CTB Theme 2 Flashcards

Question

what is the enamel organ distinguished by

Answer 1

outer enamel epithelium | with cuboidal epithelial cells

Answer 2

group of star shaped cells in the centre of the enamel organ and synthesise glycosaminoglycans

Answer 3

glycosaminoglycans and collagens I, II, III (ECM)

Answer 4

columnar | the epithelial cells differentiate into ameloblasts later

Answer 5

they continue proliferating

Answer 6

2-3 layers of flat epithelial cells that form between inner enamel epithelium and stellate reticulum

Answer 7

alkaline phosphatase | - mineralisation of enamel matrix

Answer 8

protein synthesis, transport of substances to and from inner enamel epithelium (epithelium) -ameloblasts supporting function

Answer 9

generates fibroblasts and mesenchymal stem cells of the pulp, and odontoblasts

Answer 10

it supports the enamel organ with nutrients and generates tooth supporting tissues

Answer 11

18 weeks in utero

Answer 12

its acquired its future shape

Answer 13

it moves downwards which helps protect the cellular area of the developing tooth

Answer 14

the growing end of the enamel organ (cell interactions)

Answer 15

where the IEE and OEE meet and is later involved in root formation

Answer 16

enamel organ loses contact with oral epithelium

Answer 17

they're dental papilla cells and secrete predentine that mineralises and forms dentine

Answer 18

they're inner enamel epithelial cells that secrete preenamel that mineralises and forms enamel

Answer 19

alkaline phosphate and support the enamel

Answer 20

protects and maintains tooth shape

Answer 21

maintains tooth shape and exchanges substances with dental follicle

Answer 22

- inner enamel epithelium (IEE) separated from dental papilla cells by a cell-free zone - IEE cells become elongated and secrete signalling molecules to induce odontoblast differentiation from dental papilla cells. - odontoblasts align and produce predentine - Signals from odontoblasts (in the predentine) induce differentiation of pre-ameloblasts into ameloblasts that start producing pre-enamel. Dentine produced first and enamel later due to this interaction

Answer 23

by a cell free zone

Answer 24

IEE cells become elongated and secrete signalling molecules to induce odontoblast differentiation from dental papilla cells

Answer 25

by signals from the odontoblasts in the predentine

Answer 26

produce pre-enamel

Answer 27

dentine, as signals from odontoblasts are what cause ameloblast formation

Answer 28

root formation begins | reduced enamel epithelium(REE)

Answer 29

from flattened ameloblasts and remnants of the enamel organ

Answer 30

protects enamel of erupting tooth from being attacked by osteoclasts which remodel the jaw bone once the tooth erupts

Answer 31

by demineralisation of enamel during tissue processing

Answer 32

they remain afterwards

Answer 33

lingually (not molars) | they stay dormant until further tooth development is initiated

Answer 34

they are formed by posterior growth of the dental lamina

Answer 35

gives off epithelial buds which form the molars

Answer 36

4 months in utero

Answer 37

6 months in utero

Answer 38

4-5 years after birth

Answer 39

enamel organ dental papilla dental follicle

Answer 40

``` cervical loop outer enamel epithelium stellate reticulum stratum intermedium inner enamel epithelium ```

Answer 41

odontoblasts undiff. mesenchymal cells fibroblasts

Answer 42

cementoblasts fibroblasts osteoblasts

Answer 43

``` mammary glands salivary glands teeth hair tongue papillae ```

Answer 44

signalling centre determining the shape of the tooth

Answer 45

the number of cusps

Answer 46

- dissection of mandibular arch - enzymatic digestion to isolate epithelial and mesenchyme - recombination of epithelium and mesenchyme followed by in vitro culture - transplantation of tooth germ into kidney capsule and in vivo culture for 2-3 weeks - tissue analysis

Answer 47

capability of a tissue to induce gene expression in an adjacent tissue and to initiate tooth development

Answer 48

its on the epithelium (epithelial signalling)

Answer 49

is on the mesenchyme | mesenchymal signalling

Answer 50

because after 11 days there is no tooth formation when dental mesenchyme instructs non-dental epithelium, however there is tooth formation when the dental epithelium instructs the non-dental mesenchyme

Answer 51

because after the 13 days, when the bud has formed, the dental epithelium cannot instruct the non-dental mesenchyme to form a tooth, however after 13 days the dental mesenchyme can instruct the non-dental epithelium

Answer 52

by overlapping gradients of the morphogens: FGF, BMP in the dental epithelium

Answer 53

tooth position

Answer 54

only those that express PAX 9

Answer 55

secretes signalling molecules (FGF, BMP) and induces the formation of the enamel knot in the dental epithelium

Answer 56

enamel-knot signalling

Answer 57

cell cycle arrest within the enamel knot but induces cell proliferation in surrounding cells

Answer 58

BMP- cell cycle arrest | FGF- cell proliferation in surrounding cells

Answer 59

to epithelial cells bordering the enamel inducing cell proliferation directed downwards

Answer 60

PAX9 and MSX1

Answer 61

a hypothesis for specification of tooth identity

Answer 62

mandibular molars will still form if you remove the DLX gene for maxillary molars as they have different genes which can compensate for the loss of DLX 1 and 2 Also an expressed molar gene Barx 1 in the incisor region will transform the incisor into a molar as it overrides the Msx1 incisor gene

Answer 63

tooth number and identity

Answer 64

ectodermal dysplasia, hyperdontia

Answer 65

tooth number, shape and size

Answer 66

hypodontia, hyperdontia

Answer 67

hard tissue formation

Answer 68

amelogenesis imperfecta, dentinogenesis imperfecta

Answer 69

eruption replacement tumours

Answer 70

osteopetrosis eruption cysts odontomes

Answer 71

missing teeth supernumerary teeth abnormalities of tooth shape and size

Answer 72

anomalies in structure of teeth-dentine anomalies in structure of teeth- enamel anomalies of teeth eruption and/or resorption

Answer 73

dental defects seen in combination with other anomalies

Answer 74

dental defects are not associated with other anomalies (only the dental tissue is affected

Answer 75

missing teeth e.g. | premolars, lateral incisors, peg shaped tooth

Answer 76

``` Hypohidrotic ectodermal dysplasia (→ Eda1) Rieger syndrome(→ Pitx2) Oligodontia-colorectal cancer syndrome (→ Axin2) ```

Answer 77

``` Orthodontist Child Dental Health dentist Restorative dentist Maxillofacial Surgeon Psychologist Geneticist ```

Answer 78

open spaces for bridges or implants | close spaces using orthodontic devices

Answer 79

bone defects and craniofacial malformations enamel hypoplasia, delayed eruption, malocclusion Dentigerous cysts

Answer 80

it breaks down

Answer 81

supernumerary teeth eruptions cysts odontomes (bening tumours)

Answer 82

they block the eruption pathway

Answer 83

they can receive signals from the dental follicle and abnormal cysts can form

Answer 84

bone, dentine, soft tissue

Answer 85

affects enamel matrix formation- reduced enamel thickness

Answer 86

normal enamel thickness but decreased enamel thickness

Answer 87

normal enamel thickness but mottled and softer

Answer 88

autosomal dominant autosomal recessive x-linked forms

Answer 89

AMELX, ENAM, MMP20, KLK4, DLX3, FAM83H, WDR72

Answer 90

defects in dentine formation (odontoblasts)

Answer 91

Blue-gray or amber brown, opalescent teeth | Bulbous crowns and short narrow roots; obliterated pulp chambers

Answer 92

Soft dentine => Enamel chipping => Teeth wear down rapidly

Answer 93

autosomal dominant

Answer 94

DSPP (DSP, DGP, DPP)

Answer 95

by time of development or by anatomical location/histology

Answer 96

pre-dentine primary dentine secondary dentine tertiary dentine

Answer 97

an unmineralised dentine matrix secreted by odontoblasts

Answer 98

all dentine until the completion of root formation

Answer 99

after root completion/eruption | ageing- in time it will reduce the pulp chamber and root canal size

Answer 100

in response to an external stimuli (attrition, caries, cavity preparation etc).

Answer 101

when original odontoblasts function in dentine deposition , produce few tubules (slow response=weak stimuli/injury)

Answer 102

when odontoblasts die and are replaced by newly recruited odontoblast-like cells induced from pulp stem cells. deposit dentine with very little structure (rapid response=severe injury)

Answer 103

coronal dentine | root dentine

Answer 104

``` coronal dentine (in crown) root dentine ```

Answer 105

mantle dentine | circumpulpal dentine

Answer 106

outermost layer of crown dentine, forms first

Answer 107

forms the bulk of the crown - interglobular dentine - intertubular dentine - intratubular/peritubular dentine - sclerotic dentine

Answer 108

a type of circumpulpal dentine- it forms when dentine is mineralised rapidly

Answer 109

a type of circumpulpal OR root dentine - it forms between dentinal tubules

Answer 110

a type of circumpulpal OR root dentine- forms inside dentinal tubules

Answer 111

a type of circumpulpal OR root dentine - caused by complete obliteration of dentinal tubules

Answer 112

Hyaline layer | Granular layer of Tomes

Answer 113

the outermost layer of root dentine

Answer 114

70% inorganic: calcium hydroxyapatite crystals 20% organic: mainly collagen fibrils 10% water its less mineralised than enamel

Answer 115

form between type 1 collagen fibrils | appear as uniform small plates (smaller than those in enamel)

Answer 116

mainly type 1 collagen (90%) and some type III- rest are traces of type V and VI

Answer 117

type I are linear and type III are reticular which link them together

Answer 118

``` collagen fibrils proteoglycans glycoproteins phosphoproteins growth factors ```

Answer 119

osteonectin, osteopontin and dentine sialoprotein (DSP)

Answer 120

dentsialoprotein dentoglyco protein dentphospho protein

Answer 121

dentine phosphoprotein gene (DPP) via proteolytic cleavage

Answer 122

transforming growth factors (TGF) bone morphogenic proteins (BMP) released and travel down tubules and stimulate repair in caries

