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BDS 1 > Oral Cavity > Flashcards

Oral Cavity Flashcards

1
Q

What is Waldeyer’s ring?

A

Incomplete ring of lymphoid tissue in naso-oropharynx

Body’s first line of defence against microbes

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2
Q

What are the main structures of Waldeyer’s ring?

A

Tonsils: lingual, pharyngeal, tubal, palatine

Lymphatic tissue: throughout mucosal lining of pharynx

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3
Q

What are the 6 functions of the oral cavity?

A
  1. Ingestion of food and liquid
  2. Mastication
  3. Ventilation
  4. Immunological
  5. Taste
  6. Speech
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4
Q

What are the 5 features of the maxillary vestibule?

A
  1. Vestibule
  2. Sup. labial frenulum
  3. Labial mucosa
  4. Alveolar mucosa
  5. Attached gingiva
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5
Q

What are the 2 features of the mandibular vestibule?

A
  1. Vestibule

2. Inf. labial frenulum

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6
Q

What are the 2 structures of the palate?

A
  1. Rugae - identify bodies

2. Palatine raphe - feature from development of palate (fusion of plates)

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7
Q

What are the 4 papillae on the tongue?

A
  1. Circumvallate - ~12 pointing towards oropharynx
  2. Filiform - sensitivity to vits.
  3. Fungiform - mushroom shape, tastebuds
  4. Foliate - irritated by teeth
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8
Q

What are the 2 structures of the floor of the mouth?

A
  1. Lingual frenulum

2. Sublingual papillae/folds

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9
Q

What are oral ulcers?

A

Break in surface continuity of mucosa with resulting loss of surface epithelium and exposure of underlying CT

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10
Q

Define primary and secondary ulceration

A

Primary: began as an ulcer
Secondary: began as a blister or vesicle before breaking down

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11
Q

What is RAS?

A

Recurrent aphthous stomatitis - recurrent ulcers with no obv. cause

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12
Q

What are the 3 types of RAS? Describe the main differences

A
  1. Minor: <5mm, round, shallow; erythematous halo, yellow floor
  2. Major: >1cm, deep, irregular; erythematous halo, yellow floor, scars
  3. Herpetiform: 1-2mm; >20 present, may coalesce form irregular ulcers, erythematous background
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13
Q

What are the 9 main functions of saliva?

A
  1. Diagnostic
  2. Preventative
  3. Protection
  4. Buffering
  5. Digestion
  6. Antimicrobial
  7. Maintenance of tooth integrity
  8. Taste
  9. Retention of denture
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14
Q

What are the 5 main components of saliva?

A
  1. Water
  2. Mucus
  3. Electrolytes
  4. Enzymes
  5. Antimicrobials
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15
Q

What are some inorganic components of saliva?

A

Ions

Na, Cl, K, PO4, HCO3, F, Ca

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16
Q

What is the relationship between flow rate and conc. of saliva components?

A

Proportional

Flow rate inc., inc. conc.

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17
Q

Apart from proteins name 8 other organic components of saliva

A
  1. Carbs
  2. Blood group substances
  3. Lipids
  4. AAs
  5. Urea
  6. Ammonia
  7. Glucose
  8. Cortisol
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18
Q

What are the 9 functions of proteins in salvia?

A
  1. Buffering
  2. Digestion
  3. Mineralisation
  4. Antiviral
  5. Antifungal
  6. Antibacterial
  7. Tissue maintenance
  8. Lubrication
  9. Tissue coating
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19
Q

What are the 2 main structures found in salivary glands?

A
  1. Acini: secrete saliva; mucous, serous, myoepithelial

2. Ducts: transport and alter saliva; intercalated, striated, secretory

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20
Q

What is resting secretion?

A

Saliva that is constantly produced, day and night

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21
Q

Why is resting secretion important?

A

Saliva breaks down self so more is required to be produced

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22
Q

What is the function of resting secretion?

A

Keep mouth and oropharynx moist, lubricated and protected

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23
Q

What 5 receptors can stimulate saliva?

A
  1. Olfactory - smell, taste
  2. Mechanoceptors - chewing
  3. Gustatory - start digestion
  4. Nociceptor - lick wounds
  5. Higher centres - possibly, control flow
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24
Q

What is whole mouth saliva?

A

Mixed saliva secretions from all glands

Composition and volume can vary greatly depending on type and length of stimuli

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25
Q

What are the 3 major salivary glands?

A
  1. Parotid
  2. Submandibular
  3. Sublingual
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26
Q

Describe the secretions from the 3 major salivary glands

A

Parotid: serous, high amylase, low Ca
Submandibular: mixed, high Ca
Sublingual: more mucous, high mucins

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27
Q

Describe the secretions from the minor salivary glands

A

Highly mucous

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28
Q

Describe the innervation of the salivary glands

A

PSNS: H2O release, vasodilation; watery and electrolyte rich
SNS: exocytosis; inc. protein synthesis, thick(?)

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29
Q

What are the 4 functions of mucin?

A
  1. Tissue coating
  2. Lubrication
  3. Bacterial aggregation
  4. Bacterial adhesion
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30
Q

What are the 4 main causes of xerostomia?

A
  1. Disease: autoimmune, Sjorgens
  2. Therapy: chemotherapy, H&N radiotherapy
  3. Medication: antidepressants, antihypertensive
  4. Disorder: HIV, psychogenic
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31
Q

What are the symptoms of xerostomia?

A 
Mucosa: dry, glossy, atrophic changes 
Tongue: glossitis, fissured, red, papilla atrophy
Rampant caries
Periodontitis, candidiasis, halitosis
Difficulty in speech and swallowing
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32
Q

What are some treatments for xerostomia?

A

Inc. water intake
Treat underlying condition
Artificial saliva
Chew gum i.e. trigger receptors

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33
Q

What are the 5 functions of the oral mucosa?

A
  1. Mechanical protection: compression, shearing
  2. Barrier: bacteria, toxins, antigens
  3. Immunological defence: humoral, cell-mediated
  4. Lubricate saliva
  5. Innervation: touch, pain, taste
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34
Q

What are the 3 functional classifications of oral mucosa?

A
  1. Masticatory
  2. Lining
  3. Specialised
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35
Q

Describe the masticatory mucosa

A

Area: high compression and friction; gingivae, hard palate

Highly keratinised, thick lamina propria

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36
Q

Describe lining oral mucosa

A

Area: mobile and distensible; cheeks, lips, alveolar mucosa, floor of mouth, ventral tongue, soft palate
Non-keratinised, loose lamina propria

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37
Q

Describe specialised oral mucosa

A

Area: dorsal surface of tongue (taste buds); vermilion of lips (transition between skin and oral mucosa)

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38
Q

What are the 4 layers of oral mucosa?

