Restorative - Endodontics

Question 1

1. What % of maxillary first molars have an MB2 canal?

Answer 1

93%

Question 2

2. What are the three-design objective of endodontics?

Answer 2

• Create a continously tapering funnel shape
• Keep apical formaen as small as possible
• Maintain apical foramen in position

Question 3

What do access cavities look like for maxillary teeth?

Answer 3

Question 4

What do access cavities look like for mandibular teeth?

Answer 4

Question 5

4. What are the advantages of the crown down technique?

Answer 5

• Limits the spread of infected material at the apical foramen.
• Remove the coronal aspect first leading to less extrusive material out of the apex and therefore less post-op sensitivity.
• Makes straight-line access easier
• Removes bulk of infected tissue allowing for a reservoir of irrigant
• Keep reference point for WL

Question 6

5. Name 3 laws of pulpal floor anatomy?

Answer 6

• Law of colour. The pulp floor is always darker than the walls
• Law of symmetry 1. Orifices lie equidistant from the MD line through chamber floor (Except maxillary molars)
• Law of symmetry 2. Orifices lie perpendicular to the MD line through chamber floor (except maxillary molars)

Question 7

6. Give 3 rules for locating orifices in the pulpal floor?

Answer 7

• 1- orifices always located at the junction of the walls and floor
• 2- orifices always located at right angles in the floor-wall junction
• 3- orifices always located at the terminus of the root development fusion lines

Question 8

Chemomechanical Disinfection-
1. Give 4 reasons for irrigation during endodontic treatment?

Answer 8

• Mechanical preperation allow cannot clean or remove all bacteria alone, due to the presense of lateral canals, webbing between canals and finlike extensions.
• Irrigant can reach areas files cant
• Disinfects canal
• Helps flush out debirs
• Dissolves organic tissue
• dampens canal to provide lubrication to instruments
• Removes smear layer

Question 9

Why is sodium hypochlorite a good irrigant?

Answer 9

• Disinfects canal by removing all organic tissue like pulp and collagen as well as vital and necrotic tissue

Question 10

What strength of sodium hypochlorite is used?

Answer 10

3% but anywhere between 0.5-6%

Question 11

Name another common irrigant apart from sodium hypochlorite?

Answer 11

Chlorohexidine

Question 12

How is the smear layer removed?

Answer 12

WIth 17% EDTA for one minute

Chelating agent

Question 13

6. Name 2 intracanal medicaments and state their use?

Answer 13

• Non setting calcium hydroxide, is an antibacterial as high as pH 11 so kills bacteria (works for 11 days)
• Ledermix (anti-microbrial paste). It is a cortocosteroid and tetracycline paste used for the management of hot pulps to reduce inflammation and kill microorganisms (works 5-7days)
• In general they are placed inside root canal between treatment appointment to destroy microorganisms, prevent re-infection, reduce inflammation and exudate and control root resorption

Question 14

Two periapical radiographs showing lower anterior 42-32. All teeth are treated endodontically with post and core. You can see radiolucency in all the teeth affected. The patient is referred to you for periradicular surgery.
1. Give to treatment options other than peri-radicular surgery? (2)

Answer 14

• Do nothing and monitor
• XLA
• Orthograde Re-RCT (basically re-RCT)

Orthograde is the use of this material through the coronal access point vs. retrograde which is the use of the material from the apex of the tooth as in the example of apicoectomy

Question 15

2. Give two criteria for valid consent

Answer 15

• Informed
• Non-manipulated
• Not coerced
• Patient must have capacity
• Voluntary

Question 16

3. What 6 other things should you tell the patient, to obtain informed consent for RCT?

Answer 16

• What the treatment proposed is and what is inolved
• The risks (seperated files, perforations, failure etc) and benefits involved
• The prognosis
• What would happen if you did nothing
• Alternative treatment options and there risk and benefits
• Cost of treatment
• Your recommendation

Question 17

You are carrying out root canal preparation of an upper right canines under local anaesthetic. You are irrigating with 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.

