Endo Booklet Flashcards
3 symbiotic bacteria
strep
prevotella oralis
porphyromonas
how do bacteria in caries change over time
more gram negative anaerobes
assessment of individual teeth for endo 10
- colour
- caries/restorative status
- presence of sinus
- erythematous over apex
- mobility
- tender to tapping
- tender to palpation over apex
- vitality
- local perio condition
- radiography showing pulpal morphology (number of cusps, radiography)
what % of lower incisors have 2 canals
41%
what teeth have varied root anatomy/what is it
upper first premolar. may have 1 or roots
draw/label lower premolar apex
SEE BOOK
what to look for in radiographic evaluation of
a. pulp chamber 2
b. root canals 3
a. pulp chamber 2: position of roof and floor, amount of reparative dentine
b. root canals 4: number of roots/canals, degree of calcification, pulp stones, curvature
5 cell types in ‘apical war zone’
Means Pathogens Take a Proper Beating
- polymorphonuclear leukocytes
- macrophages
- B lymphocytes
- T lymphocytes
- plasma cells
3 inflammatory mediators
- neuropeptides
- complement system
- lysozymes
periapical lesion produced by 3 IN
- prostaglandins
- leukotrienes
- cytokines
what to look for in endo assessment of mouth
dental status 3: missing teeth, active caries, restorative condition
what to do about
a. reversible pulpitis
b. irreversible pulpitis
c. necrotic pulp
what to do about
a. reversible pulpitis: pulpal irritant removed eg caries, tooth dressed
b. irreversible pulpitis + necrotic pulp: investigations, root canal therapy
what pre-operative radiographs to take
periapical
treatment tooth centrally located
3-4mm peri-radicular tissue visible
taken with film holder to minimise distortion
second film with 15-20degree horizontal parallax view
bitewing/DPT provide additional info
what to look for on pre-op radiographs 6
- previous disease/tx (caries, restorations, pulp capping)
- pulpal reactions (narrow chamber/canal, internal resorption)
- relationship to surrounding structures (alveolar bone crest loss, general tooth form/height)
- roots (number, shape, relations)
- root canal patency
- coronal structure
magnification with
a. loupes
b. microscope
magnification with
a. loupes: 2-4.5
b. microscope:16
shape of access cavity
a. incisor
b. canine
c. premolar
d. molar
shape of access cavity
a. incisor: 3 horns, triangular shape
b. canine: 2 horns, oval shape
c. premolar: 2 horns, oval shape
d. molar: variable horns, triangular in shape
burs/ handpieces for
a. initial access cavity
b. refinement of cavity
c. shape the coronal 1/3 of canal
burs for
a. initial access cavity: FAST small round (520), 554
b. refinement of cavity: SLOW speed SAFE-ENDED burs eg tapered fissue (endo Z/ blunt ended Batt), round burs eg goose neck (long shanks)
c. shape the coronal 1/3 of canal: SLOW gates glidden bur
bud diameter + calculation for gates glidden burs
0.5-1.5mm
D=20 (GG+1)+10
6 ways to locate canals
- knowledge of pulpal anatomy
- radiographs
- magnification techniques
- transillumination with white light
- canal probe eg DG explorer
- fine endo hand instruments
what is involved in
a. apical seal
b. coronal seal
a. apical seal: root fillings with stable, non-irritant and perfect seal
b. coronal seal: total obturation of canal space
examples of access problems
- crown in situ –> loss of directional sense
- obstruction in canal –> pulp stones, post crown, fractured instrument
when to apply rubber dam during endo procedure
after access cavity drilled in to pulp chamber
how to drill access cavity
- check depth from reference point of roof of pulp chamber on radiograph
- tapered fissure bur to create outline in to dentine
- continue to pulp chamber
- remove roof of pulp chamber using slow speed shank bur
- gently flare walls of pulp chamber/access cavity outwards so greatest diameter is at tooth surface
- clear debris from pulp with excavator
- irrigate with ultrasonic
- locate orifice of canals and check straight line access
advantages of rubber dam in endo 4
- protects oropharynx
- protects tissues from caustic materials
- retracts soft tissues and tongue and improves access
- maintains clear, dry aseptic working field free from salivary contamination
what is used to seal the rubber dam in place
ultradent oraseal caulking agent
3 ways to measure working length
- tables of average length: assumes tooth is ‘normal/average’
- apex locator
- radiography
