fixed pros Flashcards
When recording an impression for fixed prosthodontics, you apply the light bodied-PVS to:
a. the prepared tooth
b. the prepared tooth and adjacent teeth
c. the impression tray
d. the prepared tooth and all teeth in the arch
D - prepared tooth and all teeth in the arch
Your patient returns for the fit appointment of a full contour crown on the UR5 which is vital. The pt reports severe spontaneous pain from the tooth which wakes them at night and is painful to bite on.
What do you do next?
a. remove the provisional restoration
b. fill the definitive restoration
c. apply a desensitising agent.
d. special investigations
D - special investigations
You have just made your custom-made provisional restoration and found the occlusal aspect is below the minimum thickness for the material.
What do you do?
a. record the impression with heavy and light bodied PVS
b. cement the provisional with TempBond Clear
c. adjust the prep and make a new provisional
d. place gingival retraction cord to compensate
C - adjust the prep and make a new provisional D
For the twin cord gingival retraction technique, which cord is removed prior to recording the impression?
a. size 000
b. size 00
c. size 0
d. size 1
B - size 00
After tooth preparation for a full gold crown, what should be done next?
a. record the impression
b. facebow record
c. fabrication of the provisional restoration
d. cementation of the crown
C - provisional restoration
For the twin cord gingival retraction technique, which is placed first?
a. size 000
b. size 00
c. size 0
d. size 1
A - size 000
You have a well fitting MCC. There is good height and retention-resistance form to the preparation.
Which of the following cements would be the most appropriate?
a. aquacem
b. panavia 21
c. calibra
d. rely x unicom
e. rely x ultimate
A - aquacem
True or False
A total etch bonding system requires that you need to etch the tooth prior to applying bonding agent?
True
True or False
Oxyguard is usually used with Panavia 21
True
You are planning to cement a veneer for a patient.
How long should the initial light cure be?
a. 5 seconds
b. 10 seconds
c. 30 seconds
d. 2 mins
B - 10 seconds
You plan to cement an Emax crown with RelyX Unicem.
When and where should you apply the silane coupling agent?
a. to the tooth prior to trying in the crown
b. to the fitting surface of the crown prior to trying in the crown
c. to the occlusal surface of the crown after trying in the crown
d. to the tooth after trying in the crown
e. to the fitting surface after trying in the crown
E - to the fitting surface after tying in the crown
Calibra is an example of what?
a. GIC luting cement
b. resin cement
c. RMGIC luting cement
d. 1 step bonding system
B - resin cement
Which of these cements is recommended for cementing a resin-bonded bridge on the restorative clinic?
a. calibra
b. panavia 21
c. zinc phosphate
d. aquacem GIC luting cement
e. rely x
B - panavia 21
Which of these cements is recommended for cementing veneers on restorative?
a. calibra
b. panavia 21
c. zinc phosphate
d. zinc polycarboxylate
e. rely x
A - calibra
Which of these cements is recommended for cementing an Emax ceramic inlay on restorative?
a. calibra
b. panavia 21
c. zinc phosphate
d. zinc polycarboxylate
e. rely x unicem
E - rely X unicem
The main root filling material commonly used to fill root canals is what?
a. silver points
b. acrylic resin
c. zinc oxide eugenol
d. gutta percha
D - gutta percha
What is the limit on numbers of indirect restorations that can be provided in 1 course of treatment under the NHS?
a. 1
b. 2
c. 3
d. unlimited
D - unlimited
How many UDAs would you receive for a root filling with cuspal coverage onlay?
a. 1
b. 3
c. 12
d. 15
C - 12 UDAs
How much would you usually quote a patient who requires root filling?
a. £26.80
b. £73.50
c. £319.10
C - £319.10 (for the crown after but usually comes under band 2)
What NHS Band does a premolar root filling fall into?
a. band 1
b. band 2a
c. band 2b
d. band 2c
e. band 3
C - band 2b
If a post is necessary to retain a core, at least how much root filling material should remain in the apical third of the tooth to provide an apical seal?
a. 1mm
b. 4mm
c. 8mm
d. half the canal length
B - 4mm
If placing a nayyar core in a tooth, you should aim to remove up to how much endodontic filling material from the root canal?
a. removal of GP is not neccessary
b. 1mm
c. 4mm
d. 8mm
C - 4mm
A patient arrives in your surgery with a lower incisor fractured at gingival level.
