Restorative Flashcards
1
Q
Tooth 11 has a traumatic exposure. What 2 factors would influence your choice of treatment?
A
size of exposure
time since exposure
2
Q
How would you treat traumatic pulpal exposure in practice?
A
partial or complete pulpotomy
partial- removing 1-3mm of affected pulpal tissue whilst complete is removing full height of coronal pulpal tissue
la -> dam + isolation -> access with hi speed round bur -> remove 2-3mm with bur -> saline irrigation ->
ferric sulfate for haemostasis ->apply hard setting CaOH dressing
need to assess bleeding- if abnormal bleeding- may need to pulpectomy
indicted in: vital traumatically exposed young permanent tooth- espec with incomplete apex.
3
Q
If restoring deep carious lesion and radiographically you are concerned about extent near pulp how do you procede
A
indirect pulp cap may be placed.
• Caries should be carefully removed in a progressive manner to reduce pulpal exposure w slowly rotating contra-angle handpiece or sharp hand excavators.
- The cavity should be cleansed with 0.2% w/w chlorhexidine gluconate.
- Stained (not soft) dentine over the pulp should be left in situ and covered with a setting calcium hydroxide cement, for example Dycal
- A stronger lining material (Resin-Modified Glass Ionomer cement - Vitrebond) should then be placed to protect the Ca(OH)2 and the tooth restored with a provisional restoration, for example GIC or RMGI.
- The tooth must be vital, asymptomatic and have no history of previous pulpitis.
- The tooth should be monitored for 3 months and if vital and asymptomatic, the provisional restoration should be removed, stained dentine carefully excavated and definitive restoration placed.
- If there have been any pulpitic symptoms, then RCT should be undertaken.
4
Q
direct pulp capping restricted to:
A
teeth with a good prognosis, young patients in good health, lack of pre-existing symptoms, fresh non-carious exposure and minor pulpal haemorrhage.
5
Q
indications for ledermix use
A
Ledermix paste or cement (antibiotic/steroid mixture) should not be used as a pulp capping agent. The only indication for the use of Ledermix is as a temporary palliative agent in contact with vital (possibly inflamed) pulp either in a pulp chamber or root canal, when it is intended that the tooth should be extracted or root canal treated
6
Q
how to carry out first stage of endo- canal preparation
A
- consent gained. pt to wear bib and glasses
- pre-op radiograph PA grade 1 w/in 3 months of commencing
- assessment of tooth- must be caries free and restorable. perhaps pre-endo build up to allow for dam placement and reduce change of leakage
- LA administered
- dental dam placement. if isolation cannot be achieved XLA indicated. as early as poss. if elected to cut access cavity prior to dam placement all dam equipment should be prepped for immediate placement prior to or as soon as pulp exposed
- Disinfect access opening, clamp and dam with CHX
- Using a diamond bur in the high speed handpiece with water spray and wide bore aspiration, cut the initial outline form of the access opening into dentine.
- Using either a high-speed fissure bur or preferably the slow speed handpiece with a long shank/neck round bur make an opening into the pulp chamber
9.Using a high speed safe tipped endodontic access bur (e.g. Endo Z bur) or slow speed round bur, remove the remainder of the roof of the pulp chamber. do not allow bur to touch pulp chamber floor - Remove contents of the pulp chamber with a discoid excavator.
- Remove any remaining overhanging edges of the pulp chamber roof so that the walls of the access opening are smooth using the safe-tipped endodontic access bur.
- check integrity of dam seal prior to irrigation. opaldam used if necessary
- NaOCl irrigation
- 17% EDTA irrigation as penultimate irrigation- 1 min soak
- establish glide path,
- Once the EWL has been reached with a size 10k file an electronic apex locator should be used to determine proximity to the apical constriction / apical patency. repeated at least three times
- working length radiograph taken and correct working length established.
- coronal flare established with gates glidden (largest to smallest)
- working length radiograph taken and correct working length established.
- Root canal instrumentation
- 10 min NaOCl soak
- Manual irrigation with GP point after final instrumentation
- if finished in one- obturate and post of radiograph before definitive restoration & monitor
if not finished in one appt- non setting CaOH2 (ultracal) placed in root canals, with cotton wool above and GIC above that as temp rest.
if vital pulp remains and anaesthesia difficult to achieve- odontopaste (zoe)
7
Q
pulpotomy?
A
removal of portion of diseased pulp in hope to maintaining the vitality of the remaining portion through placement of a therapeutic dressing
8
Q
factors needed discussed for consent?
A
procedure
prognosis
risk
alternatives
9
Q
risks of endo?
A
post op pain post op swelling instrument fracture material extrusion failure to negotiate to working length perforation root fracture hypochlorite accident need for pain management
10
Q
dam placement tips?
A
For posterior teeth punch largest single hole 2 cm diagonally from the centre of the dental dam sheet and turn to appropriate quadrant. For anterior teeth the hole may be punched more peripherally, to ensure the dam does not cover the patient’s nose. When the patient’s mouth is open, the top lip should be covered by the rubber dam.For multiple tooth isolation the rubber sheet can be held against the teeth and points to be punched marked with an indelible pencil.
Suggested clamps : Anteriors “C” or “E” Premolars “E” or EW” Molars “A”, “AW”, “FW” or “K”
11
Q
measurements taken from pre op radiograph
A
- length of each root,
- the anatomical reference point
- the estimated working length of each root canal.
