5. Bonding Agents and Mechanisms Flashcards Preview

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1

Why adhesive dentistry?
Tooth colored materials for more ____ restorations More ____ because you don't need to create very retentive cavity preps
Less ____ consuming since you don't need to spend as much time prepping the cavity

esthetic
conservation
time

2

Adhesive dentistry: a branch of dentistry which deals with ____ or bonding to the natural substance of teeth, ____ and ____.

adhesion
enamel
dentin

3

Important problem in restorative dentistry

____ bonding of materials to dental hard tissues

This is a problem, especially with ____ restorations (amalgam, inlays, onlays, gold). There isn’t any bond between restorative materials and ____ or ____

weak
metallic
dentin
enamel

4

New adhesive restorative materials

bonding between cavity walls and restorative material, then restoration-cavity integration

With the help of new adhesive restorative materials, it is possible to create a bond between tissues like ____ and ____ and ____ material. That’s why adhesive dentistry is very important.

enamel
dentin
restroative

5

In operative dentistry, we create an adhesive restoration after bonding with the tooth tissues. Adhesive restorations are composed of two parts:
____ resin material (which is like amalgam, at the top of the cavity prep)
____ agent (____ material we use to stick composite material to enamel and dentin)

composite
adhesive bonding
liquid

6

Bonding Agents

Bonding agents are ____ materials used to make a dental composite filling material to stick to both ____ and ____.

They can be defined as material of ____ viscosity, when applied on the tooth surface, forms a thin film layer after setting

It’s difficult to see this bonding agent, but when we apply it to dentin or enamel surfaces, it leaves a ____ surface on
the dentin or enamel, this is the only way we can see that we applied a bonding agent.

resin
dentin
enamel
low
shiny

7

Bonding of resin materials: adhesion

A complex phenomenon involving ____ and ____ mechanism that allows attachment of one material to another and proper sealing.

The bonding between adhesive material (composite) and the tooth surface is obtained by means of adhesion. ____: used to bond composite material to dentin or enamel. Reads slide.

chemical
mechanical

adhesion

8

Mechanical means of adhesion
- bonding occurs because of penetration of one material into another at the ____ level
- for example, in composite resins the bonding involves the penetration of ____ into enamel and dentin and formation of ____

Mechanical means of adhesion: occur when one material penetrates into another material

microscopic
resin
resin tags

9

Chemical means of adhesion

Adhesion promotors-coupling agents: ____, NPG-GMA, HEMA, ____

Chemical means of adhesion: adhesion promoters or coupling agents in the ____ bonding material. Especially nowadays, different bonding materials use different ____ agents for chemical bonding with the tooth tissue.

MDP: currently the main material used in different ____ agents, different adhesive materials; it is a ____ that bon to ____ of dentin and enamel. Almost all of the companies use this monomer now that the patent has expired

4-META
MDP
adhesive
coupling

bonding
monomer
hydroxyapatite

10

For a good adhesion

Without bonding agents, we cannot get a good bond with the tooth surface. We need this glue! There are different bonding agents on the market, Dr. Ozer will explain the main groups of bonding agents to you later.

YAY

11

Concept of a dentin bonding agent:

Bonding agents bond both dentin and enamel and also to composite, it should bond both sides.

Bonding agents usually have two parts in their chemical composition. The ____ part bonds dentin because dentin has some dentinal liquid in the dental tubules, it’s not a very dry surface.

The ____ part bonds to composite. These two parts need to work in an accordance in a very strong integral mechanism

hydrophilic
hydrophobic

12

Steps in forming good ahdesion

(1) clean ____
A clean, uncontaminated tooth surface

(2) good ____
...of the surface with the bonding agent - needs to be viscous enough to seal, to wet the surface.

(3) intimate ____
...with the bonding surface

(4) ____
...with the surface by mechanical and chemical means of adhesion/bonding
with the dentin surface

(5) good ____

adherend
wetting
adaptation
bonding
curing

13

Bonding to Enamel

Enamel bonding is a bit easier and more simple to achieve.

