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- Created by: Splodge97
- Created on: 24-05-17 10:49
What are the features of enamel?
Non-living, white, 95% minerals and 4% water (makes hard/prone to fracture), mainly calcium hydroxyapetite
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*** are enamel prisms arranged?
Crystalline, form S shape using fibres through decussation (causing horizontal undulation - makes it hard), grow upwards along crown surface from cementoenamel junction.
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What are the features of dentine?
Inner living hard tissue, yellow, more flexible than enamel (as 70% minerals, 10% water) to withstand mechanical pressure
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What are the features of cementum?
Hard tissue covering the roots, yellow, 61% minerals and 12% water (less prone to fracture than enamel). Living but dies in maturity through slow death of cementoblasts.
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What is acellular/cellular cementum?
Cellular = at apex of root, below acellular cementum (contains cells). Acellular = covers the roots, contains no cells.
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What is the pulp comprised of?
Collagen, blood vessels and nerves, odontoblasts, fibroblasts, defence cells
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What is the anatomical/clinical crown?
Anatomical = covered by enamel. Clinical = observed in the oral cavity, changes with age/gingival recession.
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What are the features of alveolar bone?
45% minerals, 25% water; felxible so teeth erupt. Degenerates when teeth lost.
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In what order do the incisors erupt?
Lower central (6-7) --> lower lateral (7-8) and upper cental (7-8) --> upper lateral (7.5-8.5)
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In what order do the premolars erupt?
Lower 1st (10-11) --> upper 1st (10-12) and lower 2nd (10-12) --> upper 2nd (10.5-12.5)
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What is the cervical part of a tooth? Therefore, what is the cervical line?
Part of the tooth next to the gingival margin. Cervical line is angle between root and crown (made at cemento-enamel junction)
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What are perikymata?
Transverse and wave-like grooves on the external enamel; often made smooth through wear
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What are marmelons?
Elevations of enamel on the incisal edge of newly emerged teeth; flatten through wear
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What is linear enamel hypoplasia?
Abnormal incidence where enamel formation disrupted by poor nutrition/a stressful event; causes grooves on the surface of the tooth
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What are the features of Palmer notation?
Permanent teeth 1-8 in each quadrant, primary A-E. Easy to use and less prone to error than the FDI system (quadrants labelled with numbers), but confusing (as opposing teeth have same number) and not as universal
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What is eruption? How does it occur?
The entry of teeth through the gum-line (the eruption process being termed emergence); dates refer to the start of emergence. Anterior teeth erupt before posterior, lower before upper and in girls before boys.
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What occurs in the first growth period (age 0-6)?
Deciduous teeth calcify and complete (at 2.25 years), therefore rapid growth seen. Primary dentition fully erupted by 2.5yrs.
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What occurs in the 2nd growth periiod (age 6-12)?
Minimal growth - primary dentition shed, permanent emerge. 1st permanent molar erupts ot 6, 2nd at 12 (jaw enlarges to accomodate these).
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What occurs in the 3rd growth period (12-21)?
Slow growth (except during puberty), jawbone emerges to accomodate 3rd molars (erupt 17-21)
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Why is AlQhatani's tooth model most accurate?
Studied using a range of populatons with a large sample size, takes into account variation, more precise age ranges.
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What are ameloblasts?
Secrete enamel during development. All die at crown surface upon tooth eruption (so enamel can't be repaired). Each forms a single enamel prism.
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What are odontoblasts?
Secrete dentine. Decrease in number throughout life but remain present at pulp chamber to form new dentine in response to caries/injury.
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What are the different classifications of dentine?
Primary = present before eruption. Predentine = Newly formed unmineralised dentine in a matrix at pulp border. Secondary = formed after eruption by odontoblasts. Tertiary = formed at pulp horns for protection (from caries/attrition/injury).
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What are the classifications of tertiary dentine?
Reactionary = weak stimulus/injury causes existing odontoblasts to secrete dentine. Reparative = severe injury causes newly recruited (from progenitor cells) odontoblasts to secrete dentine.
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What are cementoblasts?
Secrete cementum
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What are cementocytes?
