Odontogenesis: cellular and Molecular Flashcards

1
Q

number of chromosomes in people

A

22 pairs of autosomes

1 pair of sex chromosomes

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2
Q

Germ cells

A

Gametes (spermatozoa and ova)

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3
Q

what do gametes hold

A

1 chromosome from each pair of chromosomes

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4
Q

DNA that encodes a protein product

A

Gene

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5
Q

Genomic DNA is converted to mRNA in the nucleus

A

Transcription

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6
Q

mRNS serves as a template for making a protein out of amino acids in the cytoplasm

A

Translation

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7
Q

Different versions of the same gene

A

Allele

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8
Q

Genetic makeup of an individuals (what alleles do they carry)

A

Genotype

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9
Q

Observable characteristics from the genotype and envrionment

A

pHenotype

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10
Q

A change in nucleotide sequence of a gene

A

Mutuations

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11
Q

Mutation in germline is what

A

Heritable and passed to offspring

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12
Q

A hereditary disease that affects bones and teeth

A

Osteogenesis imperfecta (OI)

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13
Q

what is mutatated in Osteogenesis Impoerfectta

A

COL1A1 (type I collagen)

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14
Q

what type of mutation is Osteogenesis imperfecta

A

Autosomal dominant

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15
Q

what is the result of an autosomal dominant mutation

A

1 mutant allele is enough to cause OI phenotype

Shows up in nearly every generation (50% of chance in offspring)

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16
Q

what kind of disease is Supernumerary incisor

A

Autosomal recessive

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17
Q

what is needed for autosomal recessive diseases to show in the phenotype

A

2 mutant alleles to change phenotype

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18
Q

how does Autosomal recessive diseases show

A

not every generation, as both parents need to at least be a carrier of the gene

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19
Q

the processes of a generalized cell become specialized for a job

A

Cell differentiation

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20
Q

what changes in cell differentiation

A

size, shape, products, activities, divisions

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21
Q

what is the product that initiates differentiation

A

induction

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22
Q

an agent that procides cell with a signal to differentiate

A

Inducer

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23
Q

what must a cell be to respond to an inducer

A

must be competent to receive the signal

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24
Q

the ability of a cell to receive and respond to a molecular signal

A

Competence

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25
Q

what is needed for cellular competence

A

Receptors

Internal machinery

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26
Q

what inducer binds to cell surface BMP receptor type I or II

A

Bone Morphogenetic protein (BMP)

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27
Q

what inducer binds to intracellular vitamin D receptor

A

Vitamin D

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28
Q

What inducer binds to cell surface LRP6 and Frizzled Receptor

A

WnT signal

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29
Q

what is cell signaling

A

Transfer of information to cuase change in cell gene expression and function

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30
Q

what are some cell signals

A

Signals
Growth factors
Inducer
Ligand

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31
Q

types of cell signaling receptors

A

Membrane

Intracellular/nuclear

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32
Q

what happens in cell signalling

A

Inducing signal comes from outside cell
Cell is competent to receive it
Intracellular changes
Cell function changes

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33
Q

Effects of cell signaling

A

Cell Differentiation
Cell Proliferation
Cell Migration

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34
Q

what is cell signalling

A

Secreted chemical signal directs changes in target cells that express receptors

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35
Q

what controls gene expression

A

Transcription factors

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36
Q

what are transcription factors

A

Proteins that control whether genes will be transcribed into mRNA

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37
Q

how many genes can one TF control

A

tens to hundgreds of genes

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38
Q

what do TF do for target genes

A

can activate or repress expression

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39
Q

what are Pleiotropic effects

A

1 mutations causes lots of systems to be affected

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40
Q

Amino acids in the DLX family

A

214 amino acid TF

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41
Q

what does a a mutation in DLX3 lead to

A

Pleiotropic effects

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42
Q

what does DLX3 regulate

A

Hair folicle differentiation (BMP signaling)
Enamel genes (Amelogenin, Enamelin, Kallikrein 4)
Bone (formation, resporption, hemostasis)

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43
Q

what mainly happens in weeks 0-4 of development

A

mostly proliferation and migration

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44
Q

what happens in week 4 to 8

A

cell differentiation

Morphogenesis

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45
Q

Formation of major external and internal structures

A

Morphogenesis

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46
Q

what happens in week 8 to 40

A

Growth and maturations

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47
Q

what are the 2 stages of prenatal development

A

Embryo(0-8 week)

Fetus(8-40 week)

