1. Chapter 44 Dental Liners, Bases and Bonding Systems
Copyright 2003, Elsevier Science (USA).
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2. Introduction
Dental liner, bases, and bonding systems are in a classification of dental materials that provide additional protection for the health and well-being of a tooth being restored.

3. Prepared Tooth Structures
The design of the cavity preparation gives strength within the tooth and helps determine how the tooth will hold the restoration in place.

4. Pulpal Responses Types of stimulus Examples of stimulus
Physical Thermal, electrical
Mechanical Handpiece,
traumatic occlusion
Chemical Acid from dental materials
Biologic Bacteria from saliva

5. Dental Liners
Dental liners provide a thin barrier that protects the pulpal tissue from irritation caused by physical, mechanical, chemical and biologic element.

6. Calcium Hydroxide Indications for use
Protects the pulp from chemical irritation by its sealing ability.
Stimulates the production of reparative or secondary dentin.
Compatible with all types of restorative materials.

7. Calcium Hydroxide-cont’d
Application process
Placed only on dentin.
Placed directly over the deepest portion of the preparation.

8. Fig. 44-1 Location for placement of calcium hydroxide.

9. Varnishes Indications for use* Seal the dentinal tubules.
Reduce leakage around a restoration.
Act as a barrier to protect the tooth from highly acidic cements such as zinc phosphate.
* This material is contraindicated in its use under composite resins and glass ionomer restorations.

10. Varnishes-cont’d Application process
Applied with either a small disposable applicator or a cotton pellet.
Thin coating of the varnish on the walls, floor, and margin of the cavity preparation.
Apply a second coat.

11. Fig. 44-5 Location for placement of cavity varnish.

12. Dentin Sealer Indications for use Treat or prevent hypersensitivity.
Used instead of a varnish.
Seal the dentinal tubules.
Ideal for use under all indirect restorations.

13. Dentin Sealer-cont’d Application Process Material used sparingly.
Do not allow to contact soft tissues (HEMA and glutaraldehyde).
Apply the dentin sealer with the cotton-tipped applicator.
Apply over all areas of the exposed dentin.

14. Dental Bases Dental bases provide pulpal protection.
Protective base: Protect the pulp before the restoration is placed.
Insulating base: Protect the tooth from thermal shock.
Sedative base: Soothe a pulp that has been damaged by decay or irritated by mechanical means.

15. Types of Base Materials
Zinc oxide eugenol
Zinc phosphate
Polycarboxylate
Glass ionomer

16. Fig. 44-8 Location for placement of a base.

17. Dental Bonding
Dental bonding improves retention by creating a micromechanical retention between the tooth structure and the restoration.

18. Enamel Bonding
Enamel bonding is placed directly onto the intact enamel surface.
Examples of Enamel Bonding
Sealants
Bonded orthodontic brackets
Resin‑bonded bridges
Bonded veneers

19. Dentin Bonding
Dentin bonding is placed on prepared dentin in order to bond.
Smear layer
Thin layer of debris
“Nature's bandage”

20. Etching Systems
Etching Systems remove the smear layer in preparation for bonding.
Supplied as:
Liquid/Gel
Maleic acid
Phosphoric acid

21. Clinical Application of the Etchant and Bonding Systems
Etchant is applied to remove the smear layer.
Plaque or debris is removed before the bonding process.
Avoid overdrying etched teeth.
Too much primer is better than too little.
Bonding solution covers all surfaces.
Contamination with saliva requires the entire procedure to be redone.  
Allow time for bonding material to mature before completing the restoration.      

22. Table 44-2: Supplementary Dental Materials and their Application in Order of Use