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BDS3 Endodontics > restorative endodontic interface - posterior > Flashcards

restorative endodontic interface - posterior Flashcards

1
Q

indications for direct posts on anteriot teeth

A

ferrule required

need dentine remaining

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2
Q

indications for cast posts and cores on anterior teeth

A

not a lont of dentine

replacing a cast post

no ferrule - not ideal

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3
Q

possible tx for this lateral incisor

A

lot dentine remaining - maybe try build up with core material

use fibre post (Dt light posts)

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4
Q

when building up a core with fibre post what must you have

A

rubber dam - should be using resin cemetn which needs optimal moisture and control conditions

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5
Q

doesn a tooth need a post?

A

clinical judgement

  • could you build up a core?
    • esp anterior tooth
      • enough dentine remaining?
      • post should be last resort as lost so much tooth structure
  • does toth need a post crown
  • restrorative cycle
    • want to stay simple for as long as possible before progressing
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6
Q

3 options for tx of endo tx tooth

A
  1. build up core (anterior or posterior teeth)
  2. fibre post - some dentine
  3. cast posst - so little dentine left and non-optimal ferrule
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7
Q

11 stages in cast post prep

A
  1. Assessment
  2. Design a new restoration
  3. Provisional restoration
  4. Gutta percha removal
  5. Post space prep and anti rotation features
  6. Provisional construction
  7. Impression
  8. Lab prescription
  9. Provisional placement
  10. Try in
  11. Fit
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8
Q

things to assess for in RCT

A
  • when was it done
  • how was it done
  • is it acceptable (to apex, voids)
  • has it been leaking - open for 3 months?

was it done using sodium hypochlorite?

  • not sure -> consider redo it before post placement
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9
Q

why is it important to assess RCT before post placement

A

hard to dismantle one post placed -> root fracture possible

need to be sure foundations sound and root canal clean before placing definitive post retained crown onto tooth

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10
Q

gold standard for RCT

A

dental dam and sodium hypochlorite

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11
Q

3 aspects of favourable post design

A
  • parallel sided (avoids ‘wedging’)
  • non threaded (avoids incorporating stress)
  • cement retained (buffer between masticatory forces post and tooth)
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12
Q

masticator load transfer by post

A

tapered pst act as wedges leading to root fracture

parallel sided posts do not cause wedging

posts retained solely by cement tend to distribute masticatory forces evenly to the supporting tooth, the cement acting as a buffer between post and tooth

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13
Q

5 considerations when designing new restoration

A
  • How long will post be?
  • Have you got a ferrule?
    • How wide?
  • 3-5mm remaining GP at apex beyond post
  • Is canal straight?
  • How much space for the core – need to factor in type of crown to be placed
    • Need a retentive core to retain crown Or else no mechanical retention for crown – aim (function, aesthetics for pt)
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14
Q

why do you need a retentive core

A

Need a retentive core to retain crown

Or else no mechanical retention for crown – aim (function, aesthetics for pt)

assess space for core and factor in type of crown to be placed

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15
Q

ferrule preparation

A

place crown margins on solid tooth tissue rather tahn restorative material

1.5-2mm collar dentine extending supragingivally 360o circumferentially of post

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16
Q

ferrule effect

A

when place crown on, get some bracing in coronal portion of tooth where crown meets ferrule preparation and cement retains crown in place

  • resistancce to rotational force and leakage
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17
Q

core design (2 main aspects)

A
  • core - taper and length important
    • 6 degree taper
    • length required - to allow 2mm clearnace incisally for MCC
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18
Q

when to consider provisional restoration factors

A

before begin dismantling restorations

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19
Q

4 possible provisional restorations

A

provsional post core crown (temp bond)

immediate denture

dressing? Zinc oxide eugenol

essex retainer with teeth on

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20
Q

provisional post core crown (temp bond)

use

possible issue

A

especially if dismantling an exisiting crown

  • can take putty matrix and make provisional post core wtih temp bond
  • some posts in para post kit

chewing can dislodge provisional crown -> microleakage

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21
Q

issue with immediate denture as provisional restoration

A

can cause gingival problems - margin, haemorrhage (OHI not ideal)

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22
Q

use of dressings as provsional restorations

A

zinx oxide eugenol

not aesthetic but might prevent leakage

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23
Q

removal of gutta percha to

A

create post space

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24
Q

cons of dental dam use in removing GP

A

can obscure long axis of tooth - relatively easy to lose bearings

needs to be removed for definitive impressions

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25
Q

steps in removing GP

A
  • dental dam
  • soften GP
  • gates glidden to minimum size 3 (straight part of canal only)
  • use working length and rubber stopper on GG
    • essential to leave 3-5mm GP in apical third
  • check GP plug remains
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26
Q

how much GP needs to be retained in apical third

A

3-5mm

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27
Q

how to soften GP

A

heat - super endo alpha

solvent - eucalyptus oil

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28
Q

why do you need to use rubber stopper and know working length when removing GP

A

need to leave 3-5mm GP in apical third

so need to know exactly how many mm of GP taking away from known coronal measurement point

