Endo Flashcards
name 4 problems which can occur when instrumenting teeth with only SS handfiles and curved roots explain/give reasons
- blockages
packing of debris into the apical portion, prevents proper disinfection and instrumentation, from not irrigating - ledging
internal transportation of canal, due to working short of length or instrumenting as if canal is straight - zipping/transportation
tendency of instrument to straighten, enlargement of outer curvature and under prep of inner, prevent by preserving and don’t skip sequences - file separation
torsional stress exceeding critical level, work hardening and flexural stress by repeated cyclic fatigue resulting in failure. old files, poor instrumentation - root perforation
describe process of canal shaping and cleansing using ProTaper
[apical finishing size should be 0.25mm]
- LA, rubber dam
- straight line access with 10 SS
- glide path with 15 to EWL using balanced force, NaOCl irrigation, recapitulate with 10
- s1 2/3 EWL
- confirm WL
- s1 CWL coronal third
- s2 CWL mid third
- f1 CWL apical third, enlarge to 20
- f2 CWL apical third to 25
- ensure passive in apical third with “tug back”, ISO 25 should bind coronally and mid third
- NaOCL flush and recapitulation, EDTA 17%, final NaOCL
give 2 options other than periradicular surgery
- re-tx
- XLA
criteria for valid consent
and 6 other things you you would tell pt
-> capacity, given freely, sufficient information, informed, voluntary
-> risks, benefits, cost, alternatives, tx procedure, complications, risks of no tx
tooth 11 has traumatic exposure of the pulp
-> what 2 factors would influence your choice of tx
-> how would you tx this in practice
-> length of time since exposure, depth of exposure
-> partial or full pulpotomy
what are the signs/symptoms of reversible pulpits and how is it managed
- sensitive to cold/sweet but resolves when stimulus removed
- remove cause [caries removal, seal exposed dentine]
what are the signs/symptoms of irreversible pulpits and how is it managed
pain to hot/cold, sharp throbbing, spontaneous pain, kept up at night, lingering pain >30 secs, analgesia doesn’t help, poorly localised, postural changes worsen pain
- RCT, XLA
what 3 criteria must be fulfilled before obturation on second visit
- no symptoms
- not TTP
- canal fully fried
- full chemomechanical cleaning carried out
- master cone fits
GP constituents
- GP = 20%
- zinc oxide = 65%
- radio pacifiers [barium salts] = 10%
- plasticisers = 5%
function of a sealer
- completely seals space between GP + RC wall
- aids lubrication
- creates a fluid tight seal
- prevent reinfection
- prevent microorganism/fluid flow through RC
- block apical foramen, dentinal tubules and accessory canals
give 3 common sealers used
- ZOE
- calcium silicate [MTA/BioDentine]
- resin based [CORECEM]
- GI
how do you assess obturation on a radiograph
- 1-2mm from rot apex
- well-condensed
- no space between GP + RC wall
- well adapted
- no canal space beyond GP end point
- just below or on orifice
why obturate
- prevents passage of microorganisms and fluid through the RC
- prevents reinfection
- blocks apical foramen, dentinal tubules and accessory canals
- allows healing of periradicular tissues
- seal apically
give 4 methods of obturation
- cold lateral compaction
- warm vertical compaction
- continuous wave obturation
- carrier based obturation
what percentage of maxillary first molars have an MB2 canal
70-90%
what are the 3 design objectives of Endodontics
- create a continuously tapering funnel shape
- maintain the apical foramen in the original position
- keep the apical opening as small as possible
what are the advantages of the crown down technique
removes bulk of infected tissue
reservoir for irrigant
keeps reference point for WL
makes straight line access easier
limits spread of infected material at apical foramen
name the 3 laws of pulpal floor anatomy
law of symmetry;
1 = orifice of canal equidistant from line M->D through pulp chamber floor
2 = orifice of canal lie on perpendicular line M->D direction across centre of pulp chamber
law of colour change;
= colour of pulp chamber is always darker than walls
give 4 reasons for irrigation during endodontic tx
- dissolves pulp remnants and collagen
- dissolves necrotic and vital tissue
- flushes debris from canal
- eliminates and prevents reinfection
- helps to disrupt smear layer
give 3 rules for locating orifices in pulpal floor
1 = orifice always at the junction of the walls + floor
2 = orifice located at angles of floor-wall junction
3 = orifices are located at terminus of root developmental fusion lines
why is sodium hypochlorite a good irritant
potent antimicrobial activity
what strength NaOCl is used
0.5-6%
usually 3%
name endo irrigants other than NaOCl
CHX
EDTA 17%
how is the smear layer removed
17% EDTA
acts as chelating agent with NaOCl
name 2 intracanal medicaments and state their use
- non-setting CaOH = antimicrobial activity, pH 12.5, 7 days
- LEDERMIX =
corticosteroid and tetracycline, management of hot pulps, reduces pulpal inflammation, effective 5-7 days
pt has dull throbbing pain in 37/38 region
give 3 differential diagnosis for what could be keeping them up at night
- symptomatic irreversible pulpitis
- pericoronitis
- otitis media
give 3 reasons for instrumentation of root canals
- remove necrotic or inflamed pulp tissue
- create space for chemical irritants and obturation
- ensures infection free
- allows healing of periradicular tissue
what advantages does NiTi has over K-files
- greater flexibility in curved canals
- reduces torsional stress, more resistant to breakage/fracture
- consistent and predictable
- efficient shaping and faster preparation
- reduced risk of ledges, transportations, perforations
- ease of use
name 2 rotary endodontic systems
- RECIRPOC
- ProTaper
describe envelopes of motion of files
- filing
- reaming
- watch winding = back + forward oscillation of 30-60*
balanced force = CW 1/4 turn and CCW 1/2 turn, 3x sequence
name reasons a file may separate
- torsional fatigue
- flexural stress [cyclic fatigue]
- curved canal
- error in used [too much pressure, rotation in curved canal]
You are carrying out root canal preparation of an upper right canine under local anaesthetic. You are irrigating the canal with a dilute solution of sodium hypochlorite when the patient suddenly feels intense pain. Within minutes you notice a marked facial swelling in the area and profuse bleeding into the root canal from the periradicular tissues. What is the most likely cause for these signs and symptoms and why?
sodium hypochlorite extrusion
due to extrusion through root into periradicular tissues
cause = excessive pressure during irrigation, needle locked within canal, loss of control of WL, larger apical diameters, anatomical factors
what would be your immediate and longer term management of sodium hypochlorite extrusion
- stop all tx
- stay calm, advise pt and reassure
- consider LA in area of pain
- irrigation with saline into canals
- if profuse bleeding, allow to continue til haemostasis
- steroid containing intra-canal medicament [odontopaste] in RC, avoid pressure when placing
- seal access cavity
- priority to pain relief, swelling reduction and prevention of secondary infection
- cold compress first few days
- warm compress after swelling reduced
- analgesics
- review 24hrs
- refer is severe
how would you prevent sodium hypochlorite extrusion
- careful pre-op assessment, showing EWL and any canal anomalies
- dental dam with oral seal, eye protection, bib
- luer lok 27G needle and check securely attached to 3ml syringe and test before use
- side vented needle
- keep needle moving
- syringe 3/4 full to aid control
- silicone stop 2mm from WL
- press plunger with index finger and not thumb to reduce pressure
- take care not to go too close to WL
- 1ml per 15 seconds max
