Endodontics

Question 1

Essay: Detailed steps of performing RCT on a lower first molar in a single visit (14m)

Answer 1

See page 41, long answer

Question 2

You decided to do an access cavity for endodontic treatment for tooth 36. What are the 4 aims and objectives for an access cavity? (4)

Answer 2

1. To remove the entire roof of the pulp chamber so the pulp chamber can be cleaned.
2. To enable root canals to be located and instrumented by providing straight-line access to the apical third of the root canals. (The initial cavity may be modified to achieve this objective.)
3. To enable a temporary seal to be placed. That is, the cavity provides sufficient retention for the temporary restoration as well as preserving enough bulk of tooth structure to sustain occlusal functional loading during the inter-appointment period.
4. To conserve as much sound tooth tissue as possible compatible with the above objectives.

Question 3

Pre-operative radiographs are very important for a successful endodontic treatment. What 5 things can be obtained from a preoperative radiograph? (5)

Answer 3

Root canal width, length. Any periapical lesion. Any root resorption. Lamina dura – present or not. Curvature of canal.

Question 4

What are the 3 uses of irrigation during endodontic treatment? (3)

Answer 4

• Flushing - to flush out debris, dentinal shavings, blood, and other materials used/placed in the canal.
• Disinfection - to eliminate as much microorganisms as possible without causing undue irritation to the periapical tissues.
• Lubrication - to lubricate the canal to facilitate cutting and reduce the risk of instrument breakage.
• Dissolution of organic tissues - to dissolve necrotic tissues and organic debris.

Question 5

Patient presenting with avulsed reimplanted tooth. What are the causes of external inflammatory resorption and replacement root resorption?

Answer 5

• Dental avulsion
• Trauma
• Bacterial infection
• Replacement root resorption: Destruction of PDL cells (so osteogenesis instead)

Question 6

What are the clinical and radiographic features of the two types of resorption?

Answer 6

External inflammatory resorption: no sign, symptoms of apical periodontitis; Asymmetrical bowl shaped periradicular or periapical radiolucencies
Replacement root resorption: No sign, metallic sound on percussion; Asymmetrical bony replacement of root surface and loss of PDL space

Question 7

Describe the management of the two types of resorption.

Answer 7

External inflammatory resorption: RCT

Replacement root resorption: no treatment, just monitor

Question 8

If the avulsed tooth was a primary tooth, what would be the difference in management? What advice would you give the mother?

Answer 8

Don’t need RCT

Extract (don’t want to develop ankylosis  permanent tooth cannot erupt..?)

Question 9

List different kinds of root resorption (5)

Answer 9

Internal inflammatory, internal replacement
External inflammatory, external replacement, external invasive cervical, external surface, external transient apical breakdown

Question 10

Describe root morphology and pulp canal anatomy of 16

Answer 10

• 3 roots – 2 buccal; 1 palatal
• Usually 4 root canals
• P > MB1 > DB > MB2
• MB – coronal and middle is oval or flat round; apical is round; curves distally
• DB - oval or round cross section; straight root
• P – oval or round cross section; straight root or curves buccally

Question 11

2 factors whether to do avulsed tooth or not (2)

Answer 11

Any root fracture, dentoalveolar fracture; primary tooth or permanent; time from trauma

Question 12

3 factors affecting the prognosis of a replanted permanent tooth (3)

Answer 12

• Time of replantation
• Any physiological storage before replantation
• Open or closed apex (closed apex better survival)
• RCT treatment duration

Question 13

Complications of the replanted tooth and your management (3)

Answer 13

• Ankylosis – if permanent tooth, just monitor; if primary, extract
• Periapical infection – RCT/ need to extract
• Discoloration – poor aesthetics, need crown

Question 14

List the storage medium for avulsed teeth in the order of favorable treatment outcome. (1)

Answer 14

Milk, Hank’s balanced salt solution, coconut water, (saliva is low)

Question 15

How can one minimize the complication you mentioned in 6.at the time of avulsion? (4)

