Embryology

Question 1

Neural crest cells develop from ________. Name some structures that neural crests are responsible for forming.

Answer 1

1) ectoderm on the lateral border of the neural plate. 2) bone, cartilage, dentin, dermis (not enamel)

Question 2

Dental lamina begins formation at _______ embryonic age.

Answer 2

6 weeks

Question 3

From what structure does dental lamina form?

Answer 3

basal layer of oral epithelium

Question 4

What structures form from dental lamina?

Answer 4

tooth buds

Question 5

At what age does the permanent first molar begin initiation? At what age does the permanent 2nd molar begin initiation?

Answer 5

1) 16 weeks in utero 2) 4-5 years

Question 6

Name the components of the tooth bud.

Answer 6

enamel organ, dental papilla, dental sac

Question 7

Name the components of the enamel organ.

Answer 7

Inner enamel epithelium (concavity), outer enamel epithelium (convexity), stellate reticulum (center)

Question 8

The dental papilla forms from ________.

Answer 8

neural crest

Question 9

Name the stages of tooth development in order.

Answer 9

Bud stage, cap stage, bell stage, advanced bell stage

Question 10

Hertwig’s epithelial root sheath is composed of what structures?

Answer 10

inner and outer enamel epithelia (not stratum intermedium or stellate reticulum)

Question 11

The remnants of Hertwig’s root sheath persist as _____.

Answer 11

rests of Malassez

Question 12

Problems in the initiation stage of tooth development lead to anomalies of __________.

Answer 12

Tooth number

Question 13

Problems in the proliferation stage of tooth development lead to anomalies of __________.

Answer 13

size, proportion, number, twinning

Question 14

Problems in the histodifferentiation stage of tooth development lead to anomalies of ____________.

Answer 14

anomalies of enamel and dentin (enamel hypoplasia, AI, DI, DD)

Question 15

Problems in the morphodifferentiation stage of tooth development lead to _____________.

Answer 15

Anomalies of enamel, dentin, and cementum

Question 16

Is hyperdontia more common in males or females?

Answer 16

males (2:1)

Question 17

Is hyperdontia more common in primary or permanent dentition?

Answer 17

permanent dentition (5:1)

Question 18

Is hyperdontia more common in the maxilla or the mandible?

Answer 18

maxilla (9:1)

Question 19

Name the most common teeth affected by hypodontia in order of frequency.

Answer 19

3rd molars, mandibular 2nd premolar, maxillary lateral, maxillary 2nd premolar

Question 20

Name (9) syndromes associated with hyperdontia.

Answer 20

Apert’s, cleidocranial dysplasia, Gardner syndrome, Crouzon syndrome, Sturge-Weber syndrome, Orofaciodigital syndrome I, Hallerman-Strieff syndrome, cleft lip and palate, Down syndrome

Question 21

Describe features of Apert Syndrome.

Answer 21

supernumerary teeth, cleft palate, delayed/ectopic eruption, shovel shaped incisors, hypoplastic midface, syndactyly, craniosynostosis, hypertelorism, class III with anterior openbite, crowded dentition

Question 22

Is gemination more common in the primary or permanent dentition?

Answer 22

Primary

Question 23

Describe twinning.

Answer 23

Complete cleavage of a single tooth bud which results in a supernumerary mirror image tooth.

Question 24

What is the cause of taurodontism?

Answer 24

failure of normal invagination of Hertwig’s epithelial root sheath

Question 25

Name 6 diseases associated with taurodontism.

Answer 25

Klinefelter syndrome, tricho-dento-osseous syndrome, Mohr syndrome (aka orofaciodigital syndrome II), ectodermal dysplasia, Down syndrome, amelogenesis imperfecta type IV

Question 26

The most common type of amelogenesis imperfecta is :

Answer 26

type I- hypoplastic

Question 27

What type of amelogenesis imperfecta is associated with taurodontism?

Answer 27

AI type IV with taurodontism (hypomaturation-hypoplastic)

Question 28

Dentinogenesis imperfecta is a defect of what structure?

Answer 28

Predentin matrix (normal mantle dentin)

Question 29

Which type of Dentinogenesis imperfecta occurs along with osteogenesis imperfecta?

Answer 29

Shields Type I

Question 30

Describe Shields Type I dentinogenesis imperfecta.

Answer 30

Occurs with osteogenesis imperfecta, primary teeth more severely affected, permanent first molars and central incisors most often affected, amber translucence, periapical radiolucencies without caries, autosomal dominant, rapid attrition

Question 31

Describe Shields type II dentinogenesis imperfecta

Answer 31

no OI, hereditary opalescent dentin, both primary and permanent dentitions equally affected, periapical radiolucencies, rapid attrition, pulp chamber obliteration, autosomal dominant

Question 32

Describe Shields Type III dentinogenesis imperfecta.

Answer 32

“bell-shaped crowns, ““shell teeth””, short roots, enlarged pulp chambers, enamel pitting, rare, pulp exposures”

Question 33

What type of osteogenesis imperfecta is the most common?

Answer 33

OI type I

Question 34

What type of osteogenesis imperfecta is lethal in the perinatal period?

Answer 34

OI type II

Question 35

What types of amelogenesis imperfecta are most commonly associated with dentinogenesis imperfecta?

Answer 35

Types III and IV

Question 36

Describe the features of osteogenesis imperfecta.

Answer 36

bone fractures, bowing of legs, blue sclera, bitemporal bossing, loose ligaments, impaired hearing, macrocephaly, autosomal dominant, may be treated with bisphosponates, capillary fragility, cardiac defects

Question 37

Name some systemic causes of acquired enamel hypoplasia.

Answer 37

Deficient vitamin A, C, D, calcium, phosphate; infection of rubella, syphilis, cytomegalovirus, radiation, fluorosis, Celiac disease

Question 38

Names of syndromes associated with acquired enamel hypoplasia.

Answer 38

Down syndrome, tuberous sclerosis, epidermolysis bullosa, Hurler syndrome, Hunter syndrome, Treacher-Collins syndrome, hypoparathyroidism, tricho-dento-osseous syndrome, Vitamin D-dependent rickets, Lesch-Nyhan syndrome, Fanconi syndrome, Sturge-Weber syndrome, Turner syndrome

Question 39

Describe Shields type I dentin dysplasia.

Answer 39

normal color, short roots or rootless, pulp obliteration, severe mobility, autosomal dominant

Question 40

Describe Shields type II dentin dysplasia.

Answer 40

primary teeth affected, amber-colored teeth, permanent teeth look normal but radiographically demonstrate thistle-tube shaped pulps with multiple pulp stones;

Question 41

Describe regional odontodysplasia.

Answer 41

”"”ghost teeth””, thin enamel, diffuse shell appearance, both dentitions affected”

Question 42

Describe vitamin D-resistant rickets.

Answer 42

hypophosphatemic rickets, hypomineralized dentin, enlarged pulp and pulp horns