A

Deep to superficial

  1. Submucosa
  2. CT (lamina propria)
  3. BM (basal lamina)
  4. Stratified squamous epithelium
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39
Q

Compare keratinised, non-keratinised and parakeretinised stratified squamous epithelium

A

Keratinised: non-viable cells w/o nuclei, filled with keratins (stratum corneum)
Non-keratinised: viable cells w/ nuclei (no stratum corneum)
Parakeratinised: mix of non-viable cells w/o nuclei, apoptotic cells with shrivelled nuclei

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40
Q

Describe the layers of keratinised stratified squamous epithelial

A
  1. Stratum basale: resting on BM, stem and TA cells
  2. Stratum spinosum: large, round, prickly appearance due to desmosomes, produce keratin
  3. Stratum granulosum: keratohyaline granules, larger, flatter
  4. Stratum corneum: keratinised, mechanical protection, filled with keratins, no desmosomes, sheds off
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41
Q

Describe the layers of non-keratinised stratified squamous epithelium

A
  1. Stratum basale: resting on BM, TA and stem cells, give rise to other layers
  2. Stratum spinosum: prickly, larger, rounder, produce keratins
  3. Stratum intermedium: larger, flatter, no keratohyaline granules
  4. Superficial layer: nuclei present, no desmosomes, sheds off
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42
Q

What are keratins?

A

Fibrous structural proteins composed of intermediate filaments found in all epithelia

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43
Q

What is the function of the basal lamina?

A

Mechanical adhesion between epithelium and CT

Barrier between them

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44
Q

What are the 2 layers of the basal lamina?

A

Lamina lucida: made of laminin, adjacent to epithelia

Lamina densa: made of collagen T4, adjacent to CT

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45
Q

How does the basal lamina link CT to epithelial?

A

Hemidesmosomes

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46
Q

What are the 2 layers of lamina propria?

A
  1. Superficial: thin, loosely arranged collagen

2. Deep: thick parallel bundles of collagen

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47
Q

What cells and structures are present in the lamina propria?

A

Cells: collagen, elastin, oxytalan fibres, proteoglycans - glycoproteins, macrophages, lymphocytes, mast cells, fibroblast producing ECM

Structures: blood vessels, nerve endings

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48
Q

Describe sulcular epithelium

A

Non-keratinised

Not in direct contact with enamel

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49
Q

What is the gingival sulcus?

A

Natural space between tooth and free gingiva

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50
Q

Describe junctional epithelium

A

Non-keratinised
Seals off underlying CT and bone
Direct contact with enamel via hemidesmosomes

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51
Q

Why is the junctional epithelium permeable?

A

Allows tissue fluid and immune cells to pass through into gingival sulcus for defence against invading OB

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52
Q

Explain how plaque formation damages the mucosa

A

Plaque causes recruitment of inflammatory cells, initially limited and little neutrophil emigration
As gingivitis continues; heavy neutrophil emigration, gingival crevice enlarged, extensive subgingival plaque
Periodontitis: gingival recession with fibrosis in CT, extension of subgingival plaque, apical migration and ulceration of junctional epithelium, alveolar bone resorption and periodontal ligament loss

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53
Q

What are the 3 main parts of a tooth?

A
  1. Root: below gum line; dentine covered by cementum
  2. Crown: visible part; dentine covered by enamel
  3. Pulp: centre of tooth, blood and nerve supply
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54
Q

What is the cemento-enamel margin/junction?

A

Border where enamel and cementum meet

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55
Q

What is the enamel-dentine junction?

A

Border between enamel and dentine

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56
Q

What are ameloblasts and odontoblasts?

A

Ameloblasts: enamel secreting cells, move from EDJ to surface
Odontoblasts: dentine secreting cells, move from EDJ to pulp

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57
Q

What are the 3 components of enamel?

A
  1. Hydroxyapatite crystals
  2. Organic material: amelogenin, enamelin
  3. Little water
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58
Q

What are some of the properties of enamel?

A

Derived from ectoderm
Can’t repair self: some capacity to remineralise
Brittle
Low tensile strength
Hardest biological tissue
High modulus of elasticity
Semi-permeable membrane: allows ions from salvia in, ionic substitution

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59
Q

What is the function of enamel?

A

Protective: withstand shearing and impact, resist abrasion

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60
Q

Describe the structure of enamel

A

Long, hexagonal HA crystallises arranged in rods/prisms grow from EDJ to surface in sinuous path

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61
Q

What are Striae of Retzius, surface perikymata and cross-striations?

A

Striae of Retzius are growth lines representing ~7 days in between are cross-striations showing daily growth
Cross-striations grow along enamel prism perpendicular to long axis of rod
Surface perikymata are external manifestations of Retzius lines when they overlap each other forming shallow grooves

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62
Q

What pattern of enamel do humans have?

A 
Pattern 3 - keyhole 
Thick head (towards crown) and narrow tail (towards neck)
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63
Q

How many ameloblasts contribute to 1 keyhole prism

A

4: 1 in head and 3 in tail

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64
Q

Describe the path of enamel prisms within enamel

A

Parallel to each other and at oblique angle at origin (EDJ) and termination (surface)

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65
Q

What is different about surface enamel?

A

Aprismatic - structureless
Crystallites aligned parallel to each other and perp. to surface
Highly mineralised

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66
Q

What are Tomes processes?

A

Picket fence projection caused by ameloblasts moving away from new enamel, absent in final stage of enamel deposition

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67
Q

What are Hunter Schreger bands?

A

Optical effect of light and dark ‘bands’ of enamel caused by bundles crossing each other in layers at right angles as travel from EDJ

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68
Q

What is the purpose of enamel bundles overlapping?

A

Strengthen structure
Prevent cracks
Resist fractures

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69
Q

What are the 3 weaknesses present at the EDJ?

A

Tufts: hypo-calcified enamel rods, only at EDJ
Lamellae: hypo-calcified enamel rods, structural fault from EDJ to surface
Spindle: dentine tubule ends trapped in enamel

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70
Q

What is the clinical importance of enamel?

A

Prevent demineralisation
Promote remineralisation
Restore cavitated enamel
Diagnose and treat developmental enamel malformations

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71
Q

What are the functions of incisors?

A

Cutting, scooping, picking up objects, grooming

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72
Q

What are the functions of canines?

A

Holding prey, display, puncture, slashing and tearing while fighting

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73
Q

What are the functions of premolars?

A

Holding, carrying, breaking food into small pieces

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74
Q

What are the functions of molars?

A

Shearing, crushing, grinding food into small pieces

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75
Q

How are teeth charted?

A

Maxillary right central incisor = UR1 OR 11

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76
Q

What are the 5 planes of ant. and post. teeth?

A

Ant: mesial, labial, distal, lingual, incisor edge
Post: mesial, buccal, distal, lingual, occlusal

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77
Q

What is diphyodont?

A

2 successive sets of teeth

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78
Q

What is thecodont?

A

Teeth with roots firmly fixed in socket with ligaments

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79
Q

What is heterodont?

A

Different tooth types

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80
Q

What are mamelons?

A

Ridges on incisal edge of new teeth

Rapidly worn down

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81
Q

What are cusps?

A

Major elevations on masticatory surface of 3s and post. teeth

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82
Q

What are ridges?

A

Variable, linear elevations on crown of tooth

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83
Q

What tooth has the longest root?