1. What is the most likely cause for these signs and symptoms and why does it occur? (4 marks)

Answer 17

Extrusion of sodium hypochlorite out of the apex and into the surrounding tissues
- Can occur due to high pressure injection during irrigation, needle locked within canal, loss of control of WL, larger apical diameter (immature tooth, developmental abnormalities and root resorption) or possibily anatomical factors.
Signs and symptoms
- Acute inflammatory reaction which can be oedematous and haemorrhagic and can lead to significant necrosis

Question 18

You are carrying out root canal preparation of an upper right canines under local anaesthetic. You are irrigating with 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.

2. What would your immediate action be? What would you action be after this? (8 marks)

Answer 18

• Relax the patient and assure them that this complication can be controlled
• Local anesthetic for pain relief
• Cnaals irrigated with copious amounts of physiological saline
• Dress tooth with NS calcium hydroxide
• Laterally, priority must be pain relief, reduction in swelling and prevention of secondary infection
• Cold press for first few days then warm compress for elimination of haemotoma
• Analgesics ibuprofen(400-600mg 4x daily or/and paracetamol 1g 4x daily)
• Review within 24hrs
• Consider prescription of AB if systemic symptoms occur
• Refer if severe reaction
• Ensure datex is filled out and patient incident is noted in notes.

Question 19

3. 4 weeks later the patient’s condition has resolved and they return requesting that you continue with the root canal treatment. How would you prevent a similar accident from occurring? (8 marks)

Sodium hypochlorite extrusion out of the apex of the tooth

Answer 19

• Careful pre-operative planning, looking for open apices
• Provide eyeprotection and bib
• Use dental dam
• Test the dam seal by irrigating chlorohexidine around the tooth and see if patient can taste it
• Ensure all irrigants and syringes are clearly labelled
• Use a side vented needle (reduces the force of irrigant when it is deposited)
• Fill syringe to 3/4 to aid control
• When using syringe use index finger and not thumb to reduce pressure
• Use a silcone stop 2mm short of the WL
• Pass all endo syringes behind the patients head and not over their face
• Do not rush and take your time cleaning the canals

Question 20

You are endodontically treating tooth 16 for a 49-year-old patient. The root canal system, which includes the MB2 canal, has been prepared over two visits. On the third visit you plan to obturate the tooth.
1. What 3 criteria must be fulfilled before you obturate?

Answer 20

• Tooth is asymptomatic not TTP
• Full biochemical cleaning of the canals must be complete
• Canal must be dried

Question 21

2. Give three constituents of GP other than GP?

Answer 21

• Zinc oxide
• Radiopacifiers
• Plasticisers
• Waxes, colouring agents, anti-oxidants

Question 22

3. Give the function of a sealer?

Answer 22

• To fill space between the GP and the tooth canal wall and provide fluid tight seal
• Fill voids and irregularities in the canal, lateral canal and between the GP cones
• Lubrication during obturation

Question 23

4. Give 3 common sealers used?

Answer 23

• Epoxy resin
• Calcium hydroxide
• Calcium silicate
• ZOE

Question 24

5. How do you assess obturation of a radiograph?

Answer 24

• Check the length (not too short or too long)
• Check well compacted and condensed
• Check all canals are filled

Question 25

Why obturate canals after disinfection and removal of nerve?

Answer 25

- Prevent re-infection - Fill the space preventing bacteria from getting in and causign re-infection. This is done with a good cornal and apical seal - Seal in any left over bacteria

Question 26

7. Give 4 methods of obturation?

Answer 26

- Cold lateral compaction - Warm vertical and lateral compaction - Continuous wave compaction

Question 27

Pulpitis- 1. What are the signs and symptoms of reversible pulpitis?

Answer 27

- Presense of caries on tooth, deep restoration or exposeed dentine - Short sharp pain which appears when stimualted and then disappears after a few seconds once stimulous is removed - Pain to cold or sweet - Not TPP

Question 28

How is reversible pulpitis managed?

