Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IOE > tooth development > Flashcards

tooth development Flashcards

1
Q

what are the 3 steps in root development

A

1) after crown formation, the IEE + OEE at cervical loop of enamel organ form a double layered EPITHELIAL ROOT SHEATH OF HERTWIG
2) the sheath encloses the dental papilla and grows APICALLY to outline shape of future root + form of the APICAL FORAMEN
3) cells of the dental follicle seen adjacent to the sheath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

so root development involves an interaction between which 3 components

A

1) dental follicle
2) dental papilla
3) epithelial root sheath of hertwig

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what do cells forming the inner layer of the root sheath induce

A

peripheral cells of the dental papilla to differentiate into ODONTOBLASTS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the role of the newly differentiated odontoblasts and what does this allow

A

produce root dentine
- as root dentine is laid down the epithelial root sheath breaks up allowing dental follicle cells to come into contact w root dentine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what do cells of the dental follicle adjacent to root dentine differentiate into and what does this initiate

A

CEMENTOBLAST-LIKE CELLS

- cementogenesis starts w formation of acellular primary cementum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what happens to remaining dental follicle cells after others have differentiated into odontoblasts and cementoblast like cells

A
  • become obliquely orientated

- differentiate into FIBROBLASTS of the pdl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the role of the newly differentiated fibroblasts and what do these do

A

secrete COLLAGEN which becomes embedded as SHARPEYS FIBRES into

a) ACELLULAR CEMENTUM ON ROOT SURFACE
b) DEVELOPING ALVEOLAR BONE OF TOOTH SOCKET

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what of the epithelial root sheath of hertwig may be retained and how can we see this histologically?

A

epithelial remnants

- seen as EPITHELIAL RESTS OF MALASSEZ in the pdl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

when does development of the face begin

A

4th week of prenatal development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

which 5 facial processes form around the primitive mouth

A

1) stomodeum
2) frontonasal process
3) maxillary process
4) mandibular arch
5) mandibular symphisis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the stomodeum

A
  • precursor of mouth + anterior lobe of pituitary gland

- depression between brain + pericardium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the frontonasal process

A
  • unpaired swelling

- develops to form the face

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the maxillary process

A
  • triangular, embryonic process

- grows from dorsal end of mandibular arch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the mandibular arch

A
  • lower lip, mandible, masticatory muscles, anterior part of tongue develop from it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the mandibular symphisis

A
  • line of junction where the 2 lateral halves of the mandible fuse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what happens at the beginning of week 6 of prenatal development

A
  • primitive mouth (stomodeum) is lined by ECTODERM (outer part of ectoderm gives rise to ORAL EPITHELIUM)

because basal cells of oral ectoderm proliferate more rapidly than those of adjacent areas it leads to formation of the primary epithelial band (PEB)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what happens after fertilisation?

A
  • zygotes undergoes mitosis

- w ongoing mitosis + fluid secretion by cells the zygote now becomes a BLASTOCYTE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what does the blastocyte do

A
  • travels to become implanted in endometrium of uterus

- grows and a BILAMINAR EMBRYONIC DISC develops during week 2 of prenatal development (in embryonic period)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what forms during the beginning of the 3rd week of prenatal development

A

TRILAMINAR EMBRYONIC DISC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what develops from the neuroectoderm and what do they do

A
  • specialised group of NEURAL CREST CELLS (NCCs)

- migrate from crests of the neural fold, then join the mesoderm to form ectomesenchyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the role of ectomesenchyme in development

A
  • involved in development of many face and neck structures

- ie branchial arches which differentiate to form most of connective tissue of head

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

explain primary epithelial band formation

A
  • seen as horseshoe shape on epithelial surface of developing alveolar processes (future jaws) at week 6 of prenatal development
  • here embryos oral epithelium thickens by thickening of superficial layer of cells AND multiplication of cells in the basal layer
    PEB invades underlying ectomesenchyme in 2 horseshoe shaped arches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the similarities and differences between amelogenesis and dentinogenesis