A

U3s

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84
Q

What teeth are single rooted?

A

U: 1, 2, 3, 5s
L: 1, 2, 3, 4, 5s

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85
Q

What teeth have 2 roots?

A

U: 4s
L: 6, 7, 8s

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86
Q

What teeth have 3 roots?

A

U: 6, 7, 8s

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87
Q

In what direction to root usually curve?

A

Distally

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88
Q

What are the main differences between maxillary and mandibular teeth?

A

Incisors: max long, well-rounded roots; man small, flattened roots
Canines: max bulbous on M and D aspect; man flattened M
Premolars: rectangular O outline; circular O outline
Molars: square/triangular O outline, 2B, 1P root; rectangular O outline, 1M, 1D root

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89
Q

What are the distinguishing factors between maxillary teeth?

A

Incisors: 1 much larger than 2
Premolars: 4 has B and L roots, canine fossa and developmental groove; 5 single root and no fossa or groove
Molars: 6 4 cusps, spaced roots, 7/8 smaller, roots may be fused

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90
Q

What are the main differences between mandibular teeth?

A

Incisors: 2 larger than 1, 2 crown appears rotated on root
Premolars: 4 v small L cusp, ML developmental groove; 5 L and B cusp of equal height
Molars: 6 3B, 2L cusps, 7 4 cusps, 8 irregular crown arrangement, roots may be fused

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91
Q

What are cusps of Carabelli?

A

Extra cusp on palatial surface of palatal cusp on upper molars

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92
Q

What are the main distinguishing factors between deciduous and permanent dentition?

A

5 teeth in each quadrant vs 8
ABCs markedly smaller than permanent 123s
DEs larger than 45s that replace them
Deciduous crows more bulbous
Deciduous less mineralised; crown more susceptible to wear
Roots smaller, thinner; D, Es divergent allowing space for premolars to grow

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93
Q

Which deciduous teeth have 1 root?

A

ABCs

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94
Q

Which deciduous teeth have 2 roots?

A

L: DEs

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95
Q

Which deciduous teeth have 3 roots?

A

U: DEs

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96
Q

What are the main differences between permanent and deciduous teeth?

A 
Number: 20vs32
Size: smaller, narrower, shorter
Structure: thinner enamel
Crown shape: molars less complex
Root shape: robust, spindly, divergent
Pulp size, shape: relatively larger, prominent horns
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97
Q

What are the 4 theories of tooth eruption?

A
  1. Root growth
  2. Bone remodelling
  3. Dental follicle
  4. Periodontal ligament
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98
Q

What are the 4 processes of tooth development and eruption?

A
  1. Pre-eruptive movement
  2. Intra-issues, tooth in alveolar bone
  3. Mucosal penetration: clinical emergence
  4. Post-occlusal movement: passive eruption
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99
Q

What are the 4 stages of dentition?

A
  1. Edentulous: before any teeth erupted
  2. Deciduous: 6m-5y
  3. Mixed: 6-12y
  4. Permanent: 12y+
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100
Q

Outline the timeline of deciduous eruption

A

6-12m: LABs, UABs

14m: Ds
18m: Cs
24m: Es

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101
Q

Outline the timeline of permanent dentition

A

Phase 1: 6-8y: [16] 2
Phase 2: 10-12y: [467] 3
Phase 3: 17-20y+: 8

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102
Q

What are the 2 stages of tooth development?

A
  1. Tissue differentiation

2. Hard tissue formation: enamel, cementum, dentine

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103
Q

What is the tooth germ derived from?

A

ectodermal mesenchyme

Dental lamina grows down from oral epithelium and grows bud which gives rise to tooth germ - each develops a tooth

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104
Q

What are the 3 sections of the tooth germ?

A
  1. Enamel organ
  2. Dental papilla
  3. Dental follicle
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105
Q

Where is the enamel organ derived from and what does it differentiate to?

A

Derived from ectodermal oral epithelium

Tissue differentiates to ameloblasts - secretes enamel, dictates shape of crown

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106
Q

Where is dental papilla derived from and what does it differentiate to?

A

Derived from mesenchyme neural crest cells

Tissue differentiates into odontoblasts and develops into pulp

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107
Q

Where is the dental follicle derived from and what does it differentiate into?

A

Derived from mesenchyme neural crest cells

Differentiates into cementoblasts, osteoblasts, fibroblasts

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108
Q

What are the 6 stages of tooth development and when do they occur?

A
  1. Initiation: 6/7w
  2. Bud: 8w
  3. Cap: 9/10w
  4. Bell: 11/12w
  5. Apposition: m-yrs
  6. Maturation: m-yrs
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109
Q

What happens in the bud stage?

A

Mesenchyme condenses around ectodermal bud from oral epithelium

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110
Q

What happens in cap stage?

A

Enamel organ forms ‘cap’ above dental papilla

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111
Q

What 3 things happen in bell stage?

A
  1. Enamel organ folds into shape of crown
  2. Differentiation of enamel organ tissue (pre-ameloblasts) and dental papilla tissue (odontoblasts) begins at cusp tip
  3. Dentine secretion by odontoblasts stimulates ameloblasts
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112
Q

What happens in the appositional stage?

A

Hard tissues secreted as partially calcified matrix starting at cusp tip
Crown: mineralised crown tissue deposition first
Root: after crown formation, roots grow, tooth erupts

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113
Q

What happens in maturation stage?

A

Mineralisation completes, enamel matures

Ameloblasts die, odontoblasts line pulp

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114
Q

What is the alveolar bone?

A

Part of the maxilla/mandible that supports and protects teeth

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115
Q

What is the boundary of the alveolar bone?

A

Arbitrary but apices of roots

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116
Q

Describe the morphology of the alveolar bone

A

Finer towards margins (ventral and dorsal), thickest at apices
Dense facial and lingual cortical plates: thinnest at mandibular incisors, thickest at mandibular molars
Maxilla: thicker P>B
Mandible: 1-5 thicker L>B, 6-8 thicker B>L
Radiographically: radio opaque line (lamina dura) lining alveolar socket

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117
Q

What are the 4 functions of the alveolar bone?

A
  1. Distribute and absorb forces (mastication)
  2. Serve as attachment site for tooth apparatus: PDL, muscles
  3. Framework for bone marrow
  4. Ion reservoir
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118
Q

What does the biological property of plasticity allow the alveolar bone to do?

A

Remodel according to functional demand

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119
Q

What is the possible damage when doing extractions regarding the alveolar bone?

A

At thinnest parts (mandibular incisor) remove alveolar bone w/ tooth

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120
Q

What is the dependency of the alveolar bone?

A

Dependent on tooth

Following extraction will atrophy

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121
Q

Describe the composition of alveolar bone in terms of wet weight and volume

A

Wet weight
Inorganic: 60%
Organic: 25%
Water: 15%

Volume
Inorganic: 36%
Organic: 36%
Water: 28%

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122
Q

What makes up the majority of the organic material in alveolar bone?

A

T1 collagen

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123
Q

What makes up the rest of the organic material in alveolar bone?

