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Phase 1 Boards Prep - SA > Pathways of the Pulp > Flashcards

Pathways of the Pulp Flashcards

1
Q

Fluid movement within dentinal tubules can stimulate sharp, quickly reversible dental pain. What nerve fibers are responsible for this sensation?

Chapter 1: Diagnosis

A

A-delta nerve fibers

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2
Q

What nerve fibers produce an intense, slow, dull pain that can manifest as referred pain?

Chapter 1: Diagnosis

A

pulpal C fibers

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3
Q

What is the definition of spatial resolution?

Chapter 2: Radiographic Interpretation

A

the ability to display two objects that are close to each other as two separate entities

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4
Q

What is the definition of contrast resolution?

Chapter 2: Radiographic Interpretation

A

The ability to differentiate between areas on the image based on density

Endodontics require high-contrast resolution

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5
Q

What are the advantages of CBCT over multidector CT?

Chapter 2: Radiographic Interpretation

A

Faster, low-dose, low-cost, high-contrast images
High resolution isotropic images

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6
Q

What is a voxel?

Chapter 2: Radiographic Interpretation

A

cuboidal elements that constitute a 3D volume unlike pixels which are 2D

MDCT obtain pixels while CBCT obtains voxels

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7
Q

Does CBCT have lower or higher kV and mA exposure parameters than MDCT?

Chapter 2: Radiographic Interpretation

A

Lower

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8
Q

True or false: the smaller the voxel size the higher the spatial resolution

Chapter 2: Radiographic Interpretation

A

True

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9
Q

What is the maximum voxel size that should be used for endodontic imaging?

Chapter 2: Radiographic Interpretation

A

0.2mm

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10
Q

What percent mineral content loss is needed for radiolucent regions to be visualized on conventional radiographs?

Chapter 2: Radiographic Interpretation

A

30-40%

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11
Q

Planar based radiographs overestimate or underestimate success of endodontic treatment as compared to CBCT?

Chapter 2: Radiographic Interpretation

A

Overestimate success of endodontic treatment

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12
Q

What three characteristics must be present for a diagnosis of Medication Related Osteonecrosis of the Jaws (MRONJ)? (American
Association of Oral and Maxillofacial Surgeons: Position paper
on Bisphosphonate-Related Osteonecrosis of the Jaw)

Chapter 3: Case Selection and Treatment Planning

A
  1. Current or previous treatment with an antiresorptive drug
    such as a bisphosphonate or an antiangiogenic drug (e.g.,
    sunitinib [Sutent], sorafenib [Nexavar], bevacizumab
    (Avastin), or sirolimus (Rapamune)
  2. Exposed, necrotic bone in the maxillofacial region that has
    persisted for more than 8 weeks
  3. No history of radiation therapy to the jaws
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13
Q

What factors increase the risk of developing osteonecrosis of the jaw while recieving bisphosphanotes?

Chapter 3: Case Selection and Treatment Planning

A

history of taking bisphosphonates, especially intravenous (IV) formulations
previous history of cancer
history of a traumatic dental procedure
hx of chronic corticosteroid use
hx of diabetes

human only: hx of smoking, patient more than 65 years old

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14
Q

Which of the following is most correct regarding development of bisphosphonate-associated osteonecrosis?

A. The maxilla is more commonly affected than the mandible
B. 40% of cases are preceded by a dental procedure
C. patients with skeletal multiple myeloma and metastatic carcinoma recieving IV bisphosphonates comprise 94% of published MRONJ cases.
D. Patients less than 65 years old are at an increased risk

Chapter 3: Case Selection and Treatment Planning

A

C. patients with skeletal multiple myeloma and metastatic carcinoma recieving IV bisphosphonates comprise 94% of published MRONJ cases.

A. The mandible is more commonly affected than the maxilla (2:1 ratio)
B. 60% of cases are preceded by a dental procedure
D. Patients > 65 yro are at an increased risk

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15
Q

In what percent of cases are accessory canals found in the apical third of the root, the middle third and the cervical third?