- from the anatomical reference point (incisal edge or cusp tip) to the roof of the pulp chamber.
12
Q
ACJ importance in endo
A
most reliable anatomic landmark to aid location of canal orifices.
13
Q
irrigant of choice in endo
A
2.5-5.25% sodium hypochlorite NaOCl
used in a Luer lock syringe with a gauge 27 Endo needle.
14
Q
irrigation necessities
A
label irrigants with adhesive labels 1 min to dispense 3ml syringe never forced under pressure never wedged at end of root canal rubber stopper used to provide length measurement
Aspirate effluent using a plastic disposable saliva ejector with the round tip removed or a Yankauer tip in high volume aspirator, held as close to the access cavity as possible. It is essential that irrigating solutions do not pool around the tooth.
irrigate gently with 17% EDTA solution to remove the smear layer. EDTA should be used as the penultimate irrigant and placed in the canal for one minute.
Final irrigation with Sodium hypochlorite prior to obturation, a 10 minute “soak” is recommended, this can be carried out whilst the dental nurse prepares the equipment and materials required for interappointment dressing or obturation.
Manual dynamic irrigation should be performed following completion of instrumentation. This should be done very gently with a standardized gutta percha point with an apical diameter equal to or smaller than
the master apical file( For example if the master Cone is an F2 ProTaper rotary then a standardised GP cone of apical diameter 0.25mm should be used.)
15
Q
guidelines for use of NaOCl
A
- Careful pre-operative radiographic assessment is essential – be vigilant of open apices and perforations and discuss with senior staff if either is suspected prior to commencing treatment.
- It is important that the pre-endodontic restorative state of the tooth is assessed. A pre-endodontic build-up is necessary if isolation is likely to be compromised.
- Ensure the patient is provided with a disposable bib to protect clothing. This must adequately cover clothing. If necessary use two bibs overlapping.
- Provide patient with protective eyewear.
- Always use dental dam to isolate the tooth requiring RCT and ensure this is sealed well with OrasealTM. The oral seal should be “moulded” to the tooth contours with a damp cotton wool pledget. Placing the clamp prior to dam placement can facilitate visualisation. Ensure floss is used to secure the clamp during placement and removed after dam is seated.
- Test the dental dam seal by irrigating with chlorhexidine first to ensure no leakage.
- Dam placement must be checked by the supervising clinician
. 8. Ensure that all syringes are clearly labelled with adhesive labels. - Always use a side-vented needle for irrigation of the root canal.
- Always use a Luer-Lok 27G needle and ensure this is securely attached to a 3mL syringe – test this before use.
- Fill syringe less – approximately 3/4s full to aid control.
- Always use a silicone stop on the needle and set to 2mm short of working length.
- Always pass the endodontic syringe behind the patient’s head and never over the patient’s face.
- The irrigating needle should not bind in the root canal at any time.
- Whilst irrigating, depress the plunger with index finger rather than thumb to reduce the pressure.
- Report any irrigation/endodontic incident to senior staff immediately.
16
Q
what is a DG16 used for
A
a DG16 Endodontic probe - used to identifying root canal orifices
. Following developmental root fusion lines can aid in orifice location
17
Q
difference between EWL and CWL
A
estimated and calculated
Careful assessment of the working length radiograph along with the apex locator results should allow calculation or the Corrected Working Length
CWL is calculated by adjusting accordingly from if file short or long of radiographic apex. ideally the working length should be approximately 2 mm from the radiographic apex.
CWL = KLI x ALT
/ ALI
known length of instrument x apparent length tooth
/ apparent length instrument
18
Q
modified double flare technique?
A
The modified double flare technique allows production of a continuously tapering funnel-shaped preparation. The process involves development of an initial coronal flare, followed by an apical flare. These distinct regions of preparation, upon intersection create a continuous taper. Preparation involves the use of Gate Glidden drills and stainless steel K-files. The K-files are instruments with a 2% taper.
19
Q
how to carry out obturation
A
Under dental dam isolation, irrigate the canal thoroughly using NaOCl.
If the root canal filling is being undertaken at a separate visit from canal preparation, wash out all the inter-visit dressing and confirm CWL with a small file and an apex locator, then check that the master apical file still reaches CWL before proceeding to fill the canal.
DO NOT insert the master file immediately or any material in the canal will be compacted at the apex and will block the canal.
Dry the root canal(s) thoroughly using narrow bore aspiration and matched size and measured length of sterile paper points in locking tweezers.
Select “Master” Gutta Percha point – standardized GP point - that will fit canal to the CWL and give the sensation of “tug back”.
Mix root canal sealer (AHPlus).
Using a paper point (coated lightly with sealer) coat the walls of the root canal thinly with sealer
Coat the master point tip lightly with sealer and insert slowly and carefully to WL using sterile locking tweezers. Then:
(a) Gently place a size A or B finger spreader in canal alongside the master point.
The spreader should be left in place for at least 20 seconds to achieve the desired compaction
repeat with more accessory points until firm mass of GP
heat old instrument and use to cut off end of GP mass
condense GP remaining in orifice and remove all obturation material in pulp chamber flush to orifice
20
Q
WHat factors does a dentist consider when considering implantation?
