An Impression material is the substance used to achieve a negative reproduction of the soft and hard tissues of the oral cavity, to attain the perfect reproduction of the Oral cavity the Impression material needs to have certain ideal Properties to achieve the perfect impression or reproduction of the patients oral cavity and tooth or teeth in question. There are many types of Impression materials which are classified based on multiple requirements.
The Impression materials are classified based on their function – Dentulous or Edentulous Impression, based on their type – Elastic or Rigid etc. The most commonly used Impression material in today’s dental practice is Alginate and Elastomeric Impression material for Dentulous patients and Impression compound, ZOE paste, Elastomeric or Alginate for Edentulous patients.
Desirable or Ideal Properties of an Impression material:
These are the properties an Operator looks at, which make it easy for him/her to operate and get an Ideal Impression. The All the Properties should be fulfilled to produce an Ideal Impression material, till date such an impression material has not been discovered or invented, so we have to use different Impression materials in different situations based on the requirements.
- Pleasant Odor (example of bad odor- Polysulphide)
- Pleasant Taste
- Pleasant color
- Absence of Toxic or irritant constituent
- Adequate shelf life for requirements of storage and distribution
- Should be economical, in case of high cost should be having increased characteristics
- Should be Easy to Use without requirement of much equipment
- Setting time should be adequate for clinical use – And such that the Practitioner can be able to alter it according to his requirement
- Satisfactory consistency and texture
- Should Readily wet the Oral tissues (Hydrophilic materials)
- Should not release Gasses during setting of Cast/Die/impression material
- Should be readily disinfected without loss of accuracy
- Accurate in clinical use
- Compatibility with Cast or Die materials
- Dimensional stability over temperature and humidity changes which can be seen in clinical conditions
- Should be stable long enough to make a cast or Die from the impression taken
- Should have Adequate strength so it will not break, tear during removal from mouth
- Elastic properties with freedom from permanent deformation after strain
The Impression material which satisfies all these properties is termed as the ideal impression material and it can be used to get the perfect impression for your Diagnostic or Treatment planning. After the Impression is taken, Dental Stone or Die Stone or Plaster of Paris is poured into the Impression replica to create a patient model which will be removed from impression once it is set or hardened to be used.