Final Revision Flashcards
What is the aim of RCT for teeth w/ vital pulp?
pulpectomy and prevention of apical periodontitis
What is the aim of RCT for teeth w/ non-vital pulp?
treatment of apical periodontitis
RCT Indication:
- root caries
- poor crown:root ratio
- periodontal disease
- restorative condition of tooth
- lesions that mimic endodontic pathoses but they are not of odontogenic origin
RCT Contraindications:
- poor periodontal prognosis -> extraction
- extensive loss of hard tissues due to caries, root fractures, cervical resorption
- restorations -> should be removed before
- teeth w/ vital pulp
- implants
- inadequate periodontal support which cannot be corrected
What are the RCT outcomes?
- successful outcome for short/long-term evaluation
- failure of post-treatment (apical periodontitis)
- uncertain outcome
Which factors play role in good prognosis of RCT?
- full working length
- no apical extrusion of foreign material
- no missed RC
- effective cleaning and shaping of PC and proper disinfection
- hermetic obturation
- good tooth restoration
RCT Procedure: good technical quality
- Access cavity prep
- Tooth isolation from oral environment
- Working length determination
- RC shaping and cleaning (chemomechanical prep of RC)
- RC disinfection
- RC obturation
- Tooth restoration without leakage
SOS
What is the role of radiograph in endo diagnosis?
- characterize root hard tissues normal structure
- recognize pathological alteration of root hard tissues
- determine root anatomy and root canal pathway
- identify pathological changes in root and periapical periodontal tissues
- locate RC and study their configuration
- determine WL of RC
- evaluate possible iatrogenic factors during treatment
- evaluate presence of calcification in RC space
- to identify new disease
- to evaluate periapical disease healing
What criteria to evaluate changes in periodontal tissues?
- LD (presence, absence, widening)
- periapical ligament space (normal, widening)
- periapical radiolucency (localized, large)
ex: apical periodontitis - periapical radiopacity
What are the techniques of periapical radiographs?
- parallel (long) cone technique
- bisecting angle technique
What are the ADV of Parallel (long) cone technique?
- min enlargement and less distortion
- sharp image
- represents true relationship w/ alveolar crest and bone
- reproductibility
What are the DISADV of Parallel (long) cone technique?
- difficulties in small mouths
- difficulties w/ tooth isolation
- requires film holders
- apices below zygomatic arch are usually not seen clearly
What are the ADV of Bisecting angle technique?
- easy use
- film placed in close proximity to tooth
What are the DISADV of Bisecting angle technique?
- distortion of tooth root structure
- no reproductibility
The access prep for RCT should be:
- locating all canals
- straight-line access of instruments to apical root part
- removal of roof pulp chamber and whole coronal pulp
- conservation of tooth structure
What are the forms of access cavity?
- outline form
- convenience form
Outline form definition:
=projection of internal tooth anatomy
Convenience form definition:
=modification of ideal outline form to facilitate manipulation after complete caries removal
SOS
Pulp chamber principle:
- always at the center of the tooth
- its floor is always darker in color than walls and grooves connecting RCs
- at level of CEJ
- same distance from crown’s external surface to pulp chamber wall
- RC orifices located at the junction of walls and floor
General principles of cavities:
- always include pulp horns removal
- must have parallel walls
- must provide instruments free entrance
- prep after complete caries removal
Why is the cavity access prep done after complete caries removal?
