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Oral Cavity Flashcards

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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
What are the 3 major salivary glands?
1. Parotid 2. Submandibular 3. Sublingual
26
Describe the secretions from the 3 major salivary glands
Parotid: serous, high amylase, low Ca Submandibular: mixed, high Ca Sublingual: more mucous, high mucins
27
Describe the secretions from the minor salivary glands
Highly mucous
28
Describe the innervation of the salivary glands
PSNS: H2O release, vasodilation; watery and electrolyte rich SNS: exocytosis; inc. protein synthesis, thick(?)
29
What are the 4 functions of mucin?
1. Tissue coating 2. Lubrication 3. Bacterial aggregation 4. Bacterial adhesion
30
What are the 4 main causes of xerostomia?
1. Disease: autoimmune, Sjorgens 2. Therapy: chemotherapy, H&N radiotherapy 3. Medication: antidepressants, antihypertensive 4. Disorder: HIV, psychogenic
31
What are the symptoms of xerostomia?
``` Mucosa: dry, glossy, atrophic changes Tongue: glossitis, fissured, red, papilla atrophy Rampant caries Periodontitis, candidiasis, halitosis Difficulty in speech and swallowing ```
32
What are some treatments for xerostomia?
Inc. water intake Treat underlying condition Artificial saliva Chew gum i.e. trigger receptors
33
What are the 5 functions of the oral mucosa?
1. Mechanical protection: compression, shearing 2. Barrier: bacteria, toxins, antigens 3. Immunological defence: humoral, cell-mediated 4. Lubricate saliva 5. Innervation: touch, pain, taste
34
What are the 3 functional classifications of oral mucosa?
1. Masticatory 2. Lining 3. Specialised
35
Describe the masticatory mucosa
Area: high compression and friction; gingivae, hard palate | Highly keratinised, thick lamina propria
36
Describe lining oral mucosa
Area: mobile and distensible; cheeks, lips, alveolar mucosa, floor of mouth, ventral tongue, soft palate Non-keratinised, loose lamina propria
37
Describe specialised oral mucosa
Area: dorsal surface of tongue (taste buds); vermilion of lips (transition between skin and oral mucosa)
38
What are the 4 layers of oral mucosa?
Deep to superficial 1. Submucosa 2. CT (lamina propria) 3. BM (basal lamina) 4. Stratified squamous epithelium
39
Compare keratinised, non-keratinised and parakeretinised stratified squamous epithelium
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
40
Describe the layers of keratinised stratified squamous epithelial
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
41
Describe the layers of non-keratinised stratified squamous epithelium
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
42
What are keratins?
Fibrous structural proteins composed of intermediate filaments found in all epithelia
43
What is the function of the basal lamina?
Mechanical adhesion between epithelium and CT | Barrier between them
44
What are the 2 layers of the basal lamina?
Lamina lucida: made of laminin, adjacent to epithelia | Lamina densa: made of collagen T4, adjacent to CT
45
How does the basal lamina link CT to epithelial?
Hemidesmosomes
46
What are the 2 layers of lamina propria?
1. Superficial: thin, loosely arranged collagen | 2. Deep: thick parallel bundles of collagen
47
What cells and structures are present in the lamina propria?
Cells: collagen, elastin, oxytalan fibres, proteoglycans - glycoproteins, macrophages, lymphocytes, mast cells, fibroblast producing ECM Structures: blood vessels, nerve endings
48
Describe sulcular epithelium
Non-keratinised | Not in direct contact with enamel
49
What is the gingival sulcus?
Natural space between tooth and free gingiva
50
Describe junctional epithelium
Non-keratinised Seals off underlying CT and bone Direct contact with enamel via hemidesmosomes
51
Why is the junctional epithelium permeable?
Allows tissue fluid and immune cells to pass through into gingival sulcus for defence against invading OB
52
Explain how plaque formation damages the mucosa
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
53
What are the 3 main parts of a tooth?
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
54
What is the cemento-enamel margin/junction?
Border where enamel and cementum meet
55
What is the enamel-dentine junction?
