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Module 5 - Endodontics > Endodontic Materials > Flashcards

Endodontic Materials Flashcards

1
Q

By what units do endodontic hand instruments increase by as size increases?

A

by 5 UNITS from size 10 to 60.
by 10 UNITS from 60 to 150.

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2
Q

What does the endodontic hand file size mean?

A

represents the DIAMETER OF THE FILE AT THE TIP. (ex. 10 is 10/100 and thus 0.1mm at the tip).

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3
Q

How long is a hand file working blade? Where does it start and where does it end? How much thicker is the top of the working blade compared to the bottom?

A
  • Starts at tip (D0), ends at D16.
  • 16mm long.
  • D16 is 32/100 or 0.32mm greater than D0.
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4
Q

What is the tip angle of an endodontic hand file?

A

tip angle is 75 degrees +/- 15 degrees

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5
Q

What is the taper of stainless steel hand files? What does this mean? What length are these files available in?

A
  • 2% (0.02) taper - every 1mm towards the shank the diameter of the file increases by 0.02mm.
  • length is available in 21, 25, 31mm (working part remains 16mm).
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6
Q

What are stainless steel hand files composed of?

A

iron alloys with at least 10.5% chromium

(other metals: nickel, molybedenum, titanium, copper).

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7
Q

what are the advantages and disadvantages of stainless steel hand files?

A
  • Advantages: do not easily corrode, rust or stain.
  • Disadvantages: poor flexibility, leads to many procedural errors during canal shaping.
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8
Q

What is the difference between how small and larger hand files are manufactured?

A
  • small are made from SQUARE BLOCKS (thus more resistant to torque)
  • large are made from TRIANGULAR BLOCKS (thus better cutting efficiency).
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9
Q

What are the 3 types of stainless steel files?

A
  • barbed broaches
  • roamers
  • files (K files, Flexofile, Hedstrom).
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10
Q

When are barbed broaches used? When are they NOT to be used?

A
  • used for emergency pulp extirpation (removal of pulpal tissue when present).
  • can be used in anterior teeth, CANNOT be used in NARROW, CURVED CANALS.
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11
Q

When are roamers used?

A

Were used historically.

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12
Q

What are hand instruments particularly useful for?

A

In the EARLY phases of instrumentation to establish a GLIDE PATH prior to using rotary instruments.

  • in anatomically challenging cases and in treating instrumentation complications (may be the only option).
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13
Q

What are flexofiles used for?

A
  • estabilishing glide path, apical gauging, negotiating ledges and blockages.
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14
Q

what is the tip of flexofile called?

A

BATT TIP (non-agressive tip).

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14
Q

What are 3 advantages of flexofiles?

A
  • Non-aggressive tip (BATT TIP).
  • good flexibility
  • efficient at cutting dentine with a low risk of transportation and ledge formation.
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14
Q

What is the ideal instrumentation technique to use flexofiles with?

A

balanced force

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15
Q

What are some properties of Hedstrom files (3) and when are they used?

A
  1. very stiff.
  2. can only be used in up and down motion.
  3. file cuts when moved in coronal direction.
  • used in RETREATMENT to remove gutta-percha or an overfilling of the canal.
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16
Q

What are 4 main disadvantages of hand files?

A
  1. Mishaps (ledging, transportation, zipping of foramen, blockages).
  2. Debris extrusion.
  3. Time consuming.
  4. Less predictable shapes in curved canals.
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17
Q

when were rotary nickel titanium files introduced?

A

1990s.

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18
Q

What do Ni Ti rotary files require?

A

Endodontic, torque control motor - NEVER use in slow speed.

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19
Q

What are two MAIN properties of niti files?

A
  • superelasticity
  • shape memory
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20
Q

What is the advantage of Superelasticity in NiTi files?

A
  • allows NiTi files to be placed in CURVED CANALS with LESS LATERAL FORCES
    –> less zipping, transportation, ledging.
    –> more centrally placed restoration.
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21
Q

What does superelasticity mean?

A
  • can be strained more than other alloys without permanent deformation.
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22
Q

What are NiTi files made of?

A

56% nickel, 44% titanium

23
Q

What is NiTi shape memory due to?

A
  • at root temp in AUSTENITE form.
  • when stress is applied it changes to MARTENSITE (and changes shape)
24
Q

What are two differences in the properties of SS and NiTi files?

A
  • NiTi can be elastically deformed up to 3 times more than stainless steel flies before permanent deformation.
  • NiTi have a lower modulus of elasticity –> forces exerted on root canals by deformed NiTi files is much less than ss files resulting in less iatrogenic errors during instrumentaion.
25
Q

What is the unstressed form of Niti? The stressed form?

A
  • Unstressed: Austenite
  • Stressed: Martensite
26
Q

Why can NiTi shape memory be disadvantageous?

A
  • problematic in CURVED canals as they always want to straighten –> over-instrumentation, canal straightening, unfavourable stressed (cyclical fatigue failure).
27
Q

What is the first generation of NiTi files? When was it released? Taper type?

A

1990s - Profile, system GT.
CONSTANT taper.

28
Q

What is the second generation of NiTi files? When was it released? Taper type?

A

2006 - Protaper, Protaper Universal. VARIABLE taper.

29
Q

How is superelastic NiTi wire (M wire) formed? How is this different (in terms of structure) to normal NiTi?

A

Through a thermomechanical processing procedure. Has more stable martensite under clinical conditions.

