Cohens Chapters 21, 22, 23, 25, 29

Question 1

According to Cohens Chapter 21, Periradicular surgery,

What is the primary goal of both conventional snd surgical root canal treatment?

Answer 1

Sealing off all potential routes of microbial escape from the root canal system is the goal of both nonsurgical and surgical treatmen

Question 2

According to Cohens Chapter 21, Periradicular surgery,

What new agents have been implicated in cases of RCT failure?

Answer 2

•Fungi and viruses recently have also emerged as potential causes of root canal failure and may play either a primary or secondary role in persistent periradicular pathosis

Question 3

According to Cohens Chapter 21, Periradicular surgery,

How successful is surgical endodontic treatrment?

Answer 3

•current evidence supports the contention that the prognosis for surgical treatment is approximately the same as that for nonsurgical retreatment

Question 4

According to Cohens Chapter 21, Periradicular surgery,

What are the three main phases of healing?

Answer 4

hemotasis/inflammatory phase

proliferation phase

maturation/remodelling phase

Question 5

According to Cohens Chapter 21, Periradicular surgery,

What cells predominate in the early inflammatory phase, what is the timeline for arrival and what is their funciton?

Answer 5

Neutrophils

begin showing up after 6 hours, peak at 24-48 hours

role is decontamination by phagocytosis of bacteria

Question 6

According to Cohens Chapter 21, Periradicular surgery,

What cells predominate in the late inflammatory phase, what is the timeline for arrival and what is their funciton?

Answer 6

macrophages

after 48 hours, usually peak by 3-4 days

phagocytosis of bacteria and tissue debris

process and present antigen to T cells,

secrete an array of cytokines

Question 7

According to Cohens Chapter 21, Periradicular surgery,

What 2 cell tyes are most important in the proliferative phase?

Answer 7

fibroblasts

endothelial cells

Question 8

According to Cohens Chapter 21, Periradicular surgery,

During the proliferative phase, what type of tissue is formed in the wound?

Answer 8

granulation tissue

Question 9

According to Cohens Chapter 21, Periradicular surgery,

in the proliferative phase of wound healing, Where do fibroblasts come from?

Answer 9

Undifferentiated ectomesenchymal cells in the perivascular tissue and fibroblasts in the adjacent connective tissue migrate into the wound

Question 10

According to Cohens Chapter 21, Periradicular surgery,

in the proliferative phase of wound healing, what is the timeline for arrival of fibroblasts?

Answer 10

begin after 3 days, peak after 7 days

Question 11

According to Cohens Chapter 21, Periradicular surgery,

in the proliferative phase of wound healing, which cytokines stimulate arrival of fibroblasts?

Answer 11

fibroblast growth factor [FGF],

insulin-like growth factor 1 [IGF-1],

platelet-derived growth factor [PDGF]

Question 12

According to Cohens Chapter 21, Periradicular surgery,

in the proliferative phase of wound healing, what is the most important action of fibroblasts?

Answer 12

produce most of the structural proteins (collagen) involved in wound healing

Question 13

According to Cohens Chapter 21, Periradicular surgery,

in the proliferative phase of wound healing, what do fibroblasts produce first, what comes as the wound matures?

Answer 13

type III collagen made first, type I made later

Question 14

According to Cohens Chapter 21, Periradicular surgery,

in the proliferative phase of wound healing, what special type of fibroblasts are involved in contraction and drawing wound edges together?

Answer 14

myofibroblast

Question 15

According to Cohens Chapter 21, Periradicular surgery,

in the proliferation phase of wound healing, when does angiogenesis begin?

Answer 15

48-72 hours after injury

Question 16

According to Cohens Chapter 21, Periradicular surgery,

Name 5 factors that stimulate endothelial growth

Answer 16

All the cytokines!

1. low oxygen tension
2. vascular endothelial growth factor (VEGF),
3. basic fibroblast growth factor (bFGF),
4. acidic FGF (aFGF),
5. transforming growth factors alpha and beta (TGF-α, TGF-β),
6. epidermal growth factor (EGF),
7. interleukin 1 (IL-1),
8. tumor necrosis factor alpha (TNF-α),
9. lactic acid

Question 17

According to Cohens Chapter 21, Periradicular surgery,

how quickly does epithelium spread across a wound?

