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endo 3BDS > materials > Flashcards

materials Flashcards

1
Q

what does a taper of 0.02 mean?

A

2% taper, every 1mm towards the shank the diameter increases by 0.02mm

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2
Q

what are the advantages of SS files?

A

dont corrode, rust or stain

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3
Q

what are the disadvantages of SS files?

A

poor flexibility and errors in shaping

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4
Q

what types of canals are barbed broaches not suitable for?

A

curved or narrow

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5
Q

what types of SS files are there?

A

flexofiles, K files and Hedstroem files

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6
Q

what are the advantages of flexofiles?

A

batt tip is non-aggressive, low risk of transport and ledge formation

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7
Q

what are hand files mainly useful for?

A

creating a glide path

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8
Q

what are hedstroem files used for and why are they poor for use in preparation of canals?

A

used in removal of gutta percha due to retreatment or overfilling, not useful for canal prep as they are stiff and can only be used in an up and down motion

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9
Q

what are common problems with SS file preps?

A

ledges, blockages, transportation, debris extrusion

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10
Q

what are the favourable characteristics of rotary nickel titanium instruments?

A

superelastic and memory

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11
Q

what is superelasticity?

A

allows instruments to be used in curved canals with less lateral forces so less lodging, transportation, zipping etc.

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12
Q

what is the composition of nickel-titanium instruments?

A

56% nickel, 44% titanium

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13
Q

what are the advantages of nickel titanium instruments over stainless steel ones?

A

increased flexibility, increased cutting efficiency, better safety and more user friendly

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14
Q

name a passive cutting file type and an active cutting file type

A 
passive = profile system GT 
active = ProTaper universal
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15
Q

what are the advantages of M wire?

A

superplastic, improved fatigue resistance, increased safety

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16
Q

what are the 3 crystalline phases of M wire?

A

deformed and micro twinned martensite
premartensitic r phase
austenite

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17
Q

what are the advantages of a larger taper?

A

optimum obturation, effective disinfection of canal

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18
Q

what is the purpose of an inter appointment disinfectant?

A

to reduce and prevent microorganisms that remain following careful cleaning and shaping
to prevent reinfection through coronal or apical leakage

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19
Q

requirements of a good inter appointment disinfectant?

A

long lasting disinfectant action
not irritating to periradicular tissues
non-toxic
not damaging to tooth tissue or restorative materials

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20
Q

phenolic compound inter appointment disinfectants

A

camphorated phenol or CMCP

toxic and possibly carcinogenic

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21
Q

what are the uses of calcium hydroxide?

A

used as an inter-appointment medicament, for pulp capping, for apexification and as a root canal sealer

22
Q

what is the pH of calcium hydroxide?

A

12.5-12.8 (strong base)

23
Q

what are the characteristics of calcium hydroxide as a medicament?

A

kills bacteria, inactivates endotoxins, reduces inflammation, eliminates apical exudate, controls inflammatory root resorption, prevents contamination between appointments

24
Q

what is the mechanism for the antibacterial activity of calcium hydroxide?

A

releases OH- in an aqueous environment to damage the bacterial cytoplasmic membrane, denature proteins and damage bacterial DNA

25
Q

name two commercial calcium hydroxide products

A

hydrocal, ultracal

26
Q

why is calcium hydroxide useful for weeping canals?

A

it has a high pH, calcifying potential and the ability to cauterise residual chronically inflamed pulp

27
Q

what are the ideal technical properties of an obturating material?

A

no shrinkage on setting, no solubility in tissue fluids, good adhesion/adaptation to dentine, no water absorption, no tooth discolouration

28
Q

what are the ideal biological properties of an obturating material?

A

no allergy for patients or staff, no irritation to local tissues, sterile, antimicrobial, stimulate periradicular healing

29
Q

what are the ideal handling properties of an obturating material?

A

radiopaque, sets in adequate time, easy to remove and apply using heat, solvents or mechanical instrumentation

30
Q

what is gutta percha a transionomer of?

A

polyisoprene

31
Q

what are the two crystalline forms of gutta percha?

A

alpha which is a solid compatible mass and beta which is soft and tacky when heated and shrinks on cooling

32
Q

what are the disadvantages of gutta percha?

A

lack of adhesion to dentine, shrinks on cooling, cannot be heat sterilised

33
Q

how would you sterilise gutta percha?

A

sodium hypochlorite solution 1 min

34
Q

what are 3 alternatives to GP?

A

thermoplastic GP, guttacore and thermafil

35
Q

what is the principal of thermoplastic GP?

A

continuous wave of obturation

36
Q

why is a sealer required along with GP?

A

gutta percha, no matter how well adapted to the canal walls, will not create a fluid tight seal

37
Q

what are the ideal properties of a sealer?

A

provide a fluid tight seal, no shrinkage on setting, slow setting time, fills canal irregularities, bacteriostatic, adheres to dentine, biocompatible

38
Q

what is an advantage of calcium hydroxide as a sealer?

A

therapeutic activity

39
Q

what are the advantages of bioceramic sealers?

A

biocompatible, hydrophilic, chemically stable, expand slightly on setting, form a hydroxyapatite, no inflammatory response if overfilled

40
Q

what does smart paste bio contain?

A

zirconium oxide, calcium silicates, calcium phosphate monobasic, calcium hydroxide

41
Q

name 3 advantages of smart paste bio?

A

releases calcium hydroxide and hydroxyapatite on setting, hydrophilic, antimicrobial during setting

42
Q

what do calcium silicate sealers consist of?

A

MTA and water soluble polymer

43
Q

what is advantageous about calcium silicate sealers?

A

hydrophilic, slow setting, alkaline, stimulate cementogenesis

44
Q

how do calcium silicate sealers stimulate cementogenesis and hard tissue formation?

A

by osteocalcin gene expression of osteoblast cells

45
Q

what can odontopaste be used for?

A

an inter-appointment medicament

46
Q

what is odontopaste composed of?

A

zinc oxide based with corticosteroid and antibiotic

47
Q

what are the contra-indications for odontopaste?

A

pregnancy, breast-feeding, hypersensitivity to ingredients, purulent pulpitis, deciduous teeth

48
Q

what does iodine kill?

A

bacteria, fungi, viruses and spores

49
Q

what does povidone iodine do?

A

induces non-specific cell death due to oxidising free iodine

50
Q

what are the contra-indications of povidone iodine?

A

pregnancy, breastfeeding and hypersensitivity

51
Q

what facultative anaerobe may be present in pretreatment cases and how is it destroyed?

A

enterococci faecalis destroyed with IKI or povidone 10 min soak

endo 3BDS (7 decks)

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