A Novel Functional Impression Procedure for Distal-Extension Removable Partial Dentures

Background: Functional selective pressure impression on the residual ridge is much highly recommended than the rest of the anatomic impressions in distal-extension removable partial dentures (RPD). However, the present methods are significantly more complex, require additional treatment time, and involve more laboratory procedures. Methods: This novel impression procedure involves the following steps. A special force transport unit is first designed and assembled on the stock or custom tray over the residual ridge, through which the opposite teeth can bite on the force transport unit and transport the occlusion force to the impression body. The primary full arch impression is then created using heavy body type of vinyl polysiloxane impression materials. Next, part of the impression overlapping the residual ridge is freed from the intact impression body and the tray with a scalpel. Finally, the final impression is made with a lightbody vinyl polysiloxane impression. The light-body materials are loaded onto the surface of the primary impression and the space from the scalpel cut. The primary impression is set into the mouth, allowing the opposite teeth to bite on the force transport during the impression making process. The free parts are bound to obtain the final impression after the materials are set. Results: This functional impression method could record the anatomic form of the teeth and the functional form of the residual ridge, simultaneously capturing the surface morphology and location of the saddle, which is derived from the deformation after chew loading. Conclusion: This functional pressure impression for RPD is simple, could be easily mastered by dentists, and does not increase the laboratory workload of dental technicians.