Role of Impression Materials in Dentistry

Abstract

Impression materials are used in order to make a negative replication of the both soft and hard tissues of the oral cavity and the concept of using this technique in dentistry began in mid 1800s. Major development and advancement of impression materials and their applications have been occurring during the last decade. Impression materials divide into two main groups of rigid and elastic materials. Rigid materials include: plaster, impression compound and zinc-oxide-eugenol all of which have been used in past and they are more appropriate mostly for area without undercuts, but because of lack of accuracy have become unpopular types of impression. Therefore, nowadays there is considerable replacement of rigid impression materials by elastic materials like aqueous (Agar and alginate) and non-aqueous elastomers (polysulfides, silicones and polyethers). There are several factors for determination of quality of each specific dental impression materials such as their accuracy, elasticity, stability, setting time, smell and being non-irritating or toxic to the oral tissue. Obviously, there is no specific material with all the desirable characteristics included but the variety of modern impression materials give doctors possibility to choose an adequate type taking into account the patient’s condition, level of accuracy needed and purpose of the impression. Important role of impression materials are observable in different dental fields such as prosthodontics (for instance in order to make dentures and plastic casts), orthodontics, restorative dentistry, diagnostics and oral and maxillofacial surgery for both intra oral and extra-oral aims. Clearly, without using correct type of impression material is of vital importance for achieving desirable and accurate results and advancement in the field of impression-making has made it possible to do so. In recent years there have happened not only the modification and enhancement of elastic materials, but also introduction of digital impression-making which is done by scanner systems and their adaptation in dentistry. Stereolithography is common technique for making a digital impression and with more work it is expected to see better results and development in this direction in the nearest future.