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Dental Skills Y3 > Endodontics > Flashcards

Endodontics Flashcards

1
Q

describe the bacterial mix in a compromised root canal

A

aerobic and anaerobic bacteria,
changes to more anaerobic with time,
change to more gram negative,
symbiotic relationship of: streptococci, prevotella oralis, porphyromonas

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2
Q

what should be assessed radiographically in the pulp chamber ?

A

position of roof and floor,

amount of reparative dentine

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3
Q

what should deb assessed radiographically in the root canals ?

A

number of roots and canals,
degree of generalised calcification,
pulp stones,
curvature

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4
Q

what exists at a cellular level in the apical war zone ?

A

polymorphonuclear leucocytes,
macrophages,
B and T lymphocytes,
plasma cells

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5
Q

what inflammatory mediators are present in an apical abscess ?

A

neuropoetides,
complement systems,
lysozymes

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6
Q

what produces the periapical lesion ?

A

prostoglandins, leukotrienes, cytokines

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7
Q

what are the tree types of files used in endodontics ?

A

K files, Hedstrom files, ProTaper files

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8
Q

what are the requirements for the pre - operative radiograph ?

A

tooth centrally located,
3-4 mm peri-radicular tissue visible,
second film with 15 to 20 degree horizontal parallax

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9
Q

what is the purpose of the access cavity ?

A

remove the entire roof of the coronal pulp chamber,

allows ready access to all root canals with straight line access

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10
Q

what determines the shape of the access cavity ?

A

position and number of pulp horns

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11
Q

which burs should be used to prepare the access cavity ?

A 
high speed for initial penetration:
small round 520
tapered fissure 554 
slow speed for refinement:
tapered fissure
round burs
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12
Q

what are the stages of creating the access cavity ?

A

breach pulp chamber with 554,
apply rubber dam,
remove roof of pulp chamber with slow speed long shank round bur - cut on upstroke,
flare walls of pulp chamber and access cavity so greatest diameter is at tooth surface,
clear debris with excavator,
irrigate with ultrasonic,
locate canals and check straight line access

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13
Q

what are the advantages of rubber dam in endodontics >

A 
protects oro-pharynx,
protects soft tissues from caustic materials,
retracts soft tissues and tongue,
improves access,
prevents salivary contamination
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14
Q

what are the 3 methods of measuring working length?

A

tables of average length,
apex locator,
radiography

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15
Q

how do apex locators work ?

A

measure electrical resistance with direct, alternating and high frequency currents,
measure voltage gradients,
calculate ratio between impedance

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16
Q

what is the impedance measures by apex locators between apical tissues and the lip ?

A

6.5 kOhms

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17
Q

what are the problems with the use of apex locators ?

A

wet canals (absolute AL machines only) - e.g. hypochlorite, puss, tissue exudate
heavily restored crown - eg amalgam, gold inlay
poor contact of lip electrode

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18
Q

what is the working length ?

A

distance from a fixed reference point on the crown of the tooth to the terminus near the radiographic apex

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19
Q

what is the modified step back technique ?

A

the coronal aspect is opened up first before creating terminal stop and flaring backwards to the original flare

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20
Q

when in the modified step back technique used ?

A

large canals,

most often anterior teeth or single rooted premolar teeth

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21
Q

what shape should the prepared canal be ?

A

continuously tapering cone

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22
Q

what files are used for orifice enlargement ?

A

hedstrom

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23
Q

describe the hedstrom files

A

machined from a round tapered blank,
creates a sharp cutting blade,
file has aggressive cutting action

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24
Q

what are the alternative instruments for orifice enlargement ?

A

Gates Glidden burs

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25
Q

what is the equation for calculating the diameter of GG burs ?

A

20(GG+1)+10 in hundredths of a mm

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26
Q

describe the tip of modern end files

A

Batt tip,
blunted,
enables file to follow canal wall

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27
Q

what is meant by ISO?

A

international standards applied to endodontic files

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28
Q

what are the iso standards ?

A

standardised sizing related to diameter 1mm from tip of instrument,
colour coded handles,
standardised length of working part of instrument,
standardised taper 2%

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29
Q

what 3 lengths are files made to ?

A

21mm,
25mm,
31mm

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30
Q

what length is the cutting area of endodontic files ?

A

always 16mm

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31
Q

how are endodontic files allocated sizes ?

A

one hundredths of a mm at the projected tip e.g. size 25 file is 0.25mm at the tip

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32
Q

how is instrument taper calculated ?

A

16X0.02 = 0.32 (width of files at the upper end of cutting area)
eg a iso 25 file is 0.25 mm at tip and 0.32 mm wider at top

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33
Q

what is the purpose of orifice enlargement ?

A

remove heavily infected material,
improves access to apical third,
improves irrigation,
reduces effective curvature

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34
Q

how many instrument changes are required to create the apical stop ?

A

9

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35
Q

how many file changes are required to create the step back ?