A
smoking status bone quality and quantity occlusion aesthetics oral hygiene pt motivation
21
Q
what bone dimensions are needed for implants and how are they best assessed
A
assessed via cbct
1.5mm horizontal around implant
3mm between implants
>5mm between bone crest and contact point
22
Q
3 alternatives for implant in space
A
1 nothing
2 bridge
3 rpd
23
Q
how can you check that a bridge has debonded
A
probe, floss, visually, mobility, push and check for air bubbles
24
Q
factors needing to be considered before bridge placement
A
oh
abutment health (perio and caries)
occlusion
length of span
25
alternatives to a bridge
nothing, rpd, implant, overdenture
26
signs and symptoms of reversible pulpitis & tx
short sharp pain (aB and ad fibres), pain on cold, no ttp, pain stops when stimulus removed, poorly localised
tx - removal of caries and causative factors, restore
27
signs and symptoms of irreversible pulpitis & tx
long lasting dull pain (c fibres), pain on hot, spontaneous pain, wakened at night, well localised if reached pdl
tx- rct, xla
28
how does la work
enters cell, blocks VOLTAGE gated sodium channels and prevents propagation of action potentials
29
most susceptible to least susceptible to la -nerve fibres
a delta,
C,
a beta,
a alpha
smaller nerves affected quicker (and delta is myelinated .:. affected quicker than c)
30
name one ester and three amide local anaesthetic
ester- benzocaine
amide- lignocaine, articaine, bupivacaine, prilocaine
(amide or ester bond between hydrophobic aromatic group and hydrophilic amide group)
esters less stable as ester linkage more easily broken
31
what are the 5 constituents in a la cartridge?
```
base hydrochloride,
vasoconstrictor,
fungicide,
reducing agent,
preservative
```
32
max dose of lignocaine
4.4mg/kg
1 cartridge per 10kg
44mg in one cartridge
as
1% = 1mg/100mg = 10ml/L
.:. 2.2mg (cartridge) of 2% lignocaine
2%=2mg/100mg = 20ml/L x 2.2= 44mg/ml
33
3 ideal post features
parallel
non threaded
cement retained
34
factors affecting suitability of post
```
length - 4-5mm GP remaining
width - less than 1/3 root width
ferrule of 2mm
extend below alveolar level
post:crown ratio> 1:1
```
35
post materials
metal - gold, stainless steel
fibre- glass, quartz
ceramic - zirconia, porcelain
36
core materials
RMGIC, composite, amalgam
37
principles of cavity prep
```
gain access
identify extent at adj
remove caries
remove unsupported enamel
resistance and retention form
```
38
what is the hybrid layer
prime and bond and conditioner working together make hybrid layer.
is interface between dentine and restorative material
conditioner- etch to expose dentine tubules and remove smear layer
primer- HEMA to support collagen fibrils and make space for bond
adhesive/bond - resin penetrates fibrils and makes resin tags
39
different types of dentine and how they affect bonding
primary - laid down during development. good to bond to. open tubules
secondary - formed during function. ok to bond to
tertiary- reactionary - mild stimuli or reparative - intense stimuli. poor to bond to - sclerosed or poorly organised tubules
40
what is the inorganic content percentage in dentine
70% calcium hydroxyapatite
41
icp?
intercuspal position
the position of best fit
between the maxillary and mandibular teeth. This is therefore
determined by the teeth themselves, not the maxilla and
mandible. There are two forms of ideal contact between two
teeth: cusp to base of fossa and tripod contacts.
42
guidance
```
the factors
which control movement in the mandible.
This includes the forward directions and
lateral directions. This guidance can be
from the Temporomandibular joint or the teeth themselves
```
43
rcp
retruded contact position- also called centric occlusion
44
reorganised approach?
when the objectives of restorations cannot be achieved in patients current ICP .:. need to use retruded contact position as is reproducible
45
diagram to show guidance
posselts envelope.
retruded arc - important as is determined by movements of TMJ. .:. is reproducible when occlusion is altered.
the movement is when the condyles are in their most superior position in the articular fossa
46
crown prep figures for
metal
ceramic
metal ceramic
```
metal - ceramic - metal ceramic
non functional - 1, 1.5, 1.3
functional - 1.5, 2.5, 1.8
shoulder - 0.5, 1, 1.3
chamfer - 0.5, 1, 0.5
```
47
crown fit advice to pt
The patients must be advised to floss and ensure the area is as clean as possible – this comes under oral
hygiene instruction. They must also be advised that crowns last on average 8 years but some up to 20. The
most common cause of failure is due to caries so this must also be told to the patient. The patient finally
must also be advised on post-operative sensitivity
48
veneer prep
4 staged -
incisal prep, buccal prep, interproximal extension and gingival margin
buccal prep-
0. 3mm cervically
0. 5mm mid buccally
0. 7mm incisally
gingival margin-
0.5mm into gingival sulcus no more
incisal prep-
can be feathered, window, incisally bevelled or incisally extended
49
materials used for inlays and onlays
gold type I and II
composite
ceramic
ceromer (belleglass)
50
pros cons of gold for inlayonlay
It has a high strength, will cast accurately and will
have a high polish. This means it can prevent plaque accumulation to itself and is suitable for bruxists.
