Adhesion

Question 1

Adhesion / Bonding

Answer 1

Two surfaces are held together by interfacial forces which may consist of valence forces or interlocking forces or both

Question 2

Adhesive / Adherent

Answer 2

It is a material, frequently a viscous fluid, which joins two substances together and solidifies, and therefore is able to transfer a load from one surface to the other

Question 3

Adherend

Answer 3

It is the surface or substance that is adhered

Question 4

Adhesive strength

Answer 4

It is the measure of the load-bearing capacity of an adhesive joint

Question 5

Adhesive failure

Answer 5

The bond that fails at the interface between the two substrates

Question 6

Cohesive Failure

Answer 6

The bond that fails within one of the substrates, but not at the interface

Question 7

Requirements for Adhesion

Answer 7

1. Good substrate wetting, a low ‘contact angle’

2. A clean substrate

Question 8

Wetting

Answer 8

It is an expression of the attractive forces between molecules of adhesive (adherent) and the adherend

Question 9

Wetting depends on two factors:

Answer 9

• Cleanliness of the adherend

- Surface energy of the adherend

Question 10

Contact Angle

Answer 10

It is the angle formed between the surface of a liquid drop and its adherend surface

Question 11

Mechanisms of Bonding to Tooth Structure

Answer 11

1. Micromechanical: Penetration of resin and formation of resin tags within the tooth surface.
2. Absorption: Chemical bonding to the inorganic component (hydroxyapatite) or organic components mainly type 1 collagen of tooth structure.
3. Diffusion: Precipitation of substances on the tooth surface to which resin monomers can bond mechanically or chemically.
4. Combination: Of the previous three mechanisms.

Question 12

Advantages of Adhesion

Answer 12

1. Conservation of tooth structure
2. Reinforcement of the remaining tooth structure
3. Restoration retention
4. Reduction or elimination of marginal microleakage
5. Expansion the range of esthetic possibilities

Question 13

Expanded Clinical Indications for Adhesives

Answer 13

1. TTT of dentin hypersensitivity
2. Bonded amalgam restorations
3. Indirect adhesive restorations
4. Repair of porcelain or composite
5. Bonding orthodontic appliance

Question 14

Adhesive systems according to Van Meerbeek classification

Answer 14

• Etch-and-rinse adhesive systems (Total-etch adhesive systems)
• Self-etch adhesive systems (Etch-and-dry adhesive systems)
• Glass ionomer adhesive systems

Question 15

Etching:

Answer 15

It is the process of demineralizing the substrate (removal of minerals from enamel/dentin) and creating the spaces that are responsible for micromechanical bonding between tooth and restorative resin.

Question 16

Primer / Adhesive promoting agents:

Answer 16

They are hydrophilic monomers that are capable of increasing surface wettability.

Question 17

Bonding Agents:

Answer 17

They are hydrophobic monomers that penetrate within demineralized surface and polymerize forming the micromechanical retention.

Question 18

Advantages of the Smear Layer

Answer 18

It acts as a barrier

• It decreases dentin permeability by nearly 90%
• Resists fluid movement

Question 19

Wet Bonding Technique is used in

Answer 19

Acetone based primers

Question 20

Dry bonding technique is used in

Answer 20

Water based primers

Question 21

Infiltration and polymerization of hydrophobic bonding agent monomers into the interfibrilar spaces of the collagen network forming the

Answer 21

hybrid layer

Question 22

Infiltration and polymerization of hydrophobic bonding agent monomers within the dentinal tubules forming

Answer 22

resin tags

Question 23

Advantages of SE over TE:

Answer 23

• More faster, simple and user-friendly
• Less technique-sensitive
• Spontaneously demineralization and resin infiltration
• Reduce postoperative sensitivity