Final Exam Review Flashcards
what is working length?
how long the root canal system is from incisal/occlusal reference point to the minor apical constriction
what is a patency file?
a very small file, usually size 10, that is used to keep the apical constriction open without widening it
what is the initial apical file?
the first file that binds the minor apical constriction at working length
what is the master apical file?
2-3 file sizes larger than the IAF; it goes to WL passively and stops at WL
what is straight line access?
straight preparation of the canal until the first curvature or the apical third
what are the major and minor constrictions?
the minor constriction is considered the “apical stop”
what are the GG bur sizes?
- GG #2 = 0.7
- GG #3 = 0.9
- GG #4 = 1.1
what is the taper of a regular endodontic file?
0.02mm
what hand file design is the most efficient dentin cutting file we use in endodontics?
hedstrom because it has the most positive rake angle (60 degrees), meaning it is the most efficient at shaving and cutting
what are the two basic ways a file can move in the canal?
rotational and linear
describe watch-winding file movement. what is it’s function in the canal preparation process?
- reciprocating, back and forth (clockwise/counterclockwise) rotation of the instrument in an arch and is used to negotiate canals and to work files to place
- used for mid-root prep and apical prep
describe the step-back filing technique. what is it’s function in the canal preparation process?
- start with the IAF
- determine WL
- set first 3 files to WL
- set each additional file back 1mm
- using the watch-winding movement with 4-8 cycles per file, work your way up through the files using passive gentle touch pressure only, returning to the IAF between each successive file, and irrigating between each file
- repeat as necessary
- used for apical prep
describe the balanced force technique. what is it’s function in the canal preparation process?
- the file is placed to length, rotated clockwise 1/4 turn to engage the dentin, followed by a counterclockwise rotation 3/4 turn with apical pressure to cut and enlarge the canal
- considered the most effective hand instrumentation technique
- used for mid-root prep and apical prep
describe circumferential filing movement. what is it’s function in the canal preparation process?
- the file is placed into the canal and withdrawn in a directional manner sequentially against the mesial, distal, buccal, and lingual walls
- used for pre-flare and for canals that are larger and/or not round
- not very effective beyond the coronal third of the canal
describe anti-curvature filing. what is it’s function in the canal preparation process?
- GG drills and laterally cutting niti orifice shapers are used directionally in an anticurvature fashion to selectively remove dentin from the bulky wall (safety zone) toward the line angle, protecting the inner/furcal wall (danger zone) coronal to the curve
- used for coronal flare to preserve the furcal wall in the treatment of molars
open apex case: a tooth with a WL of 22mm and the apical forament has a large diameter of size #30. describe the concerns with this case and how you would proceed to prepare and obturate this case (include instruments and sizes of instruments you would use, and length of the instruments usage, and the obturation and length used and technique of obturation)
normal routine case: tooth #19, you are going to obturate the 20mm WL distal canal using warm vertical condensation. describe the preparation dimension of the distal root you will prepare for this type of obturation (include distal canal dimensions for this case)
name and purpose of use
D16 endodontic explorer used to explore and locate canal orifices, or to aggressively dislodge calcifications
name and purpose of use
- glick plugger and placing instrument
- plugger end is used for the removal or condensation of gutta percha
- paddle end is used for placement of materials such as temporary restorations
name and purpose of use
- D11 T handled spreader used to laterally compact and adapt GP and create space for accessory cones
- you can also use finger spreaders (red for MAF <40, blue for MAF >40)
which of the following is a k-file and which is a reamer? what is the difference?
- k-file on the left (more flutes)
- reamer on the right (less flutes, also similar to rotary fluting)
hedstrom file
how do you correctly orient a butterfly clamp, and what are of the mouth are they used for?
- the tall end should be toward the lingual, and the short end should be toward the buccal
- anterior regions
what is the correct orientation of the rubber dam frame?
the open end should be toward the patients nose
what is wrong with this isolation setup?
the rubber dam is not released from the wings
describe the final irrigation steps used at the UUSOD
- EDTA 30 seconds
- alcohol rinse
- NaOCl 30 seconds
- alcohol rinse
- master cone fit (tug back)
- paper point dry
what does EDTA stand for, and what does it do?
- ethylenediaminetetraacetic acid
- chelator used for the removal of the smear layer (removes inorganic components and leaves organic tissue elements intact)
what does NaOCl stand for, and what does it do?
- sodium hypochlorite (aka bleach)
- flushes debris from the canal, dissolves vital and necrotic tissue, antimicrobial, and lubrication
what is the purpose of alcohol?
- flushes debris and cleanses the canal
- it can also be used to clean any excess sealer from the pulp chamber space
what is the purpose of a post?
to retain the build up material
what is the minimum ferrule width?
2mm
what are the 4 criteria for obturation assessment?
