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Crown And Bridge Flashcards

0
Q

What are the advantages of a 3/4?

A

More conservative than full gold crown or PFM
Assess the accuracy of marginal fit easily
Allows pulp testing from buccal cusp
Allows natural Appearnce of tooth to she

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1
Q

When is a 3/4 gold crown indicated?

A

On a tooth where the lingual cusp has been lost and would compromised the remaining core if thr buccal cusp has to be prepared for a PFM

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2
Q

What are the disadvantages of 3/4?

A

Sides of crown can splay if heavy loads applied and stengh thing features not incorporated
Greater marginal area can lead to Increaed microleakage

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3
Q

What are the uses of 3/4 gold crown?

A

Heavily restored tooth with intact buccal cusp
Conventional bridge retainer
Tooth wear
Part of treatment plan for denture

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4
Q

What assessment would you do on the tooth before placing 3/4?

A

PROVE

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5
Q

How can the resistance and retention form of the 3/4 crown be improved?

A

Incorporate slots and grooves

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6
Q

What is the disadvantage of the slots and grooves?

A

Increase the complexity of cavity since must all be parallel

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7
Q

What is the stage of 3/4 gold crown prep?

A
  1. Occlusal reduction and Bevel
  2. Axial reduction
  3. Proximal surface groove and slot
  4. Occlusal grove
    5 finish
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8
Q

How do you do the occlusal reduction 3/4?

A

Functional cusp: 1.5mm

Non : 1mm

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9
Q

What is the purpose of the reverse bevel 3/4?

A

Aka Functional cusp bevel

Brings cusp back in line, offers resistance to oblique forces

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10
Q

Which two bevels are placed on the 3/4 crown?

A

Functional and no function

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11
Q

What type of finish is at the gingival margin of a 3/4?

A

Chamfer

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12
Q

How much is the axial reduction ?

A

0.7-1.0mm

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13
Q

What taper should the 3/4 hVe?

A

3-4 degrees

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14
Q

Where do you place the slot on the 3/4 prep?

A

In the filling

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15
Q

Where do you place the groove in the 3/4 ?

A

Not commonly

Placed in teeth that are heavily restored and subjected to tooth wear and placed into natures tooth

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16
Q

What does the occlusal grove help with in 3/4?

A

Resistance and strengthened the casting to cannot splay
Aids retention and resist crown dislodgement

Should be placed as far buccal as possible in Area of fissure

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17
Q

When would you do the contemporary design for 3/4?

A

When cementing with super bond and panavia bit need to sand blast or oxidised fit surface of gold

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18
Q

What does super bond have?

A

4 META

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19
Q

What are the indication for veneers?

A 
Alter the shaoe and size of tooth
Close diastema
Align mal aligned teeth
Mask areas of Hypoplasia and hypo calcification 
Mask dis coloured teeth
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20
Q

What are the advantages of veneer over crown?

A

Less destruction
No LA
Easier to record impressions
No need to provisional restoration

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21
Q

What are the disadvantages if a veneer over a crown!

A

More challenging to place a veneer on only one tooth and get good shade match
Try in is difficult
Luting is multistage and takes time to finish well
Poor prep can lead to porcelain fracture

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22
Q

How much should you reduce the labial surface by on a veneer?

23
Q

What is the purpose of labial reduction on a veneer?

