Adhesion in dentistry Flashcards
(40 cards)
What is the key distinction between a direct and indirect restoration?
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
Why is adhesion, as a concept, is considered to be revolutionary?
Adhesion allowed for a real seal of the dentine from bacterial ingress and micromechanical retention has allowed retention of restoration in conservative tooth preparations
Define adhesion.
Adhesion refers to the bonding between two substrates.
The junction between these material is the adhesive interface.
What are the 4 main types of adhesion in dentistry with examples?
- Macromechanical (Amalgam)
- Micromechanical (Resin)
- Interfacial / chemical (Resin composite to ceramic)
- Chemical (GIC)
Define ‘macromechanical adhesion’ and give an example in dentistry?
It is a visible interlocking between dissimilar materials
E.g. An amalgam material in a slot prep of the tooth
Define ‘micromechanical adhesion’ and give an example in dentistry?
It a microscopic mechanical interlocking between dissimilar materials
E.g. A bond between enamel and composite resin
What are the differences between a 3-unit normal bridge and a 3 unit Maryland bridge?
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
What is the basic adhesive interaction between porcelain and enamel in porcelain crown bonding?
- Porcelain
- Etched porcelain
- Silane
- Resin cement
- Adhesive resin
- Etched enamel
This results in a continuous bonded layer with chemical and micromechanical bonding
What are some of the factors that influence the adhesion to tooth structure?
- Factors associated with the type and quality of the tooth structure (e.g. prismatic vs aprismatic enamel or secondary vs tertiary dentine)
- Factors associated with cavity preparation (moisture, cavity size, smear layer, foundation of the bonding substrate)
- Factors associated with restorative materials (etch concentration, patient factors, polymerisation shrinkage)
Where is aprismatic enamel located and why is it harder to etch?
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.
What is the tesnile bond strength between enamel and resin composite?
Around 20-25 Mega Pascals. 2 time less for GIC and and a quarter more than RMGIC
What is a smear layer?
It is a thin layer of tooth fragments and other materials that is formed during cavity preparation. It reduces the bonding ability.
What is hybrid layer?
It is the layer between the dentine and the primer
What occurs during dry bonding?
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.
What is one of the most common causes for secondary caries?
Microleakage that occurs due to poor moisture control
What are the main problems with etch-and-rinse adhesives that affect the formation of appropriate hybrid layer?
- Incomplete infiltration of primer into demineralized collagen
- Long-term water sorption into the hybrid layer with HEMA based adhesives
What is the main problem with self-etch adhesives that affect the formation of appropriate hybrid layer?
- Formation of water blisters at the resin/dentine interface
- Semi-permeable membranes
- Greater failure rates and poorer bonding strengths than etch-and-rinse adhesives
What is dentinal sensitivity?
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.
Which fibres within the dentine are responsible to certain pain sensations?
Alpha fibres - short and sharp pain
C fibres - dull, lingering pain
What are predisposing factors for dentinal hypersensativity?
- Erosive tooth wear
- Gingival recession
- Periodontal disease - minority of cases, the evidence is not as strong
- Periodontal therapy
What are the steps for differential diganosis of caused of dentinal hypersensitivity?
- Carious dentine
- Tooth fracture exposing dentine
- Cracked tooth syndrome
- Postoperative sensitibity
- Traumatic occlusion
- Marginal leakage with exposed dentine around the margins
- Irreversible pulpitis
- Vital bleaching
What is the main treatment for dentinal hypersensitivity?
Desensitisation of the tooth with blocking of the dentinal tubules or reducing sensitivity of the pulp to stimulus.
What are the two main stretagies for tooth desensitisation?
- Prevention - removing cuasative factors, address relevant histories
- Management - tubule occlusion by adhesion of exogenous materials, modification of nerve excitability
What are some of the good applicable solution for topical application for dentinal sensitivity?
- Potassium Nitrate
- Fuji bond LC
- CPP-ACP, F or Stanous fluoride