- it creates an aseptic environment
- it allows assessment of restorability before RCT
- it provides sound tooth structure for temporal filling
- no change in reference point for WL
SOS
Number of roots for:
maxillary I1: maxillary I2: maxillary C: maxillary P1: maxillary P2: maxillary M1: maxillary M2:
mandibular I1: mandibular I2: mandibular C: mandibular P1: mandibular P2: mandibular M1: mandibular M2:
maxillary I1: 1 maxillary I2: 1 maxillary C: 1 maxillary P1: 2 (60%) maxillary P2: - maxillary M1: 3 (91%) maxillary M2: 3 (60%)
mandibular I1: 1 (95%) mandibular I2: 1 (95%) mandibular C: 1 (95%) mandibular P1: 1 (86%) mandibular P2: 1 (86%) mandibular M1: 2 (95%) mandibular M2: 2 (95%)
Root curvatures:
maxillary I1: maxillary I2: maxillary C: maxillary P1: maxillary P2: maxillary M1: maxillary M2:
mandibular I1: mandibular I2: mandibular C: mandibular P1: mandibular P2: mandibular M1: mandibular M2:
maxillary I1: - maxillary I2: apical maxillary C: apical maxillary P1: apical maxillary P2: apical maxillary M1: apical maxillary M2: apical
mandibular I1: apical mandibular I2: apical mandibular C: apical mandibular P1: middle or apical mandibular P2: middle or apical mandibular M1: apical mandibular M2: apical
Root shape:
maxillary I1: maxillary I2: maxillary C: maxillary P1: maxillary P2: maxillary M1: maxillary M2:
mandibular I1: mandibular I2: mandibular C: mandibular P1: mandibular P2: mandibular M1: mandibular M2:
maxillary I1: triangular to round
maxillary I2: oval
maxillary C: long oval
maxillary P1: long oval coronally to round apically
maxillary P2: long oval coronally to round apically
maxillary M1: oval to long oval
maxillary M2: oval to long oval
mandibular I1: long oval
mandibular I2: long oval
mandibular C: long oval
mandibular P1: long oval coronally to round apically
mandibular P2: long oval coronally to round apically
mandibular M1: long oval
mandibular M2: long oval
Number of root canals:
maxillary I1: maxillary I2: maxillary C: maxillary P1: maxillary P2: maxillary M1: maxillary M2:
mandibular I1: mandibular I2: mandibular C: mandibular P1: mandibular P2: mandibular M1: mandibular M2:
maxillary I1: 1 maxillary I2: 1 maxillary C: 1 (70%) maxillary P1: 2 (90%) maxillary P2: 1 (53%) maxillary M1: 4 (65%) maxillary M2: 3 (65%)
mandibular I1: 1 (70%) maxillary I2: 1 (55%) mandibular C: 1 (90%) mandibular P1: 1 (70%) mandibular P2: 1 (85%) mandibular M1: 3 (70%) mandibular M2: 3 (70%)
Number of apical exists:
maxillary I1: maxillary I2: maxillary C: maxillary P1: maxillary P2: maxillary M1: maxillary M2:
mandibular I1: mandibular I2: mandibular C: mandibular P1: mandibular P2: mandibular M1: mandibular M2:
maxillary I1: 1 maxillary I2: 1 maxillary C: 1 maxillary P1: 2 (78%) maxillary P2: 1 (75%) maxillary M1: 4 (80%) maxillary M2: 3 (80%)
mandibular I1: 1 (70%) mandibular I2: 1 (55%) mandibular C: 1 (90%) mandibular P1: 1 (74%) mandibular P2: 1 (97%) mandibular M1: 3 (70%) mandibular M2: 3 (70%)
Access view:
maxillary I1: maxillary I2: maxillary C: maxillary P1: maxillary P2: maxillary M1: maxillary M2:
mandibular I1: mandibular I2: mandibular C: mandibular P1: mandibular P2: mandibular M1: mandibular M2:
maxillary I1: triangular maxillary I2: oval maxillary C: oval maxillary P1: oval maxillary P2: oval maxillary M1: oval maxillary M2: oval
mandibular I1: long oval mandibular I2: long oval mandibular C: oval mandibular P1: oval mandibular P2: oval mandibular M1: oval mandibular M2: oval
Basic instrument pack components:
mirror dental tweezers/cotton pliers dental explorer endo tweezers endo explorer DG16 periodontal probe anesthetic syringe paper points long shank spoon excavator flat plastic instrument amalgam plugger plastic/metal ruler endo stand or endo ring
Ultrasonic tips use:
- calcifications
- access cavity prep
- broken instruments removal
- intracanal posts removal
Cold lateral compaction:
Warm vertical compaction:
remove excess gutta percha
SOS
What is the objective of working length determination?
