A dental impression is a negative imprint of hard (teeth) and soft tissues in the mouth from which a positive reproduction (cast or model) can be formed. It is made by placing an appropriate material in a stock or custom dental impression tray which is designed to roughly fit over the dental arches. Impression material is of liquid or semi-solid nature when first mixed and placed in the mouth. It then sets to become an elastic solid (usually takes a few minutes depending upon the material), leaving an imprint of person’s dentition and surrounding structures of oral cavity.
Impressions, and the study models, are used in several areas of dentistry including:
- diagnosis and treatment planning
- prosthodontics (such as making dentures)
- restorative dentistry (e.g. to make impressions of teeth which have been prepared to receive indirect extracoronal restorations such as crowns, bridges, inlays and onlays)
- maxillofacial prosthetics (prosthetic rehabilitation of intra-oral and extra-oral defects due to trauma, congenital defects, and surgical resection of tumors)
- oral and maxillofacial surgery for both intra-oral and or extra-oral aims (e.g. dental implants)