Current Adhesives and Composite Bonding Flashcards
attraction between similar molecules or atoms
Cohesion:
attraction between unlike molecules, attraction between two contacting surfaces
Adhesion:
: material bonded to another material by means of an adhesive
Adherend
: substance that promotes adhesion
Adhesive
: joining two materials by means of an adhesive
Adhesive Bonding
_______ adhesion classification:
◦Interlocking
◦Undercuts, surface irregularities
◦THIS IS THE DENTAL ADHESION MECHANISM
Mechanical Bonding
-the ability of a liquid to maintain intermolecular contact with a solid surface
Surface wetting
Is enamel bonding or dentin bonding more predictable?
Enamel
Chemical “drilling”
◦30-40% phosphoric acid is most effective for enamel retention
◦Removes about 10 microns
Creates porous layer 5-50 microns deep
Acid etching enamel
What type of enamel etching?
“honeycomb” from dissolution of prism CORES
Type 1
What type of enamel etching?
“cobblestone” from dissolution of prism PERIPHERIES
TYpe 2
What type of enamel etching?
combination of I and II
Type 3
What type of enamel etching?
“pitted”
TYpe 4
What type of enamel etching?
“prismless” (flat and smooth)
Type 5
RINSE with water for ___ seconds _____ etching
◦To remove acid and leave enamel surface clean for bonding
◦25mL minimum water is necessary
10 ; after
Etching _____ wettability and surface area of the enamel
Increases
Etching raises the surface free energy to EXCEED the _______ of bonding material◦= produces spaces where resin can penetrate to for resin tags
surface tension
In what portion of the tooth is there less adhesion due to shorter and fewer enamel tags?
Cervical 1/3
Reduce microleakage at cervical and ascending walls in Class II preparations
NECESSARY!
Increases surface energy
Bevels
The micromechanical bond that is formed in enamel interlocks with etched ______
Enamel rods
The micromechanical bond that is formed in dentin interlocks with etched ______
Dentin collagen
What is the bond strength in MPa of enamel-adhesive-composite bond?
20-25 MPa
Is enamel mostly inorganic or organic material?
Inorganic material
Which is better for adhesion and bonding enamel or dentin?
Enamel
What portion of dentin do you want to bond to?
INtertubular dentin
_____ dentin: more fluid,more & wider tubules,& less intertubulardentinthan superficial dentin.
Deeper dentin
mixture of tooth debris, often contaminated with saliva, blood cells, and bacteria
DO NOT BOND to this
Remove with acid etch
Smear Layer
______ is the intermingled layer of collagen and resin
Hybrid layer
HOw long do you etch dentin?
15 secs
\_\_\_\_\_results in underfilledrestorations Steps: ◦Acid Etch TOO LONG ◦Wash and lightly dry =Demineralized zone is too thick =Primer can not infiltrate far enough =Leaves unprotected layer subject to degradation leads to premature bond failure leads to failure over time due to hydrolysis of uninfilitrated collagen
OVERETCHING
_______ results in lower bond strengths
=Collagen collapses
= lower bond strength
OVERDRYING
results in collagen that is too wet
◦Excess water
◦Poor hybrid layer formation
◦Resin unable to infiltrate intertubular dentin
◦“blister spaces” where primer and adhesive separate
UNDERDRYING
What is the etchant composed of?
Phosphoric acid
Is the primer hydrophilic or hydrophobic?
Hydrophilic
Is the adhesive bonding resin hydrophilic or hydrophobic?
Hydrophobic
Is there a lot or a little filler in bonding systems?
Little filler
How long do you etch enamel?
15-30 secs
Do you want enamel dry or slightly moist?
Dry
Do you want dentin dry or slightly moist?
Slightly moist
The primary dentin bond mechanism is from ________
Hybrid layer
Is there a better bond in superficial or deep dentin?
Superficial dentin
Do you rinse in total etch or self-etch?
Total etch
Total etch systems are ____ predictable and create a ____ bond
More; stronger
Disadvantages of \_\_\_\_\_ systems: ◦Collagen collapse is possible* ◦Etched zone is often deeper than hybrid layer ◦Exposed demineralized, collagen fibrils ◦Post-operative sensitivity
Total etch systems
Advantages of _____ systems:
◦No separate etch: overdried, collapsed demineralized collagen not a problem
◦Etched zone and hybrid layer comparable width; however, some exposed collagen ◦Low post-operative sensitivity
◦Time efficiency
-decreased operator error
Self-etch systems
DisAdvantages of _____ systems:
◦Not compatible with self-cure, dual-cure composite
◦Acidic monomers, low pH, “kills” the basic amine activator
◦Will not etch unprepared enamel
-Lower bond strength
Self etch systems
Can be used in total etch, self-etch or selective-etch mode (etch enamel only with phosphoric acid)
Universal adhesives
T/F: You Don’t want to directly etch pulp
True
Which etch system has increased bond but increased possibility for error?
Total etch
Which etch system has no etching, decreased bond strength, and increased sensitivity? Less operator error too
Self etch
______ is used on ACC crown preps
◦2% Chlorhexidine Antibacterial Solution
◦Applied after acid etching
-increases bond strength
Consepsis
