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BDS 3 Sem 1 > Adhesion in dentistry > Flashcards

Adhesion in dentistry Flashcards

1
Q

What is the key distinction between a direct and indirect restoration?

A

Direct - the tooth surfae is preparred and the material is directly applied to it
Indirect - restoration is prepared in a lab and only after inserted onto the desired tooth/teeth

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2
Q

Why is adhesion, as a concept, is considered to be revolutionary?

A

Adhesion allowed for a real seal of the dentine from bacterial ingress and micromechanical retention has allowed retention of restoration in conservative tooth preparations

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3
Q

Define adhesion.

A

Adhesion refers to the bonding between two substrates.

The junction between these material is the adhesive interface.

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4
Q

What are the 4 main types of adhesion in dentistry with examples?

A
  1. Macromechanical (Amalgam)
  2. Micromechanical (Resin)
  3. Interfacial / chemical (Resin composite to ceramic)
  4. Chemical (GIC)
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5
Q

Define ‘macromechanical adhesion’ and give an example in dentistry?

A

It is a visible interlocking between dissimilar materials

E.g. An amalgam material in a slot prep of the tooth

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6
Q

Define ‘micromechanical adhesion’ and give an example in dentistry?

A

It a microscopic mechanical interlocking between dissimilar materials

E.g. A bond between enamel and composite resin

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7
Q

What are the differences between a 3-unit normal bridge and a 3 unit Maryland bridge?

A

Tho, both involve 3 teeth, in a standard bridge system all three teeth are covered by crowns while in a Maryland system the ‘wings’ of the bridge involve the teeth partially

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8
Q

What is the basic adhesive interaction between porcelain and enamel in porcelain crown bonding?

A
  1. Porcelain
  2. Etched porcelain
  3. Silane
  4. Resin cement
  5. Adhesive resin
  6. Etched enamel

This results in a continuous bonded layer with chemical and micromechanical bonding

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9
Q

What are some of the factors that influence the adhesion to tooth structure?

A
  1. Factors associated with the type and quality of the tooth structure (e.g. prismatic vs aprismatic enamel or secondary vs tertiary dentine)
  2. Factors associated with cavity preparation (moisture, cavity size, smear layer, foundation of the bonding substrate)
  3. Factors associated with restorative materials (etch concentration, patient factors, polymerisation shrinkage)
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10
Q

Where is aprismatic enamel located and why is it harder to etch?

A

Aprismatic enamel usually occur on the outer enamel surface or permanent and deciduous teeth. It is irregular in organisation and does not have the same hexagonal structure of enamel rods.

In a sense, aprismatic enamel is not harder to etch, it is harder to achieve an even etch in aprismatic enamel thus it is less likely to retain material using micro-mechanical retention.

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11
Q

What is the tesnile bond strength between enamel and resin composite?

A

Around 20-25 Mega Pascals. 2 time less for GIC and and a quarter more than RMGIC

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12
Q

What is a smear layer?

A

It is a thin layer of tooth fragments and other materials that is formed during cavity preparation. It reduces the bonding ability.

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13
Q

What is hybrid layer?

A

It is the layer between the dentine and the primer

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14
Q

What occurs during dry bonding?

A

The collapsed collagen network is able to be revitalised with use of a primer by breaking hydrogen bonds between collagen peptides - in laymen terms the collagen network is propped up by the primer.

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15
Q

What is one of the most common causes for secondary caries?

A

Microleakage that occurs due to poor moisture control

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16
Q

What are the main problems with etch-and-rinse adhesives that affect the formation of appropriate hybrid layer?

A
  1. Incomplete infiltration of primer into demineralized collagen
  2. Long-term water sorption into the hybrid layer with HEMA based adhesives
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17
Q

What is the main problem with self-etch adhesives that affect the formation of appropriate hybrid layer?

A
  1. Formation of water blisters at the resin/dentine interface
  2. Semi-permeable membranes
  3. Greater failure rates and poorer bonding strengths than etch-and-rinse adhesives
18
Q

What is dentinal sensitivity?

A

It is a condition characterised by short, sharp pain arising from exposed dentine in response to stimuli.

Rapid onset of pain - can persist as dull, throbbing pain.

Usually associated with deeper dentine because deeper dentine wider and more dense dentinal tubules.

19
Q

Which fibres within the dentine are responsible to certain pain sensations?

A

Alpha fibres - short and sharp pain
C fibres - dull, lingering pain

20
Q

What are predisposing factors for dentinal hypersensativity?

A
  1. Erosive tooth wear
  2. Gingival recession
  3. Periodontal disease - minority of cases, the evidence is not as strong
  4. Periodontal therapy
21
Q

What are the steps for differential diganosis of caused of dentinal hypersensitivity?