Chapter 5: Tooth Morphology, Isolation and Access

A

Apical third 74%
Middle third 11%
Cervical third 15%

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16
Q

What is the definition of elastic limit in regards to endodontic instruments?

Ch 8

A

Maximal strain that allows a file to return to original dimensions

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17
Q

If you have a K file size #25 file with #.02 taper,
what mm distance is from D1 to D16 in the image, and what size in mm is the tip of the file?
What is the diameter at D16?

A

Distance: 0.32 mm
Tip: 0.25mm
Diameter: 0.57mm

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18
Q

What is the flute surface of an endodontic file?

Ch 8

A

Groove in the working surface that collects soft tissue and dentin from the walls, collects the dentin

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19
Q

What is the leading edge of an endodontic file?
What is the rake angle?

A

Leading edge: Surface with greatest diameter that follows the groove as it rotates – cuts the dentin
Rake angle: The angle formed by the leading edge and radius of file – Positive supposedly cuts; Negative supposedly scrapes

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20
Q

What is the helix angle of an endodontic file?

CH 8

A

The angle the cutting-edge forms with the long axis of file. Defines the type of file and how it is used

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21
Q

Define the order and direction of shaping the canal with each technique:

Step-back
Step-down
Crown-down

Ch 8

A

Step-back: Apical to coronal direction, taper canal
Step-down: Coronal pre-flaring before cleaning apically, WL before pre-flare
Crown-down: Coronal pre-flaring before cleaning apically, WL after pre-flare

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22
Q

What is the minimum concentration of NaOCl needed for pulp dissolution?

Ch 8

A

1 %

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23
Q

Which of the following properties of bleach leads to oxidizing pulpal tissue?
A. Saponification reaction
B. Neutralization reaction
C. Hypochlorous acid formation
D. Solvent action

Ch 8

A

C. Hypochlorous acid formation

Saponification reaction: Acts as an organic and fat solvent. Reduces the surface tension of the remaining solution.
Neutralization reaction: Neutralizes amino acids by forming water and salt. The pH is reduced.
Hypochlorous acid formation: Chlorine dissolves in water and it is in contact with organic matter: it forms hypochlorous acid. It is a weak acid that acts as an oxidizer.
Solvent action: Sodium hypochlorite also acts as a solvent, releasing chlorine that combines with protein amino groups (NH) to form chloramines (chloramination reaction). Chloramines impede cell metabolism and inhibits essential bacterial enzymes

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24
Q

What property of bleach makes it antimicrobial?

Ch8

A

High pH (>11)
The high pH interferes in cytoplasmic membrane integrity due to irreversible enzymatic inhibition, biosynthetic alterations in cellular metabolism, and phospholipid degradation observed in lipidic peroxidation.

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25
Q

What is the MOA of EDTA?

Ch 8

A

MOA: demineralizing chelating agent

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26
Q

Which of the following matches the material type and mechanism of action for GuttaFlow2 as a sealant?
A. Salicylate, Chelation
B. Silicone, Polymerization
C. Tricalcium silicate, Hydration
D. Salicylate, Ionomer formation

Ch 8

A

B. Silicone, Polymerization

Polymer formation by radical polymerization: Generation of a free radical monomer units results in polymers formation by the successive addition of free-radical building blocks

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27
Q

What is the term used to describe the histologic appearance of the coronal portion of young pulp odontoblasts?

Chp 13

A

The odontoblasts have a tall columnar form varying in height with nuclei staggered and not all at same level –> palisading

Appear 3-5 cells in thickness but only 1 layer

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28
Q

What are the layers of Dentin-Pulp Complex?

A

Dentin –> predentin –> odontoblast layer –> cell-poor zone –> cell-rich zone –> pulp proper

Ch 13

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29
Q

Are there more dentinal tubules per unit area in the root or the crown?

Ch 13

A

The crown

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30
Q

During cavity preparation what junctions in dentin are disrupted increasing dentin permeability?