Answer 17

0.5-1mm/day

Question 18

According to Cohens Chapter 21, Periradicular surgery,

What tells epithelial cells to stop spreading?

Answer 18

contact inhibition from opposite side

Question 19

According to Cohens Chapter 21, Periradicular surgery,

in primary wound healing, how long does it take to achieve an epithelial seal?

Answer 19

21-28 hours after closure

Question 20

According to Cohens Chapter 21, Periradicular surgery,

Under ideal conditions when does the wound maturation phase begin?

Answer 20

5-7 days after injury

Question 21

According to Cohens Chapter 21, Periradicular surgery,

what are the key events hapenning during the wound maturation phase?

Answer 21

• reduction in fibroblasts, vascular channels, and extracellular fluids
• upregulation of collagen fibrogenesis occurs
• collagen gradually reorganizes; this requires degradation and reaggregation of the collagen

Question 22

According to Cohens Chapter 21, Periradicular surgery,

In wound healing, what is the difference between an epithelial seal and an epithelial barrier?

Answer 22

seal is when there is a single complete layer of epithelial cells covering the wound

barrier is after seal undergoes mitosis and re-established a stratified squamous layer

Question 23

According to Cohens Chapter 21, Periradicular surgery,

In wound healing, how long does it take for an epithelial barrier to appear in primary intention wound healing?

Answer 23

36-42 hours

Question 24

According to Cohens Chapter 21, Periradicular surgery,

when an osseous wound is made, how long before new bone formation BEGINS?

Answer 24

approx 6 days

Question 25

According to Cohens Chapter 21, Periradicular surgery,

when an defect is made, how long before new bone formation typically fills the defect?

Answer 25

16 weeks

(remodelling of the cortical plate will take longer)

Question 26

According to Cohens Chapter 21, Periradicular surgery,

when root end resection is performed, when will cementogenesis begin?

Answer 26

after 10-12 days

Question 27

According to Cohens Chapter 21, Periradicular surgery,

when root end resection is performed, when will new functional PDL fibres have reformed?

Answer 27

about 8 weeks after surgery

Question 28

According to Cohens Chapter 21, Periradicular surgery,

What is this array of instruments used for?

Answer 28

root end filling/condensation

Question 29

According to Cohens Chapter 21, Periradicular surgery,

What is this array of instruments used for?

Answer 29

various carriers for placement of root end fillings

Question 30

According to Cohens Chapter 21, Periradicular surgery,

What is this used for?

Answer 30

pre-forming MTA pellets for placement in root ends

Question 31

According to Cohens Chapter 21, Periradicular surgery,

What shape of bur is best for osseous access?

Answer 31

The round bur has the best shape for removing osseous tissue

Produces a wound site with less thermal damage, and heals faster.

This type of bur also readily allows access of coolant to the actual cutting surfaces.

Question 32

According to Cohens Chapter 21, Periradicular surgery,

What is the mechanism of hemostasis for the following hemostatic agents?

• Collagen-Based Materials
• Surgicel
• Gelfoam
• Bone Wax
• Ferric Sulfate
• Calcium Sulfate
• Epinephrine Pellets

Answer 32

• Collagen-Based Materials - stimulate platelets and activate clotting cascade
• Surgicel - physical barrier, becomes a sticky mass and serves as an artificial clot
• Gelfoam - stimulates intrinsic clotting pathway by promoting platelt disintegration
• Bone Wax - mechanically plugs bleeding osseous sites
• Ferric Sulfate - necrotizing agent that helps form a surface coagulum
• Calcium Sulfate - allowed to set then mostly carved away. produces a physical barrier
• Epinephrine Pellets - powerful local vasoconstrictor

Question 33

According to Cohens Chapter 21, Periradicular surgery,

What angle is biologically the best for root end resection?

Answer 33

From a biologic perspective, the most appropriate angle of root-end resection is perpendicular to the long axis of the tooth

Question 34

According to Cohens Chapter 21, Periradicular surgery,

What agents have been advocated as root end conditioners?