In 1955, Dr. Buonocore acid etched the enamel surface for the first time and introduced the acid etch technique to the dental field.

We create a porous, irregular surface that is invaded by the bonding agent. It is ____ of the surface.

To get good adhesion, we need to bond enamel and dentin, but they have different structures. Enamel bonding is different from dentin bonding. Enamel is a very hard tissue with almost ____% inorganic hydroxyapatite structure.

When we acid etch the enamel surface, we create a porous, irregular surface because the strong acid (____ acid) creates a porous surface on enamel according to whether the surface is an uncut or cut enamel surface.

Acid etching creates a very small tiny porous surface in the center of enamel rods and around the enamel rods, we create a big ____. Then, bonding agent infiltrates in these micro and macro gap areas around or inside of enamel rods, and makes ____ or macrotags, these are kind of interlocking with the enamel.

interlocking
90
orthophosphoric

microgap
microtags

14

How about dentin
Tubules from pulp to DEJ: larger and numerous near pulp
____ extensions
Fluid movement dictated by ____
Covered with ____ layer
Contains a strong ____ matrix

Dentin is not like enamel, it’s made of inorganic hydroxyapatite crystals too, but it’s mainly ____ by it’s chemical composition.

Dentin has ____ with dentinal fluid. When we cut the dentin surface we create a ____ layer on the surface (unlike enamel, which has a clean surface with no extra layer when you cut it). Dentin has a very strong collagen network. It has collagen fibers, that’s why dentinal bonding is different from enamel bonding.

odontoblastic
pulp
smear
collagen

tubules
smear

15

Smear layer

This is a debris left on the surface after cutting, consists of ____ and altered denatured ____ which fill the orifices of the tubules

Sometimes this debris also creates a ____ plug in the dentin tubules, which is not good because it prevents us from getting into the dentin ____.

hydroxyapatite
collagen
smear
tubules

16

Smear layer cont.

When we acid etch the dentin surface, like in enamel, we also dissolve the ____ of dentin. But in dentin, there are collagen fibers. When we acid etch, the collagen fibers are not supported by the hydroxyapatite anymore, and they start to ____.

With the different parts of dentin bonding agents, we expand these collagen fibers and try to get into the collagen fibers with the bonding to create an interlocking with the dentinal surface. This interlocking is called a ____ layer.

Dr. Nakabayashi explained to the world in 1982 that there is also dentinal interlocking if we use acid etching on the surface. I will explain to you how we get this interlocking without collapsing the collagen fibers. We have to expand them, and then invade through the collagen fibers to get a good hybrid layer. Also with the dentin surface, after the hybrid layer, some of the resin material gets into the dentin tubules, like in enamel, we also get another interlocking with the dentin tubules too.

Summary: on the dentin surface, we have ____, a ____ layer, which is made of collagen fibers, ____ material, ____ tags in dentin tubules, and the ____ agent.

hydroxyapatite
collapse

hybrid

hybrid
resin
resin
bonding

17

What is the main goal for a good dentin bonding

Strong and durable ____ layer formation with stable collagen fibers

The main goal is: reads slide, because the hybrid layer is the layer we interlock with the dentin surface. We need ____ collagen fibers, otherwise we cannot get this interlocking with the collagen. We need to keep the collagen alive and strong.

hybrid
stable

18

Major components of bonding agents

Etchants : ____ acid, maleic Acid tartaric acid, ____ acid, EDTA, hydrocloric and
hydrofluoric acids

Primers for collagen expansion: Hydrophilic monomers carried in solvents such as ____, ethanol and water.

Adhesives: Hydrophobic and ____ monomers and dimethacrylate oligomers such
as ____, UDMA (Different chemical compositions)

Adhesion promotors-coupling agents in primers: 4-META, NPG-GMA, HEMA, ____

We use different types of acid etching in ____ bonding.