3 ways apex locators used to work
- measure electrical resistance with direct, alternating and high freq currents
- measure voltage GRADIENT
- calculate RATIO between impedances
name and describe 2 electrodes on apex locator
straight: file electrode
curly: lip electrode
value of impedance between apical tissues and mucosa to which the lip electrode is attached
6.5Kohms
3 problems with apex locators
- wet canals (absolute apex locator machines only. hypochlorite, pus, tissue exudate)
- heavily restoted crown (all machines. amalgam, gold inlay)
- poor contact of lip electrode)
how to calculate working length
Rerefence point to radiogrpahic apex MINUS 1MM
define working length
distance from fixed reference point on crown to terminus nr radiographic apex
difference between modified stepback and coronal flare
modified stepback (double flare): coronal aspect opened up before creating terminal stop and flaring backwards towards original flare crown down: canal instrumented from coronal aspect towards terminus
when modified stepback and coronal flare are used
modified stepback: large canals, esp max anterior teeth, single rooted premolars
coronal flare: small canals
ideal shape of canal 3
widest coronally
narrowest apically
gradual outward flare
describe shape of hedstrom file/how it is made
machined from a round tapered blank by cutting spiral groove in to shank –> 90 degree cutting blade, aggressive cutting action, diamond shape
name of sharper burs not used by students for endo, how to use them 3
gates glidden burs
- start with largest bur
- never force bur in to canal
- cut on out stroke
shape of gates glidden bur
long-shanks, bud-shaped non-cutting tip
narrowest nr shank (most likely to fracture here)
how to calculate diameter of gates glidden bur
20 (GGsize+1) +10
diameter of bud of GG bur
0.5-1.5mm
describe shape of K file/how it is made
twisted to 90 degrees
describe ends of K and hedstrom burs
blunted (Batt tips) so can be guided through curved canal
what does ISO stand for and what do they do 3
international standards organisation K and hedstrom files -standardised sizing of endo filed related to diameter 1MM FROM TIP 2% taper 16mm cutting length
3 lengths of endo files
21mm
25mm
31mm (for canines)
how big is size 25 file at tip? explainn
0.25 mm
each file is measured in hundredths of a mm at 1mm FROM tip
taper of endo files
2%
what movement to check for patency
3-5 watch winding
3stages of shaping a canal msb technique
- orifice enlargement (first flare)
- apical stop
- stepback (2nd flare)
4 reasons for orifice enlargement
- removes heavily infected material
- improves access to apical 3rd of canal
- improves irrigation
- reduces effective curvature of canal
how to do orifice enlargement in curved canal
outer side of curvature only (9 to 3 o’clock) –> reduce effective curvature but dont create fin shape
msb: how many instrument changes to create
a. apical stop
b. step back
a. apical stop:9
b. step back: 14
why must instruments be used in certain way/order 2
- avoid blockage
- avoid damage to root (apical zip, hour glass shape, elbow
how to create apical stop msb technique
plus how to identify master apical file (MAF)
10
15-10
20-15
25-20 etc until file binds
2 sizes above first file to bind = MAF
eg size 20 binds –> size 30MAF
order/where files used msb to create step back
1 file size above MAF to working length, eg size 30MAF–> size 30 to WL
size 35 to WL-1mm
size 40 to WL-2mm
size 45 to WL-3mm
until all files used
recapitulate with MAF to maintain patency
when to use
a. watch winding
b. balanced force
a. watch winding: k file Size 10,15, hedstrom
b. balanced force: k file size 20 and above
how to do watch winding
no more than 1/4 turn (45 degrees) clockwise and anticlockwise
how to do balanced force
power phase ENGAGEMENT: clockwise 60 degrees until it binds
control phase CUTTING: apply apical pressure, anticlockwise 120 degrees
advantages of balanced force technique 3
- superior shaping
- file remains central within canal
- less debris pushed apically
disadvantages of balanced force technique 3
flute cleaning
copious irrigation
discard damaged instruments
what causes apical zipping
inappropriate rotation of instruments (eg balanced force gone wrong)
what causes elbow formation
inappropriate pre-curving of instruments –> HOUR GLASS SHAPE
when is longitudinal circumferential filing used SS