Ch 13

A

Tight junctions

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31
Q

How are accessory canals formed?

A

By the entrapment of periodontal vessels in Hertwig’s epithelial root sheath during mineralization.

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32
Q

What is the most prominent cell in the pulp proper?

Ch 13

A

Fibroblast

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33
Q

Odontoblasts mainly synthesize what type of collagen?

ch 13

A

Type 1

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34
Q

What immune cells are found normally within dental pulp?

Ch 13

A

macrophages
dendritic cells
T lymphocytes

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35
Q

What type of immune cell is often found in inflamed pulp?

Ch 13

A

Mast cells

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36
Q

What is the rate of oxygen consumption of dental pulp?

Ch 13

A

3.2 ± 0.2 ml/min/100 g of pulp tissue

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37
Q

What dental materials have been shown to depress the metabolic activity of pulpal cells?

Ch 13

A

Eugenol
Zinc oxide and eugenol
Calcium hydroxide
silver amalgam

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38
Q

What primary proteogylcans are present during active primary dentinogenesis and then following eruption?

Ch 13

A

Dentinogenesis: Chondroitin sulfate
Tooth eruption: Hyaluronic acid

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39
Q

What types of collagen are present in the pulp proper?

Ch 13

A

Type I: thick striated fibrils thoughout pulp tissue
Type III: found in most unmineralized connective tissues

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40
Q

Where are Type I and Type II collagen found?

Ch 13

A

Type I: skin, tendon, bone, dentin, pulp
Type II: Cartilage

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41
Q

Where are Types IV and VII collagen found?

Ch 13

A

basement membranes

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42
Q

Where is Type V collagen found?

Ch 13

A

Interstitial tissues

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43
Q

Odontoblasts and osteoblasts synthesize what type of collagen?

Ch 13

A

Type 1

Fibroblasts synthesize types I, III, V, VII

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44
Q

Large collagen fibers are more numberous in the radicular or coronal pulp?

Ch 13

A

Radicular

Why pulpectomy procedures should engage pulp witha barbed broach in region of apex to remove tissue intact

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45
Q

What are apical deltas?

A

Apical deltas are multiple accessory canals that branch out from the main canal at or near the root apex.

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46
Q

What are furcation canals and how are they formed?

A

Furcation canals are accessory canals that are present in the bifurcation or trifurcation of multirooted teeth. These channels form as a result of the entrapment of periodontal vessels during the fusion of the diaphragm, which becomes the pulp chamber floor.

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47
Q

How are furcation lesions formed?

A

They are formed by pulp inflammation that communicates with the periodontium via furcation canals. Can be present without periodontal disease.

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48
Q

What are the functions of afferent neurons in the pulp?

Ch 13

A

conduct sensory impulses

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49
Q

What are the functions of autonomic or efferent neurons in the pulp?

Ch 13

A

Provide neurogenic modulation of the microcirculation, inflammatory reactions, perhaps regulate dentinogenesis

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50
Q

What is the path of symphathetic innervation of teeth from central to peripheral?

Ch 13

A

Superior cervical ganglion
Internal carotid nerve
Trigeminal nerve
Maxillary and mandibular division of trigeminal nerve

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51
Q

What type of A fibers compose 90% of dental pulp A fibers?

Ch 13

A

A-delta fibers

Function: Pain, temperature, touch

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52
Q

What are the characteristics and functions of A-delta fibers?

Ch 13

A

Myelinated
Function: pain, temperature, touch
Compose 90% of dental pulp A fibers
Located in periphery of pulp and penetrate the inner part of dentin

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53
Q

What are the characteristics and functions of C fibers?

Ch 13

A

Unmyelinated
Function: pain
Located in deeper part of pulp proper

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54
Q

What are the pain characteristics and stimulation thresholds of A-delta and C fibers respectively?

Ch 13

A

A-delta: sharp and pricking, stimulation threshold relatively low
C fibers: burning and aching, less bearable than A-delta fiber sensations, stimulation threshold realtively high, usually associated with tissue injury

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55
Q

What is the resting pulpal blood flow?