And we need primers; when we acid etch the dentin surface, collagen fibers are not supported by hydroxyapatite and they collapse. We need primers to ____ these collagen fibers. Adhesion promoters in bonding agents like HEMA and MDP are responsible for chemical bonding with hydroxyapatite.

phosphoric
citric

acetone

hydrophilic
Bis-GMA

MDP

expand

19

Dentin bonding process

Acid application to surface
– ____ layer removal
– ____ dissolution

Drying
– Collagen ____

Priming
– Collagen ____

Monomer penetration into tubules and collagen
– ____adhesion
– ____ sealing

Chemical interaction
– With the help of specific monomers and adhesion promoters

smear
hydroxyapatite

collapse
rehydration

micromechanical
tubule

20

Recent classification

Two types of bonding agents:
1. Etch and rinse adhesives: use strong ____ etching
2. Self-etch: don’t use ____ acid etching, dissolves smear layer (instead of ____ it)

Multi-bottle (3 steps): acid etch + primer + ____
One-bottle (2 steps): acid etch + ____ primer and adhesive.

Self-etch (2 step): acidic ____ (acid and primer combined) + ____, this is the best combination.

One step: acid, primer, and bonding all in one bottle.

The researchers and companies are trying to make the bonding agents simpler and easier to apply, but when we use one- bottle bonding agents the bond ____ and ____ is not good.

We usually prefer either ____-bottle or ____-bottle bonding agents.

acid
strong
removing

adhesive
combined

primer
adhesive

strength
durability

3
2

21

Etch and Rinse Adhesives
One step: primer and bonding are combined in one bottle.

These adhesives use a ____ acid (%35 or %37 phosphoric acid) to completely etch enamel and dentin

The acid removes ____ layer and ____ enamel or dentin surface

In three step application, ____ is used for collagen expansion

In one step application, after etching the dentin surface will be left ____ with only blotting or wiping with damp cotton pallet (____ bonding). Bonding agent will be applied in ____ coats.

strong
smear
demineralize
primer
moist
wet
two

22

Advantages of Etch and Rinse Adhesives

____ acid etching provides best bonding to enamel
High immediate bond ____
Several research supports their use in different material surfaces

Orthophosphoric acid is a very strong acid that’s good for ____ etching and enamel bonding. The immediate bond strength is quite high, but the ____ is not good and it’s not long lasting. Works on other materials, not only ____, also metals, ____ surfaces

phosphoric
strength
enamel
durability
dentin
ceramic

23

Disadvantages of Etch and Rinse Adhesives

Risk of over ____ dentin and ____irritation

Incomplete resin penetration due to thick ____ layer

Weak resin-collagen interaction (____)

In one bottle systems, over ____ or ____ the surface

etching
pulp
hybrid
nanoleakage
wetting
drying

24

Self-etch adhesives

Non-rinse acidic monomers
1. Mild self-etches (pH = ____)
____ dissolution of dentin surface

2. Strong self-etches (Ph

2
partially
1
completely
etch&rinse

25

Demineralized dentinal surface ?

Fully demineralized surface is susceptible to degradation of ____ interface because the collagen fibrils are are not covered with ____ crystals

Partially demineralized surface provides ____ bonding between the functional monomers and HAp of collagen fibrils that may lead to ____ bond strength.

adhesive
HAp

chemical
stable

26

Advantages of Self-Etch Systems

Less ____ consuming
____ application procedures
Low ____ sensitivity
Better degree of ____ into collagen
No postoperative ____
Chemical bonding with the dentinal surface

Even if you leave the surface a little bit wet, it doesn’t cause any problems. You don’t apply separate acid- etching, just primer and bonding, no rinsing. No post operative sensitivity because we are not creating a very thick ____ layer, and also we are not fully removing the ____ layer from the surface, only dissolving it. It’s good for the ____. We create a chemical bond with the dentinal surface because we still have some hydroxyapatite left on the dentin surface.

time
easy
technique
infiltration
sensitivity

hybrid
smear
pulp

27

Disadvantages
of the self-etch systems.