large irregular shaped STRAIGHT canals at step back stage. balanced force would be inappropriate as file would be loose in canal
what did Roane describe
balanced force technique
how/when to do longitudinal circumferential filing
hedstrom files up and down around edge of canal, INNER CURVATURE
-use in large irregular canals at step back stage (balanced force K files would be loose in canal)
why not do circumferential filing in curved canals, what to do instead
would cause strip perforation, would not follow curve
step back technique
6 ideal properties of irrigant
- bacteriacidal/ anti-bacterial
- dissolve organic material
- non-irritant
- remove inorganic material
- non staining to dentine
- lubrication of instruments
4 irrigants used in root canal therapy
- sodium hypochlorite
- sterile saline
- local anaesthetic soln
- chlorhexidine
% of sodium hypochlorite soln
0.5-5%
which 3 ideal properties of an irrigant does sodium hypochlorite cover
- bacteriacidal/ anti-bacterial
- dissolve organic material
- non irritant to vital tissues (at low conc)
size of irrigating needles
27 gauge
shape of irrigating needles and why
side delivery –> reduce risk of soln extrusion through apex (would cause infection, pain)
% of Milton’s, how to use it in lab
1%
50:50 with sterile water
name the chelating agent used,% and 3 functions
ethylene diamine tetra acetic acid (EDTA) 15-17%
- breaks down inorganic debris
- lubricant
- smear layer removal (with sodium hypochlorite)
contents of lubricating pastes 3
15-17% EDTA
10% urea peroxide
water soluble base
what causes effervescence
urea peroxide
alternative chelating agent
citric acid solution
alternative lubricant, formation,2 advantages and more usual use of it
chlorhexidine, hibiscrub -low toxicity -broad spectrum of activity substantivity more popular in periodontics
what are gutta percha points made of
transisomer of rubber produced from latex of tropical trees
4 purposes of instrumentation
- remove pulp/most microbes
- facilitate irrigation
- enable medicament placement
- enable placement of root filling
where are the most tapered instruments used in crown down technique
coronal parts of canal
(TIPS of tapered instruments used for apex
when can crown down technique be used
small canals with no/GENTLE curves
name and material of crown down files
ProTaper nickel titanium (flexible)
compare shape of finisher F and shaper S files
S: most tapered in middle of file/coronal
F: most tapered at tip (7-9%)
max flute diameter of pro taper files
1.2mm
cutting length of pro taper files
14mm
effect of these properties of pro taper files
a. progressive taper design 2
b. files engage smaller area of dentine 3
c. balancing pitch and helical angles
d. convex triangular cross-section
a. progressive taper design 2: improves flexibility, cutting efficiency in tighter/curved canals
b. files engage smaller area of dentine 3: reduce torsional loads, file fatigue, potential for separation
c. balancing pitch and helical angles : greater cutting efficiency
d. convex triangular cross-section:reduces contact area between file and dentine
2 unique properties of nickel titanium alloys SUPER
- super elasticity
- shape memory
2 crystallographic forms of nickel titanium. which has higher tensile strength
why are these essential to function
- Austenite (parent shape)
- Martensite (daughter shape, higher tensile strength)
good flexibility because crystal structure changes between austenite-martensite
compare nickel titanium to stainless steel 2
- 3-5x elastic flexibility
- decreased ledging/transportation
colour of each pro taper file
SX: orange S1 purple S2 white F1 yellow F2 red F3 blue
what file is used for alternative orifice enlargement
SX (orange)
how to perform alternative orifice enlargement
-engage dentine (gentle clockwise turn until snug)
-disengage (45-90 degrees anticlockwise, apical pressure like balanced force)
-withdraw and turn file clockwise to dislodge debris
only do this up until curve
what size to make apical stop and movements
size 20 k file
size 10,15 watch winding
size 20 balanced force
when may F2 and F3 files be used
if size 20 k file not smug
how to calculate MAP
first file that binds
2 file sizes up from this
where is the canal terminus? explain
apical constriction
- 5-1mm distance between this and apical foramina
- 2-2mm distance between apical foramina and secondary cementum
what properties of root canal irrigant does chlorhexidine have?