A 
Proteins in small amounts
Osteocalcin
Osteonectin
Osteopontin
Proteoglycans
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124
Q

Describe the differences between internal and external compact bone of alveolar bone

A

Internal: thin layer lines socket, gives attachment to some PDL fibres
External: thicker layers form external and internal alveolar plates

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125
Q

What is meant by cribriform plate and bundle bone in alveolar bone?

A

Cribriform: sieve-like appearance of bone produced by vascular canals
Bundle: bundles of Sharpey’s fibres bass into bone from PDL

126
Q

What are the 5 types of cell in bone?

A
  1. Osteoblast: bone secreting
  2. Osteoclast: bone resorbing
  3. Osteoclast: bone monitoring, osteoblast entombed in bone
  4. Osteoprogenitor cells: mesenchymal cell that differentiates into osteoblast
  5. Bone-lining: flattened, undifferentiated inactive osteoblast
127
Q

What is the link between osteoblast and osteoclast activity?

A

Osteoblasts secrete RANK ligand when forming bone which binds to pre-osteoclasts resulting in differentiation to osteoclasts and becomes activated

128
Q

What is the difference between caries and erosion?

A

Caries: bacterial acids
Erosion: non-bacterial acids

129
Q

What are the 3 ways in which demineralisation can occur by wear?

A
  1. Attrition
  2. Abrasion
  3. Abfraction
130
Q

What is calcium hydroxyapatite?

A

Synthetic material analogous to calcium phosphate in bone and teeth
Is bioactive and biocompatible
Is a bioresorbable implant material

131
Q

What are the 3 main properties of calcium hydroxyapatite?

A
  1. Hard
  2. Insoluble: will react w/ acid
  3. Chemically complex
132
Q

Compare the solubility of hydroxyapatite and fluoroapatite

A

HA less soluble than FA

Why fluoride is added to toothpastes, water etc.

133
Q

Describe the conditions that favour remineralisation and those that favour demineralisation

A

Demineralisation: low pH, low Ca2+ conc.
Remineralisation: high pH, high Ca2+ conc.

134
Q

Compare mature enamel to CaHA

A

Similar
Ca ions replaced by other ions; F, CO2
Enamel more soluble than HA

135
Q

Where is carbonate most concentrated in enamel?

A

Towards EDJ

136
Q

What is the effect of carbonate on CaHA?

A

Makes it more soluble thus demineralisation/dissolving is more likely to occur

137
Q

What is the effect of fluoride on CaHA?

A

Reduces solubility thus less likely to demineralise/dissolve

138
Q

What is a Stephan curve?

A

Graph showing effect of acid attack on pH of oral cavity

139
Q

What is dentine?

A

Mineralised tissue that forms bulk of tooth

Small, parallel tubules in mineralised matrix

140
Q

What 4 things do dentine tubules contain?

A
  1. Odontoblastic processes
  2. Dentinal fluid
  3. Nerve endings
  4. Antigen presenting cells
141
Q

When does formation of dentine begin and stop?

A

Begins during bell stage

Continues throughout life

142
Q

Describe the physical properties of dentine

A

Pale yellow
Harder than bone and cementum, softer than enamel
Permeable

143
Q

Compare the composition of dentine in weight and volume

A

Weight: inorganic 70%; organic 20%; water 10%
Volume: inorganic 50%; organic 30%; water 20%

144
Q

Where are the CaHA crystals found in dentine and how do they compare to enamel crystals?

A

Crystals found between collagen fibrils

Much smaller than enamel crystals

145
Q

What are the 6 components of dentine organic matrix?

A
  1. Collagen fibrils
  2. Proteoglycans
  3. Glycoproteins
  4. Phosphoproteins
  5. Growth factors
  6. Lipids
146
Q

What are dentinal tubules?

A

Tube through which odontoblastic processes project through dentine to EDJ

147
Q

Why do dentinal tubules follow a S shape?

A

Due to crowding of odontoblasts as they are squeezed into smaller space within pulp cavity i.e. shape of tooth

Known as primary curve

148
Q

What do subtle changes in direction of dentine during formation result in?

A

Wavy dentinal tubules

Can from Contour lines of Owen if coincide w/ adjacent tubules, will appear as line across dentine

149
Q

Where do secondary curves usually occur?

A

At junction between primary and secondary dentine due to all odontoblasts taking similar and simultaneous change in direction

150
Q

Describe the branching of dentinal tubules

A

Profusely at periphery near EDJ
Many side branches, may connect w/ branches of other tubules
Lateral branches to communicate w/ other odontoblastic processes

151
Q

What is the clinical important of the high density of dentinal tubules at the EDJ?

A

If carious legion breaches EDJ can cause large amount of damage do dentine even if relatively small

152
Q

Describe intertubular dentine

A

Fills gaps between tubules
Relatively less mineralised but greater collagen composition than peritubular
T1 collagen fibres arranged perp. to tubules and more loosely distributed

153
Q

Describe peritubular dentine

A

Dentine that lines inside of tubules
Lack collagenous fibrous matrix but more mineralised so appears more radiopaque
Present in unerupted teeth

154
Q

What can form translucent dentine?

A

Occluding of dentinal tubules by peritubular dentine

155
Q

Name the 4 layers of dentine

A
  1. Predentine
  2. Hyaline and granular layers
  3. Circumpulpal
  4. Mantle
156
Q

What is mantle dentine?

A

First formed dentine of crown

157
Q

Describe circumpalpul dentine

A

Forms bulk of dentine
Uniform in structure except: inner surface interglobular; outer mineralisation front

Tubules modified w/ age by: 2ndary dentine deposition in pulp, disease, tertiary dentine/sclerotic dentine deposition

158
Q

Describe the hyaline and granular layers

A

First formed dentine of root, present on periphery of root
Hypomineralised compared to circumpalpul
Tubules branch more and loop back creating air spaces
Internal reflection of transmitted light

159
Q

Describe interglobular dentine

A

Found in crown just below mantle dentine and in root in granular layer of tomes

Area of less calcified areas of dentine, appear as irregularly shaped crescents
Result of uneven fusion of mineralisation front causing little calcification

Tubules pass through but peritubular dentine absent

160
Q

Describe predentine

A

First layer of dentine, unmineralised
Innermost layer
Mineralisation front globular or linear
Thicker in younger teeth

161
Q

Describe the process of mineralisation of dentine

A

Organic matrix laid down
Ca2+ transported through odontoblasts to area of calcification
Ca2+ crystallises in dentine after deposition on collagen fibrils
Matrix deposition and mineralisation continue, zone of calcification usually visible

162
Q

Compare linear and globular mineralisation

A

Linear: apposition on pre-calcified areas
Globular: small, spherical areas become larger, fuse w/ each other

163
Q

What are Von Ebner lines?

