Dental Luting Agents & Cementation

• Cement is a material that fills a space or binds objects when it hardens
• Cementation is the process of attaching parts using cement
• A luting agent is any material used to attach or cement indirect restorations to prepared teeth

Ideal Properties

• Adhesion to restorative material is an ideal property
• Adequate strength to resist functional forces is an ideal cementing property
• Lack of solubility in oral fluids is an ideal property
• Low film thickness is an ideal property
• Biocompatibility is considered an ideal property
• Possession of anticariogenic properties is ideal
• Being Radio-opaque is an ideal property
• Ease of manipulation is ideal for cement
• Being Esthetic and color stable is ideal

Classifications based on Ingredients

Water based

• Glass Ionomer Cement is water based
• Resin Modified Glass Ionomer is water based
• Zinc Polycarboxylate is water based

Oil Based

• Zinc Oxide Eugenol is oil based
• Zinc Oxide Non-Eugenol is oil based

Resin Based

• Composite cement is comprised of resin
• Adhesive Resins contain resin
• Compomer

Classification based on Function

• Definitive Cement - Zinc Phosphate, Zinc Polycarboxylate, Composite Resin, Glass Ionomer
• Temporary Cement - Zinc Oxide Eugenol/Non-Eugenol
• High Strength - Zinc Phosphate, Zinc Polycarboxylate, Composite Resin, Glass Ionomer
• Low Strength - Zinc Oxide, Calcium Hydroxide
• Temporary Filling - Zinc Oxide, Zinc Polycarboxylate
• Liners - Calcium Hydroxide
• Varnishes - Resin In A Solvent

Classification by Matrix Type

• Phosphate Matrix - Zinc Phosphate
• Phenolate Matrix- Zinc Oxide Eugenol, Calcium Hydroxide
• Polycarboxylate Matrix - Zinc Polycarboxylate, Glass Ionomer
• Resin Matrix - Polymethyl Methacrylate, Dimethyl Methacrylate, Adhesive
• RMGI Matrix - Hybrid Ionomer

Classifications based on Mechanism

• Non-Adhesive cement fills the restoration-tooth gap and holds by engaging in small irregularities (zinc oxide, zinc phosphate)
• Micromechanical Bonding enhances surface irregularities by air abrasion or acid etch improving frictional retention (resin cements)
• Molecular Bonding results in a chemical bond between cement and tooth structure (zinc polycarboxylate, glass ionomer)

Types of Cement

• Zinc phosphate
• Zinc polycarboxylate
• Zinc oxide eugenol
• Glass ionomer
• Resin modified glass ionomer
• Resin

Zinc Phosphate

Reaction

• Zinc oxide powder reacts with phosphoric acid liquid to create zinc aluminophosphate gel
• It is an Exothermic reaction
• It is Mechanical and non-adhesive

Indication

• Used in cast crowns, metal ceramic crowns, and cast posts

Contraindication

• Should not be used with Ceramic Inlays, Ceramic Veneers, and Resin Bonded FDP

Advantages

• It has strength to maintain the restoration
• It mixes early and sets sharply

Disadvantages

• It has an Irritating effect on the pulp
• There is a lack of anticariogenic properties
• There's a lack of adhesion to the tooth

Times

• Mixing Time: 1.5 - 2 Min
• Working Time: 5 Min
• Setting Time: 5 - 9 Min
• Film Thickness: 25 micrometer

Zinc Phosphate - Frozen Glass Slab Technique

• Used to prolong working time and shorten setting time
• Glass slab must be cooled at 6°C - 10°C
• 50-70% more powder incorporation
• Working time is increased by 4-11 mins
• Setting time shortened by 20-40%

Modifications to Zinc phosphate cements

• Copper and silver cements:
  • Higher solubility
  • Lower strength Fluoride cements
  • Higher solubility
  • Stannous fluoride at 1-3%

