Dental Materials: Composition, Handling, and Importance
Dental Materials: Types, Composition, and Handling
Dentinopulpar Complex Materials
These materials are placed in contact with the dentin in cases where the dentin has been affected by cavities or bone removal. Examples include:
- Glass ionomer
- Zinc oxide-eugenol
- Zinc phosphate
- Calcium hydroxide
- Dental adhesives
Filling Materials
These materials are used to replace lost tooth structure and are also known as restorative materials. Examples include:
- Amalgam
- Gold
- Composite resins
Prosthesis Materials
These materials are used in the fabrication of prostheses when a patient has lost teeth. Auxiliary materials are crucial for preparation, manipulation, and storage.
Material Composition
Organic vs. Inorganic
- Inorganic materials: Obtained from non-living sources such as minerals, rocks, and metals.
- Organic materials: Derived from living matter, such as plants.
Organic substances, especially plastics, are widely used due to their versatility.
Importance of Material Types
- Dentinopulpar protective materials: Primarily composed of inorganic compounds with organic adhesives.
- Restorative materials: Formerly metal-based, now often adhesives (organic) and amalgam (silver or gold – inorganic).
- Prosthesis materials: Alginates, silicones, acrylics (organic); plaster, porcelain, metal alloys (inorganic).
Polymers
A fundamental characteristic of many dental materials is their structure as organic polymers. A polymer is a substance constituted by multiple units of elementary strings. Each unit is called a monomer. When a monomer is activated by an initiator, it can react with other monomers to form long chains, providing consistency and allowing the material to harden. This process is called polymerization. Resin is a type of polymer material.
Material Handling
A) Shelf Life
The shelf life is the period during which a material can be used while preserving its initial properties. Expiration dates and storage conditions (e.g., dry, cool, and dark) are specified.
B) Presentation Form
Materials are often presented as two components that are mixed, such as powder + liquid, or paste + paste + liquids. One component contains catalysts, which trigger the chemical reaction.
C) Manipulation Parameters
The objective is to create a homogeneous mass. An important property is viscosity, which affects ease of handling.
Parameters to Consider During Manipulation:
- Mixing time: The period during which the components are in contact and mixed. This is determined by the manufacturer and is usually a few seconds.
- Working time: The period during which the material can be handled in the mouth while retaining a viscous state.
- Setting time: The time it takes for the material to acquire rigidity and prevent further manipulation. Some materials set quickly, while others take several hours. Once the material has hardened, it is said to have set or, in the case of polymers, to have polymerized.
These processes are influenced by:
- Temperature: Of the components during mixing.
- Proportions: Of the components.
- Dimensional changes: Possible physical changes during setting.
- Heat: Excessive heat can damage biological structures.