Odontogenic Embryology Flashcards

1
Q

what does odontogenesis mean

A

tooth development

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2
Q

when does odontogenesis start? how long can it take

A
  • starts 6th week in utero and can take up to 20+ years
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3
Q

what are the 5 stages of odontogenesis

A

1) dental lamina
2) bud
3) cap
4) bell
5) root formation and eruption

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4
Q

what two processes occur during the bell stage

A

amelogenesis
dentinogenesis

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5
Q

what are the locations of odontogenesis

A

maxillary and mandibular prominences

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6
Q

what impacts the shape of the face

A

the expansion of the paranasal sinuses and the growth of the mandible and maxilla to *accommodate the teeth

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7
Q

where does the dental lamina arise from

A

epithelial- mesenchymal interaction between overlying oral epithelium and underlying mesenchyme derived from neural crest cells

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8
Q

what occurs at 6 weeks during

A

basal layer of the epithelial lining forms a C shaped structure called the dental lamina along the length of the upper and lower jaws

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9
Q

what does the lamina give rise to?

A

*10 dental buds in each jaw forming the primordia of the ectodermal components of the teeth

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10
Q

what are buds surrounded by

A

ectomesenchymal cells

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11
Q

when does the cap stage occur

A

approx. 10 weeks

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12
Q

how does the bud first look

A

morphs into a cap-shaped *enamel organ

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13
Q

what are the 3 structures of the bud (while cap-shaped)

A

1) outer enamel epithelium (OEE)
2) inner enamel epithelium (IEE)
3) stellate reticulum (SR)

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14
Q

what does the IEE develop into

A

the ameloblasts

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15
Q

what occurs with the SR

A

cells secrete GAGs, which draws water into the organ and causes it to swell, the cells are interconnected with desmosomes and they become star shaped

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16
Q

what happens after the bud appears

A

mesenchymal components from the neural crest start to enclose the cap and fill the indentation

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17
Q

what are the 2 components of the cap once mesenchymal components start to enclose it?

A

1) Dental papilla (DP)*
2) Dental sac (DS) or dental follicle

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18
Q

describe the details of the DP

A
  • protuberance at the underside of the cap
  • *odontoblasts eventually develop into dentin
  • remaining cells develop into the *pulp (nerve and blood supply)
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19
Q

describe the details of the DS

A

beginning to form by mesenchymal cells surrounding the cap
- stays with tooth until eruption, can cause pathology

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20
Q

what is the last step of the cap stage

A

enamel knot forms

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21
Q

describe how the enamel knot forms

A

a cluster of ameloblasts forms the enamel knot that regulates early tooth development

22
Q

what is the role of the enamel knot

A

signaling center for expression of growth factors, transcription factors

23
Q

when does the bell stage occur

A

approx. 14 weeks, the cap grows and the indentation deepens the tooth and takes the appearance of a BELL

24
Q

what does the stratum intermedium (SI) do? what does it form?

A
  • develops in the *stellate reticulum (SR) to work with the inner enamel epithelium to form *enamel
25
Q

what happens to the dental lamina* during the bell stage

A
  • degenerates and the developing tooth is released from the epithelium
26
Q

how is the crown pattern established during the bell stage?

A

established by the folding pattern of the IEE*

27
Q

what is the cervical loop (CL)

A

where the IEE and OEE fold and loop at the cervical neck region of the loop

28
Q

what is the apposition stage

A

the production of enamel and dentin as they grow away* from each other

29
Q

when does the apposition stage occur

A

during bell stage

30
Q

what happens to the OEE during the apposition stage

A

only function at this point is to contain the stellate reticulum, but will die off

31
Q

what happens to the IEE during the apposition stage

A

developed into the ameloblasts

32
Q

what do mesenchyme cells of the dental papilla differentiate to

A

*odontoblasts to make dentin
*PULP blood and nerve supply

33
Q

what do ameloblasts develop from? what is their structure?

A
  • develop from IEE
  • elongated columnar cells that produce enamel
34
Q

what is the tomes process*

A

secretes the developing enamel, makes a saw-tooth appearance

35
Q

what are the layers created by ameloblasts called

A

striae of retzius

36
Q

what are striae of retzius the microscopic description of

A

perikymata, shallow, periodic furrows on the outer surface of the enamel seen with the naked eye

37
Q

what structure is left behind but sloughs off after eruption

A

dental cuticle

38
Q

how do odontoblasts begin?

A

as *peripheral cell layer of the *dental papilla

39
Q

where do odontoblastic processes extend

A

through dentin matrix/ dentin and reach the *dentinoenamel junction (DEJ)

40
Q

what do odontoblasts secrete

A

predentin with a unique band of type 1 collagen fibers* called von korff fibers*

41
Q

where do odontoblasts go after deposition

A

dental pulp

42
Q

what is teratoma

A
  • considered benign, but can have malignant potential
  • most common ovarian tumor
  • mixture of benign tissues derived from < 2 embryonic layers
43
Q

what is compound odontoma

A

multiple teeth near root of tooth

44
Q

what is Hertwig’s epithelial root sheath

A

dental epithelial layers penetrate into the underlying mesenchyme

45
Q

what makes up the apical foramen of the tooth

A

CL surrounds developing root and guides morphologic development

46
Q

what forms a root canal

A

when more dentin is deposited, the pulp chamber narrows and forms the canal containing the blood vessels and nerves

47
Q

what are Rests of Malassez

A

cells that break off the root sheath and support the periodontal ligament (PDL)

48
Q

what are cementoblasts? what do they produce

A
  • mesenchymal cells on the outside of tooth and in contact w/ the dentin of the root diff to cementoblasts
  • produce a thin layer of specialized bone called cementum
49
Q

when do deciduous teeth erupt? what are teeth present at birth called

A
  • typically 6-24 months after birth
  • ## natal teeth
50
Q

when do permanent teeth develop

A

begin developing during 3rd trimester, but then pause for almost 6 years to continue development