Answer 123

``` softer than enamel higher tensile strength than enamel more resilient (elastic) than enamel (supports brittle enamel) porous (dentinal tubules) sensitive (pulp innervation) reactive to damage (tertiary dentine) ```

Answer 124

its a living organ

Answer 125

its less radiopaque

Answer 126

radiolucent

Answer 127

at the late bell stage at the cusp tip

Answer 128

mesenchymal cells derived from dental papilla (form dental pulp), they differentiate when receiving molecular signals from pre-ameloblasts

Answer 129

a daughter cell from the division of ectomesenchymal which HAS NOT been exposed to epithelial influence to differentiate into an odontoblast

Answer 130

formation of large von Koff's fibres (type III collagen) at 90 degrees angle to the EDJ

Answer 131

odontoblasts odontoblast secrete smaller type 1 collagen fibres parallel to the EDJ

Answer 132

the odontoblasts secrete matrix vesicles (mv) than contain highly concentrated calcium phosphate ions (mineralisation)

Answer 133

pre-dentine

Answer 134

cell processes

Answer 135

within the matrix vesicle

Answer 136

mineralisation occurs within the matrix vesicle secreted by odontoblasts, causing crystallites to burst out and form the mineralising front

Answer 137

small (25-250nm) membrane bound vesicles produced by odontoblasts, its secreted into the dentine matrix surrounding odontoblasts

Answer 138

phospholipids that bind to calcium | alkaline phosphates

Answer 139

increase phosphate concentration and destroys the inhibitor of mineralisation (pyrophosphate)

Answer 140

they have only been observed during mineralisation of mantle dentine. Therefore, they may or may not be involved with mineralisation of circumpulpal dentine

Answer 141

there is no mineralisation in or near the collagen fibres

Answer 142

because the amount that calcifies is balanced by the addition of new unmineralised matrix

Answer 143

linear or globular depending on the speed of dentine formation

Answer 144

in the mantle dentine, where the mineralisation occurs by the matrix vesicles

Answer 145

linear and globular calcification both occur depending on the rate of dentine deposition

Answer 146

calcospherites (globular masses of mineralised dentine) they form within collagen matrix and increase in size until they fuse to form a single calcified mass

Answer 147

incomplete fusion of calcospherites results in formation (of the hypomineralised) interglobular dentine

Answer 148

in the upper third of circumpulpal dentine

Answer 149

formed from an odontoblast process that has intercalated between two ameloblasts and extends into the enamel (it doesnt follow the path of enamel prisms)

Answer 150

hypomineralised region in the enamel which follwos he

Answer 151

increased surface area of the EDJ which enables a tighter interlocking between enamel and dentine

Answer 152

increased sensitivity as the odontoblast processes are involved in sensation of whats going on outside of the tooth

Answer 153

s-shaped | linear

Answer 154

in coronal dentine due to the crowding of the odontoblasts because they are pushed apically as dentine grows inwards towards the pulp

Answer 155

in the cervical dentine of the crown and in root dentine because little or no crowded results from decrease the surface areas, and tubules run in a straight course

Answer 156

slight changes in tubule direction during dentine deposition creating wavy tubules

Answer 157

von Ebner lines -short period/daily | Adresen lines - long period

Answer 158

``` daily equivalent to cross striations in enamel weakiler defines with a closer spacing dentine deposited daily each line is 3-4 microm ```

Answer 159

``` long period equivalent to striae of Retzius in enamel more sharply defined with wider spacing each line 20 micrometers 6-10 short period lines ```

Answer 160

when secondary curvature is pronounced and coincides in adjacent tubules

Answer 161

metabolic stress during dentine formation

Answer 162

accentuated incremental growth lines (von Ebner lines) and are hypomineralised

Answer 163

the neonatal line due to the disturbances of dentine formation by the birth process

Answer 164

accentuated lines in enamel

Answer 165

mostly on roof and floor of pulp chamber

Answer 166

forms within the dentinal tubule and lines the inner surface as a hyper mineralised layer of dentine (40% more mineralised than the surrounding dentine)

Answer 167

can be any primary or secondary dentine dentine between the dental tubules contains a dense network of type I collagen fibrils in which HA are deposited less mineral than intratubular dentine

Answer 168

continued formation of intratubular dentine leads to obliteration of the dentinal tubules. if complete the dentine is termed sclerotic dentine

Answer 169

due to increased mineralisation

Answer 170

when dentinal tubules have lost their odontoblast processes following death of odontoblasts or retraction of processes, the tubules become empty and air-filled, and appear as a dark lines in ground sections

Answer 171

in areas of attrition & caries of the enamel => Protection of the pulp against invading microorganisms.

Answer 172

1. extensive branching and backward looping of odontoblast processes 2. incomplete fusion of calcospherites

Answer 173

at the late bell stage, morphological changes occur in the enamel organ

Answer 174

receive signals from odontoblasts (in the predentine)

Answer 175

secrete enamel matrix which forms the aprismatic initial enamel layer

Answer 176

enamel secretion | enamel maturation

Answer 177

enamel matrix secreted by ameloblasts is partially mineralised (30%)

Answer 178

When enamel is fully formed, the mineral content increases to about 96%. Enamel crystals grow wider & thicker at the expense of the organic content and water which is gradually removed

Answer 179

presecretory secretory maturation

Answer 180

morphogenetic stage | histodifferentiation stage

Answer 181

Initial secretory stage without Tomes’ process | Secretory stage with Tomes’ process

Answer 182

Ruffle-ended ameloblasts Smooth ended ameloblast Protective stage

Answer 183

IEE cells have a cuboidal shape basal lamina produced by IEE separates IEE from the dental papilla late bell stage: predentine produced by odontoblasts, ameloblast differentiation

Answer 184

IEE cells differentiate into ameloblasts

Answer 185

Preameloblasts elongate and become columnar; cell nuclei are located proximally towards the stratum intermedium (→ establishment of polarity)

Answer 186

synthesise enamel proteins

Answer 187

Basal lamina between ameloblasts and odontoblasts is removed as its where dentine and enamel have formed

Answer 188

Ameloblasts elongate and secrete enamel matrix, form an (aprismatic) initial layer of enamel Enamel has lines, not enamel prisms (as its produced by ameloblasts without tomes process)

Answer 189

the ameloblasts form tomes' process (proximal and distal portion)

Answer 190

interprismatic enamel (‘interrod’ enamel)

Answer 191

produces prismatic enamel (‘rod’ enamel)

Answer 192

Ameloblasts become shorter, lose the distal portion of Tomes’ process → form a thin aprismatic enamel layer (similar to the initial enamel layer)

Answer 193

Distal portion of Tomes’ process develops from proximal portion. It elongates, becomes thinner and is located between prismatic & interprismatic enamel

Answer 194

amelogenins | non-amelogenin proteins

Answer 195

90% matrix component Low molecular weight roles in regulating growth and thickness of enamel crystals Form nanospheres Selectively removed by proteolytic enzymes provides scaffolding allowing controlled mineralisation of enamel

Answer 196

enamelysin (MMP20) and kallikrein 4

Answer 197

secreted first but rapidly processed by proteolytic enzymes 10% of matrix content Form the enamel sheath Larger proteins: Ameloblastin (70 kDa), Enamelin amelotin

Answer 198

facilitates adhesion of ameloblasts to enamel matrix

Answer 199

promotes and guides formation of enamel crystals; least abundant protein

Answer 200

basal lamina protein; involved in adhesion of junctional epithelium to enamel

Answer 201

by growth in width and thickness of pre-existing crystals (hardening of enamel)

Answer 202

transitional phase maturation proper (phase) cyclic modulation of ameloblasts

Answer 203

After the enamel layer has been fully formed: - Decrease in height & volume of ameloblasts - 50% ameloblasts die by apoptosis

Answer 204

Removal of water and proteins from the enamel matrix | Transport of ions is required for the increase in mineral content

Answer 205

ruffle-end and smooth-ends alternate | this increases mineral content (ruffle ended) and removal of organic matrix (smooth-ended)

Answer 206

there leaky junctions between ameloblasts at proximal (basal) end; tight junctions at distal (enamel) end;

Answer 207

20% leaky junctions at distal end enamel protein fragments and water leave the maturing enamel trace elements

Answer 208

leaks into enamel layer – when cells pump positive ions into a place this is accompanied by H+ which decrease the pH

Answer 209

e.g. strontium and fluoride enter the enamel layer and increase hardness

Answer 210

at the occlusal surface | mineralisation decreases towards the EDJ

Answer 211

because the maturation phase is shorter

Answer 212

acid (from food, stomach or of bacterial origin) causes mineral loss bicarbonate ions from saliva cause remineralisation (pH buffering), allows other ions like fluoride to incorporate into the tissue

Answer 213

reduced enamel epithelium(REE) forms inactive (cuboidal) ameloblasts and remnants of the enamel organ ('papillary layer')

Answer 214

it covers the tooth crown and protects the enamel from being resorbed by osteoclasts that resorb bone as part of the eruption process or from abnormal cementum deposition

Answer 215

forms the junctional epithelium

Answer 216

excessive consumption- "fluorosis" - faint white opacities/severe pitting and discolouration - histologically, high porosity in the outer third of the enamel

Answer 217

incorporation of fluoride ions into enamel crystals | enamel becomes more resistant to acid so reduction of dental caries

Answer 218

adhesive dental restorative materials when removing plaque or a thin layer of enamel which would increase the surface area and create a better bonding surface for adhesive materials

Answer 219

localised demineralisation of the enamel surface near the gingival margin or fissures (can be arrested or progress to cavity formation)

Answer 220

ameogenesis imperfect, fluorosis

Answer 221

- local (non-systemic) causes e.g. trauma or unknown aetiology. - systemic causes affecting the teeth developing at time of this disturbance e.g. chronological /linear enamel hypoplasia, molar-incisor hypoplasia

Answer 222

as a groove or pit on the enamel surface

Answer 223

smooth surface but abnormal colour (less mineral; abnormal maturation)

Answer 224

febrile disease treatments with tetracycline a chronic ingestion of fluoride ions

Answer 225

it can be incorporated into mineralising tissues resulting in band or total brown pigmentation

Answer 226

syndromic vs non-syndromic | pattern of inheritance: autosomal or x-liked, dominant or recessive

Answer 227

associated with opacities and loss of enamel affecting teeth in the first year of life, the molars are fragile and can develop caries easily

Answer 228

in children who have taken amoxicillin in the first year of life , usually for otis media

Answer 229

amoxicillin interferes with ameloblast function at the secretory stage and the temporal sequence of amelogenesis events.

Answer 230

It is a disruption to enamel formation that causes deep grooves forming on the surface of the tooth. Generally caused by poor nutrition during tooth development

Answer 231

highly mineralised 96% inorganic contain 4% organic content and water

Answer 232

epithelial

Answer 233

1st formed enamel is only partially mineralised (30%) | the crystals grow whilst the organic matrix and water are lost

Answer 234

it varies in thickness over different locations (thickest in . cusps, thinnest over cervical margin) it varies in thickness between different teeth (increase from 1st to 3rd) enamel is thicker in primary vs permanent

Answer 235

``` translucent extremely hard lacks resilience brittle resistant to abrasion resistant to sharing and impact forces low tensile strength ```

Answer 236

96% mineral- calcium hydroxyapatite (HA) 3% organic - proteins 1% water

Answer 237

prisms separated by the inter-prismatic region

Answer 238

when considering caries and cavity preparation

Answer 239

not entirely uniform and differ for the prism and interprismatic region

Answer 240

the structural unit of enamel, millions in enamel (each prism=1 ameloblast)