Ch 13

A

0.15 to 0.60 ml/min/g tissue

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56
Q

What is the consensus regarding the presence or absence of lymphatics in dental pulp?

Ch 13

A

Lymphatics have not consistently been demonstrated to be present in dental pulp

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57
Q

What inflammatory cytokines are elevated in inflamed pulp?

Ch 13

A

IL-1 and TNF-alpha

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58
Q

What is the definition of primary dentin?

Ch 13

A

The regular tubular dentin formed before eruption including mantle dentin

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59
Q

What is the definition of secondary dentin?

Ch 13

A

Regular circumferential dentin formed after tooth eruption
its tubules remain continuous with that of primary dentin

secondary dentin responsible for decreasing pulp width throughout life of tooth

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60
Q

What is the definition of tertiary dentin?

Ch 13

A

Irregular dentin that is formed in response to abnormal to abnormal stimuli such as excess wear, cavity preparation, restorative material, caries

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61
Q

What is the name of focal tertiary dentin formed by the original odontoblasts that made secondary dentin?

Ch 13

A

Reactionary dentin

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62
Q

What are the three anatomic and histological landmarks in the apical region of the root?

A

The apical constriction, the cementodentinal junction, and the apical foramen

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63
Q

What is the cementodentinal junction (CDJ)?

A

Histologically - where the cementum and dentin meet in the root canal. It is NOT synonymous with the apical foramen or apical constriction.

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64
Q

What is the name of the tertiary dentin that forms if the original odontoblasts are destroyed?

Ch 13

A

Reparative dentin

Tubules not continuous with those of secondary dentin, more irregular, less tubular

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65
Q

What can cause destruction of primary odontoblasts?

ch 13

A

Cutting cavity preparations dry
Bacterial products like LPS from deep carious lesions
mechanical exposure of pulps

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66
Q

What is the apical foramen (AF)?

A

The circumference or rounded edge, like a funnel or crater that differentiates the termination of the cemental canal from the exterior surface of the root.

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67
Q

What can one use to flare the canal orifice coronally?

A

Gates glidden burs or rotary nickel titanium (NiTi) orifice openers

68
Q

The final position of the incisal wall of the access cavity is determined by what two factors?

A
  1. Complete removal of the pulp horns
  2. Straight line access
69
Q

In humans pulp calcifications are present in what percent of all teeth?

Ch 13

A

At least 50%

70
Q

What are the main age related changes to dentin?

Ch 13

A

increase in peritubular dentin
increased dentinal sclerosis
increased dead tracts

dead tracts: dentinal tubules with absent odontoblast processes

71
Q

What are the reported overall success rates for orthograde root canal therapy for teeth diagnosed with irreversible pulpitis and teeth diagnosed with infected, necrotic pulps respectively?

Ch 8

A

Irreversible pulpitis: 95%
Necrotic, infected pulps: 85%

72
Q

What is considered the minimum radicular wall thickness for root canal therapy?

Ch 8

73
Q

How far do irrigants progress from the tip of the needle when using passive needle irrigation?

Ch 8

74
Q

What is a radial land?

Ch 8

A

Feature between trailing and cutting file edge that forms a larger contact area with the radicular wall
Thought to reduce tendency of file to thread into canal, less efficient compared to triangular cross sections

Triangular point of cutting edge is cut off at the top to make it flat

75
Q

A, B and C demonstrate what types of rake angles?

Ch 8

A

A. negative
B. Neutral
C. Positive

76
Q

What is the standard taper of ISO files?

Ch 8

A

0.32mm over 16mm of cutting blades
0.02mm increase in diameter per millimeter of flute length

77
Q

What are Gates Glidden drills and Peeso burs made out of?

Ch 8

A

Stainless steel

78
Q

What is pseudoelasticity?

A

Describes the ability of NiTi files to return to their original shape after being deformed

79
Q

Are K-files and NiTi files produced by milling or twisting?