to establish the length at which canal prep and obturation are completed
Root end diameter
0.5 - 1.2 mm
Topography of apical constriction:
Traditional single constriction:
Multiconstricted:
Tapering constriction:
Parallel constriction:
Traditional single constriction: 46%
Multiconstricted: 19%
Tapering constriction: 30%
Parallel constriction: 5%
Short constriction:
Long constriction:
Short constriction: 76%
0.5 - 1 mm OR > 1 mm from radiographic apex
Long constriction: 24%
1 - 3 mm form radiographic apex
Techniques used for WL determination:
tactile method
radiographic technique
electronic technique
Tactile method:
- unreliable
- well developed fingertip tactile sense can detect when the file tip reached apical constriction
What are the 2 pints for an accurate measurement of Radiographic technique:
- reference point
- apical end of file
Radiographic technique:
- # 10 file placements in RC
- measurement made in initial x-ray, with 3 mm subtracted
- then diagnostic x-ray is made using paralleling technique (to measure WL)
- empirical technique: apical constriction estimations: 1 statistical basis
- measurement w/ endo meter
- same cusp as a reference point
How is corrected WL determined for Radiographic technique?
by measuring the discrepancy b/w file tip and radiographic apex
- accurate WL determination at 0.5 mm level
- file is adjusted to 1 mm short of radiographic apex
SOS
Electronic technique:
- apex locator to find apical foramen position
- apical constriction is estimated by you
- 2 electrodes - 1 attached to patient (lip clip) and 1 clipped to file (file clip)
What are the uses of apex locator?
- provides high accuracy information when “0” measurement
- used when apical portion of canal is constricted (in impacted teeth, under zygomatic arch, in overlapping roots, excessive teeth, excessive bone density)
- used in patients w/ gag reflex and cannot tolerate x-ray films
- in pregnant women to reduce radiation exposure
- used in children, disabled children and heavily sedated patients
- easy to operate in presence of apical tissue fluids or irrigants
Working length determination:
Step 1: electronic-WL = Apex locator “O”
Step 2: subtract 1 mm
Step 3 : get the diagnostic x-ray to confirm or not
What is the goal of RCT?
to eliminate microorganisms and pathological material from the root canal system by using: mechanical instrumentation, irrigation and antibacterial dressing
What is the goal of RCT cleaning and shaping?
Shaping: (upper part of root)
- create appropriate space for apical canal access
- delivery of irrigants
- obturation material placement up to apical constriction
Cleaning: (lower part of root)
-remove pathological material (pulp tissue, hard tissue, bacteria)
-instruments used for these are in taper form
Why is difficult to remove pathological material from RC?
- narrow and complex canal space
- canal variation in size and shape
Why do we need radicular dentin?
not to weaken the root structure and prevent vertical fractures
Errors in technical challenges of instrumentation:
▪ RC transportation and straightening ▪ RC blockage ▪ Root perforation ▪ Extrusion of pathological RC components and endo materials beyond apex ▪ Root wall weakening
What is the adequate access cavity prep?
outline form
What is the best shape of root canal?
taper form
Which instruments are used for RC instrumentation?
hand-held
engine-driven
Reamers hand files use:
cut and enlarge RC w/ rotational motions
Files use:
enlarge RC w/ reciprocal insertion and withdrawal motions
SOS
What is the diameter 6 mm from apex of file F3? (size 80, taper=9)
6x9=54
F3=30
54+30=84 (thus, more)
F1=20 F2=25
SOS
Why in cavities you should always include pulp horns?
if pulp floor remains, you might have bacteria and b/c of discoloration of tooth
Which is more important?
Cleaning
Shaping
Both
Both
if vital -> shaping b/c no pathological material to do cleaning
SOS
Average width of apical RC system:
apical constriction:
apical constriction + 3 mm:
apical constriction + 6 mm:
apical constriction + 9 mm:
apical constriction: 0.2 - 0.3 mm **
apical constriction + 3 mm: 0.45 -0.5 mm **
apical constriction + 6 mm: 0.6 - 0.7 mm
apical constriction + 9 mm: 0.8 - 0.9 mm
What file is used as the final instrument for apical constriction prep?