A

14

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36
Q

how many degrees should the file be turned when watch winding ?

A

90

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37
Q

describe the balanced force technique

A 
power phase -
place file until it binds,
turn clockwise by 90 degrees
control phase -
turn file 120 degrees anticlockwise whilst applying apical pressure
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38
Q

what are the advantages of the balanced force technique ?

A

superior shaping,
file remains central within canal,
less debris pushed apically

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39
Q

what sized file should deb used to create an apical stop ?

A

2 sizes above the first file that binds in the canal

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40
Q

what errors can occur during canal preparation ?

A

incomplete debridement,
lateral perforation,
apical perforation,
blockage of canals,
ledging,
apical zipping - inappropriate rotation of instruments,
elbow formation - inappropriate pre curving of instruments

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41
Q

when and why is longitudinal circumferential filing used ?

A

large irregular shaped canals at the step back stage,

when balanced force is inappropriate as files would be loose in canal

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42
Q

what are the ideal properties of an irrigant ?

A 
non irritant,
bacteriocidal,
dissolve organic material,
remove inorganic material,
non staining to dentine,
lubrication of instruments
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43
Q

what irritants are used in RCT ?

A

sterile saline,
local anaesthetic solution,
sodium hypochlorite,
chlorhexidine

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44
Q

what is the concentration of sodium hypochlorite used in RCT ?

A

0.5-5.0%

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45
Q

what is the gauge of the irrigation needles?

A

27

46
Q

what is unique about irrigation needles ?

A

side delivery to avoid danger of solution extrusion through the apex

47
Q

what is the chelating agent used in RCT ?

A

Ethylene Diamine Tetra Acetic acid 15-17 %

48
Q

what is the purpose of the chelating agent ?

A

breaks down inorganic debris,
lubricant,
removes smear layer with NaOCl

49
Q

what lubricating pastes are used in RCT ?

A

canal +,
fileze,
glyde

50
Q

what is the contents of lubricating pastes ?

A

15% EDTA,
10% urea peroxide,
water soluble base

51
Q

what is gutta percher ?

A

transiosomer of rubber

52
Q

when is the crown down technique used ?

A

in small canals

53
Q

what are the advantages of the crown down technique ?

A

excellent shaping with minimal number of instrument changes,

flexible nickel titanium files follow gentle curves in canal morphology

54
Q

what is the cutting length of ProTaper files ?

A

14mm

55
Q

what lengths are available in ProTaper files ?

A

21mm,
25mm,
31mm

56
Q

what is the maximum flute diameter of ProTaper files ?

A

1.2 mm

57
Q

what are the advantages of ProTaper files ?

A

patented progressive taper design improves flexibility and cutting efficiency,
fewer files needed to achieve fully tapered canal,
files engage a smaller area of dentine, reducing torsional loads, file fatigue and risk of separation,
convex triangular cross section reduces contact area between file and dentine,
greater cutting efficiency through balancing the pitch and helical angles

58
Q

what are ProTaper files made of ?

A

nickel titanium

59
Q

what are the properties of nickel titanium ?

A

super elasticity and shape memory,
3-5 times elasticity of steel,
decreased ledging and transportation

60
Q

describe the structure of nickel titanium

A

two crystallographic forms -
austenite (parent shape)
martensite (daughter shape)
change from parent to daughter is stress induced

61
Q

What is the purpose of obturation ?

A

Prevent microorganisms entering and re infecting the canal, prevent tissue fluids percolating back into the canal and providing a culture medium for residual bacteria

62
Q

What is the aim of obturation ?

A

Create apical and coronal seal

63
Q

What are the ideal requirements prior to filling a canal ?

A

Dry, absence of pain, no infection, reduction in mobility

64
Q

What is the significance of the smear layer when filling root canals ?

A

1-2 microns thick but extends into tubules 40 microns, avenue for leakage of microorganisms, substrate for microbial proliferation

65
Q

How is the smear layer removed ?

A

17% edta with sodium hypochlorite

10-55% citric acid rinsed with sodium hypochlorite

66
Q

What is edta a constituent of ?

A

Glyde

67
Q

What material is used to obturation the canal ?

A

Gupta percher

68
Q

What is in a gutta percher point ?

A

Gutta percher, zinc oxide, waxes, colouring agents, metal salts

69
Q

What is the function of a root canal sealer ?

A

Cements the core material into the canal, fills voids, lubricant, bacteriocidal agent, thermal insulator

70
Q

What are the characteristics of an ideal sealer ?

A

Non irritating, hermetic sealing ability, insoluble in tissue fluids, dimensionally stable, radiolaque, bacteriostatic, non staining to dentine

71
Q

What are the different types of sealers ?