Cementoblasts develop into these upon completion of the cementum - they can secrete more cementum as needed but decrease in number with age
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What are the dentinal tubules?
Minute branching tubes going from dento-enamel junction into the dentine; exposure in root canal prompts tertiary dentine
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What causes pulp stones?
Pulp becomes more vascular and less lineralised with age/injury
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What is the junctional epithelium? What does it secrete?
Attaches the gingiva to the tooth at the cementoenamel junction (forming the ginigival sulcus). Secrete cervicular fluid (containing immune cells) through itss leakage channels to prevent infection.
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How do the gums appear when healthy?
Pink (through keratin), tight and possibly stippled (dotted) with triangular interdental papillae
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What are the different classifications of gingiva?
Free = from top of gingival margin to bottom of gingival sulcus. Attached = below free gingiva, atttached to alveolar bone, may be red (as not keratinised).
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What are the featuress of the PDL?
Dense, fibrous connective tissue with collagen grouped into bundles. Connects cementum to alveolar bone through its principal Sharpey's fibres. High turnover, rich vascular supply/innervation. Contains fibroblasts, cementoblasts and odontoblasts.
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What are the different layers of the alveolar bone?
Bundle bone = hard layer of fibrous alveolar bone at surface where Sharpey's fibres attach. Supporting bone = softer layer of non-fibrous alveolar bone, supports roots of teeth.
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What occurs in periodontitis?
Irreversible inflammation of the periodontium (as alveolar bone resorbed). Pocket formation (>3mm gingival sulcus), loss of gingival attachment, bleeding, gingival recession, tooth mobility and migration. First as bleeding/drifting front teeth.
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What occurs in gingivitis?
Reversible inflammation of gingiva (healthy level of alveolar bone). Erythematous (red), oedematous (swollen), shiny and soft gingiva; also bleeding/increased crevicular fluid. Marginal gingivitis just at gingival margin.
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How does dental plaque cause caries?
Accumulation of bacteria as a biofilm release lipopolysaccharides (to form their ECM). Cause immune cells to release collagenases which destroy host hard tissues. Osteoclasts recruited. Bacterial ammonia/sulphuric acid/collagenases minimal effect.
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How is smoking a risk factor for oral disease?
Causes vasoconstriction, affects immune response and lowers O2 content of blood so more anaerobic subgingival bacteria
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How is diabetes a risk factor for oral disease?
Causes vasoconstriction (as a by-product of high blood pressure) and affects the immune response
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How are medications a risk factor for oral disease?
Contraceptive pill and epileptic drugs cause overhanging gingiva (retention factor)
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What is open flap surgery?
Gingiva folded back so exposed roots can be cleaned; bone replacement packed in then closed by suturing
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What is the mineralising front?
Where predentine becomes mineralised and passes into dentine at pulpo-dentine junction
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What are the layers leading into the pulpal matrix from the dentine?
Mineralising front, predentine, odontoblast layer, cell free zone, cell rich zone (containing odontoblasts and collagen), pulpal matrix (with odontoblasts, collagen, fibroblasts, nerves and blood vessels)
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What is scalloping?
Occurance of troughs and pits at the dento-enamel junction; aids adhesion between enamel and dentine, absorbs masticatory stress (placing more pressure on dentine) and increases SA for ameloblasts/amelogenesis (so thicker enamel)
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What is the neonatal line?
Hypomineralised layer of enamel appearing darker due to temporary halt in enamel production by ameloblasts during stress of birth (only in primary and 1st permanent molar)
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What is odontogenesis?
Formation and development of teeth
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Why are odeontoblasts mesenchymal?
They differentiated from the dental papilla (prenatal condensation of odontoblasts) - ameloblasts develop from the epithelium
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What is scletotic dentine?
Formed when the dentinal tubules become calcified
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What suturing materials are available?
Vicryl (rapide) which is resorbable and used in the mouth, silk with is non-resorbably so used minimally and ethilon wich is used on the skin (non-resorbable)
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What are the stages of healing?
