Humankind has always been plagued by the problem of restoring parts of the body lost as
a result of accident or disease. Practitioners of dentistry have been confronted with this
problem since the beginning of dental practice, and the means of replacing missing tooth
structure by artificial materials continues to account for a large part of dental science.
Artificial restoration of the lost and missing teeth and other hard and soft tissues of the
oral cavity and the face covers a major part of the modern dental practice.
One of the essential requisites for satisfactory function of any artificial restoration is
adequate fit. To ensure the accuracy of the fit, fabrication is best carried out directly inside
the oral cavity on the affected part. However, as it is not possible to work directly inside
the oral cavity, a duplicate reproduction of the affected part in a durable material becomes
necessary for indirect fabrication in the laboratory. Hence, certain materials are used to
register or reproduce the form and relationship of the teeth and oral tissues and are
commonly referred to as impression materials.1