Border between enamel and dentine
56
What are ameloblasts and odontoblasts?
Ameloblasts: enamel secreting cells, move from EDJ to surface Odontoblasts: dentine secreting cells, move from EDJ to pulp
57
What are the 3 components of enamel?
1. Hydroxyapatite crystals 2. Organic material: amelogenin, enamelin 3. Little water
58
What are some of the properties of enamel?
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
59
What is the function of enamel?
Protective: withstand shearing and impact, resist abrasion
60
Describe the structure of enamel
Long, hexagonal HA crystallises arranged in rods/prisms grow from EDJ to surface in sinuous path
61
What are Striae of Retzius, surface perikymata and cross-striations?
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
62
What pattern of enamel do humans have?
``` Pattern 3 - keyhole Thick head (towards crown) and narrow tail (towards neck) ```
63
How many ameloblasts contribute to 1 keyhole prism
4: 1 in head and 3 in tail
64
Describe the path of enamel prisms within enamel
Parallel to each other and at oblique angle at origin (EDJ) and termination (surface)
65
What is different about surface enamel?
Aprismatic - structureless Crystallites aligned parallel to each other and perp. to surface Highly mineralised
66
What are Tomes processes?
Picket fence projection caused by ameloblasts moving away from new enamel, absent in final stage of enamel deposition
67
What are Hunter Schreger bands?
Optical effect of light and dark 'bands' of enamel caused by bundles crossing each other in layers at right angles as travel from EDJ
68
What is the purpose of enamel bundles overlapping?
Strengthen structure Prevent cracks Resist fractures
69
What are the 3 weaknesses present at the EDJ?
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
70
What is the clinical importance of enamel?
Prevent demineralisation Promote remineralisation Restore cavitated enamel Diagnose and treat developmental enamel malformations
71
What are the functions of incisors?
Cutting, scooping, picking up objects, grooming
72
What are the functions of canines?
Holding prey, display, puncture, slashing and tearing while fighting
73
What are the functions of premolars?
Holding, carrying, breaking food into small pieces
74
What are the functions of molars?
Shearing, crushing, grinding food into small pieces
75
How are teeth charted?
Maxillary right central incisor = UR1 OR 11
76
What are the 5 planes of ant. and post. teeth?
Ant: mesial, labial, distal, lingual, incisor edge Post: mesial, buccal, distal, lingual, occlusal
77
What is diphyodont?
2 successive sets of teeth
78
What is thecodont?
Teeth with roots firmly fixed in socket with ligaments
79
What is heterodont?
Different tooth types
80
What are mamelons?
Ridges on incisal edge of new teeth | Rapidly worn down
81
What are cusps?
Major elevations on masticatory surface of 3s and post. teeth
82
What are ridges?
Variable, linear elevations on crown of tooth
83
What tooth has the longest root?
U3s
84
What teeth are single rooted?
U: 1, 2, 3, 5s L: 1, 2, 3, 4, 5s
85
What teeth have 2 roots?
U: 4s L: 6, 7, 8s
86
What teeth have 3 roots?
U: 6, 7, 8s
87
In what direction to root usually curve?
Distally
88
What are the main differences between maxillary and mandibular teeth?
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
89
What are the distinguishing factors between maxillary teeth?
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
90
What are the main differences between mandibular teeth?
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
91
What are cusps of Carabelli?
Extra cusp on palatial surface of palatal cusp on upper molars
92
What are the main distinguishing factors between deciduous and permanent dentition?
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
93
Which deciduous teeth have 1 root?
ABCs
94
Which deciduous teeth have 2 roots?
L: DEs
95
Which deciduous teeth have 3 roots?
U: DEs
96
What are the main differences between permanent and deciduous teeth?
``` 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 ```
97
What are the 4 theories of tooth eruption?
1. Root growth 2. Bone remodelling 3. Dental follicle 4. Periodontal ligament
98
What are the 4 processes of tooth development and eruption?