Ch 8

A

K-files twisting
NiTi milling

80
Q

What kind of files are A and B?

Ch 8

A

A. K-files (twisting)
B. Hedstrom file (grinding)

81
Q

What is reaming vs filing motions?

A

Reaming is rotating the file while filing is an “in and out” motion

reaming generally causes less transportation

82
Q

Failure in files occurs at half the number of rotations in a clockwise or counterclockwise rotation?

Ch 8

A

counterclockwise

83
Q

What is the difference between reamers and K-files?

Ch 8

A

Reamers have fewer cutting flutes per mm of the working surface

More appropriate for twisting motion

84
Q

H-files have positive, negative or neutral rake angles?

Ch 8

85
Q

What kind of file is this?

Ch 8

A

Gates Glidden

86
Q

What is the diameter range of Gates Glidden files sizes 1-6?

A

0.5 - 1.5mm

87
Q

Gates Glidden drills should be used at what rpm?

A

750 - 1500 rpm

88
Q

Group II rotary files lack what features which improves cutting efficiency?

A

Radial lands

89
Q

What type of root canal shaping system has been associated with a higher incidence of preparation errors and reduced radicular wall thickness?

Ch 8

A

Ultrasonic devices

90
Q

What is the champagne bubble test?

A

When you allow sodium hypochlorite (bleach) to remain in the pulp chamber to help locate a calcified root canal orifice—> tiny bubbles will appear in the solution, indicating the position of the orifice

91
Q

What are problems that can occur when tooth angulations are not considered during access development?

A

Mistaken identity of an already identified canal, failure to locate a canal or extra canals, excessive gouging of crown, instrument separation during attempts to locate an orifice, failure to debride all pulp tissue from the chamber

92
Q

What were the four factors that influenced the success of a non surgical RCT based off of a meta-analysis?

A
  1. The absence of a periapical lesion
  2. Root canal obturation containing no radiographic voids
  3. Obturation to within 2 mm of the radiographic apex
  4. An adequate coronal restoration
93
Q

Combination of what two techniques has been shown to be most accurate for determining working length?

Ch 8

A

Electronic apex locators + radiographs

94
Q

A, B, C, and D show what most common preparation errors?

Ch 8

A

A. Apical zip
B. Ledge
C. Apical zip with perforation
D. Ledge with perforation

95
Q

What is the crown down root canal preparation approach?

Ch 8

A

Large instrument inserted until passive resistance met, then smaller files are used to progress more apically until terminus is reached

96
Q

What is the step-back root canal preparation approach?

Ch 8

A

Working lengths decrease in stepwise manner with increasing instrument size

97
Q

What does obturation do?

A

Reduces coronal leakage and bacterial contamination, seals the apex from the periapical tissue fluids, and entombs the remaining irritants in the canal.

98
Q

When is obturation contraindicated?

A

Presence of exudation from the canal, or when you cannot full dry the canal.

99
Q

How is removal of the smear layer generally accomplished?

A

By irrigating the canal with 17% disodium EDTA and 5.25% bleach
EDTA removes the inorganic material, and bleach or NaOCl removes the remaining organic components

100
Q

What are the radiographic criteria for evaluating obturation?

A

Length, taper, density, adequate GP and sealer removal, and adequate provisional or definitive restoration

101
Q

What are the mechanical and chemical objectives of irrigation?

Ch 8

A

1.) Flush out debris
2.) Lubricate the canal
3.) Dissolve organic and inorganic tissue
4.) Prevent formation of a smear layer during instrumentation or dissolve it once it forms

102
Q

What is the external diameter of a 27 gauge injection needle?

Ch 8

103
Q

What type of irrigation needle tips lead to maximum shear stress concentrated on the wall facing the outlet?

Ch 8

A

Side-vented
Double side-vented

104
Q

What are the benefits of using irrigants in root canal treatment?

Ch 8

A

Removal of particulate debris and wetting of the canal walls
Destruction of microorganisms
Dissolution of organic debris
Opening of dentinal tubules by removal of smear layer
Disinfection and cleaning of areas inaccessible to endodontic instruments

105
Q

What is the irrigant of choice in endodontics?