What is the prognosis for this tooth?
a. very poor
b. reasonable
c. good
d. excellent with modern restorative techniques
A - very poor
A study by Reeh et.al found that an MOD cavity prep reduces the stiffness of a tooth by what percentage?
a. 10%
b. 25%
c. 34%
d. 63%
D - 63%
What is the minimum depth of a ferrule that should be incorporated into a crown preparation?
a. 1mm
b. 2mm
c. 3mm
d. 5mm
B - 2mm
When placing an intracanal medicament, which type of calcium hydroxide is used?
a. liquid
b. non-setting (e.g: hypocal/ultracal/calcipast)
c. setting (e.g: dycal)
B - non-setting
Wave One Gold Primary has a tip diameter of which ISO size?
a. 10
b. 15
c. 20
d. 25
e. 30
D - 25
At which anatomical point should the biomechanical preparation terminate?
a. apical constriction
b. apical foramen
c. radiographic apex
d. 0.5mm beyond the root apex
A - apical constriction
What diameter are the dentinal tubules close to the pulp?
a. 1-1.5 microns
b. 3-4 microns
c. 5-8 microns
d. 10-14 microns
B - 3-4 microns
Which nerve fibres are responsible for dull throbbing pain associated with irreversible pulpitis?
a. A beta
b. A delta
c. C fibres
C - C fibres
(unmyelinated, slow conduction, small - transmit pain / temperature sensations)
What is the shape of the access cavity for the upper and lower premolars?
a. triangular
b. oval
c. round
d. rectangular
B - oval
The anterior tooth most likely to display 2 canals is:
a. maxillary central incisor
b. mandibular central incisor
c. maxillary lateral incisor
d. mandibular canine
B - mandibular central incisor
Which tooth has 2 canals 90% of the time?
a. maxillary central incisor
b. maxillary lateral incisor
c. maxillary canine
d. maxillary first premolar
e. mandibular lateral incisor
f. maxillary second premolar
g. mandibular first premolar
D - maxillary first premolar
What concentration of sodium hypochlorite will you use on clinic with LUDH when providing endo tx?
a. 0.2%
b. 1%
c. 2%
d. 5.25%
e. 17%
B - 1%
What is the most appropriate length of your irrigation needle in a tooth with a closed apex?
a. 1mm long of estimated working length
b. at the confirmed WL
c. 1mm short of confirmed WL
d. 2mm short of confirmed WL
e. 2mm short of ESL
D - 2mm short of confirmed working length
Before carrying out an indirect, which 4 preoperative records are needed?
- recent PA
- vitality / sensibility testing
- study models
- occlusal assessment
10 contraindications when providing indirect restorations:
- inability to achieve adequate ferrule
- insufficient clinical height to retain crown
- high caries risk / active caries
- active pulpal / periradicular / periodontal disease
- unfavourable occlusion or toothwear
- unfavourable crown : root ratio
- unretentive abutment
- technical issues (inaccessible via crowding, PE, rotated), limited mouth opening, unable to tolerate impressions
- unrealistic pt expectations
- past history of failure
If the base of a cusp is ____ mm or less, consider providing coverage for that cusp.
3mm
In the case of a root filled posterior teeth, which kind of coverage is recommended?
full occlusal coverage
Define retention form:
Features of the prep which prevent the restoration from being dislodged along the path of insertion / withdrawal.
Preparing along the long axis of the tooth allows which structure to dissipate occlusal forces better?
the periodontal ligament
What is the value of a clinically achievable angle of convergence?