Answer 34

citric acid, tetracycline, and ethylenediamine tetraacetic
acid (EDTA)

Question 35

According to Cohens Chapter 21, Periradicular surgery,

What is the recommended root end cavity preparation?

Answer 35

The ideal preparation is a class I cavity prepared along the long axis of the tooth to a depth of at least 3 mm

Question 36

According to Cohens Chapter 21, Periradicular surgery,

What are the most common/recommended root end filling materials?

Answer 36

These materials are

zinc oxide eugenol cements (IRM and SuperEBA),

glass ionomer cement,

Diaket,

composite resins (Retroplast),

resin–glass ionomer hybrids (Geristore),

mineral trioxide aggregate (ProRoot-MTA).

Question 37

According to Cohens Chapter 21, Periradicular surgery,

What are the main constituents of MTA?

Answer 37

The main constituents of this material are

calcium silicate (CaSiO4),

bismuth oxide (Bi2O3),

calcium carbonate (CaCO3),

calcium sulfate (CaSO4),

calcium aluminate (CaAl2O4).

Question 38

According to Cohens Chapter 21, Periradicular surgery,

What is one of the main drawbacks of MTA?

Answer 38

extended setting time of 2h 45 mins +

continues setting for weeks

Question 39

According to Cohens Chapter 21, Periradicular surgery,

in summary which materials show clear advantages over other root end filling materials?

Answer 39

MTA, followed by Retroplast, appear to have a clear advantage over the other available materials

Question 40

According to Cohens Chapter 21, Periradicular surgery,

what is one of the most important benefits of MTA in periradicular surgery?

Answer 40

Cementum regeneration adjacent to/overtop of MTA

The importance of the presence of cementum-like tissue adjacent to MTA cannot be understated.

Cementum deposition is essential to regeneration of the periodontal apparatus.

Question 41

According to Cohens Chapter 22 - Restoration of the Endodontically Treated Tooth,

How much of a difference does vitality make to the brittleness of dentin?

Answer 41

minimal.

Question 42

According to Cohens Chapter 22 - Restoration of the Endodontically Treated Tooth,

What effects are responsible for loss of strength and stiffness in endodontically treated teeth?

Answer 42

largest reduction in tooth stiffness results from additional preparation, especially the loss of marginal ridges.

possible decrease in tooth strength can be attributed to dentin aging and to a smaller extent to dentin alteration by endodontic irrigants

Question 43

According to Cohens Chapter 23, Pediatric Endodontics,

What are the two types of tertiary dentin pictured below?

Answer 43

Reactionary (left) and repairative (Right)

reactionary is made by existing odontoblasts and is tubular

repairative is made by newly differentiated odontoblast like cells and is atubular.

Question 44

According to Cohens Chapter 23, Pediatric Endodontics,

what happens when CaOH is applied directly to pulp?

Answer 44

necrosis of adjacent pulp

inflammation of contiguous tissue

beneath region of coagulation necrosis, odontoblast like cells differentiate and produce dentin matrix

Question 45

According to Cohens Chapter 23, Pediatric Endodontics,

How can profuse bleeding be controlled in deep caries excavation exposing pulp in young permanent teeth?

Answer 45

The often profuse bleeding that occurs is controlled by lavaging the pulp with NaOCl, which is not only antimicrobial but appears to have no adverse effects on pulpal healing, odontoblastic cell formation, or dentinal bridging

…Does anyone do this??? it sounds crazy. it’s on page 840 if you’re interested.

Question 46

According to Cohens Chapter 23, Pediatric Endodontics,

What is the difference between apexogenesis and apexification?

Answer 46

apexogenesis saves some vital pulp tissue in the root end and allows the tooth to mature it’s own root

apexification has no vital pulp tissue left and is based on creating an external apical stop in the form of a cementoid or osteoid layer on the outside of the tooth.

Question 47

According to Cohens Chapter 23, Pediatric Endodontics,

What procedure/process is being depicted?

Answer 47

apexogenesis

Question 48

According to Cohens Chapter 23, Pediatric Endodontics,

Why might calcium hydroxide be preferred for apexogenesis over MTA?