A

To avoid over contoured prep

24
How many planes should you prepare the labial surface for a veneer in?
3 Gingival plane Mid labial plane Incisal plane
25
Where can you place the gingival margin of the veneer?
Subginginval Equigingival Supra
26
Where should the proximal margins be placed for a veneer?
Just Labial to contact point but can consider extending round the contact when veneer is used to close a diastema
27
When would you bring the promxila preparation of a veneer interpromximal?
When recession present | Closing a diastema
28
What are the options for the incisal edge of a veneer?
Over lapped Overlap But joint
29
What are the advantages of restoring an edentulous ridge?
``` Appearnce Occlusal stability Masticatory effeciency Speech Psychological ```
30
What are the disadvantages of restoring an edentulous ridge?
``` Damage to toot and pulp Risk of Sedondary caries Failures Cost Periodontal effect ```
31
What general factors about the patent do you need to consider before placing a bridge?
Attitude: Age: young teeth have large pulps Confidence: some patient lack confidence with dentre Occupation: contact sport players do not give bridge, public speakers and singers give bridge and wind instruments too Medical: epilipetics: consider fixed appearance: high lip line, loss of tooth and bone an denture maybe better OH: perio must be stabilised, bridge maybe better for perio Disturbuton of missing teeth: multiple missing teeth consider denture Occlusion: diffucult for denture in class 2/1
32
What local factors do you need to consider before placing a bridge?
Adjacent teeth: sound or heavily restored, vital, tilted or rotated, bone support and perio Oppsing dentitions: presence of over eruption,mapping of tooth wear, occlusal stops and crowding Edentate ridge: degrees of resorption, condition of ridge, correct space for lost teeth
33
What do you need for treatment planning?
``` History Mounted study models Periaplcals Bite wings Pocket depth Vitality Crown and root ratio ```
34
What are the options for provisional restorations?
Lab made | Chair side
35
How are the chair side provisional restorations made?
Using higher acrylic (trim) Mould of mouth or from study models and then make vacum formed PVC stent
36
What are the three requirements for provisional restorations?
BAM Biological Aesthetic Mechanical
37
What should you use to cement the provisional?
ZnO eugenol
38
What can you consider getting made before the final bridge?
Metal try in Can try this and assess - seating - margin quality - occlusal stop - interference in occlusion
39
What are the clinical problems if the bridge fails to seat?
Preparation errors: undercuts on teeth or not paralle Impression error: incorrect tray Temp errors: allowed over eruption, some Luting cement stillln prep
40
What are the lab errors related to filling to seat?
Cast and die: porous or damage Wax pattern : distorted, no separator, no reservoir Investment: needs to compensate for setting expansion, hygroscopic expansion and thermal expansion Casting: insufficient temp of investment and porosity of sprue, alloy too high temp Finishing and polishing: trim margins, distorted since thing nodules on fit surface
41
What can cause a rough fit surface of a lab made commonest?
Breakdown of investment or weak | Cracking of investment
42
What do you do if bridge fails to seat?
Check fit surface for imperfections Check contacts for over contoured Section metal frames work through Pontic Re unite with duraly and recheck in mouth
43
What can you consider doing once you happy with with final bridge and before cementation?
Can consider temp cementing it using ZOE with 50% modifier paste This enables minor tooth movements Patient can inspect the crown Adjust any occlusal interferences
44
Why are bridges sometimes difficult to seat?
Hinge hydrostatic pressure due to large surface area and paralle
45
What should you check on the bridge?
Margins Occlusion Gingival health Mechanical integrity
46
How many bridges failed after 15 years?
33%
47
How many bridges failed after 10 years?
<5% abutment extracted
48
Wheh should a provisional bridge be made?
Before the impression of the bridge prep to enable checking that you have reduced the teeth enough
49
Why may provisional bridges be placed long term?
Ppfollwing pre prosthetic surgery | Assess healing of endo or perio
50
What are the biological requirements of a provisional restorations?
Biocompatible Non exothermic Stabilise tooth position eg prevention of over eruption or tilting
51
What are the mechanical requirement of a provisional restoration?
Attain rubbery stage quick Rapid hardening Suffering strength to resist wear and fracture Strong in thin sections
52
What are the aesthetic requirements of a provisional restoration?
Tooth coured Range of shades Surface texture and staining possible.
53
What are the resins available for provisional restorations?
Acrylic: powder and liquid. Powder PMMA beads + peri oxide. Liquid is MM monomer +activator Higher meathcrykate trim: powder and liqueurs. Powder: PMM beads + peri oxide, liquid: isobutylmethacrylate + activator Epimine eg Scutan: paste and liquid p. Paste: imine pre polymer + poly amide filler and liquid : soul phonic acid ester Composte eg protemp: 2 pastes methacrylic acid ester + filler
54
How does the lab made the provisional restoration ?
Minimal deoth th prep and the heat cured acrylic resin by lost wax technique an then relines at chair side using trim Ad: custom shape of retainer and Pontic, good strength, can be used for long term Dis: cost and must be made in advance if tooth prep
55
How can you make provisional restorations chair side?
Using Higher acrylic and take a mould from the mouth using ROD of waxed study model then fill PVC stent with matersl Ad: cheaper, made on same day as abutment prep, strong enough to last until final bridge,clinician can check if sufficiently reduces the prep Dis: limited customising of Pontic and retainer

Restorative (45 decks)

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