4 - Obturation

Question 1

what increases the likelihood of endodontic success?

Answer 1

• absence of a pre-treatment periodical lesion
• root canal fillings with no voids
• obturation to within 2mm of radiographic apex
• adequate coronal restoration

Question 2

what are the objectives of obturation?

Answer 2

• to achieve a complete seal (apical, lateral and coronal)

Question 3

why must endodontic treatment include sealing of the root canal system?

Answer 3

• to prevent tissue fluids from percolating in the root canal
• prevent toxic by-products from necrotic tissue and microorganisms regressing into peri-radicular tissues

Question 4

role of obturation?

Answer 4

• reduces coronal leakage and bacterial contamination
• seals the apex from periapical tissue fluids
• entombs the remaining irritants in the canal (deprives them of nutrients and lets them remain dormant)

Question 5

what type of seal is ideal?

Answer 5

• fluid tight or bacteria tight seal

Question 6

challenges of obturation?

Answer 6

• complex canal anatomy
• removal of microorganisms: mechanical cleaning does not remove all irritants from the canal (many surfaces untouched by file)

Question 7

process of successful endodontics?

Answer 7

• diagnosis and treatment planning
• knowledge of anatomy and morphology
• shaping and disinfection of RCS
• obturation
• coronal seal

Question 8

poor obturated teeth - procedural errors include?

Answer 8

• loss of length (ledging)
• canal transportation
• perforation
• loss of coronal seal
• vertical root fracture

Question 9

importance of obturation?

Answer 9

• eliminates leakage
• seals apex from peri-apical exudate
• reduces coronal leakage

Question 10

single visit - when is it acceptable?

Answer 10

• only in certain circumstances

- for teeth with vital pulp tissue, one visit is preferred

Question 11

why is one visit for obturation preferred for vital pulp tissue?

Answer 11

• bacterial infection is minimal
• prevents possible contamination between visits
• observe aseptic conditions during treatment

Question 12

guidelines for single visit obturation?

Answer 12

• no significant symptoms
• no significant clinical signs: tooth should not be TTP
• canal must be clean and dry: no blood, exudate, pus or smell
• appointment time must be of sufficient length

Question 13

multiple visit - indications?

Answer 13

• presence of acute signs or symptoms
• persistent exudate after drying the canal
• anatomical difficulties
• technical difficulties
• patient or dentist become tired or has lost patience

Question 14

what is the perceived advantage of obturating over multiple visits?

Answer 14

• allows an antibacterial dressing to be placed in canal between visits
• CaOH paste is known to reduce the number of residual bacteria following cleaning and shaping

Question 15

interappointment disinfection: what kind of paste used for dressing? how long must dressing be kept?
Cresophene - what kind of compounds does it contain and why should it be avoided?

Answer 15

• CaOH non-setting paste
• dress for at least one week
• phenol compounds. they should be avoided as they are not very effective and very toxic if they contact periradicular tissues

Question 16

checklist before obturating? what to examine?

Answer 16

• is the pt having any symptoms?
• examine for clinical signs: tooth TTP? sinus healed? temporary dressing still intact?
• place rubber dam to prevent microbial contamination and disinfect crown
• check that the canals are dry with no exudate, pus or bleeding

Question 17

ideal properties of obturating materials - technical?

Answer 17

• no shrinkage on setting
• no solubility in tissue fluids
• good adhesion/adaptation to dentine
• no water absorption
• no tooth discoloration

Question 18

ideal properties of obturating materials - biological?

Answer 18

• no allergy for patient or dental staff
• no irritation to local tissues
• sterile
• antimicrobial
• stimulate periradicular healing

Question 19

ideal properties of obturating materials - handling?

Answer 19

• radiopaque
• sets in adequate time
• easy to apply and remove using heat, solvents or mechanical instrumentation

Question 20

obturating core materials?

Answer 20

• gutta percha
• silver points
• pastes

Question 21

gutta percha: composition?

used in what form?

Answer 21

• 19-22% gutta-percha
  59-75% zinc oxide
  waxes, coloring agents, antioxidants, metallic salts
• non-standardized gutta-percha cones sizes F1-F5

Question 22

silver points:
how does it make obturation easier?
what are the issues with usage?

Answer 22

• its rigidity makes placement easier
• canals often not properly disinfected: leakage and corrosion
• not adaptable to canal therefore seal limited
• can be difficult to remove
• never obturate a silver point re-treatment in a single visit because the flare-up rate is too high

Question 23

accessory cones - what sized should be used with finger spreader?