Not adequately etch ____ enamel

Bond strengths to ____ composites
are ____.

If it is uncut, the bonding with the enamel surface is not as good as etch and rinse adhesives with the strong acid etching. That’s why with the uncut wide enamel surfaces, we prefer to use ____ acid. Some research shows that bond strengths to self-cure composites is a little bit lower than ____ composites. Usually in the clinic, we use light-cured composites. We use etch and rinse adhesives for self-cured composites.

uncut
self-cure
low

orthophosphoric
light-cured

28

Factors that reduce longevity of bonded interface

Insufficient resin impregnation of ____
High ____ of the bonded interface
Lack of ____
Phase ____ in bonding agent and degradation
Activation of endogenous colleganolytic ____ during acid-etching and ____ layer degradation.

dentin
permeability
polymerization
separation
enzymes
smear

29

New class of ____ inhibitor preserves dentin bond

In one of our studies, we are trying to inhibit these MMPs. We are collaborating with Dr. Yamazoto from Japan, he’s one of the pioneers of adhesive dentistry research. Professor Dr. D’Angelo is helping us to create an inhibitor to prevent MMPs from chewing the collagen matrix, and the results are very promising. The bond ____ increased a lot after our peptide application, immediate and after aging. This study is still continuing.

MMP
strength

30

Strong self-etch adhesives and one-step (all-in –one) adhesives

Especially to ____, rather ____ bond strength values and accelerated ____

Strong self-etch and one-step self etch adhesives are not good, especially with ____ and ____.

dentin
low
degeneration
bonding
durability

31

Disadvantages of one-step adhesives

Phase separation in ____-free products
High ____
Permitting ____ movement across the adhesive layer (water trees)
More ____ sensitive
Less ____
Reduced ____ life

If they don’t have ____, phase separation occurs even more quickly. They can absorb dentinal fluid very easily in the hybrid layer. This hybrid layer also permits water or liquid droplets to pass through the hybrid layer and degrade the dentinal surface, dentin collagen fibers. These water areas are called ____.

HEMA
hydrophilicity
water
technique
durability
shelf
HEMA
water trees

32

TEM micro-graphs of resin-dentin interfaces

One-step self-etches
a. ____ Tri- S Bond
b. Hybrid Bond
c. G Bond
d. Prompt L-Pop

We need the surface to be just wet enough (not very dry or very wet). We cannot use ____ flow, we have to use ____ pellets to clean the water from the surface, and it’s difficult to have efficient wetness on the surface, that’s why it’s very ____ sensitive. Our research showed that the shelf life of these bonding materials is very low compared to other bonding agents

Let’s see what happens with these all-in-one adhesives. These adhesives have everything all in one bottle: ____, ____, and ____. The collagen fibers don’t collapse, but the problem is ____ droplets (white circles). They immediately absorb some water from the dentinal tubules. That’s why these bonding agents are not durable like the other ones.

clearfil
air
cotton
technique

acid-etch
primer
bonding
water

33

Conclusion

____ bonding systems are preferable when large areas of ____ enamel are present in the cavity.

____ adhesives provide superior and more predictable bond strength to ____

____ adhesives do not provide a reliable bonding with ____ surfaces

If the enamel surface is wide and uncut, we prefer ____ bonding agents. If we do enamel cutting in the cavity prep like enamel margins in the cavity prep, we never use ____.

We only use ____ adhesives, primer, and then bonding. Self-etch adhesives are the gold standard for dentinal bond strength.

All in one adhesives. I showed you the reason, we get ____ or droplets and the water from the dentinal tubules infiltrates into the ____ layer, and also dentin. That’s why we don’t like them, we usually use two or three step bonding agents.

etch-and-rinse
uncut
self-etch
dentin
all-in-one
dentin

etch-and-rinse
acid etching

self-etch

watertrees
hybrid