Zinc Polycarboxylate

Reaction

• Zinc oxide powder reacts with the polyacrylic acid liquid to form polymer chain of carbonyl groups and polyacid groups
• It uses Molecular bonding at 2 MPa

Indication

• Used in Cast Crowns and Metal Ceramic Crowns

Contraindication

• Should not be used for Ceramic Inlays, Ceramic Veneers, Resin Bonded FDP or Cast Posts

Advantages

• Low irritation
• Chemical bond to tooth structure
• Easy manipulation
• Adequate strength
• Low solubility
• Anticariogenic

Disadvantages

• Lower compressive strength
• Difficult to clean
• Surface must be clean for adhesion
• Short working time

Times

• Mixing Time: 30-40 Sec

• Working Time: 2.5 Min

• Setting Time: 6-9 Min

• Film Thickness: 25 micrometer

• Polyacrylic acid reacts with the tooth surface calcium and chelates bonding

• Zinc polycarboxylate exhibits thinning with increased shear rate

• A weak bond with gold and porcelain but good bond with non-precious alloys is observed

Zinc Oxide Eugenol

• Reaction: Zinc oxide powder reacts with acid eugenol liquid Zinc eugenolate.
• It is mechanical and non-adhesive

Equation for reaction

• ZnO + H2O —> Zn(OH)2
• Zn(OH)2 + 2HЕ — -> ZnE2n + 2H2O

Indication

• Used as a temporary cement agent.

Contraindication

• Should not be used when using resin cements for final cementation.

Advantages

• Sedative effect on pulpal tissue
• Good sealing ability
• Resistance to marginal penetration
• Good thermal insulation

Disadvantages

• Low strength
• Disintegration in oral fluids
• Less anticariogeNic
• Highest solubility

Times

• Mixing Time: Until Homogeneous
• Working Time: Affected By Temp. & Moisture
• Setting Time: 4 - 10 Min
• Film Thickness: 25 micrometer

Classification based on ADA 30

• Type I is for temporary cement

• Type II is for a definitive cement

• Type III is for temporary restoration and is a thermal insulating base

• Type IV is a cavity liner

• Powder to Liquid ratio is either 4:1, or 6:1 by weight

• Two paste type has same amount

• Is Affected by moisture and temp.

• Sets faster in oral cavity

• Is a Reversible reaction

Glass Ionomer

Reaction

• Silicate glass powder reacts with polyacrylic acid liquid creating glass ionomer
• It provides Molecular bonding at 3-5 MPa

Indication

• Used for Cast Crowns, Metal Ceramic Crowns, and Cast Post

Contraindication

• Should not be used for Ceramic Restorations and Resin Bonded FDP

Advantages

• Bonding Property
• Anticariogenic Effect
• Easy To Use, available is capsule form
• Is available in Different Shades
• Biocompatible
• Good Marginal Seal

Disadvantages

• Low Flexural Strength
• High Modulus Of Elasticity
• Absorbs Water During Setting Phase
• Less Esthetic

Times

• Mixing Time: Depends on Type

• Working Time: 3 - 5 Min

• Setting Time: 5 - 9 Min

• Film Thickness: 25 micrometer

• Powder to liquid ratio is dependent on instructions

• Can be Capsule type like an amalgam

• Can be a Two paste system, must be mixed homogenous

• Sensitive to water and air

• When exposed to ambient air it will craze and crack creating a cohesive failure from micro crack formation

• Cause of post cement sensitivity is from bacterial invasion, hydraulic pressure and acidity in the early setting stage and wash of thin mix

Resin Modified Glass Ionomer

Reaction

• Radio-opaque fluroaluminosilicate glass and micro encapsulated potassium sulfate powder reacts with polycarboxylate acid modified with methacrylate groups, 2 HEMA and tartaric acid liquid creating an acid/base glass ionomer reaction
• It provides for self cured or light cured polymerization of the methacrylate group
• It provides >10 MPa of Molecular bonding

Indication

• Used in Cast Crowns, Metal Ceramic Crowns, and Cast Post
• It is the material of choice for casted restorations