1. Pre-eruptive movement 2. Intra-issues, tooth in alveolar bone 3. Mucosal penetration: clinical emergence 4. Post-occlusal movement: passive eruption
99
What are the 4 stages of dentition?
1. Edentulous: before any teeth erupted 2. Deciduous: 6m-5y 3. Mixed: 6-12y 4. Permanent: 12y+
100
Outline the timeline of deciduous eruption
6-12m: LABs, UABs 14m: Ds 18m: Cs 24m: Es
101
Outline the timeline of permanent dentition
Phase 1: 6-8y: [16] 2 Phase 2: 10-12y: [467] 3 Phase 3: 17-20y+: 8
102
What are the 2 stages of tooth development?
1. Tissue differentiation | 2. Hard tissue formation: enamel, cementum, dentine
103
What is the tooth germ derived from?
ectodermal mesenchyme | Dental lamina grows down from oral epithelium and grows bud which gives rise to tooth germ - each develops a tooth
104
What are the 3 sections of the tooth germ?
1. Enamel organ 2. Dental papilla 3. Dental follicle
105
Where is the enamel organ derived from and what does it differentiate to?
Derived from ectodermal oral epithelium | Tissue differentiates to ameloblasts - secretes enamel, dictates shape of crown
106
Where is dental papilla derived from and what does it differentiate to?
Derived from mesenchyme neural crest cells | Tissue differentiates into odontoblasts and develops into pulp
107
Where is the dental follicle derived from and what does it differentiate into?
Derived from mesenchyme neural crest cells | Differentiates into cementoblasts, osteoblasts, fibroblasts
108
What are the 6 stages of tooth development and when do they occur?
1. Initiation: 6/7w 2. Bud: 8w 3. Cap: 9/10w 4. Bell: 11/12w 5. Apposition: m-yrs 6. Maturation: m-yrs
109
What happens in the bud stage?
Mesenchyme condenses around ectodermal bud from oral epithelium
110
What happens in cap stage?
Enamel organ forms 'cap' above dental papilla
111
What 3 things happen in bell stage?
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
112
What happens in the appositional stage?
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
113
What happens in maturation stage?
Mineralisation completes, enamel matures | Ameloblasts die, odontoblasts line pulp
114
What is the alveolar bone?
Part of the maxilla/mandible that supports and protects teeth
115
What is the boundary of the alveolar bone?
Arbitrary but apices of roots
116
Describe the morphology of the alveolar bone
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
117
What are the 4 functions of the alveolar bone?
1. Distribute and absorb forces (mastication) 2. Serve as attachment site for tooth apparatus: PDL, muscles 3. Framework for bone marrow 4. Ion reservoir
118
What does the biological property of plasticity allow the alveolar bone to do?
Remodel according to functional demand
119
What is the possible damage when doing extractions regarding the alveolar bone?
At thinnest parts (mandibular incisor) remove alveolar bone w/ tooth
120
What is the dependency of the alveolar bone?
Dependent on tooth | Following extraction will atrophy
121
Describe the composition of alveolar bone in terms of wet weight and volume
Wet weight Inorganic: 60% Organic: 25% Water: 15% Volume Inorganic: 36% Organic: 36% Water: 28%
122
What makes up the majority of the organic material in alveolar bone?
T1 collagen
123
What makes up the rest of the organic material in alveolar bone?
``` Proteins in small amounts Osteocalcin Osteonectin Osteopontin Proteoglycans ```
124
Describe the differences between internal and external compact bone of alveolar bone
Internal: thin layer lines socket, gives attachment to some PDL fibres External: thicker layers form external and internal alveolar plates
125
What is meant by cribriform plate and bundle bone in alveolar bone?
Cribriform: sieve-like appearance of bone produced by vascular canals Bundle: bundles of Sharpey's fibres bass into bone from PDL
126
What are the 5 types of cell in bone?
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
What is the link between osteoblast and osteoclast activity?
Osteoblasts secrete RANK ligand when forming bone which binds to pre-osteoclasts resulting in differentiation to osteoclasts and becomes activated
128
What is the difference between caries and erosion?