Answer 15

• Replant the tooth asap (total extraoral dry time < 60 mins)
• Proper storage medium (Hank’s balanced salt solution / saline, milk, saliva)
• Atraumatic handling of the avlused tooth (grasp by the crown only)
• Ensure tooth surface and socket wall is clean

Question 16

What is ankylosis? Give a factor that contribute to ankylosis (2)

Answer 16

Ankylosis: pathological fusion between alveolar bone and the cementum of teeth
Factor: after trauma to teeth

Question 17

How to diagnose ankylosis (4)

Answer 17

• X-ray – lack of PDl
• Percussion – metallic sound
• No mobility
• CBCT

Question 18

List 2 periodontal complications of avulsed tooth.

Answer 18

External inflammatory root resorption

External replacement root resorption

Question 19

What are the clinical and radiographic findings of External inflammatory root resorption ?

Answer 19

Clinical
1. Pulpal symptoms

Radiographic

1. Bowl shaped radiolucency around the external root surface and corresponding bone
2. May be poor defined margin

Question 20

What are the clinical and radiographic findings of External replacement root resorption?

Answer 20

Clinical

1. Loss of mobility (Periotest)
2. Percussion with metallic sound
3. Tooth may be infraocclusion
4. Negative to vitality pulp test

Radiographic

1. Loss of PDL space and lamina dura
2. Root subsequently replaced by bone completely

Question 21

In the replantation of avulsed teeth, how should splinting be done to avoid ankylosis? State the reasons (4)

Answer 21

• Flexible splint, allowing slight movement of teeth + replanted permanent teeth should just be splinted up to 2 weeks
o Because this slight movement and short splinting time can promote periodontal and pulpal healing
• Splint should be on buccal surfaces to allow lingual access for endodontic procedures and to avoid occlusal interference
• Splint should not impinge on gum tissues

Question 22

How many months after RCT should we evaluate? (1)

Answer 22

6 months??

Question 23

State the conc.and the name of the root canal irrigation that BDS use in polyclinic (1)

Answer 23

Sodium hypochlorite (1.2%)

Question 24

How likely is it to have a good RCT outcome for these situations? Rank in order. The one with best outcome is 1 as follows (4)

Answer 24

Fresh trauma with exposed bleeding pulp, needing RCT: 1
Irreversible pulpitis, deep leaking restoration, no periapical lesion 2
Traumatized non­vital tooth with no periapical lesion 3
Irreversible pulpitis with periapical lesion 4
Periapical lesion around a tooth that has been endodontically treated 5

Question 25

Describe how the root canals can be disinfected. (5)

Answer 25

Chemo-mechanical instrumentation with medicaments

• Access cavity > using estimated working length for radicular access
(Hand or rotary file with anti-curvature filing + Gates-glidden burs enlarge canal orifice)

• Working length determination > apical instrumentation to full working length
(Canal shaping allow elimination of bacteria, infected dentine and facilitate irrigation )

• Copious irrigation with sodium hypochlorite solution after each file instrumentation
(Disinfection, flushing debris, lubrication, dissolution of organic tissues)

• Intracanal medicaments
(Antimicrobial effect with CaOH, or anti-inflammatory & antimicrobial with Ledermix)

Question 26

What are the factors affecting the success rate of root canal treatment? (5)

Answer 26

Preoperative factors

Intraoperative factors

Postoperative factors

Question 27

What are the preoperative factors affecting the success rate of root canal treatment?

Answer 27

• Preoperative periapical status:
Presence of symptoms and radiographic lesions
Size of lesions (<2 mm has better prognosis)

• Periodontal status:
Normally do not play an important role except in perio-endo lesion with communication poor prognosis

Question 28

What are the intraoperative factors affecting the success rate of root canal treatment?