Master Apical File
SOS
What is a Master Apical File?
=largest file to bind slightly at the final WL
SOS
What are the characteristics of the Master Apical File?
size and taper
Standardized Technique:
- same WL for all instruments in RC
- same hand movement / ‘quarter turn and pull’ until next larger instrument is used
- last instrument shape = final RC shape
Aim, technique and benefits of Step Back Technique:
Aim:
larger shape than Standardized approach, using stainless steel hand files of similar taper
Technique:
- WL decreases as instrument size increases
- incorporation of a stepwise reduction of WL for larger files; 1 mm steps
Benefits:
- applies to straight RC as well
- reduces prep errors incidence (especially in curved canals)
- results in flared shapes w/ 0.05 taper
SOS
What are the DISADV of Step Back Technique?
- difficult to irrigate the apical region
- chances of instrument fracture
- chances of pushing debris apically or beyond apex
- risk of ledge formation in curved canals!!!!!!!!!!!!!!!
ADV and DISADV of narrow apical prep:
ADV:
-min risk of canal transportation and material extrusion
DISADV:
- little removal of infected root apical dentin
- questionable irrigation and disinfection of apical RC
ADV and DISADV of wide apical prep:
ADV:
- effective removal of infected root apical dentin
- optimal access of irrigants and medications to apical third of RC
DISADV:
-risks of prep errors and materials extrusion beyond the apex
SOS
What are the criteria for evaluating cleaning and shaping?
Smooth dentinal walls:
determined by pressing the MAF against each wall in an outward stroke
Assessment of apical configuration:
identified as apical stop, apical seat of open
Open: if MAF goes beyond apex
Stop: if smaller of a MAF file stops at corrected WL
Seat: is MAF stops but smaller goes beyond corrected WL
What is Step Down Technique and when is it done?
What is Crown Down Technique and when is it done?
=Step Back modification
=Step Down modification
-BEFORE apical instrumentation and AFTER WL establishment
What are the steps for Step Down Technique?
- access cavity
- check the patency of RC w/ small K file #10 and #15
- WL establishment
- shaping 1/3 or 2/3 coronal RC w/ gates gliden burs
- apical instrumentation
What are the ADV and DISADV for Step Down Technique?
ADV:
- minimize/eliminate extruded necrotic debris amount
- unimpeded instruments - greater control, fewer procedural errors
DISADV:
- apical zip
- ledge
- apical zip w/ perforation
- ledge w/ perforation
What are the steps for Crown Down Technique?
- access cavity
- check the patency of RC w/ small K file #10 and #15
- Crown Down part w/ gates glidden burs
- WL establishment
- apical enlargement to ex: #40 size
What are the movement types w/ hand instruments?
- watch winding
- reaming
- filing
Which files do we use for Balanced Force Technique?
- flex-r-file !!
- flex-o-file !!
- k-flex files
- tapered hand files
- k-files
What are the steps for Balanced Force Technique?
3-4 steps:
- clockwise rotation 90 degrees
- counterclockwise rotation 180-270 degrees
- clockwise rotation 90 degrees
What are the ADV and DISADV for Balanced Force Technique?
ADV:
- min ledging
- better canal-centering ability
- min canal transportation
DISADV:
-learning curve
SOS
Irrigation:
- eradication of RC bacteria
- removal of organic remnants
- removal of inorganic debris and smear layer
Where does the effectiveness of Irrigation depend on?
- irrigant properties
- flow dynamics of irrigation technique
What do we use for Irrigation?
- > syringe and needle
- > irrigants activation w/ manual technique or sonic-, ultrasonic-, lazer- activated techniques
- > NAOCl
What are the ADV and DISADV of NaOCl?