Caries: bacterial acids Erosion: non-bacterial acids
129
What are the 3 ways in which demineralisation can occur by wear?
1. Attrition 2. Abrasion 3. Abfraction
130
What is calcium hydroxyapatite?
Synthetic material analogous to calcium phosphate in bone and teeth Is bioactive and biocompatible Is a bioresorbable implant material
131
What are the 3 main properties of calcium hydroxyapatite?
1. Hard 2. Insoluble: will react w/ acid 3. Chemically complex
132
Compare the solubility of hydroxyapatite and fluoroapatite
HA less soluble than FA | Why fluoride is added to toothpastes, water etc.
133
Describe the conditions that favour remineralisation and those that favour demineralisation
Demineralisation: low pH, low Ca2+ conc. Remineralisation: high pH, high Ca2+ conc.
134
Compare mature enamel to CaHA
Similar Ca ions replaced by other ions; F, CO2 Enamel more soluble than HA
135
Where is carbonate most concentrated in enamel?
Towards EDJ
136
What is the effect of carbonate on CaHA?
Makes it more soluble thus demineralisation/dissolving is more likely to occur
137
What is the effect of fluoride on CaHA?
Reduces solubility thus less likely to demineralise/dissolve
138
What is a Stephan curve?
Graph showing effect of acid attack on pH of oral cavity
139
What is dentine?
Mineralised tissue that forms bulk of tooth | Small, parallel tubules in mineralised matrix
140
What 4 things do dentine tubules contain?
1. Odontoblastic processes 2. Dentinal fluid 3. Nerve endings 4. Antigen presenting cells
141
When does formation of dentine begin and stop?
Begins during bell stage | Continues throughout life
142
Describe the physical properties of dentine
Pale yellow Harder than bone and cementum, softer than enamel Permeable
143
Compare the composition of dentine in weight and volume
Weight: inorganic 70%; organic 20%; water 10% Volume: inorganic 50%; organic 30%; water 20%
144
Where are the CaHA crystals found in dentine and how do they compare to enamel crystals?
Crystals found between collagen fibrils | Much smaller than enamel crystals
145
What are the 6 components of dentine organic matrix?
1. Collagen fibrils 2. Proteoglycans 3. Glycoproteins 4. Phosphoproteins 5. Growth factors 6. Lipids
146
What are dentinal tubules?
Tube through which odontoblastic processes project through dentine to EDJ
147
Why do dentinal tubules follow a S shape?
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
What do subtle changes in direction of dentine during formation result in?
Wavy dentinal tubules | Can from Contour lines of Owen if coincide w/ adjacent tubules, will appear as line across dentine
149
Where do secondary curves usually occur?
At junction between primary and secondary dentine due to all odontoblasts taking similar and simultaneous change in direction
150
Describe the branching of dentinal tubules
Profusely at periphery near EDJ Many side branches, may connect w/ branches of other tubules Lateral branches to communicate w/ other odontoblastic processes
151
What is the clinical important of the high density of dentinal tubules at the EDJ?
If carious legion breaches EDJ can cause large amount of damage do dentine even if relatively small
152
Describe intertubular dentine
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
Describe peritubular dentine
Dentine that lines inside of tubules Lack collagenous fibrous matrix but more mineralised so appears more radiopaque Present in unerupted teeth
154
What can form translucent dentine?
Occluding of dentinal tubules by peritubular dentine
155
Name the 4 layers of dentine
1. Predentine 2. Hyaline and granular layers 3. Circumpulpal 4. Mantle
156
What is mantle dentine?
First formed dentine of crown
157
Describe circumpalpul dentine
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
Describe the hyaline and granular layers
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
Describe interglobular dentine
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
Describe predentine
First layer of dentine, unmineralised Innermost layer Mineralisation front globular or linear Thicker in younger teeth
161
Describe the process of mineralisation of dentine
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
Compare linear and globular mineralisation
Linear: apposition on pre-calcified areas Globular: small, spherical areas become larger, fuse w/ each other
163
What are Von Ebner lines?
