DENTAL MATERIALS

Materials in Dentistry
Overview

This section covers different substances, often called dental materials, that are used to create dental fillings, crowns, bridges, and other devices. We'll look at:

  • Alginate: A material mainly used for making impressions of teeth.

  • Zinc Oxide and Eugenol: A common mix for temporary fillings and soothing dental issues.

  • Glass Ionomer Cements (GIC): A versatile material used for fillings and as a protective lining.

Alginate

General Information

Alginate is a material used to make dental impressions, which are like molds of your teeth and gums. These are commonly used in various dental procedures.

  • Types:

    • Fast Set (sets quickly)

    • PlasFast

    • Alginet

Advantages of Alginate

  • Easy to Use: Dental professionals find alginate straightforward and simple to work with.

  • Flexible (Elasticity): It's very flexible, which means it can be used to take all sorts of tooth impressions.

  • Can be Removed from Undercuts: It can be pulled away from tricky, recessed areas (like undercuts) without getting warped, torn, or broken. This makes it a popular choice for most impression types.

Disadvantages of Alginate

  • Can Get Warped: If it's not handled correctly, the impression can become misshapen (impression distortion).

  • Needs Immediate Pouring: For the best and most accurate models (casts), the impression should be filled with plaster right away after it's taken.

  • Requires Careful Handling: You need to be very careful when managing the material to stop it from distorting.

Handling Instructions for Alginate

  • Rinse and Clean: Impressions must be rinsed and disinfected with cold water.

  • Don't Soak Too Long: They should not be left to soak in disinfectant for longer than the manufacturer's directions state.

  • Storage: To keep them moist and prevent distortion, store or transport impressions wrapped in a damp cloth (damp gauze) and sealed in an airtight bag.

Zinc Oxide and Eugenol

Composition

Zinc Oxide and Eugenol is made by mixing Zinc Oxide powder with drops of Eugenol, which is a liquid derived from cloves.

Uses of Zinc Oxide and Eugenol

  • Temporary Fillings: Often used for dental restorations that are only meant to last for a short time.

  • Non-Irritant Lining: It's used as a gentle lining in deep tooth cavities, protecting the nerve without causing irritation.

  • Soothing Dressing: Acts as a pain-relieving covering (sedative dressing) for teeth that are sensitive or painful due to decay (carious teeth).

  • Other Materials: It's a key ingredient in some impression pastes, coverings for gum surgery (periodontal packs), and materials for filling tooth roots (root filling materials).

Advantages of Zinc Oxide and Eugenol

  • Soothing Effect: It's known to be calming and doesn't irritate the living tissue inside the tooth (pulp).

  • Sedative Properties: Can provide a soothing layer underneath a permanent filling (sedative lining).

Disadvantages of Zinc Oxide and Eugenol

  • Soft and Slow to Set: This material is quite soft and takes a long time to harden (sets slowly), making it not ideal as a base for permanent fillings in a single visit.

  • Not Compatible with Composites: It doesn't work well with composite fillings, a common tooth-colored filling material.

  • Allergic Reactions: Some individuals might experience allergic responses to products that contain eugenol.

Glass Ionomer Cements

Composition

Glass ionomer cement (GIC) is made from two parts that are mixed together for dental use:

  • Powder: A glass-like mixture of aluminosilicates.

  • Liquid: Composed of polyacrylic acid.

Uses of Glass Ionomer Cements

  • Applications: GIC is useful for a variety of dental needs, including fillings (restorations), protective linings, fissure sealants (to prevent cavities), and as a cement to bond dental devices (adhesive cements).

  • Key Properties:

    • Fluoride Release: It slowly releases fluoride, a substance that helps protect teeth and prevent new decay around the filling.

    • Direct Bonding: It can stick directly to the tooth's surface (enamel, dentine, and cementum) without needing a special acid treatment (acid etching).

Advantages of Glass Ionomer Cements

  • Strong Adhesion: It sticks well to different parts of the tooth, like enamel, dentine, and cementum.

  • Good for Specific Cavities: It's especially useful for fillings on the sides of teeth near the gum line (Class V cavities).

  • Excellent Seal: It creates a very good seal around the edges of the filling, helping to prevent leakage (marginal seal).

  • Continuous Fluoride Release: It keeps releasing fluoride over time, which strengthens the tooth and guards against cavities.

  • Better Appearance: It looks better than silver (amalgam) fillings because it can be made to match tooth color (aesthetic properties).

Disadvantages of Glass Ionomer Cements

  • Lower Strength: It's not as strong or durable as amalgam or composite filling materials.

  • Careful Application: It needs very precise and careful handling for accurate placement and the best results.

  • Sensitive to Moisture: It's easily affected by moisture, which can weaken it if not kept dry during placement (moisture sensitivity).

  • Exact Mixing Needed: The exact amount of powder and liquid must be mixed thoroughly to get the right consistency and setting properties (mixing ratio is crucial).