Contraindication

• Should not be used for Ceramic Restorations or Resin Bonded FDP

Advantages

• Set On Demand
• Immediate Finishing
• Better Esthetics
• Higher Tensile Strength
• Anticariogenic Bond To Resin Composite

Disadvantages

• Lower Flexural Strength
• High Modulus Of Elasticity
• Absorbs Water During Setting Phase But Less Than GI
• Less Esthetic

Times

• Mixing Time: 8 - 10 Sec

• Working Time: 2.5 Min

• Setting Time: 5 - 9 Min

• Film Thickness: 25 micrometer

• A Chemical bond is formed

• Moisture sensitivity remains an issue

• Polyalkenoic acid plays a role starting the adhesion by “diffusion based adhesion”

• Difficult to remove after set

Resin

Reaction

• Polymerization reaction, combination of dimethacrylate with other monomers containing various amounts of ceramic fillers
• It offers micromechanical bonding at 18-20nMPa

Indication

• Used in All Ceramic Restorations

Contraindication

• Light Cured Cements Are Contraindicated With Metal Or Thick Zirconia Restorations

Advantages

• Excellent Mechanical Properties
• High Bond Strength
• High Esthetics

Disadvantages

• Polymerization Shrinkage
• Microleakage
• Technique Sensitive
• Cleaning After Cementation Takes Time

Times

• Mixing Time: Depends On Type
• Working Time: Depends On Type
• Setting Time: 3 - 7 Min
• Film Thickness: 20 - 60 micrometer

Classification By Mechanism

• Light cured
• Self cured
• Dual cured

Classification Based on Bonding Procedure

• Total etch (etch + bond + resin)
• One step (etch & bond + resin)
• Self adhesive (etch + bond & resin)
• Self etch, self adhesive (etch, bond & resin)

Comparisons of luting agents

• Ideal material has Low film thickness, Long working time, Short setting time, and High compressive strength, with Dentin at 13.7 and Enamel at 84-130 Elastic modules, Low Pulp irritation, Very low Solubility, Very low Microleakage, Easy Removal of excess, or High Retention
• Zinc phosphate has <25 Film thickness, 1.5-5 Working time, 5-14 Setting time, and 62-101 Compressive strength, with 13.2 Elastic modules, Moderate Pulp irritation, High Solubility, High Microleakage, Easy Removal of excess, Moderate Retention Polycarboxylate has <25 Film thickness, 1.75-2.5 Working time, 6-9 Setting time, and 67-91 Compressive strength, with Not tested Elastic modules, Low Pulp irritation, High Solubility, High to very high Microleakage, Medium Removal of excess, and Low/moderate Retention
• Glass ionomer has <25 Film thickness, 2.3-5 Working time, 6-9 Setting time, and 122-162 Compressive strength, with 11.2 Elastic modules, High Pulp irritation, Low Solubility, Low to very low Microleakage, Medium Removal of excess, or Moderate to high Retention
• Resin ionomer has >25 Film thickness, 2-4 Working time, 2 Setting time, and 40-141 Compressive strength, with Not tested Elastic modules, High Pulp irritation, Very low Solubility, Very low Microleakage, Medium Removal of excess, or High Retention
• Composite resin has >25 Film thickness, 3-10 Working time, 3-7 Setting time, and 194-200 Compressive strength, with 17 Elastic modules, High Pulp irritation, High to very high Solubility, High to very high Microleakage, Medium Removal of excess, or Moderate Retention
• Adhesive resin has >25 Film thickness, 0.5-5 Working time, 1-15 Setting time, and 179-255 Compressive strength, with 4.5-9.8 Elastic modules, High Pulp irritation, Very low to low Solubility, Very low to low Microleakage, Difficult Removal of excess, or High Retention

Explore dental luting agents used for cementing indirect dental restorations. Understand the significance of luting agents and proper isolation during cementation. Learn about factors for selecting agents and potential issues in the process.