Answer 241

the EDJ to the crown surface in layers

Answer 242

1. prisms circular 2. prisms stacked 3. keyhole pattern

Answer 243

3- keyhole

Answer 244

form with discrete rods surrounded by interprismatic enamel

Answer 245

discontinuities- rods in vertical rows with interrow sheets of interprismatic enamel

Answer 246

horseshoe shaped (keyhole); interprismatic attached to the tail below the head of the prism when seen in cross section

Answer 247

a wide head towards coronal/occlusal surface | a narrow tail towards cervical

Answer 248

4 1- head 3- tail

Answer 249

parallel to the long axis of prism in head | oblique to the long axis of prism in tail (angled)

Answer 250

the boundary between rod and interprismatic enamel

Answer 251

organic material

Answer 252

from the EDJ to the surface like spokes of a wheel but with a 3D curve

Answer 253

obliquely oriented towards the oral cavity

Answer 254

obliquely oriented toward the alveolar crest

Answer 255

cavity prep must be done in the same direction as the rods

Answer 256

bundles of enamel rods cross eachother as they travel from EDJ to the surface

Answer 257

sinusoidal

Answer 258

it strengthens the enamel structure, prevents propagation of cracks into deeper areas of the enamel, and improves the resistance to fracture

Answer 259

an optical phenomenon occurs in the inner two-thirds of enamel, as an alternating light and dark bands

Answer 260

prism decussation

Answer 261

prism bands that are cut longitudinally (light zones)- reflective zones

Answer 262

prism bands that are cut transversely (dark zones)- transparent zones

Answer 263

an area with exaggerated prism decussation (extremely angular) over cusp tips

Answer 264

the ameloblasts adapt to the rapidly expanding enamel surface and as the crown becomes larger, cohorts of ameloblasts are displaced apically by their own enamel production

Answer 265

on the EDJ

Answer 266

increases the surface area for accommodating more ameloblasts where there is a large difference between EDJ area and crown surfaces area

Answer 267

strengthens the attachment of enamel to dentine prevents the shearing of enamel during function less scalloped in primary vs permanent

Answer 268

hunter-schreger bands and gnarled enamel

Answer 269

an incremental line that occurs at birth resulting from stress

Answer 270

its darker than other incremental lines

Answer 271

it increases from the EDJ to the enamel surface in both permanent and primary teeth

Answer 272

2-3 inner 3-4 mid 4-5 outer

Answer 273

2.5 to 4.5

Answer 274

0.5 microns per day

Answer 275

DAILY secretion of enamel

Answer 276

they are the result of a daily variation in ameloblast secretion rate and mineralisation

Answer 277

von Ebner lines however they are weaklier defined with a closer spacing

Answer 278

WEEKLY, wider lines, more defined and result from the ameloblast position at various points of time during development

Answer 279

Anderson lines

Answer 280

neonatal line also produced due to systematic disturbance

Answer 281

- Perikymata is the outward aspect of internal growth increments - Visible on teeth to naked eye - The normal transverse wavelike grooves or lines on the external surface of the tooth

Answer 282

cross striations - short daily lines striae of retzius- long period lines perikymata

Answer 283

the growth of all the prisms at that increment

Answer 284

striae of retzius

Answer 285

prism orientation

Answer 286

enamel tufts enamel lamellae enamel spindles

Answer 287

hypomineralised voids following the direction of decussation

Answer 288

inner third of enamel, start at the EDJ and project outwards | they contain organic material (mainly tuftelin)

Answer 289

like lines and only travel for a short distance

Answer 290

when enamel tufts pass through the entire thickness of enamel (contain organic material)

Answer 291

cracks are still mineralised enamel where as lamellae enamel is hypomineralised and they contain organic material

Answer 292

formed from an odontoblast process embedded into the first zone of enamel, mainly in the cusp tips

Answer 293

Tomes' process produces enamel at and an angle

Answer 294

the chemical dissolution of dental hard tissues from acid that does NOT originate from bacteria (extrinsic or intrinsic acid) , resulting in irreversible tooth surface loss

Answer 295

1. hydrogen ions dissociate from the acids & interact with the HA crystal causing dissolution (combine with carbonate/phosphate) 2. this releases all ions from that region of the crystals creating the typical honey comb etched surface 3. the core of the enamel prisms has been dissolved by the acid and the adjacent interprismatic areas appear more prominent

Answer 296

mesenchymal cells of the dental papilla

Answer 297

coronal pulp and radicular pulp

Answer 298

the periodontal ligament

Answer 299

blood vessels- nourishment nerves- sensation lymphatic vessels- lymph drainage

Answer 300

accessory canals present- they are the source of infection and inflammation

Answer 301

loose connective tissue made up of: - ECM - different cell types - blood and lymphatic vessels - nerves

Answer 302

75% water | 25% organic material

Answer 303

usually no but calcifications and pulp stones can be found in the pulp of aged teeth

Answer 304

odontoblast cell layer cell free zone cell rich zone pulp core

Answer 305

cell free zone

Answer 306

coronal are columnar cellular processes reaching into the dentinal tubule cuboidal in root

Answer 307

it becomes flatter and the number of cells is reduced by apoptosis

Answer 308

its laid at a slower rate after root completion and reduces the size of the space occupied by the dental pulp

Answer 309

in response to external stimuli, odontoblast-like cells can differentiate from progenitor cells in the pulp

Answer 310

- tight junctions - desmosomes - gap junctions

Answer 311

mechanical union between 2 cells maintain spatial relationship restrict substances in the pulp from entering the dentine

Answer 312

openings allowing exchange of small molecules and cell-to-cell communication

Answer 313

within the dental pulp (particularly in coronal & cell rich zone)

Answer 314

the collagen fibres and ground substance of the pulp matrix

Answer 315

degrade collagen (collagen turnover)

Answer 316

large, centrally located nucleus | multiple cellular processes

Answer 317

smaller, spindle-shaped fibroblasts | fewer organelles

Answer 318

fibroblasts undifferentiated mesenchymal cells dental pulp stem cells immune cells

Answer 319

differentiate into odontoblast-like cells and fibroblasts | the number reduces with age

Answer 320

Multipotent: odontoblasts, chondrocytes, osteoblasts, adipocytes and neurones depending on the tissue they're formed in

Answer 321

macrophages t and b lymphocytes neutrophils and eosinophils dendritic cells

Answer 322

patrol the pulp and remove dead cells/ bacteria (innate and adaptive immunity)

Answer 323

they respond to infection and mediate inflammation

Answer 324

present foreign antigens to T cells

Answer 325

adaptive (antibod-driven) immune system

Answer 326

``` collagen fibres ground substance (non-fibrous protein matrix) ```

Answer 327

type I and III (creates meshwork by linking type 1) | forms a scaffold providing stability to the pulp

Answer 328

- glycosaminoglycans - hydrophilic molecules (swell and form hydrogel that fills most of the extracellular space) - growth factors (cellular process regulation)

Answer 329

as bundles at the roots area not the coronal

Answer 330

blood vessels originating from periodontal ligaments (enter pulp via apical fo) -peripheral blood vessels branching out towards the odontoblast

Answer 331

the drainage of tissue fluid

Answer 332

have thinner walls and no red blood cells

Answer 333

2,500 nerve axons

Answer 334

myelinated afferent nerve fibres (25%) | unmyelinated C fibres (75%)

Answer 335

schwann cells forming the myelin sheath | transmit pain sensation to the CNS; cell bodies in trigeminal ganglion

Answer 336

afferent (main) or efferent (minor) | sense changes in extracellular environment

Answer 337

terminate at odontoblast layer or in the dentinal tubules to transmit any noxious stimulus (pain)

Answer 338

terminate on smooth muscle cells of the aterioles to regulate capillary blood flow

Answer 339

extensive nerve plus that terminates in the cell-free zone, just below the odontoblast layer of the crown (axons can pass between odontoblasts & enter dentinal tubules)

Answer 340

coronal, not in root canals

Answer 341

provide vitality to the tooth and nourishment of odontoblasts via blood vessels/capillaries

Answer 342

- sensation of external stimuli via nerves and their endings - barrier/defence- tertiary dentine triggering an inflammatory response

Answer 343

``` age changes infection spread and inflammation RCT calcifications and pulp stones dentine sensitivity ```

Answer 344

large pulp chamber so challenge for cavity/crown preparation (thin dentine layer and pulp exposure can easily occur)

Answer 345

narrow pulp chamber and narrow root canal so challenge for RCT, secondary dentine also accumulates

Answer 346

from the dental pulp into the surrounding periodontal tissues (abcess)

Answer 347

from the surrounding periodontal tissues into the dental pulp e.g. through accessory root canal

Answer 348

a chronic stimulus (e.g. caries infection or as an age related change

Answer 349

less vascular

Answer 350

calcifying blood vessels and contain bone-like material (inflammation then healing)

Answer 351

detached odontoblasts and contain dentine

Answer 352

afferent nerve endings terminating in the dentine or near odontoblasts sense pain, mechanical, thermal and tactile stimulus

Answer 353

- neural theory- dentine directly innervated - odontoblasts act as receptors - hydrodynamic theory- fluid movement in dentinal tubules is sensed directly/indirectly by nerve endings

Answer 354

after the formation of the crown

Answer 355

epithelial cells of the IEE and OEE initially proliferate downwards from the cervical loop of the enamel organ to form a double layer of epithelial cells

Answer 356

the shape of the future root

Answer 357

there is no stratum intermedium and no stellate reticulum epithelial: PTHrP and enamel proteins mesenchymal: TGF-β, BMP, RUNX2 (cementoblast differentiation and periodontal regeneration)

Answer 358

the IEE of HERS induces it

Answer 359

no ameloblast differentiation in root predentine secreted which forms dentine primary apical fo forms HERS becomes stretched

Answer 360

epithelial diaphragm

Answer 361

cell proliferation of epithelial cells- its position remains stationary and the dentine at the bottom moves the tooth upwards

Answer 362

teeth can still erupt of the root is blocked

Answer 363

rearrangement of collagen fibres and contraction, tooth is pulled up and the bone is removed to create the space

Answer 364

cementum hyaline layer tome's granular layer root dentine

Answer 365

- extensive branching and backwards looping of odontoblasts processes - incomplete fusion of calcospherites (similar to interglobular dentine)

Answer 366

- collagen fibres are deposited parallel and at a distance from the basal lamina of HERS - root dentine is less mineralised and mineralises faster - less phosphophoryn

Answer 367

dentine phosphoprotein- it binds calcium and regulates dentine mineralisation

Answer 368

as a 'curtain' hanging from the crown

Answer 369

by the fusion of epithelial folds from HERS

Answer 370

roughly 65% wide open root apex

Answer 371

1.5 years after eruption for primary | 3 years after eruption for permanent

Answer 372

undifferentiated mesenchymal cells of the dental follicle

Answer 373

odontoblast induction from dentine formation | stretching and disintegration of HERS

Answer 374

osteoblasts (alveolar bone) fibroblasts (PDL) cementoblasts (cementum)

