Characterization of tooth structure and the dentin-enamel ...
Zr Dentin and Enamel Bonding
Transcript of Zr Dentin and Enamel Bonding
-
8/3/2019 Zr Dentin and Enamel Bonding
1/33
Thomas J. Boyle, DMD, MAGD, ABGDDiplomate of the American Board of General Dentistry
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
2/33
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
3/33
Smear Layer
(produced by diamond ondentin)
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
4/33
Smear Layer
Dentinal surface andtubules areobstructed. Shattered and crushed
hydroxyapatite,fragmented anddenatured collagen,bacteria? And saliva.
Some degree of
etching is required toovercome thisobstacle
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
5/33
Dealing with the Smear
Layer
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
6/33
Classification ofAdhesives
4th 5th 6th th
HEMAhydrophylic
Bis-GMAhydrophobic
TJB
Etch
-
8/3/2019 Zr Dentin and Enamel Bonding
7/33
Brand Names of AdhesiveSystems
3-E&R
2-E&R
2-SEA
1-SEA
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
8/33
3 step-E&R Systems
TJB
4th gen
-
8/3/2019 Zr Dentin and Enamel Bonding
9/33
2 step-E&R Systems
TJB
5thgen
-
8/3/2019 Zr Dentin and Enamel Bonding
10/33
2-SEA systems
TJB
6th gen
-
8/3/2019 Zr Dentin and Enamel Bonding
11/33
1-SEA Systems
TJB
7th gen
-
8/3/2019 Zr Dentin and Enamel Bonding
12/33TJB
Hybridization
Hybridization is the commonadhesion mechanism ofall systems(E&R and SEA).
-
8/3/2019 Zr Dentin and Enamel Bonding
13/33
Hybrid Layer Achieved
by:
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
14/33
Etch and Rinse Technique vs. SelfEtch
enamel/resin interface
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
15/33
Dentin Bond
Phosphoric Acid 35% Removes Smear Layer
Demineralizes dentin to depth
of 3.0m to 5.0 m. Exposes a scaffold of collagen
fibrils nearly depleted ofhydroxyapatite.
Monomers diffuse into thenetwork of collagen fibrils and
set to form hybrid layer. Chemical rxn between collagen
and MMA is unlikely
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
16/33
. Note that collagen fibrilsmust notbe allowed to
collapse. Loose the micromechanical
retention.
Collagen fibrils are inert(s HAp) and monomers
have low affinity tothem. Therefore nanometer-sized
gaps are left that leak andgradually deteriorate thebond.
Water Trees
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
17/33
Primer Solvents
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
18/33
New Three Step Technique
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
19/33
Self Etch Systems
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
20/33
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
21/33
TJB
Variable/Unpredictable Bond Strengths with SEAsvs. E&Rs
Despite the thin hybrid layer and lack ofresin tags- some Mild SEAs can achievea satisfactory bond strength. Probably due to additional chemical rxn
between monomers and residual HAp.
(Mild SEAs leave HAp)
However : {Tooth- SEA } chemicalinteractions are highly variable. They depend on the kind of acidic functional
monomer and on the overall composition ofthe monomer.
-
8/3/2019 Zr Dentin and Enamel Bonding
22/33
TJB
The carboxylic and phosphate groups that renderthese monomers hydrophilic and that function asproton donors (acid etchants) have been provento bond ionically with the calcium inhydroxyapatite.
So the mild SEAs get some bond strength (not
as much as E&Rs) because they leave some HAp
The chemical bond is monomer specific anddepends on the hydrolytic stability of thecalcium-monomer bond. So why use SEAs?
-
8/3/2019 Zr Dentin and Enamel Bonding
23/33
TJB
SEA Bond Strength
-
8/3/2019 Zr Dentin and Enamel Bonding
24/33
TJB
Advantages of SEA
Reduced chair time Etch, rinse and drying steps are
eliminated
a whole 80 seconds can be saved!
Collapse of the collagen network is
prevented This is possible in the E&R techniques if
care not exercised.
-
8/3/2019 Zr Dentin and Enamel Bonding
25/33
TJB
Concerns about SEA
-
8/3/2019 Zr Dentin and Enamel Bonding
26/33
TJB
Concerns about SEA
-
8/3/2019 Zr Dentin and Enamel Bonding
27/33
Concerns about SEA
Phase Separation
Adhesive dispensed droplets appear rise
to surface anddisappear
Explanation Complex mix of
hydrophylic and phobiccomponents dissolvedin an organic solventwhose evaporation setsoff this event.
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
28/33
Phase Separation
TJB
-
8/3/2019 Zr Dentin and Enamel Bonding
29/33
TJB
Concerns about SEA
-
8/3/2019 Zr Dentin and Enamel Bonding
30/33
TJB
In the bottledegradation
-
8/3/2019 Zr Dentin and Enamel Bonding
31/33
TJB
Loss of Dentinal Bond
-
8/3/2019 Zr Dentin and Enamel Bonding
32/33
TJB
SEA or E&R ?
-
8/3/2019 Zr Dentin and Enamel Bonding
33/33