There are many materials that are used for dental impressions and their choice depends on the degree of precision that is required at the time of copying a tooth. When fixed prostheses are to be inserted, addition silicones generally constitute the material of choice for performing the impressions. The polyethers and reversible hydrocolloids are also used, although to a lesser degree. Alginate is an irreversible hydrocolloid that is widely used for making study models due to its easy copying and low cost. With regard to new techniques, the most recent is the use of the scanner, which performs a mapping of the dental structure from which the prostheses for oral rehabilitation are constructed (25)(33)(39).