Dental Cement Notes

Objectives

• Compare various types of cements for:
  • Pulpal protection
  • Luting
  • Restorations
  • Surgical dressing
• Describe properties of cement and explain selection criteria
• Identify components of various dental cements
• Discuss how components affect cement properties
• Compare advantages and disadvantages of each cement type
• Address manipulation considerations for mixing cements
• Outline procedure for filling a crown with luting cement
• Describe removal of excess cement after cementation
• Apply mixing techniques for each type of cement

Definition of Dental Cement

• Dental Cement: A substance that binds two surfaces together rigidly.
• Classification of Cements:
  • Type 1:
  • Luting agents for crowns, bridges, onlays, inlays
  • Bond orthodontic bands/brackets (permanent or provisional)
  • Type 2:
  • Provisional/intermediate restorations
  • Example: Glass Ionomer for long-term use
  • Type 3:
  • Bases or liners for cavity preparations

Properties of Dental Cements

• Strength:
  • Brittle; good compressive strength, limited tensile strength
  • Strongest = resin cements; Weakest = zinc oxide eugenol
• Solubility:
  • Tendency to dissolve in oral fluids causes potential microleakage
  • Bonded resin cements are nearly insoluble
• Viscosity and Film Thickness:
  • Consistency affects ability to flow under pressure
  • Primary consistency: thin (like honey)
  • Secondary consistency: putty-like
• Biocompatibility:
  • Many cements contain acids that may irritate pulp
  • Proper mixing technique mitigates concerns
• Retention and Adhesion:
  • Achieved by mechanical (interlocking) and chemical (electron sharing) means
• Esthetics:
  • Available in shades and opacities, radiopacity is crucial for visibility on x-rays

Uses of Dental Cements

• Pulpal Protection:

  • Cavity varnish, low-strength base/liner, prevent pulpal irritation caused by:
  • Bacterial caries effects
  • Chemical responses to restorative materials
  • Cutting through tooth structure
  • Liners: Thin layer over dentin to seal tubules; e.g., Calcium hydroxide for thin dentin
  • Bases:
  • Layer on dentin providing insulation/support
  • High/low strength classifications (ZOE for low strength)
  • Buildup: Reinforces remaining structure when significant tooth is lost

• Luting of Indirect Restorations:

  • Low viscosity to attach restorations to teeth
  • Orthodontic applications involve bonding to enamel with resin cements
  • Leakage concerns necessitate cements with fluoride

• Restorations:

  • Permanent cements not preferred for strength/wear resistance
  • Exceptions: Glass ionomer cement for cervical fillings
  • Temporary/provisional uses for emergency situations/awaiting further treatment

• Surgical Dressings:

  • Provide protection, support, control bleeding
  • Coe Pak commonly used;
  • Two-paste system for soft consistency that hardens on application

Types of Cements

• Type I Luting Cements:
  • Water-Based:
  • Zinc Phosphate, Zinc Polycarboxylate, Glass Ionomer
  • Resin-Based:
  • Modified composites with advantages in bond strength, wear resistance

Specific Cements

• Zinc Phosphate:

  • Weaker than resin/hybrid ionomers; rarely used today

• Zinc Polycarboxylate:

  • Primarily for long-term temporary cements; lower strength
  • Mix for 30 seconds until creamy; use immediately

• Glass Ionomer Cements:

  • Composed of aluminum fluorosilicate glass; biocompatible, fluoride-releasing
  • Moderate strength; manipulation by premeasured systems

• Resin-Modified Glass Ionomer:

  • Improves bond strength and decreases solubility with added resin
  • Light or chemical cure reactions for manipulation

• Zinc Oxide Eugenol (ZOE):

  • Used for provisional cementation, root canal sealers; neutral pH, biocompatible
  • Common products include Temp Bond

Removal of Excess Cement and Cleanup

• Removal: Must be done based on manufacturer instructions; some cements remove easily while others must set first
• Cleanup: Essential to disinfect equipment; sterilization of mixing and delivery instruments required
• Considerations: Care to avoid damaging cement during removal

Summary of Key Points

• Applications of dental cements include pulpal protection, luting, restorations, surgical dressing.
• Types of luting cements: Type 1, 2, and 3.
• Differences between GIC and hybrid GIC mainly involve bond strength and solubility.
• Advantages of resin-based cements include superior bond strength and wear resistance.
• ZOE cements can be eugenol or non-eugenol, primarily used for provisional restorations.
• Important to properly remove excess cement to prevent complications.