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Flashcards in Oral Cavity Deck (310)
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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