Ch 8

A

Sodium hypochlorite

106
Q

What is the active component of sodium hypochlorite?

Ch 8

A

hypochlorous acid

107
Q

Increasing the temperature of low-concentration NaOCl solution improves which of their characteristics?

Ch 8

A

Immediate tissue dissolving capacity
Remove organic debris from dentin shavings more efficiently

However- no clinical studies at this point to support the use of heated NaOCl

108
Q

Low concentrations of NaOCl can be effective for canal irrigation when used at what volume and frequency?

Ch 8

A

Higher volume
More frequent intervals

109
Q

What ion in bleach is responsible for its dissolving and antibacterial capacity and how quickly is it consumed?

Ch 8

A

Chlorine ion
Within 2 minutes

110
Q

When do sealers exhibit toxicity?

A

When they are freshly mixed. Their toxicity is greatly reduced once they have set.

111
Q

What types of bacteria and fungi is chlorhexidine effective against?

A

Gram-positive, Gram-negative bacteria
Yeasts

112
Q

What is the substantivity reaction/property of chlorhexidine?

Ch 8

A

A concentration dependent reversible uptake/absorption of chlorhexidine onto the tooth surface that release of chlorhex into the environment for continued antimicrobial activity.

113
Q

What sustance forms when chlorhexidine is mixed with NaOCl?

Ch 8

A

Parachloroaniline (PCA)
(4-chloroaniline)

114
Q

What are the properties of an ideal sealer?

A
  1. Exhibits tackiness when mixed for good adhesion
  2. Establishes a hermetic seal
  3. Radiopaque, so that it can be seen on rads
  4. No shrinkage on setting
  5. No staining of tooth structure
  6. Bacteriostatic
  7. Exhibits a slow set
  8. Insoluble in tissue fluids
  9. Tissue tolerant - non irritating to periradicular tissue
  10. Soluble in a common solvent - for ease of removal
  11. Fine powder, to mix well with water
115
Q

The precipitate formed by combination of NaOCl and CHX causes what effects in the canal?

A

Color changes
Formation of a possibly toxic insoluble precipitate that may interfere with the seal of the root obturation

116
Q

What forms when CHX and EDTA are combined?

Ch 8

A

A white precipitate that is a salt

117
Q

What is the definition of the smear layer? (American Association of Endodontists 2003)

Ch 8

A

A surface film of debris retained on dentin or another surface after instrumentation with either rotary instruments or endodontic files.
Consists of dentin particles, remnants of vital or necrotic pulp, bacterial components and retained irrigants

controversy regarding thoughts on if its removal either opens dentinal tubules to allow removal of bacteria or if it protects dentinal tubules
Only 1 in vivo study that found that use of EDTA sig incrased odds of success of retreatment

118
Q

What does EDTA stand for?

Ch 8

A

Ethylenediamine Tetra-Acetic Acid

119
Q

What benefits as an irrigant does EDTA provide?

Ch 8

A

It can chelate and remove the mineralized portion of the smear layer

120
Q

What is the best method of obturation to distribute the sealer in the apical portion of the canal?

A

Trick question, there is no best method. However, lateral compaction results in better distribution of the sealer in midcoronal areas of the root canal system when compared to warm vertical compaction.

121
Q

What is the MOA of EDTA’s chelating abilities?

Ch 8

A

Sequesters di and tricationic metal ions such as Ca2+ and Fe3+
After being bound by EDTA these metal ions remain in solution but exhibit diminished reactivity
Self-limiting

122
Q

What is the antibacterial MOA of EDTA?

Ch 8

A

EDTA extracts bacterial surface proteins by combining with metal ions from the cell envelope which can eventually lead to cell death
Can also detach biofilms adhering to root canal walls

123
Q

How long does it take for EDTA to remove the inorganic component of the smear layer?

