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B2B > Biomimetic Dentistry > Flashcards

Biomimetic Dentistry Flashcards

1
Q

What are guided preps and how do they work (veneer work)

A

“working from final form”
Biomimetic concept to preserve enamel
Prep the teeth with depth-cutting burs through the provisionals, this ensures you’re only taking off a very small amount of enamel.

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2
Q

What is the principle of biomemetic restorations (3)

A

Restore teeth to full function by creating hard tissue bond that allows functional stress to path through tooth

  • adhesive indirect restos distribute stress, unlike traditional alloy restos and cemented crowns
  • coronal tissue of the tooth acts as support for the bonded tooth-resto complex
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3
Q

Factors influencing enamel bonding (3)

A
  1. Surface wettability of adhesive agents
  2. Surface contamination
  3. Water
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4
Q

Why is dentine harder to bond to? (3)

A
  • more water than enamel
  • hydroxyapatite is randomly arranged in an organic matrix whereas enamel is patterned
  • Smear layer makes wetting of dentine by the adhesive more difficult
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5
Q

What does dentine bond strength depend on

A

Depth- less effective deeper you go due to change in diameter of tubules (permeability)

Age- less collagen, less tubules

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6
Q

When are calcium chelators used? Example?

Biomemetic

A

Remove smear layer without demineralising the dentin layer

used when dentine bonding as alt to phos acid

Ex. EDTA

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7
Q

2 reasons why you should bond into moist dentine

A
  1. prevent collagen collapse
  2. acetone in the bond is hydrophillic, will chase the water into tubules -> better bond strength
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8
Q

Why may dentine bonding fail? (3)

A
  1. contamination with fluids
  2. structural changes in dentine
  3. Lower penetration of bonding agent due to premature evaporation of solvent -> thickening
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9
Q

Purpose of IDS (5)

A
  1. Create interdiffusion / hybrid layer
  2. Protects tooth from contamination, bacterial leakage, and remnants of temp cement
  3. Reduces hydrodynamic water mvmt in tubules, minimising sensitivity
  4. Thickness of hybrid layer prevents collagen collapse during imps/cementation
  5. Allows for maturation of hybrid layer during provisionalisation
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10
Q

Why is IDS “immediate”?
What structure does it mimic?

A
  • Bond btw monomers and dentine mimics the DEJ
  • “immediate” bc freshly prepped dentine is uncontaminated, thus ideal for resin infiltration
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11
Q

What types of preps strongly benefit from IDS (2)

A

Short clinical crowns
Tapered preps

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12
Q

Should final impressions be taken before or after IDS

A

After

Otherwise resto will not fit properly, poor margins

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13
Q

Why should you wait 1-2 weeks before bonding to IDS

A

Need time for hybrid layer maturation
- less susceptible to polymerisation shrinkage

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14
Q

Should light cure or dual cure DBA be used with IDS?

A

LC DBA’s if IDS used

Dual-cure have higher levels of polymerisation and colour instability- thats why we only use dual cure when LC not possible (posts, opaque crown)

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15
Q

How to identify exposed dentine in veneer preps

A

Shortly etch (2-3s) the tooth surface and rinse
- enamel will be frosty
- dentine will be glossy

after this etch, if there is dentine, it will need to be re-prepped to expose fresh layer of dentine before being etched again for DBA application

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16
Q

Adhesive technique of IDS

A
  1. Etch immediately after prep (phosphoric acid)
  2. rinse, suction excess water
  3. Primer, wait to evaporate
  4. DBA applied, excess solvent suctioned, LC
  5. glycerine jelly applied, bond cured again through jelly (polymerizes oxygen inhibition layer)
17
Q

What is the best bonding generation for IDS

A

Gen 4-
3 bottles
total etch technique
research says is most favourable

however 2 bottle can still be used

18
Q

Why is glycerine jelly used in IDS to cure the bond

A

polymerizes the oxygen inhibition layer
- Prevents interaction with impression materials, esp polyether

19
Q

What provisionals to avoid after IDS

A

Maximum 2 weeks

  • Avoid resin-based cements
  • NO EUGENOL
  • Temp bond instead (ProTemp)
  • Cover tooth with vaseline
20
Q

How to prepare ceramic restoration for insertion (the actual onlay, inlay, crown, etc) (5)

biomimetic

A
  1. ask lab to send it w model- check model for damage
  2. Try in- contact, margins, fitting surface must be ideal
  3. onlay etched with HF 9.5% 60s, rinsed for 30s
  4. fitting surface of onlay then etched again with phos ac for 2 min and rinsed
  5. silane applied to resto, evaporated
21
Q

How to prepare tooth for cementation

biomimetic dentistry

A
  1. Clean tooth using pumice
  2. selective etch for 15s, rinse, dry
  3. adhesive applied to tooth and resto but not cured
  4. resin cement applied to fit surface, crown seated, excess removed, LC
  5. glycerine applied to margins, LC
22
Q

Advantages of eMax (5)

A
  1. most aesthetic
    - no metal
    - translucent
  2. Durability
    - less likely to chip than zirc
  3. Ability to mill
  4. Conservative preps
  5. Versatility
    - veneers
    - onlays
    - anteior cantilevers
    - single crowns
23
Q

Disadvantages of emax (4)

A
  1. $$$
  2. not suitable for dark teeth
  3. Not ideal for posteriors
  4. Not suitable for long bridges
24
Q

What condition is this

A

MIH

25
Q

Tx plan for this case (4)

A
  1. Immediate
    - Perio and remove any plaque traps. OHI
  2. Transitional
    - Evaluate outcome of perio and OHI
    - Prescribe diagnostic wax up
    - Direct provisional restos, aesthetic try-in
  3. Reconstruction
    - Silicone impression
    - Emax veneers
    - Occlusal splint
  4. Maintenance
    - 6 mo review
    - OH reinforced
    - Splint assessment
26
Q

What are the different thickness’ for emax veneers

A

Press/cad can be used for bruxists

27
Q

What style of preps is preferred for emax veneers

A

Typically C
D can be used for bruxists

28
Q

What is biomimetic tooth reduction?

A

Like working from final form
- diagnostic wax up based on aesthetic prescription
- Mockups in mouth
- preps based on the exact requirements from planned results (prepping into the mockups)

29
Q

When are emax onlays mainly indicated

A

compromised posterior teeth with intact buccal and lingual walls
(MOD)

30
Q

Emax onlay prep design (4)

A
  1. Prep margins should not be placed in contact areas
  2. min 1.5mm non-working cusps, 2mm working cusps (always need cuspal coverage)
  3. No bevels or retentive feats
  4. rounded shoulder margins, min 1mm
31
Q

How to address subgingival defects prior to onlay

A

This is a violation of BW

  1. Deep Margin Elevation
    - box the composite subgingivally to raise the margins
  2. Crown lengthening (surgery or ortho extrusion)
32
Q

Why are subgingival defects bad / deep preps subgingivally? (3)

A
  1. Poor access for impressions, cementation, polishing
  2. Poor moisture control
  3. BW invasion
33
Q

Why is conservative new onlay prep preferred to conventional (3)

A

Increased fracture resistance

Reduced stress concentrations

More favourable fracture modes

34
Q

What should you do if you took off old onlay and prep looked like the right?
Why?

A

Build up with composite so it looks like left

Uniformity in structure, both of tooth and the onlay will allow for better diversion of stresses = more fracture resistant

B2B (5 decks)

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