It will not have a natural appearance however, it is expensive, may not retain well and must be cemented in
place, not bonded.
51
pros and cons composite for inlayonlay
Composite has good aesthetics and when used indirectly it will be very strong (as it can be light cured for
longer). It still will not be as strong as gold however. It will also have less polymerisation shrinkage than
direct composite so there is less microleakage and pain. It is also repairable.
There may however be pooling of bonding materials leading to poor bonding.
52
pros and cons of ceromers for inlayonlay
Ceromers are aesthetic and also they are more durable than composite. This is due to their increased
fracture toughness and wear resistance. They are also repairable, as with composites. An example of a
Ceromer is Belleglass.
53
pros and cons of ceramics for inlayonlay
A ceramic inlay or onlay will be aesthetic and will be wear resistant. It also will have a better bond strength
than composite therefore is good for poorly retentive cavities. It can also transmit forces more to the teeth
and there will be less marginal leakage (especially as the fit is better than composite).
All margins must be placed on enamel! Also the wear resistance could be bad as it could wear opposing
teeth! It must also need adequate bulk due to it's low fracture resistance. This means it may break easily on
try in or if it is too thin.
54
indications of onlay inlay
heavily restored teeth
repeated fracture of direct restorations
difficult obtaining occlusion
protection of remaining tooth tissue
55
try in of restorations
This should be done under Local Anaesthetic. The provisional must all be removed, including the cement
and the restoration should have a passive fit without being forced, without undue looseness and without any
blanching of the tissues.
If there is any problems with seating of the restoration, first the proximal area overextension should be
checked. This is because adjustment to this rarely works so the restoration needs to be remade. Then the
fitting surface should be checked. If there is seating failure a sandblasted surface can show up any high
spots. These will be shown as a shiny area. A yellow banded bur can be used to adjust high spots on the
inside only!
Another method to check the fitting surface is to use occlude spray. This is sprayed onto the fitting surface
then the restoration is seated in the mouth. The high spots will have metal showing through. This is very
messy however. Also Fit Checker can be used, this is less messy. It is a condensation cured silicone. It seats
inside the crown and high spots can be shown clearly. It can then be peeled off cleanly.
56
dahl appliance
used in cases of severe wear where more than 1/3 tooth surface loss.
works by discluding posterior teeth to allow over eruption of the posteriors
usually placed palatally on upper anteriors canine to canine
57
how to cement post
gi luting cement
| comp resin luting cement
58
how to remove fractured post
```
ultrasonic
Masseran kit
Eggler post removal
Stiegler forceps
Sliding hammer
cut out fibre posts
```
59
4 reasons for a post-core to debond
```
iiuc
incorrect cementation material
inadequate post preparation
unfavourable occlusion
contamination during cementation
```
60
3 reasons why a core would fracture from post
casting errors
inadequate ferrule
trauma
parafunction
61
3 reasons why a core would fracture from post
casting errors
inadequate ferrule
trauma
parafunction
62
principles of crown preparation
```
PRSMPA
preserve tooth structure
retention and resistance form
structural durability
marginal integrity
preserve periodontium
aesthetics
```
63
sequence of crown prep
1. occlusal reduction
2. separation
3. buccal reduction
4. lingual/palatal reduction
5. finishing
64
factors considered before placing bridge (5)
```
occlusion,
length of span
health of abutment teeth
oral hygiene
perio status
```
65
indications for adhesive bridge
missing teeth - usually single
good enamel quality
large abutment surface for bodning
minimal occlusal load
66
contraindications for adhesive bridge
```
LPPP
long span
poor quality enamel
parafunction
poor perio of abutment
```
67
active component of cement for porcelain crown
silane coupling agent- bifunctional molecule in comp resin cement
oxysilane groups hydrolysed to form -OH bonds which then form Si-O-Si with porcelain
organofunctional groups c=c bonds initiated by free radicals to form c-c with comp resin
or Covalent bonds with oxide groups on prcelian surface which is hydrophilic
Hydrophobic C=C reacts with silane in composite resin
68
how to cement metal crown?
comp resin luting cement
| MDP or META form c=oh bonds from c=c
69
features that could cause failure of conventional bridge
```
unfavourable occlusion
poor crown:root ratio
no parallelism
poor health of abutment tooth
poor oral hygiene- leading to caries
```
70
types of bridge
conventional
adhesive
cantilever
fixed moveable
71
factors to consider before using tooth XX as abutment
```
occlusal load
perio status of XX
crown root ratio
root morphology
root surface area
angulation
```
72
ante's law?
root surface area of abutment should be greater than or equal to that of the teeth being replaced with pontics
73
briefly describe how to cement resin retained bridge
TRY IN - check fit &aesthetics
SANDBLAST at chairside if not done already, 50 micron Aluminium oxide
CLEAN&ISOLATE clean retainer, isolate teeth
ETCH, BOND, etch, wash, dry, prime 30 secs, airdry
CEMENT w dual core luting cement
FIT press firmly
REMOVE XS with probe
APPLY oxygen inhibitor
CURE if required
74
2 alternative names for adhesive bridge
MARYLAND
| resin retained
75
4 pros 4 cons adhesive bridge
```
:)
little to no prep
low cost
low surgery time
no la
can be used as provisional
```
```
:(
metal can shine through
occlusal interference
can de bond
longevity uncertain
```
76
why is root morphology/form so important to assessing suitability of tooth as abutment?