A 
sim = secretory cells, mineral content, periodic deposition
diffs = secretory cell renewal, initial organic matrix, tissue maturation, onset of mineralisation, reactive processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what happens by week 7

A

primary epithelial band epithelium grows / invaginates deeper into underlying ectomesenchyme tissue
it is induced to divide and produce
1) buccal placed vestibular lamina
2) lingual place dental lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the buccally placed vestibular lamina

A

oral vestibule =

contributes to development of vestibule of mouth (lining of lips, cheeks, buccal sulcus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the lingual place dental lamina

A

tooth formation =

  • arch (horseshoe) shaped thickening / invagination of the epithelium
  • lines the developing maxillary + mandibular processes which contributes to development of the teeth
  • series of swellings deep in dental lamina = correspond to size of deciduous teeth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how does the dental lamina form

A
  • initially in the midline for both arches

- progresses posteriorly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is observable by week 8 and what are these

A
  • development of a series of swellings on deep surface of lamina
  • they are EARLY DEVELOPING TOOTH GERMS
  • each surrounded by ECTOMESENCHYMAL CONDENSATION
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

how is odontoblast differentiation initiated

A

1) odontoblasts differentiate from peripheral ectomesenchymal cells of dental papilla (these cells divide into pre-odontoblasts in contact w the basal lamina + some daughter cells migrating below this layer)
2) initiated by series of epithelial signals from cells of IEE as they differentiate into pre-ameloblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what changes are seen in differentiating preodontoblasts and preameloblasts

A

both develop into columnar secretory cells with reverse polarity and intracellular secretory organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

how are odontoblasts further signalled

A
  • differentiating ameloblasts degrade the basal lamina allowing further inductive signalling to the odontoblast
32
Q

what happens when odontoblasts are induced

A
  • they develop processes and dentine matrix starts to be laid down (so dentine matrix deposited before enamel matrix)
  • matrix formed (mainly type I collagen)
33
Q

which dentine do odontoblasts form first

A

MANTLE DENTINE

  • formed by odontoblasts that are still differentiating
  • has unique properties compared to circumpulpal dentine
34
Q

what happens once mantle dentine has been formed

A

odontoblasts start to retreat
leaving single main process behind as they lay down the bulk of primary circumpulpal dentine in a regulat incremental pattern

35
Q

how does dentine become mineralised

A
  • 1st layer is unmineralised
  • when reached genetically predetermined width mineralisation begins at same rate as matrix formation - theres always a layer of unmineralised dentine on pulpal surface (PREDENTINE)
36
Q

what is peritubular dentine

A
  • diff composition but structurally continuous w intertubular dentine
  • small crystals in amorphous (non-fibrillar) matrix
  • age deposition leads to reduction in size of tubules
37
Q

how is degree of tubular occlusion measured and how is it used

A
  • by presence of translucent dentine

- to determine tooth age in forensics

38
Q

what is secondary dentine formation

A
  • continued, age related deposition of dentine throughout life by OG odontoblasts following completion of tooth formation
  • leads to gradual reduction in pulp chamber size and root canals becoming narrower w age
39
Q

when does tertiary dentine formation occur

A

response to injury

- formation limited to pulpal surface underlying the stimulus / insult

40
Q

what 5 phases occur in amelogenesis -> life cycle of ameloblast

A

1) presecretory
2) secretory
3) transition to maturation stage
4) maturation phase
5) post maturation

