dental materials - unit 2

liners, bases, cements

Describe the 4 Cavity Depths

1. Minimal depth into enamel

2. Extends beyond enamel into dentin

3. Through dentin, close to the pulp

4. Extends into the pulp

Describe the function of a cavity liner

Sooth the pulp and stimulate healing

• Seals dentinal tubules and protect the pulp from irritants found in some cements and restorative material

• primary consistency

• example: dycal/calcium hydroxide

What are dentin liners used for?

• Line the deepest part of cavity preparation

• Protect pulpal tissue from irritation caused by:

  • Physical

  • Mechanical

  • Chemical

  • Biological elements

Describe the function of a cement base

Replaces lost dentin, brings tooth structure back to the ideal depth, provide pulp protection

• secondary consistency

• example: ZOE

What are cements used for?

1. Luting agentsfor cementation**

2. Temporary restorations**

3. Thermalinsulating bases or liners**

4. Pulp capping

5. Pulp protection

6. Root canal therapy

7. Surgical tissue dressings

Classification according to use of Dental Cement (3)

• Type 1: Luting agents (primary consistency, liner)

• Type 2: Restorative applications (secondary consistency, base)

• Type 3: Liner or base application

What are the unique characteristics of Calcium Hydroxide?

1. Protects pulp from chemical irritation (promotes pulp healing)

2. Stimulates the production of reparative/secondary dentin

3. Compatible with all restorative materials

4. Bacteriostatic properties —> stops bacteria from growing/multiplying

Describe Direct Pulp Capping

• Pulp has been slightly exposed

• CaOH is placed directly on exposed pulp

• Tooth (pulp) is still alive

Describe Indirect Pulp Capping

• Leaves a thin layer of caries to prevent pulpal exposure

• CaOH is placed over the caries

What is the goal of Pulp Capping?

1. Promote pulpal healing by removing most decay

2. Bacteriostatic properties helps inhibit growth of bacteria

3. Stimulate the production of restorative/secondary dentin

What are Varnishes?

A liquid consisting 1 or more resins in an organic solvent

• CANNOT be used with composite resins, glass ionomers, or ZOE*

  • only used with amalgams!

• Applied after the liner

What is the function of Varnishes?

1. Seals dentinal tubules

2. Reduces leakage

3. Acts like a barrier to protect the tooth from acidic cements like zinc phosphate

What are Desensitizers?

A dentinal sealer that treats hypersensitivity

Describe the brand, uses, composition, properties, and manipulation of Zinc Phosphate cement

• Brand: Patterson

• Use: Final cementation of crowns, bridges, inlays

• Composition: zinc oxide powder, phosphoric acid in water

• Properties: Very strong, Viscosity affected by time & temperature

• Manipulation: Primary or secondary, mixed on glass slab for 2 minutes

  • Cement sets in mouth in 5-9min called final setting time

Describe the brand, uses, composition, properties, and manipulation of Zinc Oxide Eugenol (ZOE) cement

• Brand: IRM

• Use: Temporary restorations, insulating base, relieve discomfort

• Composition: zinc oxide powder, eugenol

• Properties: Eugenol has sedative soothing on pulp, cannot be used with composite resin

• Manipulation: Secondary consistency, 1min mixing time

Describe the brand, uses, composition, properties, and manipulation of Polycarboxylate cement

• Brand: Poly-F Plus

• Use: Luting agent, cementation for crowns bridges inlays and orthodontic brackets

• Composition: zinc oxide powder, aqueous polyacrylic acid solution

• Properties: less irritating, will chemically bond, must be glossy to be used

• Manipulation: Primary consistency, 15 sec mixing time

Describe the brand, uses, composition, properties, and manipulation of Glass Ionomer cement

• Brand: CX-Plus

• Use: Cementation for crowns bridges inlays and orthodontic appliances

• Composition: calcium fluoroaluminosilicate glass, aqueous solution of itconic acid tartric acid maleic acid polyacrylic acid and water

• Properties: can adhere to enamel/dentin/metallic materials, RELEASE FLUORIDE, dentin substitute or base material, can result in chemical adhesion

• Manipulation: Primary consistency, 30 sec mixing time, use plastic spatula to mix

  • most versatile and widely used cements