Perpendicular (to dentinal tubules) lines along tubules caused by daily alterations in formation of dentine
164
Describe primary dentinogenesis
All dentine up till eruption | May become translucent w/ age due to inc. deposition of peritubular occluded tubules
165
Describe secondary dentinogenesis
Dentine after eruption Structurally similar to primary but w/ fewer tubules Will red. pulp chamber and root canal size in time
166
Describe tertiary dentinogenesis
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
Describe sclerotic dentine
Produced in response to external challenge (caries) Appears translucent due to inc. mineralisation Tubules filled to block ingress of bacteria (protect pulp)
168
What are dead tracts?
Empty dentinal tubules due to odontoblast death or retraction process
169
What are the 3 clinical implications of dentine?
1. Permeability 2. Response to external stimuli 3. Sensitivity
170
Why is permeability of dentine of clinical significance?
When exposed, substances from external environment can reach pulp through dentinal tubules resulting in pulpitis
171
Explain the clinical relevance of external stimuli response of dentine
If stimuli not strong enough to destroy pulp can induce production of tertiary dentine as protective measure - eventually obliterate pulp
172
Explain why sensitivity of dentine is relevant
Exposed dentine is v painful: dentinal fluid compresses nerve endings on dentinal tubules
173
What are the 3 theories of dentine sensitivity?
1. Direct innervation 2. Hydrodynamic 3. Transduction
174
What is the role of the supporting apparatus?
1. Protect teeth from masticatory forces | 2. Prevent premature loss of teeth
175
Describe the thickness of cementum
Thinner coronally: 0.05-0.1mm | Thicker apically: 0.2-1mm
176
What are the 2 functions of cementum?
1. Cover dentine | 2. Provide attachment of tooth to PDL
177
What are some of the characteristics of cementum?
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
Describe the mineral and organic composition of cementum
Mineral: mainly Ca, PO4 in HA crystals Organic: mainly collagen, various glycoproteins and proteoglycans
179
Describe some of the physical and chemical properties of cementum
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
What are the 2 ways in which cementum can be classified?
1. Cell component | 2. Collagen component
181
What are the 2 types of cellular classification cementum?
1. Cellular | 2. Acellular
182
What are the 4 types of collagen classification cementum?
1. Intrinsic fibre 2. Extrinsic fibre 3. Mixed fibre 4. Afibrillar
183
Describe acellular cementum
Forms next to dentine | Greater proportion cervically and less apically
184
Describe cellular cementum
Found apically and overlying acellular cementum Formed during functional needs Numerous cementocytes
185
Describe extrinsic fibre cementum
All collagen derived from Sharpey's fibres | From PDL
186
Describe intrinsic fibre cementum
From cementoblasts All intrinsic fibres running parallel to root surface No role in tooth attachment
187
Describe mixed fibre cementum
Collagen fibres of organic matrix derived from both extrinsic and intrinsic fibres
188
Describe afibrillar cementum
No collagen fibres: thin, acellular layer | Localised regions of mineralised GS cover cervical enamel
189
What is the clinical implication of the thickness of cementum?
Gingival recession will expose thin cementum cervically which is easily abraded by tooth brushing, will reveal dentine which is highly sensitive
190
What are the 2 cells involved in cementum deposition?
1. Cementoblasts: deposit cementoid (unmineralised, pre-cementum) 2. Cementocytes: cementoblasts entombed in cementum
191
Describe cementoblasts
Produce cementum throughout life Reside in the PDL space lining cementum surface Similar to osteoblasts
192
Describe cementocytes
Former cementoblasts trapped within cementum matrix | Found in lacunae and have cellular processes that extend along caniculi which connect to each other
193
Describe the formation of cementum
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
Describe the incremental lines of cementum
Acellular: thin and even Cellular: thicker, irregular
195
Describe the 3 patterns possible at the CEJ
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
Describe the resorption of cementum
Less susceptible than bone under same pressure yet most roots still show signs of resorption Reasons unclear Multinucleated odontoclasts resorb cementum
197
What are cementicles?
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
What is the PDL?