41
Q

explain the presecretory stage of amelogenesis

A
  • cells of IEE differentiate into pre-ameloblasts (cells elongate, change internally developing secreting organelles + displaying reversed polarity ie nucleus moves to end of cell away from basal lamina and other organelles migrate towards basal lamina)
  • differentiating preameloblasts induce outer / peripheral dental papilla cells to begin differentiating into odontoblasts
  • so basal lamina degraded + reabsorbed by pre-ameloblasts
  • odontoblasts lay down dentine matrix then preameloblasts secrete intial enamel matrix
42
Q

explain the secretory stage of amelogenesis

A
  • further elongation, ameloblasts now tall columnar cells over 60um height + 2-4um wide
  • ameloblasts develop TOMES PROCESSES (short cone shaped process on bottom of ameloblast) where all secretion + modification of enamel matrix + HAP occurs
  • simultaneous secretion of organic matrix and mineral
43
Q

secretory stage of amelogenesis: what happens following mineral deposition

A

1) mineralisation of enamel matrix

2) HAP crystal formation w organic protein matrix acting as template for crystal growth and organisation

44
Q

secretory stage of amelogenesis: where do ameloblasts move to

A

move away from future ADJ (enamel matrix + mineral deposition continues as they do so)

45
Q

secretory stage of amelogenesis: what happens to HAP crystals in amelogenesis

A
  • elongate
  • become long ribbons parallel to each other in bundles that form enamel prisms or rods (prismatic structure) bc of shape of tomes processes
  • enamel prism elongation is an incremental process
  • prism core + boundary differ in orientation (determined by shape of tomes process, core crystallites parallel to long axis, boundary crystals deviate by 60 degrees)
  • developing enamel has a pitted appearance bc secretion occurs at two sites (proximal region + distal region)
  • distal region (tomes process) secretes faster forming a wall that acts as periphery of prism and interprismatic regions
46
Q

secretory stage of amelogenesis: when does it end

A
  • once full thickness (genetically predetermined) of enamel matrix is formed
  • gradual degradation of enamelin structural matrix proteins during this stage
  • when its coming to an end the nucleus moves back down towards basal lamina
47
Q

explain the transition to maturation stage of amelogenesis

A
  • once genetically pre-determined enamel thickeness is reached the cells die (50%), lose their tomes processes (no more secretion) + shrink forming a protective layer over enamel and teeth before errupt
  • continued matrix degradation + selective reabsorption prepares tissues for further development of mineral prismatic component
48
Q

explain the maturation stage of amelogenesis

A
  • 2-3x longer than secretory phase
  • 3-4 years
  • cycling of ruffled + smooth ended ameloblasts indicates alternation between resorptive and secretory activity
  • final degradation + matrix withdrawal
  • enamel crystallites get longer, thicker (to 25nm thickness) + wider as further mineral is added to calcium HAP crystals REDUCING INTER-CRYSTALLITE space until they contact each other
  • enamel reaches final level of mineralisation
49
Q

what are ectodermal-mesenchymal interactions and what are the 4 stages that they occur in

A

inductive messages (effect of 1 cell on another)

1) bioactive signalling molecules (growth factors, cytokines)
2) intitiation of tooth development
3) later stage
4) extracellular matrix

50
Q

explain bioactive signalling molecules in ectodermal-mesenchymal interactions

A
  • produced in a specific seq
  • pass between epithelium and mesenchyme
  • bind to cell receptors + set off series of intracellular cascades which regulate gene expression so altering cell behaviour
51
Q

explain intitiation of tooth development in ectodermal-mesenchymal interactions

A
  • in its early stages the first pharyngeal arch (branchial epithelium) is instructive and responsible for initiation
52
Q

explain later stage in ectodermal-mesenchymal interactions

A
  • instructive capacity for development transferred to mesenchyme (ectomesenchyme = dervived from neural crest)
  • induces epithelium to further develop
53
Q

explain extracellular matrix in ectodermal-mesenchymal interactions

A
  • imp role in inductive process as enables interaction between bioactive molecules or provides surface for attachment of cells
54
Q

how are ectodermal-mesenchymal interactions used for research into tooth regeneration

A

by understanding early odontogenic signals its possible to engineer dental tissues from stem cells