bacteriacidal, lubricant (hibiscrub)
how/why to make glide path
using K20 file
this is just larger than pro Taper files –> leaves room for pro taper files
what technique to use with pro taper files? describe
triple phase:
balanced force then rotate clockwise while withdrawing to remove debris
3 ways pro taper does not fit to ISO standards
- working part 14mm not 16mm
- variable taper 2-16% (not 2%)
- variable thread (so they only wind in a slight distance)
2 things required by pro shaper files when procedure complete
length
tugback
2 functions of medicament
- prevent canal infection where none present
- elimate bacteria already infecting canal system
3 types of canal medicaments
which one of these is rarely used and why
- chemical antiseptics (not common now)
- antibiotics / steroids
- calcium hydroxide paste
chemical antiseptics: highly irritant tto periapical tissues
2 chemical antiseptics
- beechwoods creosote
- para mono chloro phenol
2 common antibiotic/steroid pastes and their ingredients
- Ledermix: demethylchlortetracycline, triamcinalone acetonide
- odontopaste:clindamycin, triamcinalone acetonide
which antibiotic/steroid paste should be restricted and to what 2
ledermix: desensitising pulpotomy
- acutely inflamed vital pulp where LA does not work
- not enough time to complete root canal after pulp exposure
2 reasons for pulp LA failure and how steroids overcome this
- inflammation –> acidic pH –> LA does not dissociate (only in neutral environment) STEROID IS ALKALINE
- too many pain signals, LA cant handle STEROID DECREASES THIS
3 preparations of calc hydroxide as root canal medicament
- BP powder (1:8 barium sulphate) can mix to req viscosity
- proprietry pastes: hypocal, reogan
- life (setting calc hydroxide- use catalyst paste only so it does not set)
pH of calc hydroxide
12.5
6 functions of OH- ion of calc hydroxide, explain
- bacteriacidal
- effective solvent of organic debris
- promotes connective tissue repair:below
- promotes hard tissue genesis: stimulates ALKALINE PHOSPHATASE –> anabolic stages of repair in bone/ soft tissue
- neutralise acids in areas of resorption –> stops osteoclasts etc
function of Ca ion in calc hydroxide, why this is arguable
activate calcium dependent ATP reaction for hard tissue formation
BUT calcium ions in hard tissue comes from tissue fluid not CaOH paste
3 ways to place calc hydroxide, which is not used
- spiral root filler
- hand file
- injection syringe system
6 uses of calc hydroxide
- pulp capping/ pulpotomy
- inter-visit medicament
- tx of large periapical lesions
- apexification
- root resorption
- root fractures/perforations
new alternative medicament, contents and qualities 4
R4 root canal soln
20% chlorhexidine (only 0.02% used in perio)
4:
- wide spectrum antibiotic
- effective against anaerobic bacteria inc STREP FAECALIS, CANDIDA
- substantivity
- non-irritant
2 temp restorations for seal over medicament
- cotton wool dressing
- common temp restorations (GIC, zinc oxide-eugenol)
stages of modified stepback technique
- access
- estimate WL from radiograph/ apex locator
- patency with number 10
- orifice enlargement (hedstrom files)
- CWL radiographs
- apical stop at CWL: MAF, watch wind #10,#15, balanced force #20+. irrigate and recapitulate with size below
- stepback: set each file after MAF to size to 1mm less than before. recapitulate with MAF
stages of crown down technique
- access
- estimate WL from radiograph/ apex locator
- patency w #10
- orifice enlargement (SX file)
- re-establish patency #10
- CWL radiograph
- create glide path (K files up to #20)
- shaper ProTaper files S1, S2
- finisher ProTaper files F1 (F2/F3 if needed)
- check apical size w appropriate K file (F1=#20, F2=#25, F3=#30
in which part of canal are bacteria mostly found
coronal 1/3
5 pieces of info you need to record for every root canal
- canal (which canal/tooth)
- reference point
- diagnostic length (est working length)
- working length (corrected WL)
- size of master point
3 examples of lubricating pastes
glyde
canal +
fileze (file easy!)
order of lengths of tooth roots
lat incisor
premolars
central incisors
canine
how to use apex locator
- access cavity, rubber dam, orifice enlargement
- irrigation with hypochlorite
- glide path with #10k file
- apply lip and file electrode
- advance #10k file until reading of 0 is achieved (watch winding)
- set silicone stop on reference point
- retract/ advance file to check accuracy
- measure file length and -1mm
- check against radiograph
contraindications of apex locators
- wet canals
- heavily restored crown
- poor contact of lip electrode