Answer 375

inductive signals from gaps in disintegrating HERS/predentine sent to undifferentiated dental follicle cells epithelial-mesenchymal transmission (EMT) of HERS to cementoblasts

Answer 376

attachment of root dentine to PDL

Answer 377

allows the resistance to root resorption

Answer 378

type I- 90% type III type XII

Answer 379

alkaline phosphotase, bone sialoprotein, dentine matrix protein matrix protein 1, dentine sialoprotein, osteocalcin, osteonectin, osteopontin

Answer 380

the absence or presence of cells : acellular (primary) or cellular (secondary) the origin of collagen fibres in cementum : extrinsic or intrinsic

Answer 381

cementum overlaps enamel- 60% cementum meets enamel - 30& cementum and enamel dont meet - 10%

Answer 382

covering the root adjacent to dentine (primary attachment)

Answer 383

in apical and interradicular (in between roots)

Answer 384

adaption and repair | thickeness increases with age

Answer 385

lacunae and canaliculi containing cementocytes and their processes

Answer 386

towards the PDL

Answer 387

along newly formed hyaline layer

Answer 388

extension of cementoblast cell process into predentine and deposition of collagen fibres that intermingle with un-mineralised predentine matrix

Answer 389

by the extension of collagen fibres

Answer 390

it mineralises and spreads through the cementum

Answer 391

lines of salter

Answer 392

a group of cementoblast that become detached | in PDL

Answer 393

clusters of epithelial cells on PDL (potentially regenerate periodontal tissue) that have been left behind during the apoptosis of HERS

Answer 394

where the root bifurcates (of maxillary molars)

Answer 395

the distrust of attachment of the tooth creates an entry point for bacteria

Answer 396

- attachment of Epithelial Cell Rests (ECR) to predentine (caused by absence of cementum deposition) which may receive signals from predentine and initiate ameloblast differentiation - stellate reticulum and stratum intermedium cells of the cervical loop become trapped in a subset of ECRs when HERS/rot development is initiated

Answer 397

you need to the molecular signals from the pre-dentine for but you need the relevant cells that support ameloblast differentiation

Answer 398

concrescence dilacerated roots roots and canals multiple hypercementosis

Answer 399

union of two teeth after eruption resulting from a fusion of their cementum surfaces

Answer 400

trauma and tooth crowding

Answer 401

radiography and surgery

Answer 402

curved or bent roots caused by developmental trauma (playground accidents) CC: radiographs and careful extraction

Answer 403

abnormal folding of HERS

Answer 404

radiograph and variation of extraction technique | careful cleaning of extra root canal during endodontic treatment

Answer 405

lateral - connections between root canals | accessory - form in the apical foramen

Answer 406

continuity of HERS is interrupted too early during root dentin formation this affects local formation odontoblasts resulting in a canal in the dentine connecting the dental pulp and the PDL of the mature tooth

Answer 407

abnormal production of cellular cementum (produced after the root is completely developed)

Answer 408

``` age change paget's disease idiopathic occlusal trauma patients that grind their teeth - tooth moves up so space is filled with cementum ```

Answer 409

increased distance from CE junction to root apex (imp in endodontic treatment)

Answer 410

odontoblast induction and dentine formation stretching and disintegration of HERS differentiation of dental follicle cells

Answer 411

cementoblast (cementum) fibroblasts (PDL) osteoblasts (alveolar bone)

Answer 412

cell proliferation and migration in the formation of periodontal tissue

Answer 413

cell differentiation and bone formation in the formation of periodontal tissue

Answer 414

FGF2, BMP2

Answer 415

regenerative therapies in periodontal disease e.g. mesenchymal cells

Answer 416

- tooth attachment - withstand forces of mastication - sensory receptor - remodelling function - nutritive function

Answer 417

PDL fibres insert into cementum and alveolar bone to form fibrous joint with little/no movement (gomphosis, synarthrosis)

Answer 418

sensation of pain and tension/compression | repositioning of teeth to achieve occlusion

Answer 419

high turnover of extracellular matrix and collagen fibres (source of progenitor/stem cells)

Answer 420

high vascularised tissue; connected to dental arteries, bone marrow and gingiva. blood vessels needed to perform remodelling function

Answer 421

among species between tooth types between primary and permanent teeth

Answer 422

- ligament space between cementum and bone consists of an unorganised connective tissue (fibroblasts and ecm) - short fibre bundles are formed near cementum and bone and extend a short distance into the ligament space

Answer 423

fibroblasts produce more collagen fibrils that assemble as fibre bundles

Answer 424

bone side: thick fibre bundles | cementum side: thin fibre bundles

Answer 425

at cemento-enamel junction (fibres form apically as the root forms)

Answer 426

initially oblique, then parallel, then oblique

Answer 427

when teeth occlude and function - this is bc mechanical sensation induces the completion of PDL development

Answer 428

``` alveolar crest group horizontal group oblique group apical group apical group interradicular group ```

Answer 429

below CEJ- rim of alveolus resists extrusive forces (must overcome when extracting the tooth)

Answer 430

below the alveolar crest group, at right angles to tooth axis resists horizontal forces (tipping)

Answer 431

resists intrusive ('compressive') forces - mastication

Answer 432

radiates around tooth apex resists intrusive forces

Answer 433

connects to crest of interradicular septum; only in mutli-rooted teeth resists extrusive forces- overcome when extracting tooth

Answer 434

alveolar crest group | interradicular group

Answer 435

oxytalan fibres and fibrillin (no elastin) | run perpendicular to collagen fibres in cervical region

Answer 436

associated with neurovascular bundles; form 3D meshwork surrounding root and REGULATE vascular flow

Answer 437

mineralised PDL fibres in alveolar bone and cementum

Answer 438

``` fibroblasts osteoblasts and osteoclasts cementoblasts and cementoclasts rests of malassez immune cells blood vessels nerve fibres ```

Answer 439

produce collagen fibres, growth factors and ground substances (ecm) perivascular and endosteal fibroblasts surround the blood vessels

Answer 440

3-23 days (highest turnover at tooth apex)

Answer 441

adherens junctions and gap junctions

Answer 442

by mechanical/masticatory forces

Answer 443

synthesis and degradation of ECM and collagen; matrix metalloproteases

Answer 444

they're the enzyme involved in collagen turnover and are highly active periodontal disease

Answer 445

60% ground substance (mainly collagen fibres, blood vessels and nerves) fibres: 90% collagen, 10% oxytalan(microfibrils without elastin) collagen types: I(80%), III(15%), IV, V, VI, VII, XII

Answer 446

usually not during development , only after eruption fibril-associated: link other collagens. expressed on pressure side following mechanical loading

Answer 447

complex composition of glycosaminoglycans: hyaluronic acid, dermatan surface, chondroitin and heparin sulfate) ,proteoglycans and glycoproteins

Answer 448

ion and water binding 70% shock absorber orientation of collagen fibres

Answer 449

the hydration of the tissues and increases the strength of collagen fibrils

Answer 450

hyaluronan decreases during development of PDL from dental follicle proteoglycans increase during tooth development

Answer 451

mediates attachment of cells to collagen fibrils - influence on cell migration and differentiation clinically promotes wound healing

Answer 452

``` FGF TGF-beta (BMP) IGF PDGF VEGF interleukins prostaglandins ```

Answer 453

they're remnants of HERS and a source of all mesenchymal cell types e.g. fibroblasts, osteoblasts, cementoblasts

Answer 454

macrophages mast cells eosinophils

Answer 455

between species, tooth types, erupting teeth

Answer 456

branches of superior and inferior alveolar arteries branches of the lingual and palatine arteries entering through the gingiva supplying the PDL

Answer 457

enter the pulp at apex interalveolar vessels pass through the alveolar process (perforating arteries) more abundant in posterior and mandibular teeth to supply PDL

Answer 458

form interstitial areas enable PDL function after endodontic treatment- nutrients needed through interalveolar vessels extractions wounds: formation of blood clot and invasion of cells involved in healing

Answer 459

pass through perforations in the alveolar bone and form the interstitial areas in the PDL - contain blood vessels and nerves

Answer 460

closer to the alveolar bone

Answer 461

near the root surface and a postcapillary plexus from which venules pass into the alveolar bone

Answer 462

apical occlusal direction and form arteriovenous anastomoses

Answer 463

at apex, removal of waste products

Answer 464

the root surface

Answer 465

the tooth in the region beneath the gingival crevice

Answer 466

pores in endothelial cells that surround blood vessels - special feature of the PDL and not seen in other connective tissue

Answer 467

increase diffusion capacity which is consistent with the high metabolic rate in the PDL (esp during tooth eruption)

Answer 468

follows pattern of vasculature | perforating nerve fibres divide into an apical and gingival branch

Answer 469

more nerve endings at the tooth apex upper incisors have denser innervation throughout the PDL compared to molars related to masticatory response

Answer 470

sensory - nociception and proprioception autonomic - blood flow regulation myelinated- sensory only myelinated and unmyelinated- sensory and autonomic

Answer 471

free-ending, tree like ruffini's corpuscles coiled type encapsualted spindle type

Answer 472

-Evenly distributed across the PDL Unmyelinated fibres (enveloped by one Schwann cell; inset) Extend up to the cementoblast layer Sense pain and pressure

Answer 473

in PDL at root apex myelinated fibres with dendritic endings associate with collagen fibres sense pressure

Answer 474

middle of PDL

Answer 475

in PDL at root apex | surrounded by fibrous capsule

Answer 476

0.15-0.38mm thinnest in middle of root

Answer 477

periodontal remodelling increasing PDL width by 50% including thicker fibre bundles and increased alveolar bone size

Answer 478

in areas are tension rather that compression

Answer 479

reduced function

Answer 480

Excessive force can cause localised necrosis of the PDL by cutting off the normal bloody supply to the cells. E.g. too much pressure

Answer 481

Failure of repair causes localised resorption and tooth ankylosis (fusion of tooth to alveolar bone;)  problem extracting

Answer 482

- If portions of the ligament are permanently damaged, external root resorption and ankylosis could occur. Progenitor cells in the PDL can restart the process and reintegrate the toot into the socket

Answer 483

- Prevention of undesirable wound healing (guided tissue regeneration – prevent undesired wound healing in PD treatment) - Growth factors, cytokines or stem cells to stimulate PDL regeneration

Answer 484

the alveolar process of the mandible

Answer 485

endochondral ossification intramembranous ossification sutural ossification

Answer 486

bone made from a cartilage model - chondrocytes produce cartilage that is replaced by osteoid/bone produced by osteoblasts

