[Tissue displacement and impression techniques--part 1].

In order to create an accurate model of the soft and hard tissues of the mouth, a complete control of the gingiva around the prepared teeth is needed. This gingiva must be displaced and bleeding must be avoided. This article describes the three techniques for tissue displacement: mechanical, chemicomechanical and surgical. Mechanical displacing the gingiva can be done by either the use of copper bands or with plain retraction cord. By combining chemical action with packing of a retraction cord a chemicomechanical displacement of the tissue can take place. The surgical retraction is possible by Laser, Electro surgery or Rotatory curettage. The advantages, disadvantages, and limitations of each of the different techniques are discussed. In addition, the different hemostatic agents are described with their mechanism of action, indications and contra-indications of each one of them.