Answer 23

should be used with the same size finger spreader

Question 24

obturating pastes - types?

Answer 24

• zinc oxide & eugenol + formaldehyde (toxic material)

- plastics: resin based

Question 25

obturating pastes - paraformaldehyde: why was it thought to be beneficial? what happens if extruded?

Answer 25

- it mummifies and fixes pulpal tissue | - causes severe neurotoxicity if extruded

Question 26

obturating pastes - resins:

Answer 26

- resorcinol-formalin | - epiphany/realseal: polycaprolactone core and sealer material

Question 27

obturating pastes - resins - resorcinol-formalin: commonly used where? sets very hard where? + what does this mean? what happens if overfilled?

Answer 27

- used commonly in russia, china, india - sets very hard in coronal part of canal. therefore it will be hard to retreat - can cause neurotoxicity if over-filled

Question 28

obturating pastes - resins - epiphany/realseal: what kind of material? develop to do what?

Answer 28

- a polycaprolactone core and sealer material | - developed to bond with each other and canal wall to produce a bacteria tight seal with reinforcement of the root

Question 29

sealers: - must be used to fill the spaces between what? - aim for?

Answer 29

- fill the spaces between the gutta-percha cones and between the canal wall to ensure a fluid tight seal - aim for maximum gutta percha and minimum sealer

Question 30

cold lateral compaction (obturation) technique?

Answer 30

- LA - Rubber dam - disinfect tooth with chx, alcohol - remove dressing and cotton wool - irrigate with citric acid to remove CaOH then sodium hypochlorite

Question 31

cold lateral compaction (obturation) technique - canals are filled with what?

Answer 31

- gutta percha master apical cone - protaper next matched to apical size - X2-X5 - 0.02 taper master apical cone (for apical sizes >50) - sealer

Question 32

cold lateral compaction with 0.02 taper cones - spreader must fit within how much of working length? what should be done if this cannot be achieved? why?

Answer 32

- spreader must be within 1-2mm of working length - preparation should be refined - as lateral compaction in the apical third will be inadequate

Question 33

cold lateral compaction: technique?

Answer 33

- dry canal (correct size of paper points) - mix sealer, have spreader ready (rubber stop slightly short of WL) - measure MAC to WL and coat in sealer - insert slowly in canal to WL - leave 10-15 secs with light lateral pressure - remove spreader with slight rotation, place accessory cone into channel created - repeat until no more accessory cones can be fitted - take obturation verification radiograph - cut off excess gutta-percha and compact coronal GP using endodontic plugger

Question 34

cold lateral compaction: except for the apical few mm, the root canal will be more tapered than the gutta percha cone - this space is filled by?

Answer 34

compacting accessory cones that have been lightly coated in sealer

Question 35

alternative obturation techniques?

Answer 35

- thermoplastic gutta-percha (continuous wave of obturation) | - obturators: thermalfill, guttacore

Question 36

finishing, sealing access cavity - how?

Answer 36

- remove all sealer and GP from access cavity to amelocemental junction: prevents discoloration of crown - use cotton wool pledget soaked in alcohol

Question 37

finishing, sealing access cavity - what is placed over gutta-percha and pulpal floor to minimize coronal leakage? what are the bactericidal by-products?

Answer 37

- vitrebond - benzene bromine - benzene iodine

Question 38

coronal seal - possible reasons why obturated root canals may become reinfected?

Answer 38

- delay in placing permanent restoration - fracture of coronal restoration or tooth - cracks within tooth structure or exposed deninal tubules - poor margins - recurrent decay

Question 39

reinfection of the root canal space will lead to?

Answer 39

periradicular periodontitis

Question 40

definitive restoration: what is used on anterior teeth? and posterior teeth?

Answer 40

- light coloured composite - restoration on posterior teeth depends on what is needed: crown/onlay? - usually requires a core buildup in amalgam or composite

Question 41

classification of endodontic outcomes?

Answer 41

- healed: no clinical signs/symptoms, no radiolucency - healing: in progress, clinically no signs or symptoms, reduced radiolucency (follow up 4 yrs) - persistent/recurrent/emerged disease: periapical periodontitis with/without clinical signs/symptoms

Question 42

what affects periradicular healing?

Answer 42

- accuracy of periapical preparation - removal of microbes by effective irrigation - control of obturation - coronal seal (success ultimately depends on control of apical infection)