Tooth Development

Question 1

stages of tooth development

Answer 1

Initiation
Bud
Cap
Bell
Apposition
Maturation

Question 2

ondontogenesis

Answer 2

term used to describe tooth development

Question 3

what layers do teeth develop from?

Answer 3

teeth develop from two germ layers:
ectoderm-develops enamel
mesoderm-develops all other dental tissues

Question 4

initiation

Answer 4

first stage
6th-7th week
involves induction, which refers to the influence of neural crest cells on epithelial cells that cause them to proliferate (controlled growth and reproduction) and change shape (morphogenesis)
involves an initial signal from the ectoderm to the mesenchyme

Question 5

bud

Answer 5

second stage
8th week
involves proliferation
marked by growth of dental lamina into shape that resembles buds, with these oval masses penetrating into the surrounding ectomesenchyme.

Question 6

cap

Answer 6

third stage
9th-10th week
involves proliferation, differentiation of cells, morphogenesis.
primordium of tooth(tooth germ), containing each of the primordial types of tissue necessary to develop the future tooth.
tooth germ=enamel organ, dental papilla, dental sac formed.

Question 7

bell

Answer 7

fourth stage
11th-12th week
more cellular differentiation, proliferation, morphogenesis.
4 diff types of cells are now found within enamel organ: outer enamel epithelium, stellate reticulum, stratum intermedium, and inner enamel epithelium. now assumes 3D shape as the undersurface of the cap deepens.

Question 8

apposition

Answer 8

one of final stages
occurs at various times
involves induction and proliferation
the enamel, dentin, and cementum are secreted in successive layers. these hard dental tissue types are initially secreted as a matrix which is an extracellular substance that is partially mineralized.

Question 9

maturation

Answer 9

the final stage
occurs at various times
reached when the matrices of the hard dental tissue types subsequently fully mineralize to their correct levels.

Question 10

clinical considerations with initiation stage disturbances:

anodontia

Answer 10

lack of initiation within the dental lamina results in the absence of a single tooth or multiple teeth or entire dentition called anodontia.
partial anodontia is more common with 3rd molar, max lateral incisor, and mand 2nd premolar.
can also occur from endocrine dysfunction, systemic disease, and excess radiation.

Question 11

clinical considerations with initiation stage disturbances:
supernumerary teeth(hyperdontia)

Answer 11

these extra teeth are initiated from persisting clusters of dental lamina and have hereditary etiology. most common between max central incisors, distal to max 3rd molars, and in premolar region

Question 12

clinical considerations with bud stage disturbances:

Answer 12

abnormally large teeth=macrodontia, can occur with hyperpituitarism
abnormally small teeth=microdontia, common on the max lateral incisor(peg lateral), 3rd molar(peg molar).
complete microdontia rare but can occur with hypopituitarism or Down syndrome.

Question 13

enamel organ

Answer 13

formed during cap stage.
forms enamel.
formation of tooth bud in a cap shape with a deep central depression.

Question 14

dental papilla

Answer 14

formed during cap stage.
forms dentin and pulp.
condensed mass of ectomesenchyme within the concavity of the enamel organ.

Question 15

dental sac

Answer 15

formed during cap stage.
forms cementum, periodontal ligament, alveolar process.
condensed mass of ectomesenchyme surrounding outside of the enamel organ.

Question 16

succedaneous

Answer 16

permanent teeth formed with primary predecessors, include anterior teeth and premolars, which replace each primary anterior and molars. the crown of each permanent succedaneous tooth will erupt lingual to the root of its primary predecessor

Question 17

nonsuccedaneous

Answer 17

have no primary predecessors

Question 18

clinical considerations with cap stage disturbances:

dens in dente

Answer 18

enamel organ may abnormally invaginate by growth into the dental papilla, resulting in dens in dente, most commonly affected are max incisors. it produces enamel lined pocket extending from lingual surface, leaves tooth with deep lingual pit, may appear as tooth within a tooth on radiograph.

Question 19

clinical considerations with cap stage disturbances:

gemination

Answer 19

occurs as single tooth germ tries unsuccessfully to divide into two tooth germs, resulting in large single rooted tooth with a common enlarged pulp cavity, tooth exhibits twinning resulting in broader falsely macrodontic tooth, usually occurs in anteriors

Question 20

clinical considerations with cap stage disturbances:

fusion

Answer 20

results from union of two adjacent tooth germs, leads to falsely macrodontic tooth similar to gemination, however shows two distinct pulp cavities with the enamel, dentin, and pulp united, occurs most commonly with anteriors

Question 21

clinical considerations with cap stage disturbances:

tubercles

Answer 21

appear as small rounded enamel extensions forming extra cusps, noted on occlusal surface of permanent molars and lingual side of max anteriors, may be due to trauma, pressure or metabolic disease that affects the enamel organ as it forms the crown

Question 22

clinical considerations with apposition stage and maturation stage disturbances:

Answer 22

enamel dysplasia: faulty development of enamel, certain factors interfere with the metabolic processes of the ameloblasts, may result from trauma or infection, traumatic birth, nutritional deficiencies, dental fluorosis. can result in Hutchinson incisors, mulberry molars, hypocalcification which results in teeth that are more opaque, yellow, or brown.
amelogenesis imperfecta: teeth have very thin enamel that chips off or have no enamel at all. crowns are yellow because they are composed mainly of softer dentin and undergo extreme attrition.
dentin dysplasia: faulty development of dentin, can result from interference with metabolic processes of the odontoblasts during dentinogenesis, can be due to local or systemic factors.
dentinogenesis imperfecta: bluegray or brown teeth. enamel chips off because of a lack of support by the abnormal underlying dentin, severe attrition.

Question 23

root development

Answer 23

takes place long after crown is completely shaped and tooth is starting to erupt. the structure responsible for this is cervical loop: most cervical part of the enamel organ, a bilayer rim that consists of only IEE and OEE.

Question 24

ameloblast:

Answer 24

Cells that differentiate from preameloblasts and that will form enamel during
amelogenesis.

Question 25

apposition:

Answer 25

Layered formation of a firm or hard tissue such as cartilage, bone, enamel,
dentin, and cementum.

Question 26

bell stage:

Answer 26

Fourth stage of odontogenesis in which differentiation occurs to its furthest extent
and the enamel organ assume a bell shape.

Question 27

bud stage:

Answer 27

Second stage of odontogenesis with the growth of the dental lamina or buds into
the ectomesenchyme.

Question 28

cap stage:

Answer 28

Third stage of odontogenesis in which the tooth bud of the dental lamina grows
into a cap shape.

Question 29

cementoblasts:

Answer 29

Cells that form cementoid and are differentiated from the dental sac.

Question 30

cementocytes:

Answer 30

Cementoblasts entrapped by the cementum they produce.

Question 31

cementum:

Answer 31

Outermost layer of the root of the tooth.

Question 32

cervical loop:

Answer 32

Most cervical portion of the enamel organ that is responsible for root
formation.

Question 33

dental lamina:

Answer 33

Growth from the oral epithelium that gives rise to the tooth buds.

Question 34

dentinocemental junction:

Answer 34

Junction between the dentin and cementum during the formation
of the tooth root.

Question 35

dentinoenamel junction:

Answer 35

Junction between the dentin and enamel formed by mineralization
of the disintegrating basement membrane.

Question 36

enamel organ:

Answer 36

Cap or bell-shaped portion of the tooth germ that produces enamel

Question 37

epithelial rests of Malassez:

Answer 37

Groups of epithelial cells that persist in the periodontal ligament
after disintegration of Hertwig’s epithelial root sheath that can become cystic.

Question 38

Hertwig’s epithelial root sheath:

Answer 38

Portion of the cervical loop that functions to shape the

root(s) and induce dentin formation in the root area.

Question 39

initiation stage:

Answer 39

First stage of odontogenesis.

Question 40

Nasmyth’s membrane:

Answer 40

Residue on newly erupted teeth that may become extrinsically stained.

Question 41

nonsuccedaneous:

Answer 41

Permanent teeth without primary predecessors, namely molars.

Question 42

odontoblast:

Answer 42

Cells differentiated from outer cells of the dental papilla that synthesize and
secrete predentin.

Question 43

odontoblastic process:

Answer 43

Attached cellular extension of odontoblast within dentinal tubule.

Question 44

odontoclast:

Answer 44

Cell that resorbs dentin, cementum, and enamel.

Question 45

odontogenesis:

Answer 45

The process of tooth development

Question 46

preameloblasts:

Answer 46

Cells formed from the inner enamel epithelium of the enamel organ that
differentiate into ameloblasts.

Question 47

reduced enamel epithelium:

Answer 47

Layers of flattened cells overlying the enamel surface resulting
from a compression of the enamel organ

Question 48

repolarization:

Answer 48

Process that occurs in a cell in which the nucleus moves away from the center
to a position farthest away from the basement membrane.

Question 49

resorption:

Answer 49

Removal of a hard tissue such as bone, enamel, dentin, or cementum.

Question 50

root trunk:

Answer 50

Portion of the root of multirooted teeth where the root originates from the crown.

Question 51

stellate reticulum:

Answer 51

One of the two layers between the outer and inner enamel epithelium of
the enamel organ; consists of star-shaped cells.

Question 52

stratum intermedium:

Answer 52

One of the two layers between the outer and inner enamel epithelium
of the enamel organ; consist of a compressed layer of flat to cuboidal cells.

Question 53

succedaneous:

Answer 53

Permanent teeth with primary predecessors; include the anterior teeth and
premolars.

Question 54

successional dental lamina:

Answer 54

Extensions of the dental lamina into the ectomesenchyme lingual
to the developing primary tooth germs that will form the succedaneous teeth.