A

Perpendicular (to dentinal tubules) lines along tubules caused by daily alterations in formation of dentine

164
Q

Describe primary dentinogenesis

A

All dentine up till eruption

May become translucent w/ age due to inc. deposition of peritubular occluded tubules

165
Q

Describe secondary dentinogenesis

A

Dentine after eruption
Structurally similar to primary but w/ fewer tubules
Will red. pulp chamber and root canal size in time

166
Q

Describe tertiary dentinogenesis

A

Produced in response to stimuli such as damage/irritation to overlying dentine/enamel
Irregularly shaped and few dentinal tubules
W/ ageing/severe damage can obliterate pulp cavity

167
Q

Describe sclerotic dentine

A

Produced in response to external challenge (caries)
Appears translucent due to inc. mineralisation
Tubules filled to block ingress of bacteria (protect pulp)

168
Q

What are dead tracts?

A

Empty dentinal tubules due to odontoblast death or retraction process

169
Q

What are the 3 clinical implications of dentine?

A
  1. Permeability
  2. Response to external stimuli
  3. Sensitivity
170
Q

Why is permeability of dentine of clinical significance?

A

When exposed, substances from external environment can reach pulp through dentinal tubules resulting in pulpitis

171
Q

Explain the clinical relevance of external stimuli response of dentine

A

If stimuli not strong enough to destroy pulp can induce production of tertiary dentine as protective measure - eventually obliterate pulp

172
Q

Explain why sensitivity of dentine is relevant

A

Exposed dentine is v painful: dentinal fluid compresses nerve endings on dentinal tubules

173
Q

What are the 3 theories of dentine sensitivity?

A
  1. Direct innervation
  2. Hydrodynamic
  3. Transduction
174
Q

What is the role of the supporting apparatus?

A
  1. Protect teeth from masticatory forces

2. Prevent premature loss of teeth

175
Q

Describe the thickness of cementum

A

Thinner coronally: 0.05-0.1mm

Thicker apically: 0.2-1mm

176
Q

What are the 2 functions of cementum?

A
  1. Cover dentine

2. Provide attachment of tooth to PDL

177
Q

What are some of the characteristics of cementum?

A

Pale yellow, dull surface
Inner surface: firmly attached to dentine
Outer: adjacent to PDL
Clean surface is hard, has ‘glass-like’ texture
Meets enamel at CEJ

178
Q

Describe the mineral and organic composition of cementum

A

Mineral: mainly Ca, PO4 in HA crystals
Organic: mainly collagen, various glycoproteins and proteoglycans

179
Q

Describe some of the physical and chemical properties of cementum

A

Similar to bone but: avascular, no innervation and less readily resorbed

Softer than dentine, more permeable
Cellular type is more permeable than acellular type
Permeability dec. w/ age

180
Q

What are the 2 ways in which cementum can be classified?

A
  1. Cell component

2. Collagen component

181
Q

What are the 2 types of cellular classification cementum?

A
  1. Cellular

2. Acellular

182
Q

What are the 4 types of collagen classification cementum?

A
  1. Intrinsic fibre
  2. Extrinsic fibre
  3. Mixed fibre
  4. Afibrillar
183
Q

Describe acellular cementum

A

Forms next to dentine

Greater proportion cervically and less apically

184
Q

Describe cellular cementum

A

Found apically and overlying acellular cementum
Formed during functional needs
Numerous cementocytes

185
Q

Describe extrinsic fibre cementum

A

All collagen derived from Sharpey’s fibres

From PDL

186
Q

Describe intrinsic fibre cementum

A

From cementoblasts
All intrinsic fibres running parallel to root surface
No role in tooth attachment

187
Q

Describe mixed fibre cementum

A

Collagen fibres of organic matrix derived from both extrinsic and intrinsic fibres

188
Q

Describe afibrillar cementum

A

No collagen fibres: thin, acellular layer

Localised regions of mineralised GS cover cervical enamel

189
Q

What is the clinical implication of the thickness of cementum?

A

Gingival recession will expose thin cementum cervically which is easily abraded by tooth brushing, will reveal dentine which is highly sensitive

190
Q

What are the 2 cells involved in cementum deposition?

A
  1. Cementoblasts: deposit cementoid (unmineralised, pre-cementum)
  2. Cementocytes: cementoblasts entombed in cementum
191
Q

Describe cementoblasts

A

Produce cementum throughout life
Reside in the PDL space lining cementum surface
Similar to osteoblasts

192
Q

Describe cementocytes

A

Former cementoblasts trapped within cementum matrix

Found in lacunae and have cellular processes that extend along caniculi which connect to each other

193
Q

Describe the formation of cementum

A

Begins as Hertwig’s root sheath disintegrates
Undifferentiated cells come into contact with newly formed dentine
Induces differentiation to immature cementoblasts
Cementoblasts migrate to cover root dentine, laying cementum matrix (cementoid)
Become trapped in matrix forming mature cemetocytes

Process continues throughout life allowing for continual reattachment/new attachment of PDL fibres

194
Q

Describe the incremental lines of cementum

A

Acellular: thin and even
Cellular: thicker, irregular

195
Q

Describe the 3 patterns possible at the CEJ

A
  1. C overlaps E as E comes down
  2. C and E meet and join
  3. C fails to meet E: sensitivity w/ slightest root exposure
196
Q

Describe the resorption of cementum

A

Less susceptible than bone under same pressure yet most roots still show signs of resorption

Reasons unclear

Multinucleated odontoclasts resorb cementum

197
Q

What are cementicles?

A

Small, globular masses of cementum found on roots
Either attached to cementum surface or free in PDL
More common apically and mid. 1/3 root and bifurcation of root

198
Q

What is the PDL?

A

Dense fibrous CT that occupies space between root, cementum and alveolar bone

199
Q

Described the appearance of the PDL

A

Hour glass: narrowest mid root

Varies depending on functional state of tooth i.e. high occlusal force, unerupted

200
Q

Describe the boundaries of the PDL

A

From apex to CEJ
Alveolar crest: continuous with gingivae
Apical foramen: continuous with pulp

201
Q

Describe the properties of the PDL

A

Richly vascularised, has nerve endings
Uncalcified: is living, maintain shock absorbance
Appear as radiolucent line around root in radiography

202
Q

What are the 8 functions of the PDL?

A
  1. Attachment between tooth and alveolar bone
  2. Resist, displace occlusal forces
  3. Physiological mobility allows normal tooth function
  4. Keeps teeth in functional position
  5. Protects teeth from excessive occlusal load
  6. Sensory inputs allow jaw reflex activities via mechanoreceptors
  7. Neurological control of mastication
  8. Cells form alveolar bone and cementum
203
Q

Describe the structure of PDL

A

Fibres
Neurovascular channels, blood and lymphatics
Cells: fibroblasts, cementoblasts/clasts, odontoblasts/clasts, undifferentiated mesenchymal cells
GS

204
Q

What are the 6 PDL fibres from most cervical to apical?