A

Zinc oxide eugenol, calcium hydroxide, resin, glass ionomers

72
Q

Describe the zinc oxide and eugenol sealer

A

Weak and porous when set, decompose in tissue fluid, cytotoxic, most popular

73
Q

Describe the calcium hydroxide sealers

A

Designed to stimulate healing and hard tissue formation at foramen, caoh2 may leach out and weaken cement

74
Q

Describe the resin sealers

A

Good sealing and adhesive properties, initial inflammatory reaction, antibacterial properties, less popular

75
Q

Describe glass ionomers sealers

A

Adheres to dentine walls, initial inflammatory reaction, sealing ability debated

76
Q

What is the most common sealer ?

A

Tubli seal

77
Q

How is gutta percher condensed in the canal ?

A

Cold lateral condensation

78
Q

What is the sequence for placing gutta percher ?

A

Sealer around canal walls, place master gutta percher point, place accessory points

79
Q

What is used to place the sealer in the canal ?

A

Master apical k file

80
Q

What should be done once the canal is fully obturated ?

A

Radiograph, remove coronal gp with hot excavator

81
Q

What are the common errors of obturation ?

A

Inaccurate placement of gp point, incorrect spreaders, extrusion of filler or sealer through apex, excessive condensation pressure, inadequate coronal seal

82
Q

What is the purpose of obturation ?

A

Prevent microorganisms entering and re infecting the canal, prevent tissue fluids percolating back into the canal and providing a culture medium for residual bacteria

83
Q

What is the aim of obturation ?

A

Create apical and coronal seal

84
Q

What are the ideal requirements prior to filling a canal ?

A

Dry, absence of pain, no infection, reduction in mobility

85
Q

What is the significance of the smear layer when filling root canals ?

A

1-2 microns thick but extends into tubules 40 microns, avenue for leakage of microorganisms, substrate for microbial proliferation

86
Q

How is the smear layer removed ?

A

17% edta with sodium hypochlorite

10-55% citric acid rinsed with sodium hypochlorite

87
Q

What is edta a constituent of ?

A

Glyde

88
Q

What material is used to obturation the canal ?

A

Gupta percher

89
Q

What is in a gutta percher point ?

A

Gutta percher, zinc oxide, waxes, colouring agents, metal salts

90
Q

What is the function of a root canal sealer ?

A

Cements the core material into the canal, fills voids, lubricant, bacteriocidal agent, thermal insulator

91
Q

What are the characteristics of an ideal sealer ?

A

Non irritating, hermetic sealing ability, insoluble in tissue fluids, dimensionally stable, radiolaque, bacteriostatic, non staining to dentine

92
Q

What are the different types of sealers ?

A

Zinc oxide eugenol, calcium hydroxide, resin, glass ionomers

93
Q

Describe the zinc oxide and eugenol sealer

A

Weak and porous when set, decompose in tissue fluid, cytotoxic, most popular

94
Q

Describe the calcium hydroxide sealers

A

Designed to stimulate healing and hard tissue formation at foramen, caoh2 may leach out and weaken cement

95
Q

Describe the resin sealers

A

Good sealing and adhesive properties, initial inflammatory reaction, antibacterial properties, less popular

96
Q

Describe glass ionomers sealers

A

Adheres to dentine walls, initial inflammatory reaction, sealing ability debated

97
Q

What is the most common sealer ?

A

Tubli seal

98
Q

How is gutta percher condensed in the canal ?

A

Cold lateral condensation

99
Q

What is the sequence for placing gutta percher ?

A

Sealer around canal walls, place master gutta percher point, place accessory points

100
Q

What is used to place the sealer in the canal ?

A

Master apical k file

101
Q

What should be done once the canal is fully obturated ?

A

Radiograph, remove coronal gp with hot excavator

102
Q

What are the common errors of obturation ?

A

Inaccurate placement of gp point, incorrect spreaders, extrusion of filler or sealer through apex, excessive condensation pressure, inadequate coronal seal

103
Q

What does ledermix contain ?

A

Demethychlortetracycline, triamcinalone acetonide

104
Q

What does odontopaste contain ?

A

Clindamycin, triamcinalone acetonide

105
Q

What should the use of ledermix be restricted to ?

A

Acutely inflamed vital pulp where analgesia for extirpation cannot be obtained, insuffienct time to do rct following pulpal exposure

106
Q

What is the medicament of choice ?

A

Calcium hydroxide

107
Q

What are the properties of calcium hydroxide ?

A

12.5 ph, bacteriocidal, solvent of organic debris, connective tissue repair, hard tissue Genesis, neutralises acids (oh ion)
Activates calcium dependent atp reaction for hard tissue formation (ca ion)

108
Q

What are the uses of calcium hydroxide ?

A

Pulp cap, inter visit medicament, treatment of large peri apical lesions, apexification, root resorption, root fractures

109
Q

What is r4 root canal solution ?

A

20% chlorhexidiene solution

110
Q

How are canals temporarily sealed ?

A

Cotton wool dressing, gic or zinc oxide eugenol

Dental Skills Y3 (6 decks)

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