Answer 28

- Removal of the cause- e.g. removal or caries and restoration (with or without pulp cap), removal of deep restoration with placement of line or cover area of exposed dentine (or use desensitising agents) - Then review

Question 29

3. What are the signs and symptoms of irreversible pulpitis?

Answer 29

- Deep caries, grossly broken down tooth - Intial sharp pain to stimuli which remains for a few minutes even once stimulis is removed as dull aching pain - Spawntaneous pain - Constant dull aching pain - OTC analgesic ineffective - Loss of sleep - Worse when lying down - Referred pain poorly localised

Question 30

How do you manage irriversible pulpitis?

Answer 30

- RCT and restoration - XLA - Do nothing

Question 31

You are using stainless steel files in a 20-degree curved canal of molar. 1. Give 4 complications that can occur and explain then? (4)

Answer 31

- **Seperation **of instrument (too much pressure is used) - **Perforation** (instrument inserted with excess force at an inappropriate angle causes perforation out of the side of the RC - **Blockage **(caused be dentine debris and poor recopitulation and irrigation) -** Ledges** (internal transportation of the canal which occurs when curved canals are instruments as if they were straight (Can occur if working short of length resulting in apical few mm remaining non-instrumented and infected) -**Apical zipping **(over-enlargement of the outer surface and under prep of inner surface)

Question 32

2. Outline the protaper sequence for shaping and cleaning a canal to 0.25mm after working out the WL and creating straight line access?

Answer 32

* Take size 10 and 15 K files to middle 1/3 of WL to scout canal (watch wind) * Take S1 to middle 1/3 of WL * Take size 10 and 15 K files to EWL * Correct WL * Take S1 to WL (coronal 1/3 preparation) (balanced force) * Take S3 to WL (middle 1/3 preparation) (BF) * Take F1 to WL (apical 1/3 preparation) (BF) * Take F2 to WL (apical 1/3 preparation (BF) * Irrigate and recapitulate in between each file

Question 33

Instrumentation- 1. Give 3 reasons for instrumentation of root canal?

Answer 33

- Remove infected tissue - Allow irrigant to the apex - Make space for medicament and obturation - Retain integrity of radicular structures and create an enviroment for periradicular healing

Question 34

2. What is the protaper sequence

Answer 34

* Take size 10 and 15 K files to middle 1/3 of WL to scout canal (watch wind) * Take S1 to middle 1/3 of WL * Take size 10 and 15 K files to EWL * Correct WL * Take S1 to WL (coronal 1/3 preparation) (balanced force) * Take S3 to WL (middle 1/3 preparation) (BF) * Take F1,F2 etc. as required to WL (apical 1/3 preparation) (BF) * Irrigate and recapitulate in between each file

Question 35

3. What advantages do nickel titanium files have over conventional stainless steel K files??

Answer 35

- Better in curved canals as they are super elastic - Increased cutting efficiency - Less files required to shape - Easier to use - greater and more varied taper - Increased flexibility

Question 36

4. Name a rotary endo system?

Answer 36

- Pro taper gold - Reciproc

Question 37

Filing and reaming are 2 envelopes of motion for files. Describe 2 others?

Answer 37

Watch winding - Back and forth of 30-60° with light apical pressure balanced force - file engaged 90°clockwise then 180° anticlockwise with continued pressure to strip the dentine away ## Footnote Potentially 270 degree AC turn

Question 38

Name 3 reasons a file may separate?

Answer 38

- Too much pressure - Canal isnt lubricated - File is worn * Flexural stress as a result of repeated cyclic fatigue- file freely rotating in a curvature will cause generation of tension compression cycles leading to cyclic fatigue * Torsional stress as a result of extensive friction instrument surface encounters from canals walls * Torsional stress as a result of instrument tip being larger than the canal section to be shaped- tip may exceed and torque exceeds critical level (beyond elastic limit)