Answer 48

If it fails, or even if it succeeds, but still need RCT treatment later on, MTA is cement, and very challenging to remove/work through.

Question 49

According to Cohens Chapter 23, Pediatric Endodontics,

What procedure is being depicted?

Answer 49

apexification

Question 50

According to Cohens Chapter 23, Pediatric Endodontics,

What should not be expected in apexification, that could be expected in successful vital pulp therapy or apexigenesis?

Answer 50

Will not cause any continued root development in the form of increased length or wall thickness.

Question 51

According to Cohens Chapter 23, Pediatric Endodontics,

What are downfalls to the classic apexification technique with CaOH?

Answer 51

need to continue replacing CaOH every 3 months for 9-24 months

Question 52

According to Cohens Chapter 23, Pediatric Endodontics,

What is the main benefit of the artificial barrier technique for apexification with MTA?

Answer 52

significantly shorter treatment period - MTA barrier is allowed to set, then after a few weeks obturation may be completed and hard tissue barrier will grow externally over time.

N.B. There is a JVD describing a modified technique in a cat where a hard floor of glass ionomer was put over the MTA and treatment completed in a single appointment.

Question 53

According to Cohens Chapter 23, Pediatric Endodontics,

What specific stem cells are recruited in regenerative endodontics?

Answer 53

Stem cells of the apical papilla

Question 54

According to Cohens Chapter 25, Non-surgical retreatment,

What are 4 main etiologies for post-treatment disease?

Answer 54

1. Persistent or reintroduced intraradicular microorganisms
2. Extraradicular infection
3. Foreign body reaction
4. True cysts

Question 55

According to Cohens Chapter 25, Non-surgical retreatment,

What solvents will effectively dissolve gutta percha?

Answer 55

chloroform,
methylchloroform
eucalyptol,
halothane,
rectified turpentine
and xylene.

Question 56

According to Cohens Chapter 25, Non-surgical retreatment,

When is it likely that a separated instrument can be retrieved?

Answer 56

If the separated instrument extends into
the straight coronal portion of the canal, retrieval is likely,

Question 57

According to Cohens Chapter 25, Non-surgical retreatment,

When is it likely that a separated instrument can’t be retrieved?

Answer 57

if the instrument has separated deep in the canal and the entire broken segment is apical to the canal curvature, orthograde removal will not be possible, and attempts to do so could lead to a much higher rate of iatrogenic complication

Question 58

According to Cohens Chapter 25, Non-surgical retreatment,

What is a problem encountered when trying to loosen separated Ni-Ti instruments using ultrasonic energy?

Answer 58

nickel-titanium instruments often break up into fragments when subjected to the energy supplied by an ultrasonic instrument

Question 59

According to Cohens Chapter 25, Non-surgical retreatment,

What is this technique for separated instruments called?

Answer 59

Tube and H-file technique

Question 60

According to Cohens Chapter 25, Non-surgical retreatment,

What is this technique for separated instruments called?

Answer 60

Wire and loop technique

Question 61

According to Cohens Chapter 25, Non-surgical retreatment,

What are these instruments called and used for? How do they work?

Answer 61

Used for removing separated instruments,

AB are the cancellier instrument.

CD are the mounce instrument

cyanoacrylate used to bond the instrument to the separated file

Question 62

According to Cohens Chapter 25, Non-surgical retreatment,

what is the material of choice for repair of perforations?

Answer 62

MTA

Question 63

According to Cohens Chapter 29, Cone beam CT,

What is the difference between a pixel and a voxel?

Answer 63

a pixel represents a 2d area, wheras a voxel represents a 3d space

Question 64

According to Cohens Chapter 29, Cone beam CT,

What is the difference between a fan beam CT and a cone beam CT in terms of the `shape of the beam?

Answer 64

fan beam is a fan, cone beam is a cone….

Question 65

According to Cohens Chapter 29, Cone beam CT,

What are some benefits of CBCT?

Answer 65

fast aquisition time, low dose of radiation, small voxel size, high spatial resolution, MPR reconstruction software etc. etc.