Answer 487

``` long bones(epiphyseal growth plate), base of skull (synchondrosis) mandibular condoyle (secondary cartilage) ```

Answer 488

bones are made by osteoblasts that have differentiated from mesenchymal stem cells and lay down the bone directly it is determined by the spaces around where the bone forms

Answer 489

flat skull bones | facial bones: mandible, maxilla and alveolar bone

Answer 490

similar to intramembranous o. but with fibrous connection | provides stability during growth

Answer 491

postnatal growth of flat skull bones

Answer 492

mineralised living connective tissue | non-collagenous proteins

Answer 493

organic matrix is permeated by hydroxyapatite (deposited between type I collagen fibrils)

Answer 494

bone sialoprotein, osteocalcin, osteonectin, osteopontin (all of these bind to ca or HA) control of mineralisation, proteoglycans, cytokines, growth factors, serum proteins

Answer 495

support, protection, locomotion, mineral reservoir

Answer 496

``` (-)PTH (+)Calcitonin (+)Vitamin D (+)Estrogen (decreased after menopause) (+)Leptin ```

Answer 497

GF: BMP, TGF-ß, PDGF, IGF Cytokines: Interleukins, TNF, RANKL (bone also secretes neuroendocrine factors)

Answer 498

bone formed during development characterised by randomly orientated collagen fibrils. it becomes replaces by lamellar bone

Answer 499

bone fracture repair | - forms as part of the wound healing response but eventually replaced by lamellar bone

Answer 500

compact (denser outer area) and trabecular bone (cancellous, spongy)

Answer 501

cavity filled with bone marrow interrupted by a network of bone plates (trabeculae), leaving spaces in between where the bone marrow sits

Answer 502

mandible | long bones

Answer 503

different types of bone layers

Answer 504

circumferrrential lamellae concentric (Haversian) lamellae Interstitial lamellae

Answer 505

encloses the entire outer and inner perimeter of the bone

Answer 506

forms the basic unit bone (osteon) and makes up the bulk of the compact bone

Answer 507

interspersed between adjacent osteons (remnants of remodelled osteons

Answer 508

they're transient so are constantly resorbed and formed

Answer 509

cyclinder of bone (generally parallel to the long axis of he bone)

Answer 510

``` central canal (haversian canal) including a blood capillary lined by a layer of osteoblasts volkmann's canals - interconnect adjacent central canals ```

Answer 511

they can enter through blood vessels

Answer 512

connective tissue membrane consisting of two layers

Answer 513

outer fibrous layer- dense collagen fibres | inner cellular layer- osteoblasts and their precursors, highly vascularised

Answer 514

the internal surface not well demarcated, loose connective tissue including osteoblasts; separates bone surface from marrow; less active in bone formation than periosteum

Answer 515

osteoblasts osteocytes osteoclasts

Answer 516

cuboidal cell shape | inactive: flat, bone lining cells

Answer 517

mesenchymal stem cells | synthesise organic bone matrix

Answer 518

osteoid (mainly collagen type I) alkaline phosphatase- cleaves inorganic phosphate to initiate and promote mineralisation growth factors- : IGF1, TGF-ß, PDGF which increase bone repair (dental therapy - implants)

Answer 519

osteoblasts that become trapped in unmineralised or mineralised matrix

Answer 520

spaces in the matrix produced by | osteocytes becoming smaller in size

Answer 521

canals between lacunae | formed from a network of cellular processes that connect adjacent osteocytes

Answer 522

sensors of changes in the bone environment | signalling centres to maintain bone integrity (induce bone remodelling)

Answer 523

large multinucleated cells; derived from haematopoietic cells

Answer 524

Howship's lacunae (resorption bays -holes in bone) | acid phosphates and lysosomal enzymes

Answer 525

- attachment of osteoclasts to bone - creation of acidic microenvironment for demineralisation - degradation of exposed matrix by enzymes - endocytosis of degradation products

Answer 526

mesenchymal cells in the cellular periosteum differentiate to become osteoblasts which produce woven bone (irregular) gradual turnover/remodelling of woven bone to lamellar bone - formation of primary osteon continued bone replacement produces highly organised mature bone with fewer cells, secondary and tertiary osteons and circumferential lamellae

Answer 527

mineralised bones and very few osteocytes

Answer 528

mandible takes the shape of a trough underneath the inf. alveolar nerve. the alveolar process begins to grow towards the tooth germ and will start surrounding it alveolar process almost surround the incisor tooth germ. the inferior alveolar nerve is enclosed in a bony canal to accommodate the growing tooth germ, the alveolar bone must be resorbed on the inner wall of the alveolus and new bone must be deposited on the outer wall

Answer 529

osteoblasts- area of bone formation osteoclasts- area of bone resorption (lacunae) osteocytes- osteoblasts embedded in bone bone lining cells- flat area of no bone activity

Answer 530

protection from resorption by osteoclasts initiating bone remodelling mineral metabolism source of progenitor cells

Answer 531

resorption- osteoclasts reversal- cessation of resorption, disappearance of osteoclasts formation- recruitment, migration and differentiation of osteoblasts (bone formation) resting- bone in tact but remodelled, cessation of bone formation, surface covered by flat bone-lining cells

Answer 532

resting lines- pause in bone deposition, osteoblasts stop producing bone- parallel reversal lines- change from bone resorption to deposition (position of howships lacunae)- scalloped

Answer 533

resting formation reversal resorption

Answer 534

``` buccal cortical plate lingual cortical plate cribiform perforations in bone for blood vessels and nerves to enter PDL interdental septum (between teeth) interradicular septum (between roots) ```

Answer 535

- outer compact layer: cortical plate - central trabecular layer: spongiosa - inner compact layer: alveolar plate, perforated to allow access to blood vessels connecting PDL - alveolar crest (1.5-2mm below CEJ)

Answer 536

surface layer of lamellar bone supported by osteons thinner in maxilla than mandible thickest on buccal aspect of mandibular premolars and molars

Answer 537

trabecular (cancellous) bone | -bone marrow spaces rich in adipose tissue which is an energy storage

Answer 538

in anterior teeth; cortical and alveolar plate fused

Answer 539

lamellar bone and bundle bone | - contains sharpeys fibres

Answer 540

The innermost layer of the alveolar plate (directly lining the socket) is referred to as bundle bone because the collagen fibre bundles of the PDL are embedded

Answer 541

Provides the attachment for PDL fibres | Where fibres are inserted is bundle bone

Answer 542

Resorption by osteoclasts on the right side of the alveolar plate creates the space that the tooth can move into To compensate for this bone loss new bone must be formed onto the cortical plate on the opposite side. Keeps thickness constant Because the tooth moves to the right, the space in the socket on the left must be filled by bone deposition onto the alveolar plate The excess bone must then be resorbed by osteoclasts from the cortical plate on the opposite side

Answer 543

resorption, formation, resting

Answer 544

- Unworn teeth have very few interproximal contact points - Attrition cause hard tissue loss on occlusal and interproximal surfaces - Increase in interproximal distance is compensated by mesial (forward) drift of teeth to fill the gap - Broader interproximal contact points

Answer 545

During trauma or infection can cause tooth ankylosis (fusion of tooth root to alveolar bone ) toot cannot move anymore, can no longer erupt and exfoliate Most common in primary molars e.g. partial root resorption

Answer 546

- Prevents exfoliation; leads to impaction of successor tooth - Further growth of alveolar bone results in “submergence” of ankylosed tooth - Extraction to prevent malocclusion or periodontal problems

Answer 547

alveolar plate on the dental radiograph is lamina dura An interrupted lamina dura in the apical region indicates a periapical abscess.

Answer 548

Following tooth extraction or chronic periodontitis, the alveolar process can resorb: - Placement of dental implants will be difficult - Implanting soon after tooth loss decreases the rate of alveolar ridge resorption. Should not but implant soon after bone resorbed - Bone loss impacts on construction of removable prostheses

Answer 549

the Close proximity of premolar/molar roots and alveolar bone to maxillary sinus flow means During tooth extraction, maxillary floor can rupture (bone can fracture) (oro-antral connection/fistula; infection)

Answer 550

After tooth extraction, socket fills with blood and forms blood clot: Important step in wound healing- detachment of blood clot and it falls out- 'dry socket'. leads to painful bone inflammation and bad odour

Answer 551

the part of the oral mucosa that surrounds and is attached to teeth and alveolar bone - continuum with the oral mucosa or pdl

Answer 552

tooth eruption | during eruption the REE fuses with the oral epithelium

Answer 553

simple epithelium: cuboidal cells

Answer 554

stratified squamous

Answer 555

degeneration of central epithelial cells, this causes a continuum between the 2 epithelia which prevents the tooth from creating a wound

Answer 556

there is epithelial continuity at all times between REE and OE which means there is no connective tissue exposure. if there is blood it is the remaining blood from the tooth pulp

Answer 557

junctional epithelium (JE)

Answer 558

entirely REE attaches gingiva to tooth it is non-keratinised JE is very simple and primitive

Answer 559

gingival epitehlium appears to overgrow and replaces the REE | sulcular epithelium occurs

Answer 560

Junctional epithelium Sulcular epithelium Gingival epithelium

Answer 561

simple, non keratinised

Answer 562

stratified, non keratinised

Answer 563

stratified keratinised

Answer 564

gingival cells change to sulcular which is non keratinised | stratification of early REE and rete peg formation

Answer 565

by masticatory forces acting on the gingiva base of the sulcus at the same level as free gingival groove, deeper in disease tooth

Answer 566

JE is simple non keratinised and REE is simple cuboidal - very primitive

Answer 567

the gingival epithelium appears to have completely replaced the REE small epithelial tag remains from the REE (cell remnants and primary enamel cuticle)

Answer 568

internal basal lamina that the epithelial cells sit, it covers the tooth once erupted but usually worn away by mastication

Answer 569

molecular markers REE could become stratified and develop rete pegs

Answer 570

tooth attachment is restored after gingi-vectomy | gingival tissue grafting possible

Answer 571

amelotin (AMTN; A) | odontogenic ameloblast-associated (ODAM:B)

Answer 572

in the basal lamina | normally expressed by the maturation stage ameloblasts forming the REE

Answer 573

in internal basal lamina and junctional epithelial cells

Answer 574

REE | its not a downgrowth of the gingiva

Answer 575

epithelial cells secrete it onto the enamel surface where it bonds with enamel proteins

Answer 576

half a desmosome by which cells below the internal lamina attach

Answer 577

lamina propria

Answer 578

there reduced number of desmosomes and larger intracellular spaces allows the passage of GCF and defence cells into the sulcus

Answer 579

antibodies complement factors macrophages (phagocytes) desquamated sulcular and junctional epithelial cells (5-6 days turnover) cytokines and metalloproteases (during infection)

Answer 580

inflammatory exudate which is secreted to cleanse out the gingival crevice first line of defence against bacteria

Answer 581

provide subgingival bacteria with excess nutrients potentially allowing harmful bacteria to survive tissue destruction caused by inflammation GCF can be an indicator of periodontal health