Dense fibrous CT that occupies space between root, cementum and alveolar bone
199
Described the appearance of the PDL
Hour glass: narrowest mid root | Varies depending on functional state of tooth i.e. high occlusal force, unerupted
200
Describe the boundaries of the PDL
From apex to CEJ Alveolar crest: continuous with gingivae Apical foramen: continuous with pulp
201
Describe the properties of the PDL
Richly vascularised, has nerve endings Uncalcified: is living, maintain shock absorbance Appear as radiolucent line around root in radiography
202
What are the 8 functions of the PDL?
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
Describe the structure of PDL
Fibres Neurovascular channels, blood and lymphatics Cells: fibroblasts, cementoblasts/clasts, odontoblasts/clasts, undifferentiated mesenchymal cells GS
204
What are the 6 PDL fibres from most cervical to apical?
1. Transseptal 2. Alveolar crest 3. Horizontal 4. Oblique: principal 5. Apical 6. Inter-radicular
205
Describe the principal fibres of PDL
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
Describe the 2ndary fibres
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
What are the 5 main components of PDL GS?
1. Hyalironidate GAGs 2. Proteoglycans 3. Glycoproteins 4. Fibronectin 5. Tenascin
208
What are the 6 cell types in PDL?
1. Fibroblasts 2. Osteoblasts/clasts 3. Cementoblasts/clasts 4. Undifferentiated mesenchymal cells 5. Defence cells 6. Epithelial cells (Cell Rests of Malassez)
209
Described the innervation of the PDL
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
What are the clinical implications of the PDL in terms of disease?
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
What are the clinical implications of PDL in terms of orthodontics?
Tension: inc. PDL space w/ inc. CT and osteoid deposition Pressure: red. PDL, inc. resorption
212
Define ideal occlusion and normal occlusion
Ideal: based on morphology of unworn teeth Normal: satisfies functional and aesthetic requirements but may have minor irregularities in individual teeth
213
What are the 3 features of OC at birth?
1. Dental arches represented by gum pads 2. Upper gum pad longer and wider than lower 3. Segmented elevations: represent in-erupted teeth
214
Describe the development of deciduous dentition? Commence, calcification, complete
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
What are the 3 features of deciduous dentition?
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
What is the general function of deciduous dentition? Apart from mastication
Hold space for permanent teeth | If removed may cause permanent to not erupt or be impacted
217
Describe the eruption of permanent dentition
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
Where do the permanent incisors develop?
Palatal/lingual to deciduous incisors
219
What 3 features accommodate for the inc. width of permanent incisors?
1. Pre-existing space: primate spacing 2. Proclination: erupt inclined giving more space 3. Growth: inc. inter-canine space
220
Describe the ugly duckling stage of development
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
Define Leeway space
Difference between the mesio-buccal distance of C,D,Es compared to 3,4,5s
222
What is the purpose of the leeway space?
Allows 6s to drift forward (after Es exfoliate) and form class I molar relation
223
Quantify the leeway space
Mandible: 2mm/quadrant Maxilla: 1mm/quadrant
224
Define class I molar relation
Mesio-buccal cusp of U6 occludes w/ mid-buccal groove of L6
225
Define class I incisor relation
L incisal edge occludes w/ cingulum plateau of U incisors
226
How are the permanent molars guided into place?
By flush terminal plane of Es
227
What is biomineralisation?
Process by which inorganic crystal growth and formation is controlled by organic molecules (proteins)
228
Describe the growth of crystals and why control is required
Crystals grow in all directions thus proteins required to control rate in some directions or completely stop
229
What is minimal intervention dentistry?
Approach by which dentists base patient care on disease risk assessment, earliest diagnosis and minimal invasive treatment
230
Describe amelogenin
Forms 90% developing enamel ECM Highly species conservative Unique to enamel High in proline and glutamate
231
Describe the structure of amelogenin
N: TRAP, hydrophobic, 44-45AAs Core: hydrophobic, proline, leucine repeats, 100-130AAs C: hydrophilic, acidic, 15AAs; charged region binds to HA
232
Describe the regional and molecular structure of amelogenin
Regional: secondary Molecular: tertiary Poorly defined Beta sheets detected by NMR; could act as Ca2+ channels
233
What post-translational modification occurs in amelogenin?