Ch 8

A

< 1 minute

124
Q

What are the pros and cons to zinc oxide and eugonol sealers?

A

Pros: Will absorb if extruded into periradicular tissues, soluble, antimicrobial

Cons: Slow setting time, shrink on setting, can stain teeth

125
Q

What properties of NaOCl and EDTA are influenced the two are mixed?

Ch 8

A

NaOCl loses its tissue dissolving capacity
EDTA retains its calcium-complexing ability

EDTA and NaOCl should be used separately

126
Q

What are the pros and cons to glass ionomer sealers?

A

Pros: Good dentin-bonding properties

Cons: Minimal antimicrobial activity, difficult to remove if retreatment is required

127
Q

Should EDTA be heated?

Ch 8

A

No!
When chelators are heated the calcium binding capacity decreases

128
Q

What is the consensus regarding adding detergants/surfactants to irrigants?

Ch 8

A

Not needed b/c they do not enhance the ability of NaOCl to dissolve pulp tissue or the efficacy of common chelators to remove calcium or smear layer

129
Q

What are the contents of MTAD and Tetraclean?

Ch 8

A

Doxycycline
Broad spectrum antibiotic
Citric Acid
Detergent

The two differ in concentrations of doxycyline (MTAD higher)

130
Q

What are the advantages of MTAD and Tetraclean?

Ch 8

A

CAn remove both the smear layer and organic tissue from the infected root canal system

Recommended as a final rinse after normal chemomechanical preparation

131
Q

Tetracyclines are effective against what type of bacteria and are bacteriostatic or bacteriocidal?

Ch 8

A

Effective againist Gram-positive and Gram- negative (more Gram-negative effect)
Bacteriostatic but in high concentrations may have bacteriocidal effect

132
Q

What does the term monoblock mean?

A

The idealized scenario in which the canal space becomes perfectly filled with a gap-free, solid mass that consists of different materials and interfaces, with the purported advantages of simultaneously improving the seal and fracture resistance.

133
Q

What are the two major categories of resin sealers?

A

Epoxy resin and methacrylate resin

134
Q

What type of sealer is GuttaFlow?

A

Silicone sealer

135
Q

What are Pathways’ general recommendations for when to use EDTA and NaOCl during the procedure?

Ch 8

A

Bleach used throughout procedure as the irrigant of choice
EDTA or other chelators used at end of procedure to remove smear layer
Final flush with NaOCl for 1 minute for maximum cleaning efficiency and to minimize dentin erosion

136
Q

What is passive ultrasonic irrigation (PUI)?

A

Introduction of noncutting ultrasonically activated small file into canal with irrigant once the final apical size has been reached

137
Q

What are the pros and cons to GuttaFlow?

A

Cons: Setting time is inconsistent

Pros: Fills canal irregularities, biocompatible, working time 15 minutes, cures in 25-30 minutes, may promote PDL stem cells into cementoblasts

138
Q

What are the negative side effects of having paraformaldehyde in sealers?

A

Overextension can result in osteomyelitis, dysesthesia, and permanent toxic effects on periradicular tissues.

139
Q

What is ultrasonic instrumentation (UI)?

Ch 8

A

Cutting file brought into contact with wall during irrigation –> can lead to uncontrolled cutting of root canal walls without effective disinfection

140
Q

What is the main advantage of negative apical pressure systems?

Ch 8

A

Irrigation solutions will not extrude through apex

141
Q

What instrument is shown and what is its function?

Ch 8

A

Safety irrigator
Delivers irrgant apically under positive pressure and evacuates solution through large needle at canal orifice creating a negative pressure system
Designed to limit risk of NaOCl accidents

142
Q

What laser and wavelength are best suited to root canal treatment?

Ch 8

A

Er:YAG laser
wavelength 2940nm

Highest absorption in water and high affinity to hydroxyapatite

143
Q

What are the two ways laser energy may be used to activate irrigant solutions?

Ch 8

A

Molecular level: photoactivated disinfection (PAD)
Bulk flow level: laser activated irrigation (LAI)

144
Q

What method of laser energy activation is best removing the smear layer and dentin debris?

