Cohens Chapters 21, 22, 23, 25, 29 Flashcards
According to Cohens Chapter 21, Periradicular surgery,
What is the primary goal of both conventional snd surgical root canal treatment?
Sealing off all potential routes of microbial escape from the root canal system is the goal of both nonsurgical and surgical treatmen
According to Cohens Chapter 21, Periradicular surgery,
What new agents have been implicated in cases of RCT failure?
•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
According to Cohens Chapter 21, Periradicular surgery,
How successful is surgical endodontic treatrment?
•current evidence supports the contention that the prognosis for surgical treatment is approximately the same as that for nonsurgical retreatment
According to Cohens Chapter 21, Periradicular surgery,
What are the three main phases of healing?
hemotasis/inflammatory phase
proliferation phase
maturation/remodelling phase
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?
Neutrophils
begin showing up after 6 hours, peak at 24-48 hours
role is decontamination by phagocytosis of bacteria
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?
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
According to Cohens Chapter 21, Periradicular surgery,
What 2 cell tyes are most important in the proliferative phase?
fibroblasts
endothelial cells
According to Cohens Chapter 21, Periradicular surgery,
During the proliferative phase, what type of tissue is formed in the wound?
granulation tissue
According to Cohens Chapter 21, Periradicular surgery,
in the proliferative phase of wound healing, Where do fibroblasts come from?
Undifferentiated ectomesenchymal cells in the perivascular tissue and fibroblasts in the adjacent connective tissue migrate into the wound
According to Cohens Chapter 21, Periradicular surgery,
in the proliferative phase of wound healing, what is the timeline for arrival of fibroblasts?
begin after 3 days, peak after 7 days
According to Cohens Chapter 21, Periradicular surgery,
in the proliferative phase of wound healing, which cytokines stimulate arrival of fibroblasts?
fibroblast growth factor [FGF],
insulin-like growth factor 1 [IGF-1],
platelet-derived growth factor [PDGF]
According to Cohens Chapter 21, Periradicular surgery,
in the proliferative phase of wound healing, what is the most important action of fibroblasts?
produce most of the structural proteins (collagen) involved in wound healing
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?
type III collagen made first, type I made later
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?
myofibroblast
According to Cohens Chapter 21, Periradicular surgery,
in the proliferation phase of wound healing, when does angiogenesis begin?
48-72 hours after injury
According to Cohens Chapter 21, Periradicular surgery,
Name 5 factors that stimulate endothelial growth
All the cytokines!
- low oxygen tension
- vascular endothelial growth factor (VEGF),
- basic fibroblast growth factor (bFGF),
- acidic FGF (aFGF),
- transforming growth factors alpha and beta (TGF-α, TGF-β),
- epidermal growth factor (EGF),
- interleukin 1 (IL-1),
- tumor necrosis factor alpha (TNF-α),
- lactic acid
According to Cohens Chapter 21, Periradicular surgery,
how quickly does epithelium spread across a wound?
0.5-1mm/day
According to Cohens Chapter 21, Periradicular surgery,
What tells epithelial cells to stop spreading?
contact inhibition from opposite side
According to Cohens Chapter 21, Periradicular surgery,
in primary wound healing, how long does it take to achieve an epithelial seal?
21-28 hours after closure
According to Cohens Chapter 21, Periradicular surgery,
Under ideal conditions when does the wound maturation phase begin?
5-7 days after injury
According to Cohens Chapter 21, Periradicular surgery,
what are the key events hapenning during the wound maturation phase?
- reduction in fibroblasts, vascular channels, and extracellular fluids
- upregulation of collagen fibrogenesis occurs
- collagen gradually reorganizes; this requires degradation and reaggregation of the collagen
According to Cohens Chapter 21, Periradicular surgery,
In wound healing, what is the difference between an epithelial seal and an epithelial barrier?
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
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?
36-42 hours
According to Cohens Chapter 21, Periradicular surgery,
when an osseous wound is made, how long before new bone formation BEGINS?
approx 6 days
According to Cohens Chapter 21, Periradicular surgery,
when an defect is made, how long before new bone formation typically fills the defect?
16 weeks
(remodelling of the cortical plate will take longer)
According to Cohens Chapter 21, Periradicular surgery,
when root end resection is performed, when will cementogenesis begin?
after 10-12 days
According to Cohens Chapter 21, Periradicular surgery,
when root end resection is performed, when will new functional PDL fibres have reformed?
about 8 weeks after surgery
According to Cohens Chapter 21, Periradicular surgery,
What is this array of instruments used for?
root end filling/condensation
According to Cohens Chapter 21, Periradicular surgery,
What is this array of instruments used for?
various carriers for placement of root end fillings
According to Cohens Chapter 21, Periradicular surgery,
What is this used for?
pre-forming MTA pellets for placement in root ends
According to Cohens Chapter 21, Periradicular surgery,
What shape of bur is best for osseous access?
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.
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
- 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
According to Cohens Chapter 21, Periradicular surgery,
What angle is biologically the best for root end resection?
