The effect of impression tray relief holes on tissue displacement: an in vitro simulation

Abstract

Background: Mobile fibrous tissue can cause excessive movement of a complete denture during function, causing discomfort for the patient. Extensive tissue displacement during definitive impression making can have a direct impact on the anatomical form on which the complete denture will be fabricated. When displaced mobile fibrous tissues return to their relaxed state, dislodgment forces might work against the denture base. As a result, the manner in which the tissues are recorded is critical to the retention and durability of the complete denture. The addition of relief holes to the custom tray allows impression material to escape and decreases the pressure exerted to the underlying alveolar tissue, hence minimizing tissue displacement. Aim of the study: To assess the degree of simulated fibrous tissue displacement on edentulous maxillary analogues when three dimensional (3D) printed custom impression trays with various relief hole sizes and quantities are utilised during a one-step secondary impression technique. To achieve this aim, impressions were digitally analyzed by superimposing the 3D digital control and test models for quantitative analysis utilising metrology software.