A

laser activated irrigation (LAI)

MOA: generates secondary cavitation effects with expansion and successive implosion of fluids

145
Q

What antibacterial nanoparticles have been evaluated for endodontics?

Ch 8

A

Chitosan (CS-np)
Zinco oxide (ZnO-np)
Silver (Ag-np)

146
Q

What are the 10 properties of an ideal obturation material?

A
  1. Easily manipulated with ample working time
  2. Dimensionally stable with shrinkage once inserted
  3. Seals the canal laterally and apically
  4. Nonirritating to the periapical tissues
  5. Impervious to moisture and nonporous
  6. Unaffected by tissue fluids
  7. Inhibits bacterial growth
  8. Radiopaque
  9. Does not discolor tooth structure
  10. Sterile
  11. Easily removed from the canal if necessary
147
Q

What is the mechanism of action for bioactive glass in root canal disinfection?

Ch 8

A

maintains an alkaline environment over time and kills bacteria
MOA not pH related

148
Q

What is the MOA of ozone for killing bacteria?

Ch 8

A

destruction of cell walls and cytoplasmic membranes by oxidant potential –> increased permeability –> immediate function cessation

149
Q

What rates of manual and rotary instrument fracture are reported?

Ch 8

A

Manual file: 1-6%
Rotary: 0.4-5%

150
Q

Does the presence of a retained instrument result in a significantly higher rate of RCT failure when done by specialists?

Ch 8

151
Q

What is torsional fracture of rotary instruments?

Ch 8

A

Occurs when an instrument tip is locked into a canal while the shank continues to rotate and fractures the tip

152
Q

What is flexural fracture of rotary instruments?

A

Occurs when the cyclic loading leads to metal fatigue

153
Q

What is the most popular core material used for obturation and why?

A

Gutta-Percha. Advantages to GP are its plasticity, ease of manipulation, minimal toxicity, radiopacity, and ease of removal with heat or solvents.

154
Q

How many flexural cycles can NiTi instruments withstand before they fracture?

Ch 8

A

several hundred

155
Q

Which canal shaping technique reduces torsional loads and risk of fracture by preventing a large portion of the tapered rotating instrument from engaging root dentin (taper lock)?

Ch 8

A

crown-down technique

156
Q

What is the definition of canal transportation?

Ch 8

A

the removal of canal wall structure on the outside curve in the apical half of the canal due to the tendency of files to restore themselves to their original linear shape during canal preparation

157
Q

What are the disadvantages to Gutta Percha?

A

Lack of adhesion to dentin, and when heated, it will shrink once it is cooled down.

158
Q

GP is the trans-isomer form of polyisoprene or natural rubber. What are its two crystalline forms?

A

Alpha and Beta
The beta form is when it is unheated - a solid mass that is compactable
The alpha form occurs when it is heated, it becomes pliable and tacky and can flow under pressure

159
Q

What is a disadvantage of lateral compaction?

A

The technique may not fill canal irregularities as the process does not produce a homogenous mass

160
Q

What are the disadvantages to warm vertical compaction?

A

Slight risk of vertical root fracture, less length control compared to lateral compaction, and therefor potential for overextrusion of obturation materials into periradicular tissues

161
Q

What are the advantages of warm vertical compaction?

A

Filling of canal irregularities and accessory canals

162
Q

Continuous wave obturation uses what equipment?

A

System B unit, hand pluggers, and a master cone

163
Q

Continuous wave compaction is a variation of lateral or warm vertical compaction?

A

Warm vertical compaction

164
Q

What are the contents of Gutta Flow

A

gutta percha, polydimethylsiloxane sealer, and nanosilver preservative particles

165
Q

The cell-poor zone of the pulp is often not apparent in what age of pulps?

Ch 13

A

Young pulps where dentin forms rapidly
Older pulps where reparative dentin is being produced

Phase 1 Boards Prep - SA (22 decks)

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