if roots are divergent occlusal load is displaced improperly on retainer causing strain as long axis of tooth in relation to crown is altered
77
how to treat porcelain to improve adhesion?
etch with hydrofluoric acid
78
when is dual cure cement indicated?
thick or opaque indirect restorations need cementing
| light cannot penetrate
79
6 factors to consider pre implant tx
```
aesthetics
occlusion
smoking status
bone qual and quan
oh
pt motivation
```
80
main cavity design features of composite
no unsupported enamel
bevel at cavosurface margin angle (increasing area to bond)
no sharp internal line angles
81
main cavity design features of amalgam
```
no unsupported enamel
flat occlusal floor
undercuts for retention
cavosurface margin angle 90-120 degrees
retentive features like lock and key
```
82
3 reasons composite over amalgam
```
low thermal conductivity
aesthetics
supports remaining tooth tissue
minimal prep
sets on demand
marginal seal
```
83
technique for successfully placing composite
1. flowable at base - reduce contraction stress
2. incremental placement - low configuration factor
3. increments of <2mm - to make sure completely cured
84
problems with overhang amalgam
why it happens
tx
plaque trap/ food packing .. secondary caries.. gingivitis, perio, fracture of restoration
why - matrix band / wedge not placed properly, band not contoured and adapted well, inadequate condensation of amalgam
tx replace with better contoured amalgam or try and repair in situ
85
give 5 reasons (and their restorative solutions) of why a pt could be experiencing sensitivity and pain on biting (w no pathology or caries) after having a composite placed
1. occlusal height too high - use articulating paper when checking occlusion to adjust correctly
2. deep prep w/o liner placed- sensitive deep caries removal and RMGIC or CaOH liner placed
3. polymerisation contraction stress - use incremental placement to keep configuration factor low
4. comp not fully cured- "soggy bottom" >2mm increments- keep increments <2mm to prevent uncured comp
5. pulp irritated during prep - high speed w/ water then slow speed then use excavator carefully
6. cts- cracked tooth syndrome, diff diag, use tooth slooth, consider cuspal coverage
86
types of wear and their appearance
erosion- chemical wear not from bacteria, cupping, smooth polished surface, exposed dentine, loss of surface detail
attrition- tooth to tooth contact wear. incisal edge and contact point loss
abrasion- wear due to physical force e.g tooth brush, tsl shown at site of exposure
abfraction- wear due to eccentric occlusal forces. cervical fracturing/wear
87
how to assess erosion (3)
BEWE basic erosive wear exam
smith and knight
photos
models
88
% with tooth wear
60% adolescents
| 17% >70s
89
indications for tx of cervical wear lesions
- sensitivity
- aesthetics
- defective restoration margin
- plaque retentive cavitation
90
tx options for attritional tooth wear
1. dahl appliance- to allow overeruption of posterior teeth
2. orthodontics - to create interocclusal space
3. surgical crown lengthening - increase clinical crown height
4. ovd increased - occlusal splint
5. reorganised approach - icp to rcp when icp does not allow restorative options
DOSOR
91
indications for direct pulp capping and how to do it
indications:
- mechanical exposure of clinically vital and assymptomatic pulp
-exposure occurred under dam
-bleeding is controlled at exposure site
-exposure permits direct access with CaOH to pulp
• If dentine in close proximity to the pulp is to be removed and an exposure anticipated then dental dam must be placed immediately before proceeding any further.
* The size of the exposure is irrelevant as long as the tooth is isolated under rubber dam, vital, symptom free and there has been no history of pulpitis.
* Haemorrhage from the exposed pulp and any dentine chips should be washed away with copious irrigation with sterile saline.
* The cavity should be cleansed with 0.2% w/w chlorhexidine gluconate.
* The cavity is then blotted dry using sterile cotton wool pledgets. (Do not blow the exposure dry with a 3-in-1 air syringe).
* The exposed pulp should then be covered with hard-setting calcium hydroxide cement such as Dycal or Life.
* This in turn should be covered with a layer of resin-modified glass ionomer lining material, for example Vitrebond, and the restoration completed as planned.
92
19 yr old patient traumatic exposure 11 a few days ago, 2mm pulpal exposure. immediate management?
la
radiographs for path checking
soft tissue check, account for missing parts
pulpotomy as emergency procedure for mature permanent teeth until RCT can be started
la->dam+isolation->gain access hi speed round->remove coronal pulpal tissue->irrigate saline->hard setting CaOH dressing->hermetic seal->reassess next visit
93
fracture of tooth below gum line. why unrestorable?
subgingival fracture - v difficult/ impossible to restore satisfactorily
moisture control difficult -> secondary caries and failure rate increased. susceptible to bacteria gaining access
closed apex -> unlikely to regain vitality
94
pt has large MOD AM fracture, GP exposed, give two definite tx options
XLA
| Re-RCT if exposed >3/12 months + crown +/- post/core
95
nayyar core
amalgam core in pulp chamber, extending 2-3mm into root canals
96
4 extrinsic 4 intrinsic causes tooth discolouration
extrinsic-
dietary, smoking, chromogenic bacteria, CHX
intrinsic-
fluorosis, amelogenesis imperfecta, loss of vitality, restoration materials
97
how does vital bleaching with hydrogen peroxide work?
h2o2 breaks down to form h2 and o2.
| ho2 then forms - oxidising agent. oxidises tooth surface .:. breakdown in pigments and lighter colour shown
98
active ingredient in tooth whitening bleach. how does it relate to h2o2
carbamide peroxide
-> breaks down to h2o2 and urea.
approx 1/3 conc of carbamide peroxide is hydrogen peroxide.