A
  1. Transseptal
  2. Alveolar crest
  3. Horizontal
  4. Oblique: principal
  5. Apical
  6. Inter-radicular
205
Q

Describe the principal fibres of PDL

A

Embedded in cementum or in bone lining socket known as Sharpey’s fibres
Attachment site smaller at cementum than alveolar bone
T1 (90%) and some T3 fibres arranged in bundles that provide elasticity to teeth

206
Q

Describe the 2ndary fibres

A

Oxytalan, elastin
Randomly oriented between principal fibres
Can connect to bone or cementum, don’t become Sharpey’s fibres
Supportive role for principal fibres, blood vessels and nerve endings

207
Q

What are the 5 main components of PDL GS?

A
  1. Hyalironidate GAGs
  2. Proteoglycans
  3. Glycoproteins
  4. Fibronectin
  5. Tenascin
208
Q

What are the 6 cell types in PDL?

A
  1. Fibroblasts
  2. Osteoblasts/clasts
  3. Cementoblasts/clasts
  4. Undifferentiated mesenchymal cells
  5. Defence cells
  6. Epithelial cells (Cell Rests of Malassez)
209
Q

Described the innervation of the PDL

A

Sensory: nociception and mechanoreception
Autonomic: associated w/ periodontal blood supply
Enter PDL through root apex or from openings in alveolar wall
Myelinated at apex and unmyelinated coronally

210
Q

What are the clinical implications of the PDL in terms of disease?

A

Gingivitis, periodontitis, periapical infection
Causes loss of PDL, deeper pocket formation
Inc. motility of tooth due to dec. tooth attachment

If remove diseased tissue or regenerate tissue allows PDL to regenerate

211
Q

What are the clinical implications of PDL in terms of orthodontics?

A

Tension: inc. PDL space w/ inc. CT and osteoid deposition
Pressure: red. PDL, inc. resorption

212
Q

Define ideal occlusion and normal occlusion

A

Ideal: based on morphology of unworn teeth
Normal: satisfies functional and aesthetic requirements but may have minor irregularities in individual teeth

213
Q

What are the 3 features of OC at birth?

A
  1. Dental arches represented by gum pads
  2. Upper gum pad longer and wider than lower
  3. Segmented elevations: represent in-erupted teeth
214
Q

Describe the development of deciduous dentition? Commence, calcification, complete

A

Commence w/ eruption of LAs @ 6/12 +/- 6/12
Teeth present at birth called neonatal teeth

Calcification begins 4-6/12 in utero

Complete 2.5 yrs

215
Q

What are the 3 features of deciduous dentition?

A
  1. Incisors spaced
  2. Primate spacing: M to UCs, D to LCs; allows space for permanent dentition
  3. Flush terminal plane: Es in straight line
216
Q

What is the general function of deciduous dentition? Apart from mastication

A

Hold space for permanent teeth

If removed may cause permanent to not erupt or be impacted

217
Q

Describe the eruption of permanent dentition

A

Commences w/ L6s @ 6yrs +/- 18/12

6: L6,1s, U6s
7: U1s, L2s
8: U2s

11: L3,4s, U4s
12: U3s, U+L5s, U+L7s

218
Q

Where do the permanent incisors develop?

A

Palatal/lingual to deciduous incisors

219
Q

What 3 features accommodate for the inc. width of permanent incisors?

A
  1. Pre-existing space: primate spacing
  2. Proclination: erupt inclined giving more space
  3. Growth: inc. inter-canine space
220
Q

Describe the ugly duckling stage of development

A

Erupting 3s impact on roots of 2+1s cause crowns to spread out distally
As 3s clinically erupt influence crowns of 2+1s pushing them back to straight

221
Q

Define Leeway space

A

Difference between the mesio-buccal distance of C,D,Es compared to 3,4,5s

222
Q

What is the purpose of the leeway space?

A

Allows 6s to drift forward (after Es exfoliate) and form class I molar relation

223
Q

Quantify the leeway space

A

Mandible: 2mm/quadrant
Maxilla: 1mm/quadrant

224
Q

Define class I molar relation

A

Mesio-buccal cusp of U6 occludes w/ mid-buccal groove of L6

225
Q

Define class I incisor relation

A

L incisal edge occludes w/ cingulum plateau of U incisors

226
Q

How are the permanent molars guided into place?

A

By flush terminal plane of Es

227
Q

What is biomineralisation?

A

Process by which inorganic crystal growth and formation is controlled by organic molecules (proteins)

228
Q

Describe the growth of crystals and why control is required

A

Crystals grow in all directions thus proteins required to control rate in some directions or completely stop

229
Q

What is minimal intervention dentistry?

A

Approach by which dentists base patient care on disease risk assessment, earliest diagnosis and minimal invasive treatment

230
Q

Describe amelogenin

A

Forms 90% developing enamel ECM
Highly species conservative
Unique to enamel
High in proline and glutamate

231
Q

Describe the structure of amelogenin

A

N: TRAP, hydrophobic, 44-45AAs
Core: hydrophobic, proline, leucine repeats, 100-130AAs
C: hydrophilic, acidic, 15AAs; charged region binds to HA

232
Q

Describe the regional and molecular structure of amelogenin

A

Regional: secondary
Molecular: tertiary

Poorly defined
Beta sheets detected by NMR; could act as Ca2+ channels

233
Q

What post-translational modification occurs in amelogenin?

A

No glycosylation

Some phosphorylation: serines to phosphoserines

234
Q

Describe the supramolecular structure of amelogenin

A
  1. Bipolar
  2. Self-assembly into nano-spheres
  3. 100 monomer units
  4. C-terminus on exterior
235
Q

Describe the primary and secondary functions of amelogenin

A

Primary: myocells bind to lat. aspects of growing HA crystals, prevent/slow lat. growth, crystals grow sup. forming v long crystals

Secondary: proteins lost, crystals grow lat.

236
Q

Describe enamelin

A 
5-10% enamel matrix 
AA sequence unknown: high in glycine and proline 
pI 4-6.5 
Bind to HA
Known to retard seeded growth
237
Q

Describe tuftelin

A

Secreted before amelogenin
Mainly located @ DEJ
Has Ca binding domain
Associated w/ regulation of HA crystal nucleation

238
Q

What are another 3 examples of non-amelogenin matrix proteins?

A

Serum albumins: don’t bind crystals
Proline-rich: in un-erupted enamel
Enzymes: proteases, serine proteases

239
Q

What is the clinical relevance of proteins of enamel biomineralisation?

A

When process disturbed can lead to conditions such as AI

240
Q

What is AI?

A

Inherited condition causing disfigured enamel: smooth, thin, creamy or yellow, localised pits etc.

4 types: hypocalcified, hypomatured, hypoplastic, X-linked
Hypocalcified prone to caries and fracturing

Only 50-53% mineral, enamel usually >90% mineral
More protein: 4-5% rather than 0.06-0.75%

Proposed that TRAP region protein is not removed preventing maturation

241
Q

Describe the composition of dentine

A

20% organic; predentine almost completely organic

90% collagen: structural and associated w/ mineralisation
T1: high proline triple helix, Pro rings stick out
Glycine every 3rd residue
Stabilised by interchain H bonding

242
Q

What are 3 main proteins found in dentine?

A

Phosphoproteins: Ca binding
Osteocalcin: mainly found in bone; Ca binding
Osteonectin: bind HA and collagen

243
Q

What are the 3 dentine specific non-collagenous proteins?