Answer 582

alveolar mucosa | submucosa

Answer 583

``` free gingival groove(border between free and attached) gingival margin gingival sulcus junctional epithelium sulcular epithelium ```

Answer 584

boundary between the alveolar mucosa and attached gingiva

Answer 585

parakeratinised (and partially orthokeratinised)

Answer 586

epithelium lamina propria mucoperiosteum (submucosa absent

Answer 587

thick parakeratinised- live cells in keratin layers can also be orthokeratinised which occurs when there is a strong masticatory force on gingiva (appears white)

Answer 588

fibres attach with underlying alveolar bone long, narrow papillae dense collagen fibres- makes tissue tough to resist masticatory forces

Answer 589

stability | submucosa acts as a cushion

Answer 590

difficult to inject and painful for patients | doesn't require suturing

Answer 591

submucosa provides mobility- acts as a cushion e.g in lining mucosa . contains loose connective tissue and salivary glands or adipose tissue. however in order to withstand masticatory forces the lamina propria is directly joined with the periosteum of bone in e.g. masticatory mucosa to provide stability

Answer 592

interdentally from CEJ over the alveolar crest to the CEJ of neighbouring tooth controls mesio-distal spacing

Answer 593

when braces come off, teeth move back into their original position due to these fibres

Answer 594

(largest group) | connects cervical cementum to lamina propria of free and attached gingiva

Answer 595

connects the alveolar bone crest to lamina propria of free and attached gingiva

Answer 596

runs from the cementum over the outer surface of the alveolar process and insert either into the alveolar process or the vestibular muscle and floor of the mouth

Answer 597

(smallest group) forms bands around the neck of the teeth and interlaces with other fibres in the free gingiva. binds free gingiva to the tooth

Answer 598

denal col- depression | doesnt attach to any teeth

Answer 599

the inflammatory response in connective tissue attracts immune cells- 70% of collagne fibres are destroyed by this. as a response the sulcular epithelium grows downwards to comepensate for the loss of connective tissue here

Answer 600

deep in growth of both epithelium

Answer 601

further destruction of connective tissue by inflammatory cells causes apical migration of junctional epithelium- forming a gingival pocket if advanced: loss of PDL and alveolar bone

Answer 602

growth until intact connective tissue is reached, compensation for the loss of mechanical stability

Answer 603

insertion of membrane which prevents cells from growing down (guided tissue regen) formation of fibrin clot against root surface

Answer 604

the insertion of membrane allows new tissue regeneration, bone can regenerate and connective tissue reformed with new fibroblasts and collagen

Answer 605

continuum from the gingiva and lines the whole mouth

Answer 606

embryonic ectoderm

Answer 607

early structure where the epithelial from the ectoderm meet the epithelia from the endoderm

Answer 608

in the pharyngeal region (inside) formed by endoderm

Answer 609

oral vestibule | oral cavity proper

Answer 610

the space between the lips, cheeks, alveolar bone and gingiva. Slit-like space between lips/cheeks and alveolar bone/teeth

Answer 611

vestibular fornix upper labial frenlum frenlum near maxillary molars

Answer 612

a large labial frenlum with an attachment site near the alveolar crest can affect the stability of dentures

Answer 613

by alveolar bone/teeth

Answer 614

anterior pillar of the fauces (palatoglossal fold)- formed by glossopalatine muscle posterior pillar of the fauces (palatopharyngeal fold) - formed by pharyngopalatine palatine tonsil uvula soft palate hard palate

Answer 615

epithelium-mesenchyme

Answer 616

``` mechanical protection-masticatory forces barrier to microorganisms and toxins immunological defence (immediate and adaptive) lubrication and buffering sensation ```

Answer 617

``` epithelial thickness degree of keratinisation interface with connective tissue composition of connective tissue presence or absence of a submucosa ```

Answer 618

60% | floor of the mouth, cheeks etc.

Answer 619

25% | mainly the hard palate

Answer 620

15% | dorsal surface of the tongue

Answer 621

``` oral epithelium (epidermis) lamina propria (dermis) submucosa (hypodermis) ```

Answer 622

stratified squamous epithelium - epithelial ridges - epithelial projections - keratinocytes

Answer 623

connective tissue - papillae - fibroblasts, macrophages, lymphocytes - collagen (I, III) and elastic fibres - blood vessels and nerves

Answer 624

loose connective tissue: fibroblasts - larger blood vessels and nerves - fat deposits - salivary glands - found in cheeks, lips, lateral palate(no clear boundary with lamina propria) - much looser than the lamina propria to provide tissue mobility

Answer 625

in lining mucosa

Answer 626

masticatory mucosa in the middle of the hard palate or the gingiva

Answer 627

skin- 27 days | oral mucosa- 9-14 days

Answer 628

basal cell layer prickle (suprabasal) cell layer granular layer keratinised layer

Answer 629

Cuboidal cells; proliferating single cell layer; basal lamina attached to lamina propria; contains stem cells and transit-amplifying cells (regeneration); expresses keratins 5 (Type II, Basic) and 14 (Type I, Acidic)

Answer 630

molecular markers e.g. to diagnose cancer

Answer 631

round, “spiny” cells (increase in desmosomes); several layers; differentiating; only parabasal cells proliferate; expresses keratins 1 and 10, loricrin and involucrin

Answer 632

Larger, flatter cells; several layers maturating loss of cell organelles and cytoplasm filled with keratohyaline granules (contain profilaggrin and lipids; secreted)

Answer 633

- Very flat cells; ~20 cell layers; - cornified (dead); no cell organelles (nucleus) - filaggrin binds keratin filaments together (“keratin”); - crosslinking of involucrin→ cornified envelope (barrier); - cell shedding (desquamation) Cornified envelope forms a barrier against microorganisms

Answer 634

orthokeratinised- hard palate, tongue parakeratinised- gingiva nonkeratinised- lining mucosa

Answer 635

cornified layer: dead cells, no cell nuclei

Answer 636

cornified layer: dead cells, | cell nuclei present

Answer 637

superficial layer: live cells | no keratohyalin granules

Answer 638

melanocytes- basal; produce melanin pigment and transfer it to keratinocytes via dendritic processes Merkel cells: Basal; sensory receptor cells => sense light touch Langerhans cells (immune cells) : Suprabasal; dendritic cells; antigen processing & presenting to immune system Lymphocytes: Often associated with Langerhans cells; Inflammatory response

Answer 639

masticatory mucosa

Answer 640

Incisive papilla: Prominence overlying nasopalatine foramen (→ denture fitting). Palatine raphe: Midline epithelial ridge; directly attached to bone Palatine rugae: Unique epithelial folds; food transport towards pharynx Alveolar bone: Submucosa present at junction with lateral hard palate Fovea palatini (openings of the ducts of minor salivary glands; posterior border for an upper denture)

Answer 641

incisive papilla | fovea palitini

Answer 642

thick epithelium can be OC or OC+PK lamina propria - long, narrow papillae - dense collagen fibres mucoperiosteum (submucosa) absent

Answer 643

lining mucosa

Answer 644

fordyce's spots parotid papilla- level of 2nd max molar, opening of parotid duct linea alba- parakeratinisation of buccal mucosa at moar occlusal plane

Answer 645

Ectopic sebaceous gland without associated hair follicle Sebum (oily substance) lubricates the buccal mucosa or the lips

Answer 646

keratinised epidermis hair follicle sebaceous gland dermis

Answer 647

lining mucosa

Answer 648

Lingual frenum Sublingual papilla- opening of the submandibular salivary ducts Sublingual folds- openings of the sublingual salivary ducts Fimbriated folds- irregular folds; remnants of tongue development Deep lingual veins

Answer 649

``` Epithelium: -Thick; Nonkeratinised Lamina Propria: -Dense; Long and slender papillae Submucosa: -Dense; firmly attached to muscle; minor salivary and sebaceous glands -Function: Mobility and Stability ```

Answer 650

``` Epithelium: -Thin; Nonkeratinised Lamina Propria: -Thin; Short papillae Submucosa: -Thin and irregular -Function: Mobility ```

Answer 651

- Vermillion zone: Lining mucosa - Intermediate zone; parakeratinised - Labial mucosa: Lining mucosa; nonkeratinised - Alveolar mucosa: Lining mucosa; nonkeratinised - Gingiva: Masticatory mucosa; parakeratinised (+ orthokeratinised) - Mucogingival junction: Junction between alveolar mucosa and gingiva

Answer 652

Transition zone between skin and labial mucosa Keratinised. Thin epithelium; numerous capillaries => red colour; contains no salivary glands, only a few sebaceous glands in corner of the mouth.

Answer 653

Mastication, swallowing, speech, taste, immune function

Answer 654

filiform papillae- masticatory fungiform papillae-taste foliate papillae- taste circumvallate papillae - taste

Answer 655

Epithelium: - Thick - Orthokeratinised (filiform papillae) Nonkeratinised (taste papillae and interpapillary regions) Lamina Propria: - Long papillae - Nerves, minor salivary glands Submucosa: -Absent (lamina propria attaches directly to muscle) Function: Stability & Taste

Answer 656

Smoother and dryer surface (→ ‘dry mouth’) Thinner epithelium, flattening of epithelial ridges (arrow) Decreased cellularity of lamina propria and increase in fibrous tissue (asterisk; fibrosis) Fewer Langerhans cells (reduced immunity) - Systemic disease - Medication (decreasing salivary flow) Increase in Fordyce’s spots (buccal, lips) Atrophy of minor salivary glands

Answer 657

Epithelial atrophy (loss of FF papillae) - smooth, often fissured surface (e. g. nutritional deficiencies; medication) Burning sensations; loss of taste – poorly understood Development of nodular, varicose veins on underside of tongue (‘caviar tongue’)

Answer 658

Hypertrophy of filiform papillae - TOO MUCH FILLIFORM PAPILLAE The papillae trap food, accumulation of food debris and microorganisms

Answer 659

(Benign migratory glossitis) Atrophy (loss) of filiform papillae; migrating depapillated patches with white border; inflammation (arrows) occurs in children

Answer 660

Painful lesions in the mouth Recurrent mouth ulcers 20% of population (familial history) starts in childhood or adolescence

