4: Adhesion and cohesion

4

Adhesion and cohesion

Figure 4.1 Adhesion and cohesion.

c4-fig-0001

Figure 4.2 Adhesive and cohesive failures of cemented restorations.

c4-fig-0002

Figure 4.3 Adhesion zone between adhesive and substrate (schematic).

c4-fig-0003


Box 4.1 Molecular forces determining cohesive strength of an adhesive
1 The chemical bonds within the adhesive material
2 Chemical bonds due to cross-linking of the polymer(s) within a resin-based material
3 Intermolecular interactions between the adhesive molecules
4 Mechanical bonds and interactions between the molecules in the adhesive

Table 4.1 Basic types of adhesion

Type Characteristics
Specific Molecular attraction between contacting surfaces
Mechanical Adhesion through mechanical interlocking between adhesive and substrate surfaces
Effective Bonding between adhesive and substrate due to a combination of specific and mechanical adhesion

Table 4.2 Bond energies and bond lengths in adhesive forces

Average bond energy
(kJ/mol)
Average bond length
(nm)
Ionic bond 600 0.25
Covalent bond 550 0.15
Metallic bond 250 0.40
Hydrog/>

Only gold members can continue reading. Log In or Register to continue

Jan 1, 2015 | Posted by in Dental Materials | Comments Off on 4: Adhesion and cohesion
Premium Wordpress Themes by UFO Themes