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29
Q

GG3

A

0.9mm

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30
Q

3 ways to check GP plug remains

A

loupes

microscope

periapical radiograph

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31
Q

once obturated what is sensible practice

A

to leave tooth for 24hrs to allow AH plus (resin sealer) to set inside the tooth

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32
Q

what is the risk if there is post prep at same appointment as obturation

A

risk disruption whilst removing GP

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33
Q

para post components

A
  • provisional post (titanium)
    • use in conjuction with protemp and putty matrix to construct provisional post crown
  • burn out post (not important)
  • para post drill (colour coded)
  • impression post
    • smooth sided
    • placed into tooth when taking deficintive impression for indirect cast post
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34
Q

para post narrowest post space bur

A

0.9mm - same as tip for GG3

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35
Q

how to use para post drills

A

parallel sided

run through sequence to desired size

36
Q

post space prep

A
  • heat source to remove some GP (super endo alpha)
  • start with small gates glidden (2) with rubber stopper on to remove some coronal GP
  • irrigate to wash out debris
  • GG again – brushing motion
  • Irrigate
  • Larger GG size (3) to remove more GP
  • Irrigate
  • Rubber stop on parapost drill to same length GG got to (dentine collar is reference point), in slow speed do not force drill
    • if feel hard surface, stop
    • may have angulation wrong – risk perforation of tooth
  • Irrigation – important for efficiency of parapost drill cutting to wash out debris
  • Continue this sequence up parapost drills – widen post space
  • Move up sequence of parapost drills
  • Try in pre-op putty matrix once feel completed to ensure it fits
  • Fabricate provisional post crown
37
Q

provisional construction

A
  • Try in provisional parapost
  • Inject protemp into putty matrix and make sure firmly place into mouth
  • Remove as one (provisional parapost retained in the protemp)
38
Q

how to adjust provisional parapost

A

if too long cut with Mons wire cutters (as titanium)

  • cut from apical end
    • leave little nail head in place - retain para core
39
Q

how long do you have provisonal para post

A

2mm short of incisal edge of adjacent tooth

40
Q

how to take defintive master impression

A

Definitive master impression

  • Use a putty wash technique – light body wash injected round prep
    • incorporate all margins
    • ensuring post is fully covered with wash material
  • Place putty impression over the top

Remove and impression post should be retained – send to lab with instructions to make cast post and core

41
Q

anti-rotation notch/groove

role

A

cut into preparation to try and prevent rotational displacement

42
Q

anti-rotation notch/groove

placed when and why

A

If sufficient coronal structure is present rotation is prevented by a vertical coronal wall

  • If coronal dentin is absent then a small vertical groove in the canal serves as an anti rotational element
  • Located in the bulkiest area of the root, usually lingual
43
Q

lab presciption for definitve restoration (sent with definitive impressions)

A

please construct a cast post and core

para post (colour)

core 6 degree taper

please leave 2mm space in occlusion for crown

enclosed registration/opposing impression/ (shade - making crown as well)

44
Q

try in

A

received post and core back from lab

  • check post space for temp bond, debris etc (ultrasonic cavitron to clean out)
  • irrigation chlorhexidine 0.2% - can be under dental dam if you want
    • can be slippy - protect pt airway
  • dry paper points
  • ensure fits around prep
  • do you have enough occlusal cleanrance?
    • be sure before cementing in
45
Q

fit

A

cement

  • be careful not to fill post space - prevent seating
  • use firm apical pressure - to ensure seated properly
  • remove excess

can ask lab for provisonal acrylic crown

practice fit sequence

  • slick enough to get everything in right position (esp if placing crown too)
46
Q

issue if not seat restoration properly

A

harder to remove

47
Q

what to check for when taking crown impression/fitting MCC

A

no excess and no gingival bleeding

48
Q

when may you ask for a provisonal acrylic crown from lab?

A

e.g. if leaving in cast post in place for a while

can be useful as protemp provisional with post is now useless

  • if have another putty matrix can construct another protemp restoration – but challenging
49
Q

what may occur if get post core and crown made on same impression

A

one may fit and other won’t

but potentially less visits for pt

50
Q

impact of NHS fee for post core

A

Metal alloy £39.95 (para) (lab fee £31) DTS

Non-precious metal £20.75 (lab fee £18.75) Leca

no large profit

51
Q

post core is in what stage of restorative cycle

A

last resort

52
Q

impact of post core being last resort tx on planning

A

may only get 1 go at doing it

ensure

  • quality of root treatment
    • ensure RCT right
    • ensure post cornw fit right
53
Q

issue here

A

post placement off to both sides and not deeply placed

54
Q

issue here

A

parapost drill has gone through side of tooth

55
Q

methods of post removal (6)