A
  1. Phosphophoryn
  2. Sialprotein
  3. AG1
244
Q

What is dentinogenesis imperfecta?

A

Genetic condition characterised by malformed dentine
Opalescent teeth that have malformed, unmineralised dentine
Obliterated pulp chambers and shorted roots w/ bulbous centres
Abnormally soft dentine, undergoes rapid and severe functional attrition

245
Q

Why are apatites important?

A

Loss of bone/tooth mineral basis of

  1. Osteoporosis
  2. Tooth decay and caries
  3. Acid erosion
  4. Periodontal disease
246
Q

In non-stoichiometric solid solutions formed what are magnesium, manganese, fluoride, carbonate each substituted by?

A

Mg2+, Mn2+: Ca2+
F-: OH-
CO32-: PO43-

247
Q

Compare the degree of crystallinity in enamel and bone and dentine

A

Enamel apatite: sharp diffraction lines; higher conc. F- probably favours more ordered crystal structure

Bone/dentine: diffusion diffraction pattern

248
Q

What is tooth decay?

A

Caused by bacteria in plaque and carious lesions producing acids which dissolve tooth mineral
Also produce enzymes which hydrolyse protein component of tooth

249
Q

What is erosion?

A

Acid dissolution of mineral

Natural acids: no bacteria involved

250
Q

What is the significance of the hexagonal lattice structure of HA?

A

OH slightly too large to fit perfectly into hexagonal lattice thus disoriented/monoclinic structure
F- smaller and fits much better thus readily exchanged for OH in enamel surface
FA chemically and thermodynamically more stable: more resistant to dissolution

251
Q

Why is fluoride toothpaste important but what does it lack?

A

F substitutes OH to form FA: more stable, withstand dissolution

To remineralise require Ca2+ and PO43-

252
Q

What is fluorosis?

A

Mottling of teeth of children associated w/ fluoride

253
Q

What may mottling also be a result of?

A

Disrupted enamel mineralisation resulting from viral disease

254
Q

Why can fluoride be toxic?

A

Form complexes with elements in
Electron transport system
Enzyme cofactors

255
Q

What are the 5 effects of fluoride poisoning?

A
  1. Nausea, epigastric pain, vomiting
  2. Limb spasms, tetany, convulsions
  3. BP, pulse rate fall
  4. Respiration depressed
  5. Unconsciousness
256
Q

Why is solid state NMR important for apatite?

A

Only good way to distinguish between HA and FA

257
Q

What is the water fluoridation level in the UK?

A

1ppm

Beneficial as withstand acid dissolution

258
Q

What DM is fluoride releasing?

A

GIC, can also release other ions: strontium

Can also uptake and re-release F: act as F battery

259
Q

Why are bioactive glass toothpastes good?

A

Release Ca2+, PO43- and raise pH
Forms hydroxycarbonated apatite
Binds directly to bone/tooth

260
Q

What is NovaMin and what are its disadvantages?

A

Bioactive glass toothpaste: forms hydroxycarbonated apatite that binds to tooth surface and blocks dentinal tubules where it releases Ca, PO

Disadvantages:
FA is better
Not quick to form apatite
Glass is harder than enamel, will wear enamel

261
Q

What are bitewings?

A

Check up X-rays
Show crowns of premolars and molars
Used for caries risk assessment and bone loss

262
Q

What are peri-apical X-rays?

A

Can be of posterior or anterior teeth
Show crown and root
Used for RCT, extraction, bone loss and caries assessment

263
Q

What is a pan-occlusal X-ray?

A

X-ray of occlusal view

Useful for un-erupted teeth

264
Q

What is a panoramic X-ray?

A

X-ray from condyle to condyle
Can see sinuses, orbits, nose and soft tissue spaces
Useful for orthodontics

265
Q

What are the 2 most important factors when taking X-rays and how do they relate?

A
  1. Dose
  2. Image quality

For safety need lowest dose as reasonably practical

266
Q

Describe the process of X-ray production in an X-ray tube

A

Leaded glass vacuum to prevent radiation leaking

Tungsten cathode and copper anode w/ tungsten target
Current applied to cathode, heat generated and electron cloud formed
Potential difference applied, electrons accelerate towards anode
Release energy in X-ray photon (1%) others produce heat (reason for copper block)

Surrounded in oil to dissipate heat

267
Q

What is the function of aluminium filters in X-rays?

A

Remove the lower energy photons that would be absorbed by body tissues and potentially cause problems

268
Q

Describe the effect of inc. voltage in the generation of X-rays

A

Inc. energy of photos, inc. penetrating power
If too high, non will be absorbed produce grey image
If too low, all absorbed produced light image

269
Q

How does inc. time current is applied for alter X-rays?

A

Inc. no. photons produced

Potential for more to be absorbed creating darker image

270
Q

Why is rectification important in radiography?

A

Convert AC to DC current

Current always on (when pressed) thus less dose to patient as more photons produced

271
Q

What is the importance of rectangular collimation?

A

Changes tube head from circular to rectangular

Red. dose by 50%

272
Q

Describe the 2 mechanisms by which radiation can cause damage

A

Direct: more catastrophic
DNA/RNA; disturbs nucleic acid bonds, causes mutations

Indirect: more likely
Water molecules; radiolysis of water creates free radicals H2, H2O2 cause cellular damage

273
Q

What are the 3 types of harmful radiation effects?

A
  1. Somatic deterministic: threshold (only caused if above)
    cataract formation: lens becomes opaque
    obliterative endarteritis: radiolysis of small vessels
  2. Somatic non-deterministic: no threshold (potential every time)
    malignancy
  3. Genetic non-deterministic
274
Q

Describe dental pulp

A

Unmineralised tissue composed of soft CT, vasculature, lymphatics and nerve endings
Mostly water: 75-80%
Developmentally, structurally and functionally closely related to dentine: both from neural crest-derived CT that forms dental papilla
Occupied pulp chamber and root canals
Pulp chamber molars ~4x larger than incisors
No inorganic components in normal pulp: pulp stones found pathologically in ageing pulp

275
Q

What is the primary function of pulp?

A

Provide vitality to tooth: loss of pulp (RCT) doesn’t mean lose tooth; tooth functions w/o pain but loses protective mechanisms

Maintains health of dentine through odontoblast layer

276
Q

What are the inductive, formative and protective functions of pulp?

A

Inductive: early development; future pulp interacts w/ surrounding tissues initiating tooth development

Formative: odontoblasts of outer layer pulp organ form dentine that surrounds and protects

Protective: pulp reacts to stimuli; cold, hot, pressure, operative cutting, caries,

277
Q

What are the 2 types of pulp?

A
  1. Coronal

2. Radicular

278
Q

Compare the 2 types of pulp

A

Coronal: occupies crown, 6 surfaces; mesial, distal, occlusal, floor, buccal, lingual

Radicular: extends down from cervix to apex, pre/molars have multiple radicular pulps, tapered and conical

279
Q

Describe the fibrous matrix of pulp

A

Composed of T1 and 2 collagen
Unbundled and randomly dispersed, greater dentistry around blood and nerve vessels

T1: thought to be formed by odontoblasts
T2: probably produced by pulp fibroblasts

Older pulp contains more collagen

280
Q

What is present in the GS of pulp?

