enamel essentials

Question 1

enamel location

Answer 1

crown

Question 2

color

Answer 2

yellow to grayish

Question 3

composition

Answer 3

96% mineralized inorganic substrates - hydroxyapatite (calcium phosphate); 4% organic substrates

Question 4

basic unit

Answer 4

enamel rod (prism)

Question 5

cross-section of enamel

Answer 5

keyhole

Question 6

enamel formation

Answer 6

amelogenesis; occurs from ameloblasts after dentin formation

Question 7

stages of amelogenesis

Answer 7

secretory stage - partially mineralized

maturation stage - completion of mineralization

Question 8

cleavage planes

Answer 8

created by rod orientation and crystalline structure

enamel fractures along cleavage planes from trauma or during tooth preparation

Question 9

striae of retzius

Answer 9

incremental growth lines seen in tooth enamel during amelogenesis (similar to tree growth rings)

disruptions during appositon can result in changes in enamel structure and appearance (for example malnutriton or high fever)

Question 10

neonatal line

Answer 10

dark stria of retzium occurs during stress of birth

Question 11

gnarled enamel

Answer 11

enamel at cusps of posterior teeth have a wavy patter; protect enamel from cleaving at cusp tips

Question 12

perikymata

Answer 12

at tooth surface straie of retzius overlap forming shallow grooves

Question 13

clinical implaction of DEJ

Answer 13

enamel gains structural strength being bound to dentin; in tooth preparations enamel will better survive with dentin support

Question 14

enamel spindles

Answer 14

short spindle-like sturctures that are ends of dentinal tubules trapped in enamel

Question 15

enamel tufts

Answer 15

hypocalcified enamel rods

Question 16

false enamel lamellae

Answer 16

cracks in enamel extending into dentin

Question 17

true enamel lamellae

Answer 17

rods that are poorly calcified or uncalcified due to developmental disturbances affecting the ameloblasts

Question 18

Hunter-Schreger Bands

Answer 18

inference that formation of enamel rods during amelogenesis increases fracture resistance of enamel

Question 19

diagnosis of fluorosis

Answer 19

differentiated from other conditions of teeth/enamel by the characteristic bilaterally symmetric distribution of the enamel defects

Question 20

enamel hypoplasia

Answer 20

disturbances in enamel formation/tooth development

enamel is hard but thin and deficient in the amount of enamel; tooth defects seen are pitting of the enamel; either a line of demarcation or a pit in areas of the enamel; can be related to high fevers, malnutrition (prenatal, postnatal) or slow enamel formaiton

Question 21

amelogenesis imperfecta

Answer 21

rare abnormal formation of enamel due to the malfunciton of the proteins in the enamel (ameloblastin, enamelin, tufteline, and amelogenin); genetic mutation; characterized depending on the enamel defect type

Question 22

proteins in the enamel

Answer 22

ameloblastin, enamelin, tuftelin, amelogenin