10% CP = 3% H2o2
99
4 risks of vital bleaching
sensitivity (60% pt)
effect wears off
ST irritation
bonding problems
100
Pt presents with discoloured 11 no symptoms is worsening can remember trauma years ago.
1 how would you find aetiology, 2 what SI would you take and 3 how would you treat discolouration.
1 thorough history and clinical examination
2 vitality testing and PA radiographs
```
3
accept,
vital/non vital bleaching
porcelain veneer
direct/indirect composite
```
101
what 3 criteria must be satisfied before obturation
assymptomatic
chemomechanically disinfected
canals dried
102
3 constituents of GP other than gutta percha
zinc oxide
plasticisers
radiopacifiers
103
describe the function of a sealer
fill lateral canals
fill gaps between tooth and gp
provide hermetic seal
104
give 3 common sealers
epoxy resin
zinc oxide
calcium hydroxide CaOH
GIC
105
how do you assess obturation on a radiograph?
- length - 1-2mm from radiographic apex
- well compacted - no voids
- all canals filled
106
methods of obturation
cold lateral compaction
warm vertical compaction
thermafill
thermoplastic injection
107
why obturate?
provides apical and coronal seal
prevents reinfection
entombs any remaining bacteria
108
percentage of maxillary first molars with mb2 canal
93%
109
3 design objectives of endodontics
continuously tapering funnel shape
maintain position of apical foramen
keep apical foramen as small as possible
110
3 benefits of crown down technique (endo)
provides reservoir for irrigant
eliminates coronal interferences
facilitates removal of debris
reduces change in WL during apical prep
removes bulk of infected tissue
benefits of straight line access
keeps WL reference points
111
3 laws of pulp floor anatomy
colour - the pulp floor is darker in colour than the surrounding dentinal walls
symm 1 - except in maxillary molars, the canal orifices lie equidistant to a line drawn in a mesiodistal direction along the pulp chamber floor
symm 2 - except in maxillary molars, the canal orifices lie on a line perpendicular to a line drawn in a mesiodistal direction along the pulp chamber floor
112
3 laws of orifice location (endo)
1 orifices lie on the junction of the walls and floors
2 orifices lie on angles of wall/floor junction
3 orifices lie at terminus of root developmental fusion lines
junction
angle
terminus
113
why is sodium hypochlorite a good irrigant
| what % used in endo
- tissue dissolution agent- dissolves pulp, collagen, vital and necrotic tissue
- antimicrobial
3% used (0.5-6%)
114
5 reasons for irrigating during endo
1. lubrication
2. mechanical prep alone cannot remove all bacteria
3. access areas files cannot
4. flush out debris
5. remove smear layer
6. dissolves organic and inorganic content
115
Name another irrigant rather than NaHCl?
CHX
116
What is the smear layer comprised of?
organic pulp material and inorganic dentinal debris
117
Give 3 reasons for removing the smear layer.
Bacterial contamination
Prevents sealer penetration
Interferes with disinfection
118
Give 3 methods of removing the smear layer
17% EDTA
10% Citric acid
sonic and ultrasonic irrigation
119
Name two intracanal medicaments and their uses
Ledermix- corticosteroid and tetracycline paste
used for 5-7 days
mgmt of "hot pulp"
NS Ca(OH)2. used for 7 days
ph 11
antibacterial
may weaken root if left for long
120
Give 4 reasons of instrumentation of canals
1. removal of disinfected tissue
2. allow irrigant to reach root apex
3. create space for medicaments and obturants
4. retain root support and integrity
121
Correct protaper sequence?
```
ISO 10/15 - scout canal
S1 - shape coronal 1/3- goes to 2/3 WL
SX - widening coronal
10, 15,S1,S2 to working length
F1-5 to working length
```
122
Advantages of Pro Taper over K files
- shape memory
- reduced lateral pressure .:. reduced zipping, ledging
- Reduced No Instruments
- increased cutting efficiency
123
Name a rotary endo system
Reciproc
124
Name four envelopes of motion for endodontic files
| describe two of them
Filing
Reaming - insert file in, quarter turn to engage, pull out passively and repeat until no resistance felt.
Watch winding - quick back and forward oscillations of 30/60 degree w light apical pressure. used to reach working length
Balanced force technique- 60 degree clockwise to engage, then 120 degree turn to cut
125
Name three reasons a file might separate
torsional fatigue
torsional stress
CYCLIC fatigue
FLEXURAL stree
126
Draw the access cavity for max and mand, incisors (c+l), canines, premolars, molars
Answer on onenote surface
127
give 3 disadvantags to using handfiles to prep
time consuming
technique sensitive
increased number of instruments
mishaps -ledging, zipping
128
how long is the cutting flute of a ISO S.S file?
16mm
129
success rate for endo if...