10-20º (but ideal is 6º)
A minimum crown height of ___ mm is advised for conventionally retained restorations on molars and ___ mm on other teeth.
a - 4mm
b - 3mm
Where is the first plane located?
Parallel with the long axis of the tooth allows which- cervical 1/3.
(top part)
Where is the second plane located?
In the middle and incisal 1/3 following the external contour of the tooth.
How does resistance form differ to retention form?
Retention form is features which resist displacement along the path of insertion / withdrawal, whereas resistance form is features which resist displacement along an axis other than the path of insertion / withdrawal.
Margins should be placed on which kind of tissue?
sound tissue - avoid restorative materials unless impossible (sound composite preferred).
Which part of the tooth is the most susceptible to caries and so should therefore be avoided when placing the margins of an onlay?
contact points
Which of the 3 types of margins are preferable and why?
supragingival margins - easily cleansible, easy to prepare, take impression of and finish.
On anterior teeth, the labial margin should be placed where to help with aesthetics?
equi-gingivally
Where sub-gingival margins are indicated, where should they remain and why?
In the gingival sulcus (0.5mm) so they don’t impinge on the epithelial attachment.
In the case of sub-gingival margin placement, which condition may present similarly to gingivitis?
supra-crestal attachment invasion
What are the 3 translucencies of lithium disilicate (e.Max) restoration available?
- high translucency
- low translucency
- opaque
What are the 3 different types of metal available when producing a metal ceramic indirect?
- non-precious alloy - cobalt chromium
- precious alloy - palladium
- ceramic component - feldspathic porcelain
Veneers can be provided directly or indirectly.
What materials would be used for each?
direct = composite
indirect = composite or ceramic
In which part of tooth structure should a veneer prep remain in and why?
Remain within enamel for maximum bond strength.
Indications for Veneers:
- repair chipped / fractured teeth
- closing diastemas / spacing
- peg lateral incisors
- intrinsic or extrinsic staining resistant to tooth whitening
- mild enamel hypoplasia
- TSL (erosion / abrasion)
Contraindications for Veneers:
- unrealistic expectations
- lack of quality enamel
- pre-existing large restoration
- inability to achieve dam isolation
- severe crowding
- unfavourable occlusion
- parafunctional habits
- high lip line
- active caries / perio
- inadequate OH
What occlusal classification is considered unfavourable occlusion?
edge-edge contact
or
class III
Onlays can be made from which 3 materials?
- gold
- ceramic (lithium disilicate)
- composite
The decision to break a contact point should be made on what basis?
If doing so would mean finishing on a contact area and creating a plaque retentive area.
What piece of equipment should be used to assess if the base of the cusp is 3mm or less?
Iverson Gauge
Indications for Onlays:
- teeth with large restorations
- badly damaged teeth which have lost their peripheral rim
- teeth with weakened cusps which may fracture without occlusal protection
- restore correct occlusal plane
- aesthetic considerations
- support the crown of an endo-tx tooth
Contraindications for Onlays:
- heavy occlusal forces
- deep subgingival preparations
- lack of quality enamel
- no dam isolation
Which shade guide is used for onlays?
vita classic
How much incisal reduction is required for an anterior MCC?
2mm
How much occlusal clearance is needed for a posterior MCC in areas of porcelain or metal only?
porcelain = 1.5mm
metal only = 1mm
(porcelain thicker than metal)
How big is a shoulder margin?
1.2mm
How big is a chamfer margin?
0.5mm
3 contraindicated restorations for Lithium Disilicate:
- cantilever bridges
- posterior bridges (molars)
- bridges spanning over 3 units
Which shade guide is used for bridges?
vita classic
Which material is used when taking an impression of the finished preparation?
PVS (silicone)
2 types of temporary custom crown material:
- integrity
- densply
Process of temporising with a prefabricated crown:
- polycarbonate directa crown - roughen internal surface.