Inflammatory response, protein rich exudate released, fibrinogen-->fibrin to coagulate, WBC's to area to from granulation tissue, epithelial cells multiply to form skin, fibroblasts secrete collagen so wound contracts, fibrous tissue matures to scar
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What are the different suture techniques?
Single interrupted = loop tied, secure. Horizontal matress = closes extraction sockets (pull tissue together), single stiches secure. Vertical matress = encompasses more subgingival tissue. Continuous = rapid, less secure (tied once) unless use lock.
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What substances can be used for debridement before a suture is placed?
Iodine or chlorohexidine
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Describe oral cancer
Mainly squamous cell carcinoma at gums/border of tongue. Appears as ulcers, red/white paches or a cauliflower lump through swelling). If detected early survival rate 80-90%, drops to 30% if detected late.
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What types of cancer can occur?
Carcinomas (of the skin/epithelia), sarcomas (of bone, cartilage or fat), leukaemias (in WBC's) and lymphomas (from lymphatic/immune tissue)
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Why is alcohol a risk factor for oral cancer?
Generates toxic acetaldehyde and free radicals which mutate DNA
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Why is smoking a risk factor for oral cancer?
The polycyclic hydrocarbons, nitrosamines, aldehydes and aromatic amines in tobacco form DNA abducts (prevent DNA repair/inluence rate of cell cycle)
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Why is betel quid usage a risk factor for oral cancer?
Releases nitrosamines, generate reactive oxygen species which act as carcinogens
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Why is a fruit/vegetable deficiency a risk factor for oral cancer?
Reduces antioxidant protection
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Why are HPV infections a risk factor for oral cancer?
HPV oncoproteins bind to p53 (normally inhibits cell cycle if fault/induces apoptosis) causing it to be degraded. It also blocks downstream tumour supressor genes.
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What is caries?
Loss of tooth substance through demineralisation of inorganiss and destruction of organic materials of the tooth through microbial action (mainly Streptococcus mutans). Appears as a tactile surface with a leathery/slippery texture.
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What does the acidogenic theory state?
For caries to occur there must be plaque microorganisms, a susceptible tooth surface, a substrate (carbohydrate) and time
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What are the different types of caries?
Smooth surface (reversible white spot lesion through insufficient brushing), root surface (in elderly through gingival recession/low slaiva flow), recurrent (around restoration through poor oral hygiene), milk bottle (night bottles when saliva low)
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What is DMFT data?
Decayed, missing and filled teeth. Teeth may not have been removed through caries, doesn't indicated extent of decay.
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How can fluoride reduce the risk of caries?
At conc of 1ppm converts enamel to strong fluoroapetite (though conc too high causes fluorosis)
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What are the two types of fissure sealant?
First etched with 37.5% phosphoric acid using metal burnisher. Light cured = one resin, sets in 15 sec under blue light, Self cured = two liquids mixed and polymerise under a catalyst in 2 minutes; often get wet so set ineffecttively.
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What must be ensured for a fissure sealant to be passible?
Occlusion correct, sealant fully cured, covers all pits/fissures, right depth, no air blows
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What causes pulp necrosis?
As pulp in rigid chamber vasodilation increases intrapulpal pressure, compressing vessels within it so lack of blood flow to tissues. Tissue damage instigates inflammation which causes necrosis. Leads to periapical peiodontitis causing resorption.
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What are the stages of root canal treatment?
Gain access to pulp chmber then unroof it. Determine length of each root using apex locators/radiograph. Pulp removed and canals disinfected (using Na+ hypochlorite/chlorohexidine). Then obturation (filling).
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What is peritubular dentine decomposition?
Occurs around dentinal papillae in age. Papillae further up the crown have a narrower lumen (as surrounded by more mineralised/secondary dentine)
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Other cards in this set
Card 2
Front
*** are enamel prisms arranged?
Back
Crystalline, form S shape using fibres through decussation (causing horizontal undulation - makes it hard), grow upwards along crown surface from cementoenamel junction.
Card 3
Front
What are the features of dentine?
Back
Card 4
Front
What are the features of cementum?
Back
Card 5
Front
What is acellular/cellular cementum?
Back
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