- without periapical lesion
- with periapical lesion
- re-endo
paper for this?
w/o PA lesion 95%
w/ " 85%
re-endo 60%
sjogren et all, 1990
130
components of local anaesthetic?
```
base hydrochloride,
vasoconstrictor,
fungicide,
reducing agent,
preservative
```
131
max safe dose la
4.4mg/kg
1 cartridge per 10kg
```
1% = 1g/100ml
2% = 2g/100ml
2g/100ml = 20mg/ 1ml
20mg/1ml x 2.2 = 44mg in 2.2ml
44mg in 1 2.2ml cartridge
```
132
landmarks for idb
pterygomandibular raphe
coronoid notch and neck
contralteral premolars
133
alternative anaethesia techniques for mand posteriors
akinosi - closed mouth/ "tuberosity" technique.- good for trismus
gow gates - entering needle lateral side of condyle neck, mucous membrane mesial side of ramus.
134
how to manage pt with la administered to parotid
can either be immediate or delayed
if imm:
inform pt, reassure, provide with eye patch, advise to time to wear off will be ~3 hours, review
if delayed: wear off will be weeks or months
135
what is the shortened dental arch?
reduced dentition comprising of 4 occlusal units. reduced number or absent molars or premolars.
usually 5-5 u&l arches.
136
Why is shortened dental arch accepted?
function and aesthetics acceptable -
no increase in tmd
no decrease in occlusal stability
no increase in attrition
137
3 indications for sda
- missing teeth - posteriors
- good prognosis of remaining teeth
- pt preference
- limited resources
138
3 contraindications for sda
- tmd
- parafunction
- poor prognosis remaining teeth
- periodontal disease
- malocclusion
139
What is stable occlusion
when occlusal contacts help limit possibility of tooth movement (tipping, drifting, over-eruption)
140
What is the intercuspal position
the position that the mandible aims for upon end of chewing cycle.
where maxillary and mandibular teeth fit together best.
is determined by teeth
141
During chewing cycle describe the action of the working and non working side
working: rotation about vertical axis
| non working: translation; down, forward, in
142
Give 3 advantages of anterior guidance
- protects posterior teeth and restorations
- easy to reproduce
- relaxing effect on MoM
143
In normal function, what is the length per day of maximum intercuspation?
15 minutes/ day
144
what are the 5 requirements for occlusal stability?
- stable and even occlusion in ICP
- anterior guidance
- disclusion of all posterior teeth in mandibular protrusion
- disclusion of posterior teeth on working side in mandibular lateral excursion
- disclusion of posterior teeth on non-working side in mandibular lateral excursion
145
what are 4 signs of occlusal trauma?
```
pain not from infection
NCTSL
TMD
pronounced linear alba
tongue scalloping
fractured restorations/teeth
```
146
Draw and label Posselt's envelope
on onenote
147
What does each part of Posselt's envelope mean?
T : Maximum mandibular opening w/ condyles in full anteroinferior translation
R : maximum mandibular opening w/ condyles in most superior position in mandibular fossa (R-RCP: rotation about terminal hinge axis)
RCP: retruded contact position
ICP: intercuspal position
E: edge to edge incisors
PR: maximum protrusion
148
What plane of movement does the envelope depict?
sagittal plane
149
What is centric occlusion? Why is it important (3)
the movement of R to RCP, where condyles are in most superior position, and movement is about the terminal hinge axis.
Movement is determined by anatomy of TMJ, as a border movement and is reproducible.
Useful for registration in edentulous patients.
150
How can you assess occlusion intraorally?
shimstock (8 microns)
| thin articulating paper (20 microns)
151
indications for reorganised approach?
| what is different in reorganised approach?
when conforming to existing occlusion would not allow objectives of restorations to be achieved
icp occurs on retruded axis .:. ICP=RCP
152
hanau's quint
5 determinants that affect occlusal balance
1. condylar inclination
2. incisal guidance
3. occlusal plane inclination
4. cuspal inclination
5. compensating curve inclination
153
4 types of articulator
simple hinge
average value
semi adjustable
fully adjustable
154
functions of facebow
- to record relationship between maxillary plane and condyles
- to transfer the above relationship onto an articulator
- to allow for accurate mounting of the upper cast
- to record the upper anterior incisal angle against the horizontal reference plane
155
what is balanced occlusion
bilateral, simultaneous anterior and posterior contact of teeth in centric and eccentric occlusion
if occurs in natural teeth is considered premature contact and pathologic, is used in complete dentures for comfort when masticating, bruxism at rest, swallowing etc
156
types of facebow
kinematic - can produce exact result of location of condyles on terminal hinge axis
arbitrary- use an arbitrary value of location of condyles - e.g ear held or location on soft tissue (gsir)
157
what is the dahl concept?
concept in which a localised appliance or restoration is used to increase the interocclusal space for restorations.
technique: add composite platform on palatal side of incisors, allow dentoalveolar compensation (3-6 months), build up incisors
158
You are carrying out an endo. Suddenly pt feels intense pain and within minutes you notice a marked facial sweeling and profuse bleeding into canal from periradicular tissues. What is the most likely cause for these signs and symptoms and why?
Extrusion of sodium hypochlorite through root apex.
- due to high pressure injection, injecting too deep, locking syringe in canal.