- density
- voids
- taper
- length
for effective irrigation, where should the needle be placed?
in the apical third of the root (should not bind)
what are the properties of an ideal irrigant?
- organic tissue solvent
- inorganic tissue solvent
- antimicrobial action
- nontoxic
- low surface tension
- lubricant
what can you do to increase the effectiveness of sodium hypochlorite?
warm it up
the action of EDTA is most effective in which areas of the canal?
coronal and middle thirds
EDTA exposure over 10 minutes causes what?
excessive removal of both peritubular and intratubular dentin
what are two important points to know about chlorhexidine?
- broad spectrum antimicrobial
- sustained action
2% chlorhexidine has an antimicrobial action similar to that of ___
5.25% NaOCl
2% chlorhexidine is most effective against what bacteria?
enterococcus faecalis
chlorhexidine and ___ are syndergistic in their ability to eliminate microorganisms
NaOCl
an alternative method for disinfecting while at the same time removing the smear layer, is the use of a mixture composed of tetracycline isomer, an acid, and ___ as a final rinse
MTAD (a detergent)
QMix is similar to MTAD in that it follows the same underlying strategy. However, in addition to removing the smear layer, QMix also provides ___ activity
antibiofilm
what is the purpose of an ultrasonic?
- enhances irrigation (effectiveness of solution) and removal of materials from the canal, including posts and siler cones
- may also be used for thermoplastic obturation and root-end preparation during surgery
is it recommended to use ultrasonic instruments to shape curved root canals? why or why not?
no because it has been shown to create preparation errors
what are 5 examples of preparation errors?
- loss of WL
- apical transportation and zipping
- instrument fracture
- stripping perforations
- ledging
what are the causes of loss of WL?
- failure to have an adequate reference point
- packing of tissue and debris in the apical portion
- ledge formation
- inaccurate measurement of files
what are the causes of apical transportation and zipping?
- inflexible files are used to prepare curved canals
- inadequate coronal flare (enlargement of curved canals at the WL beyond a #25 file can only be done when an adequate coronal flare is developed)
what are the causes of instrument fracture?
- torsional and cyclic fatigue
what are the causes of stripping perforations?
- commonly occurs in furcal areas, so anti-curvature filing helps prevent stripping perforations
what are the causes of ledging?
- canals most prone to ledging are small, curved, and long
- appropriate file size and maintaining patency help prevent ledging
what are the objectives of cleaning and shaping?
- remove infected hard/soft tissue
- give disinfecting solutions access to apical canal space
- create space for medicaments and subsequent obturation
- retain the integrity of radicular structures
- obtain glassy smooth walls
- create a continuously tapering funnel from canal orifice to apex
what are 5 filing movements?
- watch winding
- reaming
- filing (up/down)
- circumferential
- balanced force
what are the advantages of lateral condensation?
- uncomplicated, simple armamentarium
- length control
- predictable
- positive dimensional stability
- post space
what are the disadvantages of lateral condensation?
- not homogenous mass
- does not work well in curved canals
what are the advantages of warm vertical compaction?
- adapts well to canal irregularities
what are the disadvantages of warm vertical compaction?
- more complex/technique sensitive
- difficult length control
- larger preparation
- more complex armamentarium
list the typical instruments found in an endo casette
- mirror
- D16 endo explorer
- glick #1 plugger/paddle
- explorer/perio probe
- other pluggers/spreaders
- spatula
- millimeter ruler w/sponge
- scissors
- hemostats
- bur block w/burs
- syringes
for warm vertical compaction techniques, the coronal enlargement must permit the placement of pluggers to within ___mm of working length
3-5mm
with respect to the restoration of endodontically treated teeth, what is a major cause of endodontic failure?
salivary microleakage
what is the best design for a post to decrease the risk of failure?
- the narrowest and longest parallel post that one can fit into the post space
- parallel serrated is best
why should smooth posts be avoided?
not good for retention
what is the minimum amount of gutta percha that should be left in the apical end of the canal to prevent leakage when placing a post?
minimum of 4-5mm of GP
what is the proper length for a post?
at minimum, as much post is embedded in the root as the crown is long
what are the objectives of final restorations?
- maintain coronal and apical seal
- protect and preserve remaining tooth structure
- provide supportive and retentive foundation for the placement of a definitive restoration
- restore function and esthetics
what are good temporary filling materials?
cavit and term are better than IRM
an orifice seal with ___ or ___ minimized coronal leakage
alloy or glass ionomer
the amount of root fill (GP) left after post space affects ___
coronal leakage
what are the risks associated with posts?
procedural accidents (perforations, root fractures, treatment failures)
what are the indications for a post?
only used when other options are not available to retain a core (build-up)
what is the purpose of posts?
to retain a core in a tooth with extensive loss of coronal tooth structures (DOES NOT strengthen roots)
what are the materials used for posts?
metal, fiber, and ceramic
