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Dental Liners, Bases,and Bonding Systems
Chapter 44
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Introduction
Dental liners, bases, and bonding systems are a supplemental classification of dental
materials that provide additional protection for the health and well-being
of the tooth being restored.
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• Design of the Cavity Preparation
– Gives strength within the tooth
– Helps determine how the tooth will hold the restoration in place
Prepared Tooth Structures
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Types of Stimulus Examples of Stimulus
Physical Thermal, electrical
Mechanical Handpiece, traumatic occlusion
Chemical Acid from dental materials
Biologic Bacteria from saliva
Pulpal Responses
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Dental liners provide a thin barrier to protect the pulpal tissue from irritation
caused by physical, mechanical, chemical and biologic elements.
Dental Liners
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• 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.
Calcium Hydroxide
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• Application Process
– May be an advanced function in your state
– Placed directly over the deepest portion of the preparation
– Placed only on dentin
Calcium Hydroxide-cont’d
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Fig. 44-1 Location for placement of calcium hydroxide
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Varnish
A liquid consisting of one or more resins in an organic solvent applied to the
internal preparation structure.
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• Indications for Use*
– Seal 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
Varnishes
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• Application Process
– Applied with either a small disposable applicator or cotton pellet
– Thin coating of varnish placed on the internal walls, floor, and margin of a cavity preparation
– Allowed to air dry
– A second application is recommended
Varnishes-cont’d
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Fig. 44-3 Location for placement of cavity varnish
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• Indications for Use
– Treat or prevent hypersensitivity
– Used instead of a varnish
– Seal the dentinal tubules
– Ideal for use under all indirect restorations
Dentin Sealer
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• Application Process
– Use material 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 exposed dentin
Dentin Sealer-cont’d
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• Dental bases provide different types of pulpal protection:
– Protective Base: Protects the pulp from a large restoration.
– Insulating Base: Protects the tooth from thermal shock.
– Sedative Base: Soothes a pulp that has been damaged by decay or irritated by mechanical means.
Dental Bases
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Zinc Oxide Eugenol (ZOE)
Zinc Phosphate
Polycarboxylate
Glass Ionomer
Types of Base Materials
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Fig. 44-5 Location for placement of a base
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Dental bonding improves retention by creating a micromechanical retention
between the tooth structure and the restoration.
Dental Bonding
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• Enamel bonding is placed directly on the intact enamel surface.
• Examples of Enamel Bonding
– Sealants
– Bonded orthodontic brackets
– Resin‑bonded bridges
– Bonded veneers
Enamel Bonding
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• Dentin bonding is placed on the prepared dentin for the bonding of a restorative material to tooth structure.
• Smear Layer
– Thin layer of debris
– “Nature's bandage”
Dentin Bonding
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• Etching Systems remove the smear layer in preparation for bonding.
• Supplied as:
– Liquid/Gel
– Maleic acid
– Phosphoric acid
Etching Systems
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• Plaque or debris is removed before the bonding process.
• Etchant is applied to remove the smear layer.
• Rinsing and Drying of tooth structure (avoid overdrying etched teeth).
• Bonding solution covers all surfaces.
• Too much bonding is better than too little.
• Contamination with saliva requires the entire procedure to be redone.
• Allow time for bonding material to mature before completing the restoration.
Clinical Application of the Etchant and Bonding Systems
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Table 44-1 Supplementary Dental Materials and Application in Order of Use