A
  • ultrasonic (tips £££)
  • trephan e.g. Masseran
  • eggler device
  • moskito forceps (screw retained)
  • sliding hammer
  • anthogyr (safe relax)
56
Q

Maseran useful for removal of post by

A

coring around fracured post insturements/posts

57
Q

hybrid post removal technique

US and masseran

A

core a channel around fractured pience and grab with Masseran tube

58
Q

intact/post core removal fee

A

£0

can be timely for no £

may consider referral as not routinely done in GDP

59
Q

fractured post removal fee (below dentine collar)

A

£18.20

consider referall

60
Q

why are referral consider for post removal

A

can be timely for little £

can break an expensive US tip in process

may also need dental microscope £££

61
Q

5 post removal problems

A
  • you can’t remove it
  • root fracture (immature or delayed)
  • render tooth unrestorable
  • post space too wide
  • break post

tell pt as part of consent process

62
Q

planning treatment key

A

if can do simple (build up core (avoid post)) - BEST

leave option for post at later date - as posts do not strengthen teeth

63
Q

endo tx posterior teeth restorations avoid

A

posts at all costs

64
Q

3 core materials for posterior teeth

A

composite

amalgam

Glass ionomer

65
Q

composite as a core material

A
  • most commonly used core material
  • tooth coloured as good aesthetics
  • bonds to tooth structure
  • technique sensitive, so moisture control required
  • used with fibre posts
66
Q

amalgam as core material

A
  • tend to avoid as retention is required
  • poor aesthetics
  • core cannot be prepared straightaway - needs 24hrs to set
  • avoid pinned amalgams - ideally want bond to tooth
67
Q

if assessing an amalgam core and unsure on its status (age, if secondary caries under) what to do

A

remove if in doubt to check what is underneath core

68
Q

glass ionomer as a core material

A

not really used as it absorbs water and core expands in size

69
Q

examples of core materials and how to use

A
  • Biodentine
  • Paracore (available in GDH)

can cure and prep tooth straight away (unlike amalgam)

utilise pulp chamber space

undercuts in roof of pulp chamber

cut 1-2mm into orifice

  • inc SA for bonding, and mechanical retention
70
Q

why to cut 1-2mm into orifice for core build up

A

inc SA for bonding, and mechanical retention

71
Q

restoration of endo tx posterior teeth considerations

A

molars and premolars have narrow roots

  • post preparation may lead to a strip or lateral perforation in these teeth

disadvantages of posts in molars outweigh advantages

core retention can be obtained from physical undercuts and dentine pins or preferably bonding agents

72
Q

disadvantages of posts in endo tx posterior teeth

A

post preparation may lead to a strip or lateral perforation in these teethcurved roots

  • perforation risk
  • longer posts not possible retention poor
73
Q

restoration of molars if no coronal tissue

A

posts may be inserted for a short distance into largest straightest root canal

74
Q

restoration of molar teeth in general

A
  • most cases have sufficient natural retention for a core
  • at least 1mm ferrule of definitive coronal restoration required unless all-porcelain restoration
  • nayyer core (amalgam) should be avoided
75
Q

if posts need to be used in posterior teeth

use them in

A
  • distal roots of mandibular molars
  • palatal roots of maxillary molars

normally provide a large and usually straighter canal for post insertion

76
Q

minimum tx required for endondontically treated molar or premolar

A

cast restoration with occlusal coverage

e.g. MOD onlay

77
Q

why is it important to give coronal coverage to endo tx posterior tooth

A

94% of endodontically treated molars receiving coronal coverage were successful compared with 56% of occlusally unprotected teeth

78
Q

what to consider prior to RCT of posterior teeth is restorations going to involve more than one surface

A

reducing cusp heigh by 1.5-2mm

79
Q

3 reasons for posterior teeth cuspal protection

A
  • prevent catastrophic fracture
    • e.g. furcation
  • maintain coronal seal
  • prevents microbial ingress
80
Q

why in GDH do we place coronal protection of endo tx posterior tooth

A

increases longevity of the tooth by placing an extra coronal restoration

short, narrow, spindly roots are easily damage

81
Q

premolar restorations after endo

A

cuspal coverage should be considered first option

posts should only be used if roots are adequately long, bulky and straight

  • only one canal should be used
  • radix anker posts produce extreme stress on root structure (threaded, screw posts)
82
Q

restoration when no post needed

A

build up with composite, paracore

83
Q

restorative when dentine remaining but not enough to build up core

A

fibre post (need ferrule)

84
Q

restorative when very little remaining tooth structure and no ferrule

A

indirect cast and post crown

85
Q

tx for posterior teeth

A

avoid posts at all costs

1st line is cuspal coverage (MOD onlay)

but after consider extraction and aesthetic replacement

BDS3 Endodontics (10 decks)

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