Root canal process

Question 1

discuss NaOCl as an irrigant

Answer 1

pros - antimicrobial , dissolves pulp remannts and collagen
requires mechanical agitation
cons: opthalmic injury risk, apical extrusion risks tissue necrosis, discolours fabrics

Question 2

what is formed if CHX and NaOCl are mixed

Answer 2

parachloroaniline - cytotoxic and carcinogenic

Question 3

symptoms of a NaOCl extrusion

Answer 3

pain
swelling
bruising
haemmhorage
airway obstruction

Question 4

risk factors for sodium hypochlorite extrusion

Answer 4

excessive pressure during irrigation
needle locked within canal
loss of control of working length
large apical diamters e.g immature teeth/ RR

Question 5

treatment for hypochlorite extrusion

Answer 5

• stop procedure and inform patient
• flush canal with saline
• place steroid containing intracanal medicament and seal access cavity
• recommend analgesics
• review within 24 hours, refer if severe

Question 6

what are the active ingredients in ledermix

Answer 6

corticosteroid
tetracycline

Question 7

EWL

Answer 7

determined from pre-op radiograph
radiographic apex - coronal reference minus 1mm

Question 8

CWL

Answer 8

end point of obturation and preparation
most accurate using electronic apex locator

Question 9

master apical file

Answer 9

largest file taken to working length and represents the final prepared size of the apical portion of the canal

Question 10

when would a barbed broach be use

Answer 10

extirpation

Question 11

ideal properties of an obturation material (4)

Answer 11

biocompatible
radiopaque
dimensionally stable
retrievable
insoluble

Question 12

what do gutta percha cones consist of

Answer 12

zinc oxides
gutta percha
radiopacifiers
plasticisers

Question 13

describe the cold lateral compaction technique

Answer 13

Select master GP cone according to master apical file

Lightly coat master cone in sealer, ensure it goes to CWL

Use finger spreader, set to 1-2mm short of CWL and place alongside master cone

Insert accessory point in spreaders place

Repeat until fully obturated

(master cone should show ‘tug-back’)

Question 14

what method of obturation may be used in a tooth with internal root resorption

Answer 14

warm vertical compaction

Question 15

purpose of sealers

Answer 15

Seals space between dentinal wall and GP

Fills voids and irregularites in canal and between GP points used in condensation

Lubricates during obturation

Question 16

name 3 options for sealers

Answer 16

• zinc oxide - poor
• glass ionomer - poor
• resin sealers - AH plus
• calcium silicate - excellent seal

Question 17

sealers containing what are not recommended

Answer 17

organic materials e.g aldehydes

Question 18

what should GP and orifices be sealed off with

Answer 18

zinc oxide eugenol
RMGI
flowable composite

Question 19

favourable RCT outcome

Answer 19

RCT should be assessed at least after 1 year

Absence of pain, swelling and other symptoms

No sinus tract

No loss of function

Radiographically normal PDL

Question 20

uncertain RCT outcome

Answer 20

radiographic changes remain the same size or has only slightly reduced. If lesion persists 4 years after RCT usually considered to be associated with post treatment disease

Question 21

unfavourable RCT outcome

Answer 21

Tooth has associated signs and symptoms of infection

Radiographically visible lesion has apppeared subsequent to treatment or existing lesion has increased in size

Lesion has remained the same size or slightly diminished after 4 year assessment period

Signs of continuing root resorption are present

Question 22

operator factors contributing to RCT success (3)

Answer 22

Well condensed root filling with no voids

Filling extending to within 2mm of radiographic apex but not extruded

Good quality coronal restoration

Question 23

reasons for RCT failure

Answer 23

• inadequate coronal seal
• persistent intra radicular infection
• extra radicular infection
• poorly condensed root filling
• filling not too length - broken file, blockage etc

Question 24

what can be utilised for GP removal

Answer 24

H files
reciproc
eucalyptus oil

Question 25

when do ledges occur

Answer 25

when curved canals instrumented as if they are straight