

Striae of Retzius
Striae of Retzius run from the DEJ in an ________ direction to the occlusal surface.
Oblique
Shape of striae of retzius over the dentinal core?

Horseshoe shaped
In cross section, striae of retzius appears as?
Concentric rings
It marks the birth of individual, characterized by a darker and more obvious line?
Neonatal line
Alternating constrictions and expansions of the rods
Transverse striations
Marks the daily apposition of enamel
Transverse striations
Marks weekly apposition of enamel?
Striae of retzius
Optical phenomenon due to the change in direction of enamel rods?

Bands of Hunter-Schregger
These are enamel rods cut transversely perpendicular to their long axes
Diazones
Enamel rods that are parallel to their long axes
Parazones
Dark bands?
Diazones
Light bands?
Parazones
These are avenues for the lateral spread of caries at the DEJ?

Enamel tufts
Hypomineralized enamel from the DEJ?
Enamel tufts
True or false. Enamel tufts increase as we age.
False
It occurs developmentally due to the abrupt changes in the direction of group of rods
Enamel tufts
Cracks on the surface of enamel

Enamel lamella
Short straight dark structures extending for short distances into enamel?
Enamel spindle
Formed when the odontoblastic process extend across the DEJ
Enamel spindle
Causes hypersensitivity along the DEJ
Enamel spindle
Where can you mostly find enamel spindles?
Cusp tips
Intertwining of groups of enamel rods following a curving irregular path toward the tooth surface?

Gnarled enamel
True of false. Gnarled enamel makes enamel stronger.
True
Scalloped in cross section
DEJ
Area where you can find bigger scalloping of DEJ?
Cervical area
Increases the attachment of enamel to dentin?
Scalloped DEJ
Process of enamel formation
Amelogenesis
What induces amelogenesis?
Deposition of dentin
Stages of amelogenesis. (4)
- Presecretory stage
- Secretory phase
- Maturation stage
- Protective stage
Phases of presecretory stage?
- Morphogenic phase
- Differentiation phase
Formed during morphogenic phase?
Membrana preformativa
It determines the form and shape of the crown?
Membrana preformativa
True or false. Membrana preformativa is removed after deposition of enamel matrix.
False
*Before deposition of enamel
Part of ameloblast that penetrates into the enamel?
Tome’s process
What stage: Crystals grow in length and diameter.
Maturation stage
It allows incorporation of inorganic material to the enamel?

Ruffled ended ameloblast
Ruffled ended ameloblasts occurs __% of time.
80%
It permits exit of protein fragment and water from enamel?

Smooth ended ameloblasts
Smooth ended ameloblasts occurs __% of time.
20%
It marks the partial mineralization of enamel as the matrix reach a certain thickness?
Striae of retzius
Marks the weekly apposition, remember?
% of mineralization that occurs in primary calcification?
25-30%
Deposition of the rest of the enamel content?
Secondary calcification
True or false. When enamel first forms, it is only partially mineralized.
True
True or false. As enamel is exposed to the oral cavity, it becomes more mineralized.
True
What stage: Laying down of primary enamel cuticle
Protective stage
Another term for primary enamel cuticle.

Nasmyth’s membrane
What stage: Ameloblasts become low cells and become part of reduced enamel epithelium
Protective stage
Loss of tooth structure by mechanical forces from opposing teeth
Attrition
Loss of tooth surface by mechanical forces from a foreign element?
Abrasion
Loss of tooth structure due to chemical dissolution by acids and not by bacterial origin?
Erosion
Incremental growth lines that appear on the surface of enamel?
Perikymata

Why can’t you find perikymata on cusp tips and incisal edges?
Because of horseshoe shaped striae of retzius found there
Three rounded protuberances present on the cutting edges of incisors when it first erupts?

Mamelons
True or false. Enamel is impermeable.
False. It is partially permeable
Part of tooth prone to caries?
Pits and fissure
Process of dental caries follows the direction of ____?
Enamel rods
True or false. Overhanging enamel must be removed during cavity preparation.
True
Application of topical fluoride (eg. Toothpaste)
Fluoridization
Addition of fluoride in drinking water?
Fluoridation
Enamel conditioning
Acid etching
It provides better bonding surface for restorative material?
Acid etching
True or false. Enamel is more mineralized at the surface than at the area next to dentin?
True