A

Glycoproteins
Proteoglycans
Water

281
Q

Where are odontoblasts found in pulp?

A

Outermost region, immediately adjacent to dentine

Responsible for secretion of dentine, formation of dentinal tubules

282
Q

What is special about pulp fibroblasts?

A

Shown ability to degrade and form collagen

283
Q

Describe perivascular cells

A

Undifferentiated mesenchymal cells present in pulp

Give rise to odontoblasts, fibroblasts, macrophages

284
Q

What other cells are common in the pulp?

A

Lymphocytes, plasma cells, eosinophils

285
Q

What are the 4 zones of pulp from outer to inner?

A
  1. Odontoblastic
  2. Cell-free
  3. Cell-rich
  4. Pulpal-core
286
Q

Describe the odontoblastic layer of pulp

A

Lines outer pulpal wall, consists of odontoblast cell bodies
2ndary dentine may form here from apposition of odontoblasts

287
Q

Describe the cell-free zone of pulp

A

Fewer cells than odontoblastic

Capillary and nerve plexus

288
Q

Describe the cell rich zone of pulp

A

Inc. density cells, more extensive vasculature

@ base; nerve plexus of Raschow

289
Q

Describe the pulpal-core of pulp

A

Located in centre of pulp chamber
Many cells, extensive vasculature
Similar to cell-rich

290
Q

Describe odontoblasts

A

Polarised columnar cells w/ single process extending into dentinal tubules
Form continuous lining @ junction between pulp and dentine
Form dentine
Contribute to protection of pulp

291
Q

What inflammatory cells are present in the pulp?

A
  1. T lymphocytes
  2. Macrophages
  3. Dendritic antigen presenting cells
292
Q

Describe the distribution of inflammatory cells found in the pulp

A

T lymphocytes: usually low no. inc. w/ inflammation

Macrophages: predominately around central blood vessels, adjacent to odontoblast layer

Dendritic presenting cells: similar to macrophages; may be found between odontoblasts and dentine

293
Q

Describe the vascular supply to the pulp

A
  1. Small arterioles enter pulp via apical foramen
  2. Ascend through radicular pulp of root canal
  3. Branch peripherally to form dense capillary network immediately under and extending into odontoblast layer
  4. Small venules drain capillary bed, eventually leave as vein through apical foramen
294
Q

Describe the structure of vascular supply in pulp

A

Pulpal vessel walls v thin as pulp protected by unyielding sheath of dentine
Capillary walls have many pores reflecting metabolic activity of odontoblast layer
Blood flow more rapid and BP quite high
Arterio-venous anastomoses freq.

295
Q

Describe the innervation of the pulp

A

Pre/molars: several large nerve fibres enter apical foramen of each
Ant.: one fibre enters

  1. Autonomic
  2. Afferent
296
Q

Describe the autonomic innervation of the pulp

A

Sympathetic fibres, unmyelinated
From neurons whose cell bodies lie in sup. cervical ganglion at base of skull
Travel w/ blood vessels
Innervate arteriole SM, function in regulation of blood flow

297
Q

Describe the path of afferent nerves in the pulp

A

Maxillary and mandibular branch of CN5
Terminate in central pulp
Send out small individual fibres that form subodontoblastic plexus under odontoblast layer
Terminate as free nerve endings: extend up between odontoblasts or further up into dentinal tubules

298
Q

Describe the afferent fibres of the pulp

A

Transmit pain sensation from heat, cold, pressure
Subodontoblastic plexus: found in lat. walls and root of coronal pulp, less developed in root canals
Few nerve endings found among odontoblasts of root

299
Q

What is the clinical importance of pulp?

A
  1. Living pulp required to maintain dentine integrity and sensitivity
    Inflammation causes high fluid conc. and swelling; nerve fibres compressed causing pain
    Mechanical injury to dentine may induce pain and tertiary dentine formation
    Severe damage/infection result in removal, filling of pulp chamber and root canal
  2. Age related: cell death results in dec. no. cells, fibroblasts respond by producing more fibrous matrix but less GS w/ less water
    Pulp becomes: less cellular, more fibrous, red. vol. due to continued dentine deposition
300
Q

Define absorbed, equivalent and effective dose

A

Absorbed: amount of energy absorbed from radiation beam per unit mass tissue; Gray

Equivalent: absorbed dose x radiation weighting factor; Sievert

Effective: equivalent x tissue weighting factor; Sievert

301
Q

Explain the effect of age on radiation risk

A

Indirect

Children much more at risk due as cells are dividing, growing
Older people have negligible risk as won’t see effect

302
Q

What is the main justification for radiographs?

A

Benefit to patient must outweigh detriment

303
Q

What are the 5 justifications of radiographs?

A
  1. Findings and availability of previous X-rays
  2. Alternatives: little or no radiation w/ same objective
  3. Total benefit to patient
  4. Risk: radiation risk associated w/ examination
  5. Objectives in relation to history and examination
304
Q

Describe the optimisation and limitation of radiographs

A

Optimisation: patient doses should be red. to as low as reasonably practicable

Limitation: equivalent dose to patient should not exceed limits recommended by ICRP

305
Q

What are the 4 areas where radiation dose can be reduced?

A
  1. Equipment
  2. Clinical decision
  3. Practical technique
  4. Diagnostic interpretation
306
Q

What are the 5 equipment factors that can red. dose?

A
  1. Focus to skin distance: 15-20cm
  2. Rectification: AC-DC, more photons, lower dose
  3. Aluminium filtration: remove low energy photons
  4. Rectangular collimation: rectangular sensor to rectangular film
  5. Film and sensors: digital vs conventional
307
Q

Describe conventional and digital radiographs films

A

Conventional: can’t be exposed to light, long time to develop, develop in dark room

Indirect digital: phosphorus plate, quicker, use reader to develop

Direct: charge-coupled device, instant, no lag time, special holders, bulkier

Digital red. dose by 50% but may require more retakes (less careful as so quick and easy)
Latitude (range of exposures image will be captured) wider for digital which could inc. dose as high quality images obtained at extremes thus don’t check everything working

308
Q

What are the 6 remits for radiographs?

A
  1. Caries diagnosis
  2. Developing dentition
  3. Endodontics
  4. Periodontal assessment
  5. Implant dentistry
  6. Good practice
309
Q

What are the 3 practical technique factors for taking radiographs?

A
  1. Aligning tube w/ film
  2. Lead aprons: no justification, discouraged for panoramics
  3. Pregnancy: justification, optimisation, delay, lead for physiological reasons
310
Q

Explain the controlled area

A

Area that only exists when X-rays being taken: indirect beam of X-ray (when no shielding or sufficient distance) and 1.5m from beam and patient in all other directions

If distance is not sufficient shielding must be used

BDS 1 (11 decks)

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