Obturation of the Cleaned and Shaped Root Canals

Question 1

what is the key objective of RCT

Answer 1

provide an environment that allows healing of periradicular tissues so that the tooth is retained as a functional unit in the dental arch

Question 2

triad of ……. to complete RCT

Answer 2

preparation, disinfection and obturation

Question 3

what 6 things must be done/considered when obturating

Answer 3

• apical/lateral seal
• sealer/core materials
• timing of obturation
• length
• assessment
• coronal seal

Question 4

why is the RC system filled after the nerve is removed

Answer 4

prevent passage of microorganisms and fluid along root canal
blocks apical foramina, dentinal tubules and accessory canals

Question 5

where should preparation of the RC end

Answer 5

at the junction of pulpal and periradicular tissues
as close to CDJ as possible
1-2mm short of working length

Question 6

apical constricition

Answer 6

narrowest part of canal

Question 7

what are some requirements of materials used to fill RC

Answer 7

biocompatible, dimensionally stable, able to seal, unaffected by tissue fluids, insoluble, non-supportive of bacterial growth, radiopaque, removable if retreatment needed

semi solid material as well as root canal sealer to fill voids

Question 8

what is the most common RC filler material

Answer 8

gutta percha
polymer of isoprene

Question 9

types of gutta percha obturation techniques

Answer 9

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

Question 10

warm vertical compaction

Answer 10

place cone of GP, sever with heat and plug apically

Question 11

continuous wave obturation

Answer 11

use of electrically heated pluggers and GP, deliver and remove GP

Question 12

carrier based obturation

Answer 12

stick and handle, warm GP into canal

Question 13

what is the function of a RC sealer

Answer 13

seal space between dentinal wall and core, fills voids and irregularities in canal, lateral canals and between GP points used in lateral condensation, lubricates during obturation

Question 14

what are some properties of an ideal sealer

Answer 14

exhibits tackiness to provide good adhesion, establishes hermetic seal, radiopaque, easily mixed, no shrinkage on setting, non-staining, bacteriostatic, slow set, insoluble in tissue fluids, tissue tolerant, soluble on retreatment

Question 15

zinc oxide eugenol based sealer

Answer 15

effective antimicrobial, cytoprotection, but cytotoxic

Question 16

glass ionomer sealers

Answer 16

advocated due to dentine bonding properties, minimial antimicrobial activity, greater solubility
removal for retx is difficult

Question 17

resin sealers

Answer 17

AH plus
good seal, slow setting, good flow, initial toxicity declines after 24hrs
EndoRez = UDMA, good penetration into tubules, biocompactible, good radio-opacity

Question 18

calcium silicate sealers

Answer 18

high pH 12.8 in first 24hrs of setting
enhanced biocompatibility, no setting shrinkage, non-resorbable, excellent sealing ability, quick set 3-4hrs, ease of use

Question 19

how to assess quality of obturation

Answer 19

post-op radiograph
length, taper, density, GP and sealer position assesed
assessed in all canals

Question 20

what to do with the tooth after obturation

Answer 20

adequately restored to prevent bacterial recontamination of RC or fracture of tooth
GI, vitrebond

Question 21

is coronal or apical seal more important

Answer 21

both must be equally good to ensure best possible outcome

Question 22

orifice closure

Answer 22

finish obturation at or just below orifice level
GP becomes rapidly infected if exposed directly to oral bacteria