30
Q

What are four advantageous properties of M wire compared to normal NiTi?

A
  • Higher tensile strength.
  • improved FATIGUE RESISTANCE.
  • greater flexibility
  • increased safety (protection against instrument fracture).
31
Q

What are the 3 crystalline phases of M wire?

A
  • deformed and microtwinned martensite.
  • Premartensitic R phase.
  • Austenite.
32
Q

By how much (in %) does M wire improve resistance to cyclic fatigue? Why is this advantageous?

A
  • 400%
  • reduces potential for separated instruments in curved canals.
33
Q

What is the fifth generation of NiTi files? When was it released? What is its rotary motion?

A
  • Released in 2013 - Protaper NEXT.
    -offset from central axis of rotation –> asymmetrical rotary motion that travels along the length of the file “SWAGGERING EFFECT”
34
Q

What is the SWAGGERING EFFECT

A

In Protaper Next files, the cros-section is offset from the central axis of rotation, causing asymmetrical rotary motion that travels the length of the file.

35
Q

What is the taper, use and mode of use (how to use it) of Proglider?

A
  • 2% taper.
  • used to EXAGERRATE THE GLIDE PATH.
  • In and Out motion.
36
Q

What are controlled memory files? Give 4 examples.

A
  • Thermomechanically processed, have martensitic properties at room temperature –> very flexible files with NO MEMORY (no SPRING BACK).
  • Thus can adapt to root canal curvatures without creatung undesirable lateral forces.
  • typhoon, edgetaper platinum, hyflex cm, PROTAPER GOLD
37
Q

What are 4 advantages of NiTi vs SS.

A
  • increased flexibility in larger sizes.
  • increased cutting efficiency.
  • better safety in use.
  • better user friendliness.
38
Q

What are 4 disadvantages of NiTi files?

A
  • Instrument fracture (TORTIONAL STRESS or CYCLICAL FATIGUE).
  • expense
  • access can be difficult in posterior teeth.
  • unsuitable for complex canal anatomy (ex. dens invaginatus).
39
Q

What are 3 advantages of larger tapers? To what taper should canals be prepared?

A
  • MINIMUM OF 6% to achieve optimum obturation.
  • Greater taper allows more effective disinfection.
40
Q

What are interappointment medicaments and what are their aims (2)?

A
  • ANTIMICORBIAL agents placed in the root canal system between appointments.
  • Aims:
  • reduce and prevent multiplication of microorganisms.
  • prevent reinfection from apical and coronal leakage.
41
Q

What is a type of HISTORICAL inter-appointment medicament? Why?

A
  • Phenolic compounds: camphorated phenol, formocresol, cresophene.
  • Highly toxic to vital tissues, carcinogenic?, not effective.
42
Q

why are phenol medicaments not effective?

A
  • work by release of vapors and are therefore fairly short-acting.
43
Q

What are 5 uses of calcium hydroxide? Setting or non setting?

A
  • pulp capping (setting)
  • root canal sealer
  • apexification (non setting)
  • treatment of root perforations, root fractures, root resorption and dental trauma.
  • inter-appointment intracanal medicament (non setting).
44
Q

What is the pH of calcium hydroxide? What does it dissociate to and what does that cause?

A
  • Strong base (12.5-12.8).
  • Dissociates to calcium and OH ions –> induce hard tissue deposition + are antibacterial.
45
Q

What are 5 functions of CaOH when used as a medicament?

A
  • kills bacteria and inactivates endotoxin (LPS).
  • reduces inflammation.
  • helps eliminate apical exudate.
  • controls inflammatory root resorption.
  • prevents contamination between appointments.
46
Q

How does CaOH affect bacteria?

A

Hydroxyl ions:
- damage bacterial cytoplasmic membrane.
- protein denaturation.
- damage to DNA.

47
Q

What is requirement for maximum CaOH antibacterial effect?

A
  • DIRECT CONTACT with bacterial cells.
48
Q

For what microorganism is the efficacy of CaOH doubted?

A

enterococcus faecalis.

49
Q

Is CaOH as an inter appointment medicament setting or non-setting? Gives two product names.

A
  • NON setting paste.
  • Ultracal, Hypocal.
50
Q

What are the steps to placing CaOH as an inter-appointment medicament?

A
  • dry the canal with paper points to working length.
  • use spiral fillers or disposable tips 2mm from WL.
  • completely fill canal without extruding excess.
51
Q

What is a weeping canal?

A

discharge in the canal at each opening.

52
Q

How do you treat a canal with exudate?

A
  • dress the canal with CaOH
    (calcifying potential, high pH, may cauterise residual chronically inflamed pulpp).
53
Q

What is apexification?

A
  • creating an environment AFTER PULP DEATH that allows a CALCIFIED BARRIER to form across an OPEX APEX of an IMMATURE TOOTH.
  • calcified barrier: osteocementum, bone-like tissue.
54
Q

What products are used for apexification?

A

Mineral trioxide aggregate, calcium hydroxide.

55
Q

What are two indications for apexification?

A
  • Vital radicular pulp in an IMMATURE tooth pulpotomy (may have some root formation from surviving Hertwig’s epithelial root sheath).
  • Pulpless immature tooth with other without periapical radiolucency. (use MTA)
56
Q

What would you use to perform an apexification in an pulpless immature tooth with or without periapical radiolucency?

A

Mineral Trioxide Aggregate

Module 5 - Endodontics (11 decks)

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