Answer 28

• Iatrogenic complications like perforations, instrument fracture, extrusion of materials
• Apical extent of treatment

1. Shortness of full working length (> 2 mm) impair prognosis
2. Insufficient enlargement may leave infected dentine unclear
3. Extrusion of instrumentation and obturation beyond apex result in irritation of periradicular tissue as debris, chemicals together pushed out persistence inflammation

• Treatment sessions

1. Some suggested teeth treated in 2 sessions or less have better survival than multiple sessions (greater risk of becoming infected with E. faecalis and developing persistent apical periodontitis)
2. While intracanal infection may not be eliminated completely in single session
3. Medicaments improve prognosis thus 2 sessions may be ideal

Question 29

What are the postoperative factors affecting the success rate of root canal treatment?

Answer 29

• Integrity of coronal restoration
• Post placement

1. Remaining apical seal < 3 mm likely to cause leakage failure
2. Complications like vertical root fracture, root perforation

Question 30

Define chemo-mechanical instrumentation in endodontics. (4 marks)

Answer 30

• Cleaning of root canal system involve the combination of chemical action by irrigation and mechanical shaping action by hand or rotary filing, where 2 processes facilitate each other
• Irrigation: flushing debris, lubricating, dissolving organic tissues, disinfection
• Shaping: provide optimum shape for irrigation, cleaning, and obturation, remove debris, microorganism and pulp tissues

Question 31

Suggest at least four ways to prevent the pulp from being minimally infected prior to obturation (4 marks)

Answer 31

• Keep canal dry with paper point before placing coronal restoration/ obturation
• Double seal with intracanal medicaments
• Proper cleaning with instrument up to minimal acceptable MAF size and correct working length, with copious irrigation and recapitulation
• Intact coronal restoration without leakage
• All procedures performed under rubber dam isolation and with other moisture control technique
• Ensure periodontal condition is favorable (in perio-endo lesion with communication)

Question 32

Types of intracanal medicament provided in PPDH (3)

Answer 32

Non-setting calcium hydroxide paste, iodine potassium iodide/iodoform, Ledermix

Question 33

Vertucci Canal configurations of 15 (2m)

Answer 33

See image on page 44

Question 34

Objectives of pre-endo restoration (4M)

Answer 34

• Rule out cracks and fractures.
• Rule out and remove recurrent caries.
• Ease of treatment
• Check restorability.
• Creates a “tank” for the irrigating solution
• Rubber dam clamp fixture

Question 35

Advantage of coronal flaring and crown down technique (4M)

Answer 35

See image on page 45 old written doc
Ken:
Coronal flaring:
1. Allows for better straight line access
2. Allows for better irrigation, reduced potential of excrutiating debris beyond the apex

Pros and cons of the Step-down technique table on Pg 45

Question 36

Risks associated with root canal treatment of 15 (3M)

Answer 36

• Mild temporary pain due to inflammation of the tissues surrounding the tooth
• A darker tooth: there are procedures available which may lighten the tooth if this occurs
• Tooth fracture: due to reduced strength and durability of the tooth:

1. a tooth extraction may be required
2. this risk is reduced when a crown is used.

These are the main ones, more uncommon risks on page 46

Question 37

Post space/post length(?) of 15, tooth length 18mm root below alveolar bone 11mm (1M)

Answer 37

The length of the post should be greater, if not equal to the clinical crown height and one third of its length should be in the part of the root that is supported (surrounded) by alveolar bone.
Increasing the diameter of the post but sacrificing the remaining tooth structure would weaken the tooth, predisposing it to fracture. The diameter of the post should reflect the size of the canal in order to prevent excessive removal of dentine.

Question 38

Cross section of k-flexo and hedstrom and their respective motion of use (4M)

Answer 38

K-flexo: rhomboid; watch-winding
(K-file is square)
Hedstrom: tear-drop; one direction only

Question 39

What is smear layer? How to remove it? (3M)

Answer 39

Smear layer is a gelatinous surface layer of coagulated protein, highly contaminated with bacteria and also contains cutting debris. Can be removed by irrigation with sodium hypochlorite solution and K files.

Question 40

Dental avulsion management table pg41-42

Answer 40

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