A
  1. Carious dentine
  2. Tooth fracture exposing dentine
  3. Cracked tooth syndrome
  4. Postoperative sensitibity
  5. Traumatic occlusion
  6. Marginal leakage with exposed dentine around the margins
  7. Irreversible pulpitis
  8. Vital bleaching
22
Q

What is the main treatment for dentinal hypersensitivity?

A

Desensitisation of the tooth with blocking of the dentinal tubules or reducing sensitivity of the pulp to stimulus.

23
Q

What are the two main stretagies for tooth desensitisation?

A
  1. Prevention - removing cuasative factors, address relevant histories
  2. Management - tubule occlusion by adhesion of exogenous materials, modification of nerve excitability
24
Q

What are some of the good applicable solution for topical application for dentinal sensitivity?

A
  1. Potassium Nitrate
  2. Fuji bond LC
  3. CPP-ACP, F or Stanous fluoride
25
Q

How does potassium nitrate works?

A

Potassium nitrate is able to over-saturate the space outside the nerve cell membrane with positive potassium ions (K+) thus blocking the re-polarisation phase of the action potential, thereby blocking pain impulses.

26
Q

What options do you usually have with larger cavities?

A
  1. Direct - resin, amaglam, liners and basis
  2. Indirect - crowns, bridges, inlay, onlay
27
Q

What are the desirable properties for resin composites?

A
  1. Aesthetics
  2. Durability
  3. Ease of handling
  4. Low shrinkage
  5. Wear resistance
  6. Radiopacity
  7. Anticariogenic
  8. Biocompatibility
28
Q

What makes up a standard resin composite?

A
  1. Inorganic phase - filler particles like glasses containing quartz or zirconia + barium or strontium for radiopacity
  2. Organic pahse - BisGMA, UDMA and TEGDMA
  3. Interfacial phase - silane coupling agent - essentially bind the organic and inorganic phases
  4. Miscellaneous parts - like accelerators
29
Q

What is the use of flowable RCs?

A

Because of their relatively less filler content compared with resin matrix, they are suitable for:
1. Restoration in no-load bearing areas
2. Re-paring old RCs
3. Fissure sealing

30
Q

What is the use of pack able RCs?

A

Because of their relatively more filler content compared to resin matrix, they are suitable for:
1. Restoring area under load
2. Easier to handle

31
Q

What are contraindications for use of composites?

A
  1. Deep gingival restorations
  2. Lack of peripheral enamel
  3. High loard bearing areas - tooth grinding
  4. Poor moisture control
  5. Caution with large restorations
32
Q

Why are 5th and 7th generation of adhesive system kinda mid?

A
  1. Because they are known to leave moisture bubles at the surface as well as water tress that impare bonding
  2. Because there is an issue with the acid that is used with self etching. Essentially a special compound is used to neutraulise the acid over time so that self etching does not continue to destroy tooth structure - but unfortunaley that compound affect may be delayed thus the created resin tags are not formed properly - this reduced their effectiveness thus making the restoration last less time :(
33
Q

What is the process of activation and initiation of dental composite material?

A
  1. Photo-initiator - in a form of specific frequency of light (light cure or UV light) initiates the creation of free radicals within the composite material
  2. The free radicals with an extra electron will bind with monomers in order to create a polymer - at the end of this process an electron is loss thus another free radical can be initiated
  3. This continues when around 80% of resin is polymerised and 20% is not - this is important to allow addition of other composite resin
  4. Over time, free radicals will combine - creating a stable compound
34
Q

How would you explain to the patient the CR survival?

A

An average composite may last around 3-8 years but only if it is maintained. Give car analogy.

35
Q

Why do amalgams last more than composites?

A

Amalgams last longer due to the hardness of the material - but if they fail they fail spectacularly

36
Q

How do we treat hypersensitivity?

A
  1. Block dentinal tubules - using restorations or protective coverings
  2. Block nerve activity - stanous fluoride and potassium nitrate
  3. Remove the cause - erosion and toothbrushing technique change
37
Q

How do we manage dentine hypersensitivity?

A
  1. Occlude dentinal tubules to reduce impact of stimuli on fluid movement - can be done through chemical occlusion (fluorides) or physical occlusion (sealed resorations)
  2. Reduce sensitivity of nerves - using potassium nitrate
38
Q

What are indications for indirect pulp capping?

A
  1. Deep cavity
  2. No pulpal exposure
  3. Removal of all infected dentine may result in pulpal exposure
  4. No signs or symptoms of irreversible pulpits
39
Q

What is the most important aspect of indirect pulp capping?

A

CORONAL SEAL IS VITAL.

40
Q

What happens to the pulp during direct pulp capping?

A

The varnish that is used is able to neutralise necrotic tissue and cause the deposition of tertiary dentine

BDS 3 Sem 1 (21 decks)

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