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48
Q

the inner cell mass of the Blastocyst stage

A

Embyroblast

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49
Q

what does the Embryobalst form

A

All tissues of the embryo

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50
Q

what are the cells of the embryoblast

A

Embryonic stems

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51
Q

the outer cells of the blastocyst

A

trophoblast layer

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52
Q

when is the Morula

A

3-4 days

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53
Q

what does the Blastocyst form

A

day 5-13

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54
Q

what are the layers of the Bilaminar embryo

A

Ectoderm- dorsal

Endoderm- ventral

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55
Q

what do he ectoderm cells look like

A

Columnar cells

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56
Q

What do the endoderm cells look like

A

More cuboidal

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57
Q

how does the mesoderm form

A

Ectodermal cells converge to the midline to form the primitive streak
Extoderm migrate through the streak between the ectoerm and endoderm to create the mesoderm

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58
Q

what is the conversion to a trilaminar embryo

A

Gastrulation

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59
Q

when does gastrulation occure

A

3rd week

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60
Q

what layers make up the buccopharyngeal membrane

A

Extoderm and endoderm without any mesoderm

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61
Q

what eventually forms the notocord

A

Cephalic (more rostal) migrating cells

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62
Q

when does Rostro-caudal(front back) folding occure

A

week 4

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63
Q

why does Rostro-caudal folding occur

A

directed growth at both ends

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64
Q

when does lateral (side to side) folding occure

A

week 4

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65
Q

what happens in lateral fodling

A

middle parts grow upwards and close to form the neural tube and neural crest cells
lateral parts of the ectoderm grow downwards to sournd the endoderm

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66
Q

what does Rostral-caudal folding form

A

A mouth

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67
Q

The primitive oral cavity

A

Stomatodeum

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68
Q

what defines the most rostral boundry of the primitive gut

A

Buccopharyngeal membrane

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69
Q

what origin are neural crest cells

A

Extoderm

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70
Q

where are neural crest cells formed

A

Adjacent to neural tube to separate from the neural plate when the neural tube closes

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71
Q

when does the neural tube close

A

day 22/end of 3rd week

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72
Q

what do the Neural crest cells do

A

Migrate and differentiate extensively

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73
Q

what do Cranial Nueral crest cells undergo

A

Epithelial- mesenchymal transformation

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74
Q

other name for Crnail neural crest cells

A

Ectomesenchymal cells

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75
Q

why are Cranial neural crest cells also called ectomesenchymal cells

A

Act like mesenchyme to form the connective tissues of the head

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76
Q

what part of Cranial neural crest cells is important to dentist

A

Create the connective tissue of teeth and supportive tissues

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77
Q

why are neural crest cells important

A
Become some of the craniofacial bones
Cranial and sensory ganglia and nerves
Adrenal medulla
dentin
Periodontal ligaments
Alveolar bonds
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78
Q

where do skeletal bones come from

A

Mesoderm

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79
Q

where do Neural crest cells populate

A

head and oral cavity

80
Q

what does the neural tube do during brain development

A

expands to become to forebrain, midbrain, and hindbrain

81
Q

what does the hindbrain form

A

8 rhombomeres (buldges)

82
Q

what do the Rhombomeres define

A

the origins of distinct populations of NCCs

83
Q

what controls Neural crest cell migration

A

Tightly controled by signals

84
Q

what neural crest cells contribute to branchial arch 1

A

From midbrain and Rhombomeres 1 and 2

85
Q

First stream of neural crest cells from the midbrain and rhombomeres 1 and 2 contibute to what

A

The embryonic connective tissue of the face

86
Q

the second stream of neural crest cells from the midbrain and rhombomeres 1 and 2 contibute to what

A

the embryonic connective tissues of the First branchial arch

87
Q

what do Rhombomeres 3 and up contribe to

A

To other strucutures not the face or 1st branchial arch

88
Q

what Rhombomeres express Hox TFs

A

NCC from rhombomeres 3 and up

89
Q

what are Hox TF genes

A

Ancient rostral-caudal patterning genes that define body segments

90
Q

why does the Craniofacial region not have Hox genes

A

it is a more recent evolutionary strucutre so it has its own set of TFs

91
Q

what are Hox Free NCCs

A

NCCs that migrate from mid-brain and rhombomeres 1 and 2 to the face and first brnachial arch

92
Q

what do all transciprtion factors include

A

a DNA binding domain that allows them to interact with genes

93
Q

what is included in Homeobox TFs

A

Have a specific 180 base pair homeobox with specific sequences

94
Q

what are HOX TFs a part of

A

a subset of Homeobox genes that are very ancient body patterning directors

95
Q

what are the NCC body patterning Genes

A

The head organizes (NO HOX)

96
Q

what patterning TFs direct craniofacial development

A

Otx2: orthodenticle homeobox 2
Msx: muscle segment homeobox
Dlx: Distal-less homeobox
Barx: barH-like Homeobox