Answer 661

``` Virus infections (e.g. Herpes, HIV) Iron and vitamin B deficiency Crohn’s disease ```

Answer 662

- Fungal hyphae (stained purple) - Older ages - Shows up at white spots - Fungal hyphae in the stain

Answer 663

recurrent aphtous stomatitis lichen planus- reticular patches (autoimmune disease) white sponge naevus- spongy leukoplakia- white patches

Answer 664

cellular therapy- stimulate bodys own stem cells into repairing defect tissue engineering - collagen netword to modulate tooth shape biomedical engineering gene therapy- altering genome

Answer 665

Unspecialised (undifferentiated) cells that: - can self-renew - can differentiate into other cell types Function: Development and Regeneration (become active in an injured tissue)

Answer 666

all cell types (e.g. fertilised egg)

Answer 667

all cell types of the three embryonic germ layers (e.g. embryonic stem cells) rare, not accessible in the adult body.

Answer 668

many cell types (e.g. haematopoietic stem cells; mesenchymal stem cells)

Answer 669

few cell types (e.g. Myeloid precursors -Five blood cell types)

Answer 670

four cell types (e.g. mesenchymal progenitor cells: cartilage, bone, stroma, fat) Unipotent: one cell type (e.g mast cell precursors)

Answer 671

1. Stem cell-mediated regeneration 2. Epimorphosis 3. Morphallaxis 4. Compensatory regulation

Answer 672

Replacement of lost tissue by stem cell activity. Production of new progenitors Examples: Hair growth from follicular stem cells in the hair bulge.

Answer 673

Dedifferentiation of cells at the wound site and formation of undifferentiated cells that redifferentiate to form the lost structure. Example: Planarian flatworms; Amphibian limbs

Answer 674

Repatterning of existing tissue with little new growth. Example: Hydra (freshwater polyp- if you cut across middle)

Answer 675

Differentiated cells divide and maintain their differentiated functions Example: Liver regeneration- liver injury, the cells start to divide again and maintain their function

Answer 676

Hemostasis Inflammatory response Reparative phase (epithelial response) Reparative phase (connective tissue response)

Answer 677

* Vascular damage causes hemorrhaging into the tissue defect and results in the formation of a blood clot (Coagulation: fibrin deposition & aggregation of platelets) * Forms barrier that unites the wound margins and protects the exposed tissue; provides provisional scaffold for subsequent colonisation by reparative cells.

Answer 678

Cell activation, migration and function Microorganisms and toxins have likely entered through the wound and induce an acute inflammatory response Leakage of plasma proteins and platelet-derived cytokines and growth factors leukocyte migration towards the wound Neutrophils- kill bacteria (appear within a few hours) Monocytes- remodelling lymphocytes- humoral (appear after 24hrs)

Answer 679

epithelial response Mobilisation of epithelial cells within 24 hours Increased basal cell proliferation and epithelial cells adjacent to the wound margin start to migrate beneath the blood clot (24-48 hours). basal lamina deposition facilitates movement and epithelial sheet formation (stratification- squamous stratified ep produced) Migration stops when cells reach opposing wound margin and increased cell proliferation and differentiation leads to stratification

Answer 680

connective tissue response Fibroblasts proliferate and migrate into wounded connective tissue within 24- 48 hours and deposit disorganised collagen fibres Formation of new blood capillaries from existing vessels (angiogenesis) at the wound margin ECM (fibronectin, laminin, collagen) formed by new fibroblasts provides scaffold for forming blood vessels. scar tissue formation-Increased collagen deposition between days 5 and 20 but reduced tensile strength

Answer 681

VEGF, FGF and TGF-β

Answer 682

nutrients and oxygen, enable access of inflammatory cells, stimulate connective tissue formation

Answer 683

its remodelled and converted into better alignment of collagen fibres in around 5 months

Answer 684

First fibroblasts to enter the wound site are contractile myofibroblasts and Pull the wound together Different from connective tissue fibroblasts Pericytes implemented in the formation of myofibrocytes- pull wound together Form connections with each other and with collagen fibrils → alignment Contraction draws edges of the wound together

Answer 685

inferior quality deposition of disorganised collagen leads to immobilisation and rigidity at repair site remodelled in oral mucosa - wound regenerates to normal function

Answer 686

they do not involve the inflammatory response

Answer 687

repair: tooth socket fills with a clot epithelial response: epithelialisation of socket (by day 10) inflammatory response: polymorph and macrophage response osteogenic precursors migrate into blood clot proliferation phase: osteoblasts differentiate and form bone

Answer 688

Day 3: Colonisation of gingival wound by epithelial cells and formation (regeneration) of the junctional epithelium Day 5-7: Expansion and down-growth of the junctional epithelium. Re-establishment of dento-gingival junction

Answer 689

PDL fibres must insert into cementum and bone | Coordinated repair requires complex regulation at cellular and molecular level

Answer 690

Fibroblasts- remodelling collagen fibres Endothelial cells- form new blood vessels from existing vessels Cementoblasts- perivascular and endosteal fibroblasts Osteoblasts- mesenchymal progenitor cells in the endosteum or periosteum

Answer 691

No inflammation, e.g. tooth movements

Answer 692

Inflammatory response required to combat infection and initiate repair

Answer 693

chronic inflammation inhibits stem cell activation, cell recruitment, cell proliferation and differentiation so cannot restore tissue function

Answer 694

Dental plaque accumulation causes inflammatory response in connective tissue. -70% of collagen fibres destroyed within 3-4 days!

Answer 695

Further destruction of connective tissue by inflammatory cells causes apical migration of junctional epithelium (arrow) Formation of gingival pocket. Advanced: Loss of PDL and alveolar bone.

Answer 696

Growth until intact connective tissue is reached Compensation for loss of mechanical stability.

Answer 697

Insertion of membrane (physical barrier). Guided tissue regeneration preventing abnormal wound healing by inducing the clot

Answer 698

EGF, FGF, IGF, PDGF, TGF-ß

Answer 699

Forms a link between the fibroblasts and collagen fibres

Answer 700

Cementum formation may stimulate periodontal repair. Loss of bone in PD- reinduction if new bone in the area required to save the tooth

Answer 701

Remineralisation by calcium, phosphate and fluoride ions in saliva

Answer 702

can be reversed WSL reversible if surface enamel intact (underlying body may contain destroyed enamel prisms) and acid producing bacteria are removed remineralisation by ion precipitation from saliva

Answer 703

Extent and duration of stimulus Structural variations in dentine:open or occluded dentinal tubules Age of tooth:Smaller pulp chamber, diminished blood and nerve supply

Answer 704

Occlusion of dentinal tubules: Collagen plug or sclerotic dentine – closes up tubules Reactionary dentine in the pulp: formed by existing odontoblasts (slow, tubular)

Answer 705

Reactionary dentine: could form if odontoblasts survive (slow, tubular) Reparative dentine: formed by newly differentiated odontoblast-like cells if original odontoblasts have died (rapid, amorphous, less collagen

Answer 706

e. g. from 3rd molars; primary teeth: - Dental pulp (DPSC) - Dental pulp from exfoliated primary teeth (SHED) - Dental follicle of unerupted teeth - Periodontal ligament (PDLSC) - Root apical papilla (SCAP) Tooth germs - Epithelial rests of Malassez

Answer 707

1. Tissue engineering: a) Biodegradable scaffolds for cell seeding; 3D printing b) Bioengineering, material sciences and nanotechnology: - Nano)materials with novel properties that can be stimulate biological tissues c) Implants with bioactive surfaces allowing for better tissue integration. 2. Gene therapy: Ex vivo or in vivo • CRISPR/Cas9 genome editing tools; RNAi; novel viral delivery vectors • May not be applied well in dental practice

Answer 708

Conventional: amalgam, composites, metallic implants, tissue grafts. Limitations: non-biological, immune rejection, pathogen transmission, lack of remodelling with recipient tissue, donor site morbidity. Novel: Engineering of precise tissue shape using biodegradable scaffolds onto which cells can grow and re-establish morphology and function.

Answer 709

to the root and then to the cementum in the PDL and to the bone.

Answer 710

Collagen Vascular supply Nerve endings – pain & proporioception Fluid – shock absorber contains undifferentiated mesenchymal cells → fibroblasts & osteoblasts

Answer 711

osteoblasts osteoclasts osteocytes

Answer 712

to the root and then to the cementum in the PDL and to the bone.

Answer 713

Collagen Vascular supply Nerve endings – pain & proporioception Fluid – shock absorber contains undifferentiated mesenchymal cells → fibroblasts & osteoblasts

Answer 714

osteoblasts osteoclasts osteocytes

Answer 715

PDL doesn't compress, alveolar bone bends which sends a piezoelectric signal

Answer 716

force applied to crystalline structure (bone/collagen) movement of electrons short flow of current

Answer 717

PDL fluid expressed | Tooth moves in socket

Answer 718

PDL fluid redistributed | Tissue compressed- pain

Answer 719

tooth moves in socket | bone changes occur

Answer 720

Piezoelectric effect Streaming potential- movement of ground substance Change in blood flow- increase in tension, decrease in compression Microfractures- hyalinisation * Chemical signals- e.g. prosdaglandins, IL-1, Leukotrienes, MMPs * Cellular response- osteoblasts, osteoclasts, osteocytes * Systemic response- PTH, VitD, Calcitonin etc.

Answer 721

force tooth PDL and bone biological electricity & pressure-tension osteoblasts (tension) and osteoclasts (compression) bone resporption/deposition

Answer 722

blood vessels in PDL occluded on pressure side

Answer 723

blood flow cut off to compressed PDL area

Answer 724

Cell death in compressed area- hyaline layer. Bone adjacent to squashed PDL doesn’t have a blood supply

Answer 725

Cell differentiation, undermining resorption starts

Answer 726

undermining resorption removes lamina dura, tooth movements

Answer 727

blood vessels in PDL - Pressure side- partially compressed on pressure side - Tension side- dilated

Answer 728

blood flow altered, this allows release of cytokines

Answer 729

metabolic changes - Chemical messengers- cellular activity - Enzymes

Answer 730

cell differentiation in PDL e.g. osteoclasts and osteoblasts

Answer 731

tooth movement more gradual by remodelling

Answer 732

``` Tipping Translation/ Bodily Movement Rotation Extrusion Intrusion ```

Answer 733

Simple movement Around centre of resistance Tips the tooth 1/3 from apex Forces greatest furthest from CoR- forces on the tooth are greatest at the apex. Can be achieved by any appliance Force 50-75g

Answer 734

Harder to achieve- moving tooth through the bone All PDL uniformly loaded Force 100-150g

Answer 735

Theoretically need high force BUT Tipping occurs → Excessive compression of PDL Force – 50-100g Not too hard to achieve with fixed appliance

Answer 736

Pull out the bone Produce tension in PDL fibres- don’t want too high of a force or risk of loss of vitality of tooth Force 50-100g

Answer 737

Push into the bone Forces concentrated at root apex Fairly low force Force 15-25g Missing part of tooth- tooth moved with too heavy of force, damage to cementum, osteoclasts get to the dentine and caused root resorption

Answer 738

Transient inflammatory response Can cause loss of vitality

Answer 739

Root resorption inevitable Commonly decreased 1-2mm root length Some repair – however only ever filled in by cementum (rest periods) Increased with: Distorted apices (roots bend) , Thin roots, Compromised teeth, Excess force, History of root resorption, Asthma

Answer 740

Minimal transient damage BUT : lose ½-1mm of alveolar crest

Answer 741

Minimal transient damage Unless: Excess force maintained, Existing periodontal disease, Important in relapse- teeth go back to where they were

Answer 742

Protects tooth from root resorption Limited capacity to repair

Answer 743

Tooth won’t move In growing patient causes infraocclusion Root fused to the bone Periodontal ligament lost, bony union between tooth and bone Tooth sounds ‘tinny’ on percussion. Aetiology often trauma

Answer 744

* Root resorption * Ankylosis * Decalcification * Retention / relapse

Answer 745

teeth tend to continue to erupt if no occlusal contacts- Tendency for teeth to erupt to maintain contact Problems: gingival trauma , restoration difficult, occlusal problems Not inevitable- within limits bone/growth Importance: restorations Anterior wear- continue to erupt and maintain contact

Answer 746

Teeth drift mesially Maxilla > mandible Early loss of primary teeth- space loss so posterior teeth drift Importance to space maintain Mesial drift can be useful- if early loss of first molars, second molars can erupt mesially

Answer 747

Mandible continue to grow after maxilla stops, mandibular teeth don’t have anywhere to go so stay crooked. other theories pressure from Third molars? Mesial drift?