No glycosylation | Some phosphorylation: serines to phosphoserines
234
Describe the supramolecular structure of amelogenin
1. Bipolar 2. Self-assembly into nano-spheres 3. 100 monomer units 4. C-terminus on exterior
235
Describe the primary and secondary functions of amelogenin
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
Describe enamelin
``` 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
Describe tuftelin
Secreted before amelogenin Mainly located @ DEJ Has Ca binding domain Associated w/ regulation of HA crystal nucleation
238
What are another 3 examples of non-amelogenin matrix proteins?
Serum albumins: don't bind crystals Proline-rich: in un-erupted enamel Enzymes: proteases, serine proteases
239
What is the clinical relevance of proteins of enamel biomineralisation?
When process disturbed can lead to conditions such as AI
240
What is AI?
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
Describe the composition of dentine
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
What are 3 main proteins found in dentine?
Phosphoproteins: Ca binding Osteocalcin: mainly found in bone; Ca binding Osteonectin: bind HA and collagen
243
What are the 3 dentine specific non-collagenous proteins?
1. Phosphophoryn 2. Sialprotein 3. AG1
244
What is dentinogenesis imperfecta?
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
Why are apatites important?
Loss of bone/tooth mineral basis of 1. Osteoporosis 2. Tooth decay and caries 3. Acid erosion 4. Periodontal disease
246
In non-stoichiometric solid solutions formed what are magnesium, manganese, fluoride, carbonate each substituted by?
Mg2+, Mn2+: Ca2+ F-: OH- CO32-: PO43-
247
Compare the degree of crystallinity in enamel and bone and dentine
Enamel apatite: sharp diffraction lines; higher conc. F- probably favours more ordered crystal structure Bone/dentine: diffusion diffraction pattern
248
What is tooth decay?
Caused by bacteria in plaque and carious lesions producing acids which dissolve tooth mineral Also produce enzymes which hydrolyse protein component of tooth
249
What is erosion?
Acid dissolution of mineral | Natural acids: no bacteria involved
250
What is the significance of the hexagonal lattice structure of HA?
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
Why is fluoride toothpaste important but what does it lack?
F substitutes OH to form FA: more stable, withstand dissolution To remineralise require Ca2+ and PO43-
252
What is fluorosis?
Mottling of teeth of children associated w/ fluoride
253
What may mottling also be a result of?
Disrupted enamel mineralisation resulting from viral disease
254
Why can fluoride be toxic?
Form complexes with elements in Electron transport system Enzyme cofactors
255
What are the 5 effects of fluoride poisoning?
1. Nausea, epigastric pain, vomiting 2. Limb spasms, tetany, convulsions 3. BP, pulse rate fall 4. Respiration depressed 5. Unconsciousness
256
Why is solid state NMR important for apatite?
Only good way to distinguish between HA and FA
257
What is the water fluoridation level in the UK?
1ppm Beneficial as withstand acid dissolution
258
What DM is fluoride releasing?
GIC, can also release other ions: strontium Can also uptake and re-release F: act as F battery
259
Why are bioactive glass toothpastes good?
Release Ca2+, PO43- and raise pH Forms hydroxycarbonated apatite Binds directly to bone/tooth
260
What is NovaMin and what are its disadvantages?
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
What are bitewings?
Check up X-rays Show crowns of premolars and molars Used for caries risk assessment and bone loss
262
What are peri-apical X-rays?
Can be of posterior or anterior teeth Show crown and root Used for RCT, extraction, bone loss and caries assessment
263
What is a pan-occlusal X-ray?
X-ray of occlusal view | Useful for un-erupted teeth
264
What is a panoramic X-ray?
X-ray from condyle to condyle Can see sinuses, orbits, nose and soft tissue spaces Useful for orthodontics
265
What are the 2 most important factors when taking X-rays and how do they relate?
