Dental Liners, Bases, & Bonding Systems

Dental liner

thin layer in deepest part of deep cavity preps

• Protect pulp & stimulate reparative dentin

Dental bases

Thicker layer for moderate-deep preps

= Protect pulp from temperature + physical irritation 

When must a liner be placed before a base?

When the base material irritates the pulp

What stimuli causes pulp response?

Cold, heat, pressure, sweets, trauma, caries, bacteria → perceived as pain

Calcium hydroxide

Protects from chemical irritation

• Stimulates reparative dentin

Compatibility + placement rule for calcium hydroxide?

Compatible with all restorative materials 

• Must not be placed on margins 

Varnish

Seals tubules , releases fluoride →

• Prevents caries

• Desensitizes

• Prevents microleakage

Who needs varnish most?

High-caries-risk patients

• (Ortho, cervical caries)

What materials can be used as bases?

• ZOE 

• Zinc Phosphate

• Polycarboxylate 

• Glass ionomer 

• Resin 

Etchant

• Removes smear layer

• Increases micromechanical retention

Etch time, material, and appearance

• 15-20 sec

• 35-37% phosphoric acid

• Frosty white

What forms the hybrid layer?

Bonding agent placed on etched dentin 

What procedures require bonding ?

• Sealants

• Ortho brackets/bands

• Composite restorations

• Indirect restorations

What are the 3 bonding system types?

• Self-cured

• Dual-cured

• Light-cured

How do liners and bases help the pulp?

Reduce irritation and minimize pulp response to stimuli

What’s the main difference between liners and bases?

• Liner = thin/chemical protection

• Base = thick/thermal & physical protection