Enamel and Dentine Bonding Flashcards
What are the 3 principles of adhesion?
- seal vulnerable pits and fissures
- conserve tooth tissue
- reduce/ eliminate microleakage
What are the 3 materials used for bonding?
- acid etches
- coupling agents
- dentine bonding agents
The ability of a liquid to form an interface with a solid surface is known as?
contact angle - degree of wetting
What does the degree of wetting allow?
lowers surface tension of adhesive so it will flow into irregularities
What is the etching time?
10-60 seconds
Why is etching time important?
enough time for effect but not too long as this will allow precipitation of calcium and phosphate
What do you do after you have applied acid etch?
wash for 60 seconds to remove debris
Why do you dry after washing off acid etch?
enables hydrophobic resin to penetrate and attach
What is the etch pattern?
selective decalcification of enamel prisms and micromechanical tags which resin flows in to
How does acid etch impact surface ?
increases surface roughness and enamel surface energy
- removes contaminants
- increases wetting
- micromechanical retention
Is dentine hydrophillic or hydrophobic?
hydrophillic
Are adhesives hydrophillic or hydrophobic?
hydrophobic
What must be removed from dentine when preparing a cavity?
smear layer
Why must the smear layer in dentine be removed?
open the tubules
What are primers?
coupling agents - acids that alter surface appearance and stickiness of dentine
How deep should the surface of dentine be demineralised?
4 microns
What is an example of a primer?
HEMA
What does HEMA bind to?
hydroxyl apatite and amino groups of collagens
What seals dentine?
sealers - methacrylate
What is the purpose of sealer?
endures bonding to resin in the composite
What is the 3 stage adhesion?
- apply and wash etchant
- apply primer
- apply sealer
What is the 2 stage adhesion?
- apply self-etching primer
- apply sealer
What is the single stage adhesion?
self etching primer and sealer applied as a single solution.