Result of acute inflammatory reaction - can be oedematous +/- haemorrhagic.
can lead to tissue necrosis
159
immediate action after extrusion of NaHCl
```
LA for pain relief
irrigate canals with copious amount of saline
relax pt
reassure can be controlled
dress tooth with non setting CaOH
```
then>
priority given to pain relief, reduction of swelling and prevention of secondary infection
cold compresses first few days,
warm compresses for resolution of swelling and elimination of haemotoma after that
analgesic ibuprofen 400-600mg qds, paracetamol 1g qds
review within 24 hours
prescription antibiotics case specific
refer if severe
160
how do you prevent a NaOCl accident occuring (8)
1. careful preoperative radiographic assessment (ensure no open apices)
2. use rubber dam. use chx to test if leaking before irrigation
3. ensure all syringes are labelled correctly with adhesive labels
4. do not wedge needle in canal
5. silicone stop on needle 2mm before working length
6. do not fully fill syringe- easier to handle
7. depress plunger with index finger not thumb
8. make sure to build up tooth before endo if needed
9. bib and glasses worn
161
2 components of alginate
sodium alginate, calcium sulphate
162
what is impression compound
a) used for
b) made up of
used for primary impressions of edentulous arches
- as is too rigid to be used in dentate arches as undercuts would rip
reversible
resin, carnauba wax, stearic acid, talc
163
composition of alginate and their functions
sodium alginate - react with calcium sulphate
calcium sulphate - reactor- react with alginate salt
zinc oxide - filler
potassium titanium fluoride- gypsum hardener
diatomacous earth - filler
sodium phosphate - retarder. react with calcium sulphate
colourings, flavourings
164
What is the setting reaction for amalgam?
```
Ag3Sn = y
Ag2Hg3 = y1
Sn7Hg9 = y2
```
y + Hg = y + y1 + y2
165
what changes have been made to modern amalgam to improve it? (3)
1. high copper content (>12%)
copper reacts with tin to reduce availability of tin for y2 phase - as y2 has poor strength and abrasion resistance.
2. zinc not used- as reacts with water .:. poor marginal seal
3. Use of spherical cut
166
Advantages and disadvantages of amalgam
```
:) durable
high mechanical strength
radiopaque
long lasting
cheap
short placement time
rarely sensitive to clinical technique
```
```
:(
excessive tooth prep needed
marginal leakage
aesthetics poor
creep
mercury toxicity
high thermal conductivity
tattoo
```
167
benefits of modern amalgam (3)
less y2 - copper enriched
| .:. higher early strength, less creep, higher corrosion resistance
168
Purpose of zinc in amalgam?
As a scavenger -> that preferentially oxidises instead of other metals .:. preventing their oxidation and forming zinc oxide.
169
What negative can occur as a result of zinc presence in amalgam?
mechanism?
symptoms caused?
Interaction of zinc with saliva/ blood forms bubbles of hydrogen within amalgam. pressure builds up causes expansion
Zn + H20 -> ZnO + H2
Causing: downward pressure .:. pulpal pain, and forcing restoration to sit proud.
170
Pt presents with MCC in hand from upper central.
4 features of tooth that will predict tx prognosis
3 short term options for replacement
```
amount of tooth tissue present,
quality "
mobility
perio status
crown root ratio
```
```
tx:
re-cement failed MCC as temp crown
make protemp provisional crown- use non-eugenol temp cement
adhesive cantilever temp bridge
preformed provisional crown
```
171
4 pieces of info needed by lab for bridge fabrication
bridge design
master impressions
bite registration
shade of teeth
172
how does caries present differently radiographically v clincally?
clinically presents deeper
173
components of composite?
```
RGPSL
resin - bis-GMA
glass filler - Quartz
photoinitiator - Camphoquinone
silane coupling agent
low weight dimethacrylate - TEGMA
```
174
4 different types of composite
```
microfilled
macrofilled
nanofilled
hybrid
flowable
```
175
clinical disadvantages of composite and how are they minimised?
polymerisation contraction shrinkage - account for C-factor during placement
moisture sensitive - good moisture control, dam
post op sensitivity- correct placement and bonding, lining used
soggy bottom- increments of <2mm cured each time
176
average biological width
define
approx. 2mm from alveolar crest to sulcus of gingiva
the dimension of soft tissue which is attached to the tooth coronol to the crest of alveolar bone
177
crown prep reductions for
all metal: ax 0.5mm, chamfer 0.5mm
mcc: buccal shoulder 1.5mm, palatal 0.5mm
all ceramic: 1-1.5mm
occlusal 2mm in all
178
define: indirect retention
part of RPD, that assists direct retainers in preventing displacement of distal extension denture bases by functioning through lever action on opposite side of fulcrum line
179
define: fulcrum line
imaginary line in which a RPD tends to rotate, passes through terminal abutments
180
features of nayyar core
retention obtained from undercuts in divergent canals and pulp chamber
2-4mm GP removed from canal, replaced with amalgam
181
stainless steel file in 20 degree curved canal of molar, give 4 complications that could occur
```
zipping,
perforations,
blockages,
ledges,
fractured instruments
```
182
6 goals of crown prep
1. preserve tooth structure
2. resistance and retention form
3. structural durability
4. marginal integrity
5. preserve periodontium
6. aesthetics