ADV:
-dissolves organic tissues
-effective against bacteria (antibacterial)
(affects directly microbial cell vital functions resulting in death (even if its low conc))
DISADV:
- depends on conc, vol and action time
- irrigant vol and time is important when NaOCl is in low conc
- cannot remove smear layer’s inorganic component (poorer and more superficial area of its antibacterial effect in smear layer presence)
17% EDTA:
=a chelator which removes smear layer’s organic component + no antibacterial effect
DISADV:
-increased EDTA application time results in dentin erosion and dentin micro hardness decrease
CHX Vs NaOCl:
CHX has:
antibacterial !!! lower cytotoxicity lack of foul smell bad taste cant dissolve organic substances and necrotic tissues -cannot remove smear layer
CANT REPLACE NaOCl OR EDTA
Tissue damage from NaOCl extravasation:
Pain
Ecchymosis
Swelling & cellulitis
Necrotic ulcer
What is the purpose of Irrigation?
fluid flow through RC
Treatment of non-infected teeth:
standard irrigation protocol w/o CHX
Can you complete irrigation w/ 0.5%?
Better w/ 5%
What is the role of bacteria dressings?
- pain control
- exudation/bleeding control
- inflammatory root resorption control
Which are the inter-appointment dressings?
- Ca(OH)2
- CHX
- Corticosteroids
- Phenols and Aldehydes
SOS
What is the effectiveness of cleaning and shaping procedure?
- well designed RC instrumentation
- complete irrigation w/ standard protocol
- antibacterial intracanal dressing
The following are true regarding shaping procedures, except:
- Shaping is performed a er cleaning of the apical one third of the canal to ensure patency
- Shaping facilitates placement of instruments to the working length by increasing the coronal taper
- Shaping permits a more accurate assessment of the apical, cross-sectional canal diameter
- Shaping is necessary procedure because calcification occurs from the coronal portion of the canal to the apex
-Shaping is performed a er cleaning of the apical one third of the canal to ensure patency
The result of RCT in establishing patency is:
A.It prevents procedural errors, such as canal blockage and transportation
B.It causes irritation of the periodontal attachment apparatus and increased post operative pain
C.It enlarges the apical terminus and increases the potential for extrusion of obturating material
D.It requires insertion of a file 1.0 to 2.0 mm beyond the canal terminus
A.It prevents procedural errors, such as canal blockage and transportation
Calcium hydroxide is advocated as an inter appointment medication primarily because of:
A.Its ability to dissolve necrotic tissue
B.It ability to stimulate hard-tissue formation
C.Its antimicrobial activity
D.Its ability to temporarily seal the canal
C.Its antimicrobial activity
K-files and Hedstrom files:
=enlarge canals with reciprocal insertion and withdrawal motions
The smear layer on dentin walls acts to prevent pulpal injury for which of the following?
A.It reduces diffusion of toxic substance through the tubules
B.It resists the effects of acid etching of the dentin
C.It eliminates the need for cavity liner or base
D.Its bactericidal activity against oral microorganism
A.It reduces diffusion of toxic substance through the tubules
When is endodontic treatment is contraindicated?
A.The patient has no motivation to maintain the tooth
B.The canal appears to be calcified
C.Class III mobility and loss of bone support
D.The tooth needs periodontal drown lengthening before restoration
E.A large periapical lesion is present
A.The patient has no motivation to maintain the tooth
When using the balanced-force technique for canal preparation, which of the following statements are accurate?
A.The cutting stroke involves apical pressure and a counterclockwise rotation
B.Clockwise rotation balances the tendency of the file to be drawn into the canal during the cutting stroke
C.Dentin is engaged with a counterclockwise rotation and cut with a 45 to 90 degree, clockwise rotation
D.It requires the use of a crown down technique
A.The cutting stroke involves LIGHT APICAL PRESSURE and a counterclockwise rotation
The distance from the apical exit of the root canal up to the reference point on the crown of the tooth is referred to as:
A.Root length
B.Root canal length
C.Computed working length
D.All of these
C.Computed working length
Electronic apex locator may be useful when:
a. the patient is physically impaired
b. anatomic structures overlay the root apex
c. a pregnant patient wishes to avoid x-ray exposure
d. all of the above
d. all of the above
he functions of the irrigation solution are the following, except:
a. lubrication
b. debridement
c. sterilization
d. disinfection
c. sterilization