- reline with integrity/densply
Which 2 materials would a lab fabricated provisional crown be made out of?
composite or acrylic
Which cement should not be used when cementing a provisional inlay / onlay?
GIC cement
Which cement should be used when cementing a temporary?
Tempbond NE - non-eugenol.
Which value retraction cord is larger - 00 or 000?
000 is smaller: placed first and then removed before imp taking.
Which material should be used when taking an impression of the opposing arch?
alginate
When cementing a conventionally retained restoration (FGC or MCC), which cement should be used?
preferred: GI luting cement, aquacem, densply
- can also use poly F (zinc polycarboxylate) or rely x unicem.
Indications for RBBs:
- small edentulous span
- unrestored / minimally restored abutments
- favourable occlusion
- long clinical crown
- hypodontia
Indications for RBBs:
- small edentulous span
- unrestored / minimally restored abutments
- favourable occlusion
- long clinical crown
- hypodontia
Contraindications for RBBs:
- active caries and perio disease
- lack of enamel
- heavily restored abutment teeth
- unfavourable occlusion
- compromised crown:root ratio
- unable to put on dam
- parafunctional habits
- poor OH
Which type of cement should be used to bond an RBB?
panavia 21
Which type of cement should be used to bond a lidi inlay/onlay and crown?
RelyX unicem
Which type of cement should be used to bond an All Ceramic Veneer?
Calibra (densply)
Examples of non-adhesive luting cements:
- zinc phosphate
- zinc polycarboxylate
- glass ionomer cement
Examples of adhesive resin cements:
- calibra universal
- panavia 21
- rely x unicem
Which shade guide is used for an MCC?
3D master shade guide
What 2 types of restoration is calibra usually used for?
inlay/onlay
veneers
Which type of restoration is panavia 21 usually used for?
RBB
What is a lumineer?
Thin veneer (similar thickness to a contact lense) made from cerinate porcelain.
5 types of articulator:
- hand
- simple hinge
- fixed average value
- semi adjustable
- fully adjustable
FAV measurements:
condylar guidance - 30º
intercondylar distance - 100-110mm
incisal guidance angle - 9-12º
How much coronal tooth structure is removed during a full coverage crown prep?
63-72%
Which piece of equipment is used for measure occlusal thickness?
Iverson Gauge
3 types of conventional bridges:
- fixed-fixed
- cantilever
- fixed movable
Which 2 components form a hybrid bridge?
conventional + adhesive
4 treatment options for missing teeth?
- leave and accept space
- dentures
- bridge
- implant
Define Span:
space to be restored
3 types of RBB wing design:
- rochette (mechanical retention with holes)
- maryland (micromechanical retention)
- virginia bridge (medium mechanical retention)
Survival rates of RBBs:
87% over 5 years
80% over 10 years
What is meant by a cantilever bridge?
One or more abutment teeth on 1 side of the pontic.
What is meant by fixed-fixed bridge?
supported by abutment teeth on either side of the pontic
In which 2 situations are fixed moveable bridges used?
- short span
- where opposing proximal walls of the abutment can’t be prepped parallel.
What is a ridge lap / full saddle?
Where the pontics overlap the buccal and palatal surface fo the ridge.
What is the modified ridge lap?
Where the pontic doesn’t contact the palatal aspect - used for anterior teeth.
RBB Indications:
- young pt
- in tact abutment tooth
- short span (1 pontic)
- single saddle
- good ridge form
- moderate loading
- long clinical crown
RBB Contraindications:
- insufficient enamel for bonding
- high caries risk
- poor OHI
- unfavourable occlusion
- short clinical crowns
- long span
For longer span bridges up to 4 units, which type of bridge would be indicated?
conventional bridge (fixed)
Describe Antes Law
The root surface area of abutment teeth should equal or be greater than the teeth to be replaced by pontics.
Which 3 special investigations are needed before starting bridgework?