97
Q

what do NCCs contribute to in the branchial arches

A

Contribute to the mesoderm

98
Q

what separates arches externally

A

Groove/cleft

99
Q

What is the internal depression on a arch

A

Pouch

100
Q

what makes up the the arch

A

NCC, mesoderm

101
Q

what makes up a groove

A

Ectoderm

102
Q

what makes up a pouch

A

Endoderm

103
Q

what does Brnachial arch/groove//pouch 1 make

A

Mandible and maxialla (teeth)

Outer and middle ear

104
Q

How do we understand the head organizer genes

A

Mutate mice (Dlx1/2) to show that altered craniofacial morphology and lack of maxillary molars

105
Q

what does Dlx1/2 affect

A

teeth in maxillary process of BA1

106
Q

what is treacher-collins syndrome

A

Underdeveloped craniofacial region and mandible

107
Q

what causes Treatcher-collins syndrome

A

Failure/impairment of NCC migration to facial region due to a mutation in TCOF1, POLR1C, or POLR1D

108
Q

what drives tooth formation

A

Epithelial-mesenchymal interactions

109
Q

why is understanding tooth formation important

A

The epithelial-mesenchumal interactions for formation is conserved for many extodermal organs (hair, mammary gland, Feathers)

110
Q

stages of ODontogenesis

A

Placode - bud - morphogenesis

111
Q

what is essential for a tooth organ to form

A

Both adjacent tissues are essential for proper formation

112
Q

what kind of signalling is done in Epithelial-mesenchymal sinaling

A

Reciprocal
Reiterative
Sequential

113
Q

what is Reciprocal signalling

A

E-M signals back and forth

114
Q

Reiterative signalling

A

Cells use same signaling pathways again and again at different stages

115
Q

What are the major signalling pathways for Epithelial-mesenchymal signaling

A

BMP, FGF, SHH, WNT

116
Q

what is sequential signalling

A

Orderly sequence of events determine whether cells are ready to receive the signal and how they respond

117
Q

when does the stomatodeum develop

A

26th day

118
Q

when does Odotogenic epithelium form

A

27th day

119
Q

what are the nasal pits bound by LNP, MNP

A

34th day

120
Q

when is fusion of the face complete

A

38th day

121
Q

when does the processses of fusing occure with the dental lamina stage initiating odontogenesis

A

6th week (36 day)

122
Q

what happens with the primary epithelial band forms

A

Proliferation of epithelial cells
Altered orientation of axis of division
Formation of dental lamina and 20 dental placodes

123
Q

what is the dental lamina

A

Odontogenic bands

124
Q

what are dental placodes

A

Local thickening of ectoderm for primary teeth

125
Q

what is the main thing that occurs in the dental lamina

A

Proliferation

126
Q

what tissues hold the odontogenic potential for the dental lamina stage

A

First epithelial factors direct odontogeneis ( we’ll make a tooth)
then mesenchymal signals take over ( we’ll make a molar)

127
Q

what happens if you combine odontogenic epithelium with 2nd BA mesenchyme

A

Together they still form a tooth

128
Q

If you combine molar mesenchyme with incisor epithelium

A

Form a molar shaped tooth

129
Q

what are the theories for tooth type determination

A

Field model

Clone theory

130
Q

what is the field model for tooth type determination

A
Epithelial signals (BMP, FGF) induce mesenchymal expression of TFs
Mesenchymal TF expression in overlapping domains
131
Q

what is the clone theory of tooth development

A

Each tooth type is derived from a close of mesenchymal cells programmed by epithelium
When close of cells reaches a critical mass, a tooth bud initiates
Next bud does not initiate until clone moves outside of inhibitory zone

132
Q

what occures in the bud stage of odontogoensis

A

Down growth of dental lamina into a bud

Up growth of mesenchyme packing into a condensation

133
Q

what occurs mainly during the bud stage

A

Proliferation

134
Q

what is the condensed ectomesenchyme in the cap stage

A

Dental papilla

135
Q

what is the surrounding ectomesenchyme in the cap stage

A

Dental follicle

136
Q

what occurs in the cap stage of odontogenesis

A

PRoliferation and morphogenesis

137
Q

What is part of the tooth germ

A

Enamel organ
Dental follicle
Dental papilla

138
Q

what is the signaling in the cap stage

A

The Piary ENamel knot

139
Q

what mkaes up the primary enamel knot

A

Non-dividing enamel organ cells in the cap stage

140
Q

what does the Primary enamel knot express

A

Numerous signaling molecules

141
Q

what does the Primary enamel knot direct

A

Proliferation of surrounding epithelial cells

142
Q

what is the Primary enamel knot essential for

A

Bud to cap transition by regulating cap morphology

143
Q

why does the Primary enamel knot dissappear

A

Apoptosis

144
Q

Components of the enamel organ at the bell stage

A

Outer enamel epithelium
Inner enamel epithelium
Stratum intermedium
Stellate reticulum

