Tys Flashcards
Enamel tuft description
Hypomineralised, contain greater concentration of enamel proteins
Ribbon like structure, longitudinal to tooth acids, extend from DEJ 1/3 into enamel
Wavy look within enamel microstructure
Relationship between cross striation and enamel prisms
Cross striations formed across adjacent enamel prisms
Changes in dental pulp as tooth ages
Reduce cellularity
Calcification (pulp stone)
Odontoblasts down regulate
Decreased volume
Key feature of PDL and associated clinical application
Contains cells with regenerative potential, can regenerate new cementum/bone/PDL through guided tissue regeneration
What is the role of Hertwig’s epithelial root sheath
HERS grow horizontally into dental papilla to form epithelial diaphragm. Induce dental papilla to differentiate into odontoblasts which deposit radicular dentin. Secrete hyaline layer. Dental follicular cells attach to hyaline layer, induce differentiation to cementoblasts and periodontal fibroblasts. HERS disintegration signals start of cementogenesis
Where are blood vessels in pdl derived from
Periapical area, gingiva, PDL of overlying deciduous teeth
List the differences between oral mucosa and skin
Hair follicles, sweat glands, colour differences due to melanin production
How is junctional epithelium different from oral epithelium
Larger cells, lesser desmosomes, lesser tonofilaments, wider gap junctions/intercellular spaces, no acid phosphatase activity, lower glycolytic enzyme activity
Advantages and disadvantages of pulp being surround by dentine
Advantage: hard protective covering
Disadvantage: Low compliance of dentine, limited capability to respond to revere inflammatory reaction
How does tertiary dentine aid in defence of pulp against carious lesion
Make dentine less permeable to reduce diffusion towards pulp
Maintain buffer zone
Mantle dentine vs circumpulpal dentine
Mantle dentine is first formed dentine
Mantle dentine lower density, less mineralised. Circumpulpal dentine harder, less elastic.
Mantle dentine mineralised by vesicle mineralisation. Circumpulpal dentine mineralised by crystal growth (nucleation)
Function of odontoblasts
Secrete dentine
Sensory organ - mechanical/thermoreceptor
APC to defend pulp
Difference between mineralisation pattern of collagen in bone and dentine
Both have extrafibrillar calcification
Only dentine has intrafibrillar calcification/calcification in gap zones
Describe PDL fibres
Reticular: form lattice in PDL, collagen 3
Oxytalan: more in teeth bearing abnormal occlusal load, immature elastic fibres
Principal: collagen 1, high turn over rate
Elastin: walls of blood vessels
What are the 3 parts of alveolar bone histologically
Compact bone, bundle bone, trabecular bone
Five functional roles played by bone
Structural support
Protection
Movement
Haemapoiesis
Calcium metabolism