From a biologic perspective, the most appropriate angle of root-end resection is perpendicular to the long axis of the tooth
According to Cohens Chapter 21, Periradicular surgery,
What agents have been advocated as root end conditioners?
citric acid, tetracycline, and ethylenediamine tetraacetic
acid (EDTA)
According to Cohens Chapter 21, Periradicular surgery,
What is the recommended root end cavity preparation?
The ideal preparation is a class I cavity prepared along the long axis of the tooth to a depth of at least 3 mm
According to Cohens Chapter 21, Periradicular surgery,
What are the most common/recommended root end filling materials?
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).
According to Cohens Chapter 21, Periradicular surgery,
What are the main constituents of MTA?
The main constituents of this material are
calcium silicate (CaSiO4),
bismuth oxide (Bi2O3),
calcium carbonate (CaCO3),
calcium sulfate (CaSO4),
calcium aluminate (CaAl2O4).
According to Cohens Chapter 21, Periradicular surgery,
What is one of the main drawbacks of MTA?
extended setting time of 2h 45 mins +
continues setting for weeks
According to Cohens Chapter 21, Periradicular surgery,
in summary which materials show clear advantages over other root end filling materials?
MTA, followed by Retroplast, appear to have a clear advantage over the other available materials
According to Cohens Chapter 21, Periradicular surgery,
what is one of the most important benefits of MTA in periradicular surgery?
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.
According to Cohens Chapter 22 - Restoration of the Endodontically Treated Tooth,
How much of a difference does vitality make to the brittleness of dentin?
minimal.
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?
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
According to Cohens Chapter 23, Pediatric Endodontics,
What are the two types of tertiary dentin pictured below?
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.
According to Cohens Chapter 23, Pediatric Endodontics,
what happens when CaOH is applied directly to pulp?
necrosis of adjacent pulp
inflammation of contiguous tissue
beneath region of coagulation necrosis, odontoblast like cells differentiate and produce dentin matrix
According to Cohens Chapter 23, Pediatric Endodontics,
How can profuse bleeding be controlled in deep caries excavation exposing pulp in young permanent teeth?
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.
According to Cohens Chapter 23, Pediatric Endodontics,
What is the difference between apexogenesis and apexification?
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.
According to Cohens Chapter 23, Pediatric Endodontics,
What procedure/process is being depicted?
apexogenesis
According to Cohens Chapter 23, Pediatric Endodontics,
Why might calcium hydroxide be preferred for apexogenesis over MTA?
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.
According to Cohens Chapter 23, Pediatric Endodontics,
What procedure is being depicted?
apexification
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?
Will not cause any continued root development in the form of increased length or wall thickness.
According to Cohens Chapter 23, Pediatric Endodontics,
What are downfalls to the classic apexification technique with CaOH?
need to continue replacing CaOH every 3 months for 9-24 months
According to Cohens Chapter 23, Pediatric Endodontics,
What is the main benefit of the artificial barrier technique for apexification with MTA?
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.
According to Cohens Chapter 23, Pediatric Endodontics,
What specific stem cells are recruited in regenerative endodontics?
Stem cells of the apical papilla
According to Cohens Chapter 25, Non-surgical retreatment,
What are 4 main etiologies for post-treatment disease?
- Persistent or reintroduced intraradicular microorganisms
- Extraradicular infection
- Foreign body reaction
- True cysts
According to Cohens Chapter 25, Non-surgical retreatment,
What solvents will effectively dissolve gutta percha?
chloroform,
methylchloroform
eucalyptol,
halothane,
rectified turpentine
and xylene.
According to Cohens Chapter 25, Non-surgical retreatment,
When is it likely that a separated instrument can be retrieved?
If the separated instrument extends into
the straight coronal portion of the canal, retrieval is likely,
According to Cohens Chapter 25, Non-surgical retreatment,
When is it likely that a separated instrument can’t be retrieved?
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
According to Cohens Chapter 25, Non-surgical retreatment,
What is a problem encountered when trying to loosen separated Ni-Ti instruments using ultrasonic energy?
nickel-titanium instruments often break up into fragments when subjected to the energy supplied by an ultrasonic instrument
According to Cohens Chapter 25, Non-surgical retreatment,
What is this technique for separated instruments called?
Tube and H-file technique
According to Cohens Chapter 25, Non-surgical retreatment,
What is this technique for separated instruments called?
Wire and loop technique
According to Cohens Chapter 25, Non-surgical retreatment,
What are these instruments called and used for? How do they work?
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
According to Cohens Chapter 25, Non-surgical retreatment,
what is the material of choice for repair of perforations?
MTA
According to Cohens Chapter 29, Cone beam CT,
What is the difference between a pixel and a voxel?
a pixel represents a 2d area, wheras a voxel represents a 3d space
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?
fan beam is a fan, cone beam is a cone….
According to Cohens Chapter 29, Cone beam CT,
What are some benefits of CBCT?
fast aquisition time, low dose of radiation, small voxel size, high spatial resolution, MPR reconstruction software etc. etc.
