Dental Bonding: Enamel vs Dentin

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Questions and Answers

What is the primary component of enamel, making up more than 90% by volume?

Dentin tubules

Organic material

Type I collagen

Hydroxyapatite (correct)

What decreases dentin permeability by nearly 90% in vitro?

Smear layer (correct)

Smear plugs

Peritubular dentin

Dentinal tubules

What is the purpose of the peritubular dentin?

To increase the bonding strength of resin

To line the tubules (correct)

To reduce the dentin permeability

To provide a pathway for nutrients to the pulp

What is the main difference between dentin and enamel bonding?

Dentin contains a substantial proportion of water and organic material Signup and view all the answers

What is the composition of the smear layer?

Hydroxyapatite and altered denatured collagen Signup and view all the answers

What type of tissue is dentin?

Intrinsically hydrated tissue Signup and view all the answers

What is the primary purpose of using phosphoric acid gel in enamel adhesion?

To etch the enamel and increase its surface free energy Signup and view all the answers

What is the minimum recommended shear bond strength for composite to phosphoric acid-etched enamel?

20 Mpa Signup and view all the answers

What is the formation of resin microtags within the enamel surface a result of?

The application of a fluid resin-based material to the etched surface Signup and view all the answers

What is a challenge unique to bonding to dentin compared to enamel?

The complexity of its composition and structure Signup and view all the answers

What is the typical concentration of phosphoric acid gel used in enamel adhesion?

30%–40% Signup and view all the answers

What is the recommended etching time for phosphoric acid gel in enamel adhesion?

15 s Signup and view all the answers

What is the literal meaning of the word 'adhesion'?

To stick to Signup and view all the answers

Which of the following is NOT a mechanism of adhesion in dentistry?

Electrostatic Signup and view all the answers

What is the primary component of tooth structure that adsorption bonding occurs with?

Hydroxyapatite Signup and view all the answers

What is the name of the process by which resin penetrates the tooth surface and forms tags?

Mechanical locking Signup and view all the answers

What is the main component of tooth structure that is responsible for the mechanical mechanism of adhesion?

Dentin Signup and view all the answers

What is one of the uses of adhesives in dentistry?

Desensitizing non-carious cervical lesions Signup and view all the answers

Study Notes

Enamel and Dentin Bonding

Enamel is a highly mineralized tissue composed of more than 90% hydroxyapatite.
Dentin contains a substantial proportion of water and organic material, primarily type I collagen.
Dentin has a dense network of tubules that connect the pulp with the dentinoenamel junction (DEJ).
Peritubular dentin lines the tubules and is a cuff of hypermineralized dentin.
Intertubular dentin contains collagen fibrils and is less mineralized.

Smear Layer

Residual organic and inorganic components form a ‘smear layer’ of debris on the surface after tooth preparation.
The smear layer fills the orifices of dentin tubules, forming ‘smear plugs’ and decreases dentin permeability by nearly 90% in vitro.
The composition of the smear layer includes hydroxyapatite and altered denatured collagen.

Enamel Adhesion

Phosphoric acid etching facilitates adhesion of paints and resins to metallic surfaces.
Phosphoric acid gels with concentrations of 30%–40% are used for etching, with 37% phosphoric acid gel being the most common.
The recommended etch time is 15 seconds.
Shear bond strengths of composite to phosphoric acid-etched enamel usually exceed 20 Mpa.

Resin Microtag Mechanism of Enamel Adhesion

Acid etching transforms the smooth enamel into an irregular surface and increases its surface free energy.
Penetration of a fluid resin-based material into the irregular etched surface facilitates adhesion.
Monomers in the material are then polymerized, and the material becomes interlocked with the enamel surface.
Formation of resin microtags within the enamel surface is the fundamental mechanism of resin–enamel adhesion.

Dentin Adhesion

Bonding to dentin presents a much greater challenge.
Adhesion is the state in which two surfaces are held together by interfacial forces.
Four possible mechanisms of adhesion in dentistry include:
- Mechanical—penetration of resin and formation of resin tags within the tooth surface
- Adsorption—chemical bonding to the inorganic component (hydroxyapatite) or organic components (mainly type I collagen) of tooth structure
- Diffusion—precipitation of substances on the tooth surfaces to which resin monomers can bond mechanically or chemically
- A combination of the previous three mechanisms

Uses of Adhesives

Restore Class I, II, III, IV, V, and VI carious lesions or traumatic defects.
Change the shape and color of anterior teeth (e.g., with full or partial resin veneers).
Improve retention for porcelain-fused-to-metal (ceramometal) or metallic crowns.
Bond all-ceramic restorations.
Seal pits and fissures.
Bond orthodontic brackets.
Bond splints for tooth luxations and periodontally involved anterior teeth and conservative tooth replacement prostheses.
Repair existing restorations (composite, amalgam, ceramic, or ceramometal).
Provide foundations for crowns.
Desensitize non-carious cervical lesions (NCCLs) and exposed root surfaces.
Bond fractured fragments of anterior teeth.

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Description

This quiz covers the differences between enamel and dentin bonding in dental care, including their composition and characteristics.