Answer 748

progressive thinning of enamel due to tooth wear and thickening of dentine produces yellowish teeth stains become trapped in microscopic pits of enamel during enamel remineralisation

Answer 749

pronounced striae of retzius

Answer 750

produce free oxygen radicals that penetrate through the enamel pores and reduce large chromogenic molecules to smaller molecules that might diffuse out of the pores or absorb less light.

Answer 751

over time the enamel surface becomes more mineralised by incorporation of fluoride present in saliva- this forms fluorapatite rather than hydroxyapatite, which is more resistant

Answer 752

Remineralisation of enamel by re-incorporation of calcium, phosphate and fluoride ions that are present in saliva

Answer 753

Shift towards demineralisation causes caries. Earliest sign on teeth: ‘White spot lesion’

Answer 754

hypomineralised lesions have a shiny appearance, whereas chalk-white lesions don't (they're active and non cavitated)

Answer 755

Dark zone: enamel remineralisation is ongoing Translucent zone: enamel demineralisation

Answer 756

transmitted v polarised Surface zone: Greenish/brown → Blue Body of lesion: Orange → ‘Light’ black Dark zone: Black → ‘Dark’ black Translucent zone: Not visible here

Answer 757

may represent a combination of enamel staining and hypomineralised enamel undergoing remineralisation, or where a WSL has developed, but has been arrested over time.

Answer 758

lines the pulp and root canals after the completion of tooth roots more common on the roof and floor of pulp chamber (masticatory forces directly act in the cusp region) pulp recession

Answer 759

continuous with primary dentinal tubules but fewer in number due do odontoblast death contour line of owen- tubules can bend between primary and secondary dentine

Answer 760

on the walls of dentinal tubules | Begins to form in outermost dentine

Answer 761

About 90 % mineralised Usually does not contain collagen Can fill whole dentinal tubules

Answer 762

formation of sclerotic dentine

Answer 763

Physiological: - Ageing process - Found mostly in roots Pathological: - Response to caries - It is Found between carious lesion and pulp- in the dentine directly affected by progression of caries lesion

Answer 764

Reactionary dentine: slow response mediated by existing odontoblasts lining the dental pulp, fewer tubules. => response to tooth wear (attrition) Reparative dentine: rapid response mediated by new odontoblast-like cells induced from dental pulp stem cells (existing odontoblasts have died), less structure. => response to caries or cavity preparation

Answer 765

slow, natural wear of the crown

Answer 766

peritubular dentine formation dentine becomes less permeable and insensitive if exposed reactionary dentine forms in the pulp to compensate for dental tissue loss

Answer 767

``` Young tooth: • Little tooth wear • Larger pulp volume • Defined pulp horn • Pulp volume large Old tooth: • Worn cusp • Smaller pulp volume • Pulp horn filled in with reactionary dentine to compensate for tissue loss • Narrowed root canal – due to ageing as well ```

Answer 768

Group of odontoblasts die due to continuous, strong stimulus Results in reparative dentine formation that acts to seal off the pulp from invading micro- organisms The tubules do not contain odontoblast processes anymore Empty dentinal tubules contain air causing a dark appearance on ground sections

Answer 769

Decreased number of cells (e.g. odontoblasts) size reduction of the pulp chamber Calcified structures in pulp

Answer 770

False pulp stones: Have not been produced by odontoblasts, they are calcified areas characterised by Concentric layers of calcified degenerated pulp tissue. True pulp stones (Denticles): - Produced by true odontoblasts - Organic matrix and dentinal tubules Diffuse calcifications: - Through the pulp - Usually associated with blood vessels or collagen fibres- as you age blood vessels can calcify

Answer 771

Cementum thickness increases 3x from 16-70 years of age | Cellular cementum- Forms at root apex in response to attrition at the occlusal surface

Answer 772

increase in cementum - response to physiological process such as attrition - Pathological process causing excessive build up

Answer 773

Decrease in cell numbers, density and mitotic activity Fibroblasts have shorter live spans and diminished collagen synthesis and degradative activity Increased collagen fibrosis, thicker fibre bundles and mineralisation of fibres Irregular insertions of Sharpey’s fibres Teeth become less “mobile” (→ decreased remodelling capacity able to move teeth in the jaw)

Answer 774

Loss of teeth => loss of alveolar bone

Answer 775

Thinning of tongue epithelium on dorsal and lateral surfaces (oral cancer) Reduced taste sensation Gingival recession – but may be unclear if due to decreased oral hygiene or normal age change Increasing susceptibility to precancerous lesions and oral cancer

Answer 776

Decrease in amount of glandular tissue Increase in fibrous tissue, fat cells and inflammatory cells. Dry Mouth (Xerostomia): - Usually not presented in healthy older people - Associated with increased use of medications - Increases the rate of attrition (due to reduced enamel mineralisation

Answer 777

natural process - tooth wear caused by mastication, e.g. contact with food particles Affects interproximal and occlusal surfaces Reactionary dentine has formed in response to attrition and blocked off the dentine tubules, which have become dead tracts.

Answer 778

tooth wear caused by chewing with abnormal movement or habitual jaw clenching, e.g. bruxism

Answer 779

tooth wear caused by frictional contact with foreign objects, e.g. pipe smoking

Answer 780

progressive loss of hard tissues due to chemical dissolution Dietary: e.g. carbonated drinks, fruit/citrus juices and other acidic drinks and foods. Environmental: e.g. competitive swimmers & professional wine tasters Medication: e.g. Iron tonics, vitamin C and nutritional supplements.

Answer 781

Pathological attrition Habitual jaw clenching and tooth grinding: Flat occlusal plane Dentine hypersensitivity due to exposed dentine

Answer 782

V-shaped cervical lesions due to: • excessive tooth brushing • abrasive toothpastes

Answer 783

Regurgitated stomach acid • Acid reflux or repeated vomiting • Eating disorders: Anorexia, Bulimia • After vomiting, tooth brushing should be avoided for one hour

Answer 784

Enamel doesn’t dissolve in calcium-phosphate super-saturated saliva (pH 7) but at pH < 6, saliva is under-saturated and cannot efficiently remineralise the acid. Acidic dissolution initiates erosion and makes the tooth more susceptible to abrasion. The lower the pH of the oral environment, the higher is the enamel surface loss.

Answer 785

Amount of drink consumed Frequency & manner of consumption Timing of consumption Strength of acid

Answer 786

* Diabetics who consume fruit juice * People who have low salivary flow (e.g. older people on medication) should avoid acidic drinks * Children with asthma (Inhaling lowers the pH) * Consumers of sports drinks (high sugar) * Ecstasy and cocaine users

Answer 787

host diet time microbes

Answer 788

subsurface translucent zone development of dark zone early WSL cavitation, spread along ADJ, relative changes in dentine

Answer 789

can arrest the decay if just filled with a sealant

Answer 790

caries is arrested as a metal crown is placed over the tooth, which will remove the substrate going to the caries

Answer 791

``` dentine hypersensitivity reversible pulpitis irreversible pulpitis apical periodontitis (asymptomatic/symptomatic) peri-apical abscess (acute/chronic) ```

Answer 792

short sharp pain arising from exposed dentine in response to stimuli (e.g. periodontitis so dentine exposed due to gum recession)

Answer 793

thermal, evaporative, tactile, osmotic (e.g. draws fluid through tubules) or chemical

Answer 794

rapid shifts of fluid within the dentinal tubules, following stimulus application, results in activation of sensory nerves in the inner dentine region of the tooth

Answer 795

1. dentine innervated directly 2. odontoblasts act as receptors 3. odontoblasts at the base of odontoblasts are stimulated directly or indirectly by fluid movement through the tubules

Answer 796

block tubules de-sensitising agents adhesive restorations- physically block tubules elective devitalisation- remove the nerve from the tooth

Answer 797

1. removal of dentinal tubule plugs by oxygenating bleaching gels that remove micro debris within the tooth 2. outward movement of fluid within the dentinal tubules due to osmosis from bleaching gels

Answer 798

Tooth with crack or fracture Exhibits a sudden sharp pain- fluid pushed through the tubules Usually on mastication and classically on release of pressure. Non vital teeth/ obturated teeth can give ‘dull ache’ and be sensitive to mastication.

Answer 799

History Orthodontic band Transillumination- shine light through the tooth Dyes Magnification Tooth sloth- specific occlusal force can be place on one cusp

Answer 800

Bonded restoration ‘Cuspal coverage’ (crown) Endodontic treatment Extraction

Answer 801

caries defective restorations trauma dens investigation

Answer 802

chronically inflamed pulp- can be painless acutely inflamed pulp can be painful with stimuli from hot, cold, sweet

Answer 803

pain is short in duration pain disappears when stimulus is removed poorly localised

Answer 804

remove irritant and restore preserve pulp review

Answer 805

Pain is longer in duration. Pain persists (minutes to hours) when stimulus removed. Cold can reduce pain- dental emergency clinic Poorly localised May have percussion sensitivity- sore when pressure applied Spontaneous pain

Answer 806

Pulpotomy- half of pulp removed Pulpectomy- all of pulp removed Extraction Not antibiotics- not bacterial infection

Answer 807

remove the worst, seal and then re-enter

Answer 808

Symptomatic apical periodontitis Asymptomatic (chronic) apical periodontitis Acute apical abscess Chronic apical abscess Cyst formation (radicular)- unsure why.

Answer 809

TTP, can respond to sensibility tests, can have apical widening of periodontal ligament.

Answer 810

Not TTP, no response to sensibility tests, usually shows apical radiolucency.

Answer 811

TTP, non- responsive, swelling (intra or extra-oral), febrile, lymphadenopathy.

Answer 812

As for asymptomatic apical periodontitis but with draining sinus. Can be mildly TTP.

Answer 813

Irreversible pulpitis

Answer 814

Acute apical periodontitis | Beyond pulpitis- pulp necrotic

Answer 815

Abrasion, abrasive tooth wear