145
Q

what type of cells make up the outer enamel epithelium

A

Cuboidal cells

146
Q

what type of cells make up the inner enamel epithelium

A

Columnar cells

147
Q

what cells make up the stratum intermedium

A

2-3 cells thick layer adjacent to IEE

148
Q

what cells make up the stellate reticulum

A

Star-shaped cells with spaces between them

149
Q

what occures during the bell stage

A

Proliferation
Morphogenesis
Differrentiation

150
Q

what does the signaling in the bell stage

A

Sexondary enamel knots

151
Q

what is the secondary enamel knots

A

Non-dividing enamel organ cels in the bell stage that appear at the sites of cusps(not th incisors)

152
Q

what do Secondary enamel knots express

A

Signaling molecules (FGF4)

153
Q

what do the secondary enamel knots do

A

Direct proliferation of surroudning epithelial cells, IEE completes folding, determines number and location of cusps

154
Q

what does the secondary enamel knot stimulate

A

stimulates terminal differentiation of odontoblasts to begin dentinogenesis

155
Q

where does Dentinogenesis begin always

A

at the cusp tip

156
Q

Dental Papilla becomes

A

Odontoblasts

157
Q

IEE becomes

A

Ameloblasts

158
Q

where are the zone of maturation

A

the very cusp tip

159
Q

Anodontia

A

Absence of all primary or secondary teeth (tooth agenesis)

160
Q

Oliogodontia

A

6+ missing teeth

161
Q

Hypodontia

A

1-5 missing teeth

162
Q

Hyperdontia

A

More than the normal number of teeth

163
Q

why do dental anomalies exist

A

Disruption in epithelial or mesenchymal function in early stages of odonotogensis

164
Q

what causes Oligodontia

A

Autosomal dominant mutation in PAX9 transcription facts

165
Q

where is PAX9 expressed

A

In dental mesenchyme early in development

166
Q

what are people with oligodontia missing

A

Missing maxillary and mandibular 2nd and 3rd molars (incisors less affected)

167
Q

the mineralized tissues in the oral cavity

A

Enamel, dentin, cementum, bone

168
Q

The process of making a composite material

A

Biomineralization

169
Q

the organic component of enamel

A

Enamel-specific Proteins

170
Q

The inorganic component of all things in the oral cavity

A

Hydroxyapatite

171
Q

CElls for the enamel

A

Ameloblasts (ectodermal)

172
Q

Organic component of dentin

A

Collagen

173
Q

Organic component of cementum

A

Collagen

174
Q

ORganic component o bond

A

Collagen

175
Q

Cells of the dentin

A

Odontoblasts(mesenchymal)

176
Q

Cells of the Cementum

A

Cementoblasts (mesenchymal)

177
Q

Cells of bone

A

Osteoblast (mesnchymal)

178
Q

what makes up 90% of the matrix of dentin, cementum and bone

A

Type I collagen

179
Q

what directs mineral initation,deposition, and growth in dentin, cementum, and bone

A

Fibrillar collagens

180
Q

Shape of HAP in bone dentin, and cementum

A

Plate like “habit”

181
Q

Length and width of Bone, dentin, cementum HAP

A

W: 12-20nm
L: 20-50 nm

182
Q

shape of enamel HAP

A

Elongated

183
Q

width and length of Enamel HAP

A

Greater the 10x W and L

184
Q

wy is biomineralization highly regulated

A

Don’t want Ca and P to be in blood and tissues
Need to trasnport ions to site of mineralization
Deposite extracelular matrix
hard tissue removal/remodeling

185
Q

what is the roll of other matrix proteins in biomineralization

A

Positively and negatively regulate mineral initiation and growth

186
Q

Result of Biomineralization regulation loss

A

Hypomineralization (Too little mineral)

Hypermineralization (ectopic Mineral)

187
Q

Hypomineralization leads to

A

Poor bone growth
Thin, weak bones and teeth
Fractures, abscesses…

188
Q

Hypermineralization leads to

A

Inappropriate mineralization of soft tisues
Debilitating and lethal
FTC and ACDC/CALJA

189
Q

the ability to differentiate to all 3 germ layers

A

Pluripotent

190
Q

Pros of Embryonic stem cells

A

Pluripotent
Divide indefinitely
can make any tissue and repair any defect

191
Q

cons of embryonic stem cells

A

Control induction
Teratoma tumor formation
Ethical concerns

192
Q

The ability to differentiate within lmits

A

Multipotents

193
Q

Pros of Adult stem cells

A

Ability to make several types of tissues

Easier to control

194
Q

Cons of Adult stem cells

A

Only Multipotent
Divide asymmetrically (not indefinitely)
quality and quantity decrease with age

195
Q

where are dental stem cells found

A

Dental pulp
Deriodontal ligament
Dental follicle
Apical papilla