1. Dose 2. Image quality For safety need lowest dose as reasonably practical
266
Describe the process of X-ray production in an X-ray tube
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
What is the function of aluminium filters in X-rays?
Remove the lower energy photons that would be absorbed by body tissues and potentially cause problems
268
Describe the effect of inc. voltage in the generation of X-rays
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
How does inc. time current is applied for alter X-rays?
Inc. no. photons produced | Potential for more to be absorbed creating darker image
270
Why is rectification important in radiography?
Convert AC to DC current | Current always on (when pressed) thus less dose to patient as more photons produced
271
What is the importance of rectangular collimation?
Changes tube head from circular to rectangular | Red. dose by 50%
272
Describe the 2 mechanisms by which radiation can cause damage
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
What are the 3 types of harmful radiation effects?
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
Describe dental pulp
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
What is the primary function of pulp?
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
What are the inductive, formative and protective functions of pulp?
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
What are the 2 types of pulp?
1. Coronal | 2. Radicular
278
Compare the 2 types of pulp
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
Describe the fibrous matrix of pulp
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
What is present in the GS of pulp?
Glycoproteins Proteoglycans Water
281
Where are odontoblasts found in pulp?
Outermost region, immediately adjacent to dentine | Responsible for secretion of dentine, formation of dentinal tubules
282
What is special about pulp fibroblasts?
Shown ability to degrade and form collagen
283
Describe perivascular cells
Undifferentiated mesenchymal cells present in pulp | Give rise to odontoblasts, fibroblasts, macrophages
284
What other cells are common in the pulp?
Lymphocytes, plasma cells, eosinophils
285
What are the 4 zones of pulp from outer to inner?
1. Odontoblastic 2. Cell-free 3. Cell-rich 4. Pulpal-core
286
Describe the odontoblastic layer of pulp
Lines outer pulpal wall, consists of odontoblast cell bodies 2ndary dentine may form here from apposition of odontoblasts
287
Describe the cell-free zone of pulp
Fewer cells than odontoblastic | Capillary and nerve plexus
288
Describe the cell rich zone of pulp
Inc. density cells, more extensive vasculature | @ base; nerve plexus of Raschow
289
Describe the pulpal-core of pulp
Located in centre of pulp chamber Many cells, extensive vasculature Similar to cell-rich
290
Describe odontoblasts
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
What inflammatory cells are present in the pulp?
1. T lymphocytes 2. Macrophages 3. Dendritic antigen presenting cells
292
Describe the distribution of inflammatory cells found in the pulp
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
Describe the vascular supply to the pulp
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
Describe the structure of vascular supply in pulp
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
Describe the innervation of the pulp
Pre/molars: several large nerve fibres enter apical foramen of each Ant.: one fibre enters 1. Autonomic 2. Afferent
296
Describe the autonomic innervation of the pulp
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
Describe the path of afferent nerves in the pulp
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
Describe the afferent fibres of the pulp
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
What is the clinical importance of pulp?
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
Define absorbed, equivalent and effective dose
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
Explain the effect of age on radiation risk
Indirect Children much more at risk due as cells are dividing, growing Older people have negligible risk as won't see effect
302
What is the main justification for radiographs?
Benefit to patient must outweigh detriment
303
What are the 5 justifications of radiographs?
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
Describe the optimisation and limitation of radiographs
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
What are the 4 areas where radiation dose can be reduced?
1. Equipment 2. Clinical decision 3. Practical technique 4. Diagnostic interpretation
306
What are the 5 equipment factors that can red. dose?
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
Describe conventional and digital radiographs films
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
What are the 6 remits for radiographs?
1. Caries diagnosis 2. Developing dentition 3. Endodontics 4. Periodontal assessment 5. Implant dentistry 6. Good practice
309
What are the 3 practical technique factors for taking radiographs?
1. Aligning tube w/ film 2. Lead aprons: no justification, discouraged for panoramics 3. Pregnancy: justification, optimisation, delay, lead for physiological reasons
310
Explain the controlled area
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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