Endo

Question 1

name 4 problems which can occur when instrumenting teeth with only SS handfiles and curved roots explain/give reasons

Answer 1

• 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

Question 2

describe process of canal shaping and cleansing using ProTaper
[apical finishing size should be 0.25mm]

Answer 2

1. LA, rubber dam
2. straight line access with 10 SS
3. glide path with 15 to EWL using balanced force, NaOCl irrigation, recapitulate with 10
4. s1 2/3 EWL
5. confirm WL
6. s1 CWL coronal third
7. s2 CWL mid third
8. f1 CWL apical third, enlarge to 20
9. f2 CWL apical third to 25
10. ensure passive in apical third with “tug back”, ISO 25 should bind coronally and mid third
11. NaOCL flush and recapitulation, EDTA 17%, final NaOCL

Question 3

give 2 options other than periradicular surgery

Answer 3

• re-tx
• XLA

Question 4

criteria for valid consent

and 6 other things you you would tell pt

Answer 4

-> capacity, given freely, sufficient information, informed, voluntary

-> risks, benefits, cost, alternatives, tx procedure, complications, risks of no tx

Question 5

tooth 11 has traumatic exposure of the pulp

-> what 2 factors would influence your choice of tx
-> how would you tx this in practice

Answer 5

-> length of time since exposure, depth of exposure

-> partial or full pulpotomy

Question 6

what are the signs/symptoms of reversible pulpits and how is it managed

Answer 6

• sensitive to cold/sweet but resolves when stimulus removed
• remove cause [caries removal, seal exposed dentine]

Question 7

what are the signs/symptoms of irreversible pulpits and how is it managed

Answer 7

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

Question 8

what 3 criteria must be fulfilled before obturation on second visit

Answer 8

• no symptoms
• not TTP
• canal fully fried
• full chemomechanical cleaning carried out
• master cone fits

Question 9

GP constituents

Answer 9

• GP = 20%
• zinc oxide = 65%
• radio pacifiers [barium salts] = 10%
• plasticisers = 5%

Question 10

function of a sealer

Answer 10

• 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

Question 11

give 3 common sealers used

Answer 11

• ZOE
• calcium silicate [MTA/BioDentine]
• resin based [CORECEM]
• GI

Question 12

how do you assess obturation on a radiograph

Answer 12

• 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

Question 13

why obturate

Answer 13

• 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

Question 14

give 4 methods of obturation

Answer 14

• cold lateral compaction
• warm vertical compaction
• continuous wave obturation
• carrier based obturation

Question 15

what percentage of maxillary first molars have an MB2 canal

Answer 15

70-90%

Question 16

what are the 3 design objectives of Endodontics

Answer 16

1. create a continuously tapering funnel shape
2. maintain the apical foramen in the original position
3. keep the apical opening as small as possible

Question 17

what are the advantages of the crown down technique

Answer 17

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

Question 18

name the 3 laws of pulpal floor anatomy

Answer 18

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

Question 19

give 4 reasons for irrigation during endodontic tx

Answer 19

• dissolves pulp remnants and collagen
• dissolves necrotic and vital tissue
• flushes debris from canal
• eliminates and prevents reinfection
• helps to disrupt smear layer

Question 19

give 3 rules for locating orifices in pulpal floor

Answer 19

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

Question 20

why is sodium hypochlorite a good irritant

Answer 20

potent antimicrobial activity

Question 21

what strength NaOCl is used

Answer 21

0.5-6%
usually 3%

Question 22

name endo irrigants other than NaOCl

Answer 22

CHX
EDTA 17%

Question 23

how is the smear layer removed

Answer 23

17% EDTA
acts as chelating agent with NaOCl

Question 24

name 2 intracanal medicaments and state their use

Answer 24

- 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

Question 25

pt has dull throbbing pain in 37/38 region give 3 differential diagnosis for what could be keeping them up at night

Answer 25

- symptomatic irreversible pulpitis - pericoronitis - otitis media

Question 26

give 3 reasons for instrumentation of root canals

Answer 26

- remove necrotic or inflamed pulp tissue - create space for chemical irritants and obturation - ensures infection free - allows healing of periradicular tissue

Question 27

what advantages does NiTi has over K-files

Answer 27

- 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

Question 28

name 2 rotary endodontic systems

Answer 28

- RECIRPOC - ProTaper

Question 29

describe envelopes of motion of files

Answer 29

- filing - reaming - watch winding = back + forward oscillation of 30-60* balanced force = CW 1/4 turn and CCW 1/2 turn, 3x sequence

Question 30

name reasons a file may separate

Answer 30

- torsional fatigue - flexural stress [cyclic fatigue] - curved canal - error in used [too much pressure, rotation in curved canal]

Question 31

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?

Answer 31

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

Question 32

what would be your immediate and longer term management of sodium hypochlorite extrusion

Answer 32

- 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

Question 33

how would you prevent sodium hypochlorite extrusion

Answer 33

- 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