55
Q

list the 9 stages of tooth development

A

1) primary epithelial band (6 weeks)
2) dental lamina formation (7 weeks)
3) bud (week 8)
4) early cap (10 weeks)
5) late cap (12 weeks)
6) early bell (by week 14)
7) late bell / apposition (18 weeks)
8) root sheath + start of root formation
9) root formation continues along w formation of alveolar bone and pdl

56
Q

what happens in the bud stage (stage 3 of tooth development)

A
  • growing tooth bud appears as simple spherical-ovoid epithelial structure
  • epithelium of dental lamina separated from ectomesenchyme via basement membrane
  • round / ovoid swellings at 10 points correspond to sites of deciduous teeth
  • cells of enamel organ + surrounding mesenchyme undergo mitosis leading to formation of dental papilla below enamel organ and dental follicle (surrounds enamel organ + papilla)
  • cells of tooth bud derived from ectoderm show no morpho or histo differentiation
  • ectomesenchyme undergoing proliferation, surrounds tooth bud, is growing + condensing
57
Q

what happens in the early cap stage (stage 4 of tooth development)

A
  • enamel organs deeper surface begins to invaginate forming a cap shape (cap because enamel organ proliferation / enlargement is not uniform - occurs more at the edges than in middle)
  • POOR HISTODIFFERENTIATION - round cells in centre, peripheral cells become arranged to form IEE + OEE
  • peripheral cells of the cap stage are cuboidal and cover convex surface of cap referred to as OEE
    cells in the concavity of the cap become tall columnar cells know as IEE
58
Q

what happens in the late cap stage (stage 5 of tooth development)

A
  • basement membrane separates OEE from dental sac and IEE from dental papilla
  • early histodifferentiation = enamel organ enlarges, central cells in it become separated (held together by desmosomes) = STELLATE RETICULUM (SR)
  • SR cells separate OEE + IEE and form a cellular network (held together by desmosomes) so sr cells act as a shock absorber + have role in nutrition of cells of IEE + OEE
  • IEE cells become more columnar
  • OEE cells remain cuboidal
  • ectomesenchymal cells continue to proliferate + surround enamel organ = DENTAL FOLLICLE and ones beneath IEE condense into a mass in concavity of cap of enamel organ = DENTAL PAPILLA
59
Q

what 4 tissue are formed in the process of tooth development and what is their origin

A

1) enamel organ = derived from ectoderm (enamel is ectodermal product)
2) dental papilla = derived from ectomesenchyme (derived from NCCs) + produces future dentine and pulp so the 2 are mesenchymal origin
3) dental follicle (dental sac) = derived from ectomesenchyme + produces supporting tissues of tooth (cementum, pdl, some alveolar bone)
4) basement membrane = between enamel organ + dental papilla, site of future ADJ

60
Q

main features associated w presecretory phase of amelogenesis

A
  • cytodifferentiation = differentiation of ameloblasts
  • morphodifferentiation = bell stage inc formation of an enamel knot
  • resorption of basal lamina of IEE
  • epithelial mesenchymal interactions
61
Q

main features associated w presecretory phase of amelogenesis

A
  • initial layer of aprismatic enamel formed
  • ameloblasts develop tomes processes
  • matrix secretion to final thickness
  • initiation + continuation of mineralisation to 30% by weight
  • crystallite elongation
  • matrix degradation
  • prismatic structure developed
62
Q

main features associated w transition phase of amelogenesis

A
  • ameloblasts shorten, 50% die
  • vascular invagination of enamel organ
  • reformation of ameloblast basal lamina
  • matrix secretion stops
  • matrix degradation continues
  • selective matrix withdrawal
63
Q

main features associated w maturation phase of amelogenesis

A
  • cycling of ruffled + smooth ended ameloblasts
  • final degradation + withdrawal of matrix
  • crystal growth (continues to completion)
  • final 1/3rd of mineralisation after protein removal complete
64
Q

main features associated w post maturation phase of amelogenesis

A
  • enamel organ degenerates
  • enamel coverings established
  • eruption
  • exposure to oral environment + post eruptive changes
65
Q

what 6 structures exist in the bell stage of tooth development from most superficial to most deep

