For the impression or mouth records there are different biomaterials, one of them, is the irreversible Hydrocolloid called Alginate, It is a gelling agent and viscocifier that allows to reproduce in detail the hard and soft tissue structures of the oral cavity. Alginate is commercially available in powder form, formed of alginic acid, which comes from marine algae; calcium sulfate, trisodium phosphate and diatomaceous earth; that when mixed with water, they form a colloidal sun (plastic mass). When in contact with the patient‘s mouth, begins the gelling process and ends in 7 minutes, in this way the exact reproduction of the dental arches is obtained. Finally, the emptying with plaster is performed, to obtain the duplication of the maxillary.