- vitality testing
- PA
- study models
Favourable Bridges
anterior > posterior
cantilever > fixed-fixed
maxillary > mandibular
3 materials used for temporary bridges:
- acrylic
- bis-acryl composites
- restorative composites
True or False:
All fixed movable bridges are contraindicated in long spans.
True
True or False:
Cantilever resin-retained bridges are not preferred over fixed-fixed design because they are mechanically weaker.
False
True or False:
When using conventional fixed-movable bridges, the pontic is connected ridgidly to the smaller retainer at one end and via a moveable connector to the larger retainer at the other.
False
True or False
A pier abutment is a terminal abutment of a long span bridge.
False - it is a natural tooth between 2 edentulous spaces.
True or False:
Fixed-moveable bridges can overcome the problem of divergent abutments.
True
True or False:
With the introduction of modern resin cements, resin-retained bridges can also be used confidently as long span bridges.
False
What provides the ferrule effect?
Coronal Dentine
(the ferrule effect is when a band of natural tooth is used to reinforce the structure by increasing the resistance and stability of a restored tooth)
How much minimum dentine height is needed for an effective ferrule?
2mm
True or False:
The wider the post diameter, the more retention it will have.
False
True or False:
Post retained crowns have the poorest performance as bridge abutments.
True
True or False:
Roots that are broader buccolingually are more retentive than those with round cross section.
True
True or False:
In cases with gingival recession, the increased clinical crowns length would provide extra retention and support to the bridge.
False
True or False:
Shorter roots of teeth with wider surface area provide the same strength and stability to smaller teeth with long roots.
False
True or False:
Porcelain material has low tensile strength and high toughness when compared to other ceramics.
False
True or False:
Base metal alloys are the best materials used in the fabrication of bridge substructure.
True
How would you overcome the weakness of porcelain materials?
Build over the metal or strong ceramic core.
In relation to dental porcelain, which of the following is true?
a. can fail as a result of micro cracks
b. increasing the porcelain thickness will provide the required support to retain a crown for a short clinical crown
c. are stronger under tensile loading and weaker under compressive loading
d. can be finished in thin sections
e. have weaker outer than inner surfaces
a - can fail as a result of micro cracks
What is the brand name of custom-made chairside bisacryl provisional restoration material?
integrity
What is the purpose of immediate dentine sealing?
Applying the agent to freshly cut dentine after crown prep reduces the risk of loss of vitality as dentine tubules are sealed.
At what angle is the functional cusp bevel placed at to the prep?
45º
What is the minimum crown height required for an ACC?
4mm
IPS e.max is a brand name for which material?
lithium disilicate
When preparing a veneer, the chamfer is taken up to the contact points but they aren’t broken.
What is this margin known as?
gingival elbow
What are no prep veneers known as?
lumineers
For fixed-fixed bridges, occlusal forces are applied more to which retainer?
distal
Which pontic design requires surgical preparation?
ovate
After the successful try in of an MCC and disinfecting in pro form for 10 mins, what should be done prior to cementation?
send to lab for sandblasting of intaglio
After successful try in of porcelain restoration and disinfection, what should be done prior to cementation?
- send to lab to be etched with 5% hydrofluoric acid for 8 mins
- silane coupling agent applied to intaglio on clinic
After successful try in of LiDi restoration and disinfection, what should be done prior to cementation?
- etch with 5% hydrofluoric acid for 20 seconds
- silane coupling agent applied to intaglio
Which type of occlusion may not require prep for an RBB?
class II div I
Which type of metal is used for RBB framework?
cobalt chrome
What reduces the fracture propagation of porcelain?
glaze
What is the best option for a pt with missing laterals and which tooth would be the best abutment?
RBB - use the 3 as an abutment.
Why is occlusal reduction important during crown preparation?
To create sufficient space for the crown material without interfering with occlusion.
Why is a non-rigid connector used in long-span bridges?
To prevent stress on abutments caused by differential tooth movement.