A

1) dental sac
2) OEE
3) stellate reticulum
4) IEE
5) outer cells of dental papilla
6) central cells of dental papilla

66
Q

what are the
a) histological features
b) role in tooth formation
of the dental sac

A

a) increasing amnt of collagen fibres form around enamel organ
b) differentiate into cementum, pdl, alveolar process

67
Q

what are the
a) histological features
b) role in tooth formation
of the OEE

A

a) outer cuboidal cells of enamel organ

b) protective barrier for enamel organ

68
Q

what are the
a) histological features
b) role in tooth formation
of the stellate reticulum

A

a) more outer star shaped cells in many layers forming network in enamel organ
b) supports enamel matrix production

69
Q

what are the
a) histological features
b) role in tooth formation
of the IEE

A

a) innermost tall columnar cells of enamel organ

b) differentiate into ameloblast (form enamel matrix)

70
Q

what are the
a) histological features
b) role in tooth formation
of the outer cells of dental papilla

A

a) near IEE but basement membrane between them

b) differentiate into odontoblasts (form dentine matrix)

71
Q

what are the
a) histological features
b) role in tooth formation
of the central cells of dental papilla

A

a) central cell mass

b) differentiate into pulp tissue

72
Q

explain embryological tissues

A
  • inner cell mass of embryo forms 2 distinct layers (epiblast and hypoblast)
  • epiblast forms 3 layers
    1) lower germ layer = endoderm
    2) middle germ layer = mesoderm
    3) outer germ layer = ectoderm
73
Q

what are mesenchyme and ectomesenchyme

A

mesenchyme = connective tissue derived from mesoderm

ectomesenchyme = similar properties to mesenchyme, derived from mesenchyme or neural crest cells, role in formation of hard + soft tissues of h+n (bones, muscles, teeth)

74
Q

which 3 factors drive histological / morphological changes

A

1) initiation = occurs at diff times, requires signalling molecules to pass between ectomesenchyme and epithelial cells
2) morphodifferentiation = genetic programming, cellular signalling, interactions between ectoderm and mesenchymal cells
3) histodifferentiation = cells differentiate into morphologically + functionally distinct groups of cells responsible for secretion of various tooth tissues

75
Q

what happens in the early bell stage (week 14)

A
  • morphodifferentiation as shape of IEE outlines occlusal pattern of tooth due to differing rates of mitosis + differences in rate of cell maturation
  • histodifferentiation established = 4 different types of epithelial cells seen across OEE, IEE, SR + stratum intermedium (junction between IEE + SR)
76
Q

what happens in the late bell stage (week 18)

A
  • morphodifferentiation complete, mineralisation + root formation begin
  • histodifferentiation = epithelial cells of IEE into ameloblasts which has inductive effect on ectomesenchyme peripheral cells of dental papilla causing them to differentiate into odontoblasts
  • boundary between IEE (ameloblasts) and odontoblasts of dental papilla mark the ADJ
  • lamina breaks down once mineral deposited + enamel organ is released from oral epithelium
77
Q

explain the process of root formation in tooth development

A
  • follows crown formation
  • IEE + OEE at cervical loop form double layered epithelial root sheath of hertwig
  • encloses dental papilla + grows apically to outline root shape
  • dental follicle extends to sheath + deposits cementum, PDL + alveolar bone
  • cells forming internal layer of root sheath induce peripheral cells of papilla to differentiate to odontoblasts and dentinogenesis begins
  • at same time ectomesenchyme cells of follicle next to root dentine differentiate to cemento-blast like cells
  • cementogenesis begins with deposition of acellular cementum
  • later cementoblasts form more distinct layer of cuboidal cells that secrete collagen forming matrix of cellular cementum
  • cells of follicle change orientation + progress to fibroblasts of PDL
  • secrete collagen which becomes embedded as sharpeys fibres into developing acellular cementum

IOE (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions