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    How to fabricate flexible removable partial dentures

    Using modern materials and techniques allows for cost savings and superior dentures.

    Traditional methods for fabricating removable partial dentures (RPDs) require the use of prefabricated sets of denture teeth made from polymethyl methacrylate (PMMA).

    The practice of using prefabricated teeth often requires modification to the individual teeth in order to fit the shapes, sizes and contours of the natural teeth that abut and oppose the partial denture. The denture teeth are then combined with cast chrome-cobalt, polymerizing acrylic resins, injection molded polyamides or a combination of these materials. Processing these materials traditionally involves tasks that can be digitized through recent advancements in additive manufacturing. This case study explores the use of modern digital technology to plan, design and fabricate a set of maxillary and mandibular flexible partial dentures.

    Overview

    The practice of RPD fabrication by dentists and dental technicians generally focuses on how to properly survey and design a case to accommodate clasp placement based on path of insertion and undercuts for retention.

    Fig 1.Fig. 1Less emphasis is placed on the selection and arrangement of denture teeth for partially edentulous patients for whom the RPD is being prescribed. RPD patients commonly display situations that make tooth replacement challenging, such as wide or narrow spacing between abutments that have drifted, opposing dentition that has worn or supra-erupted, and natural morphology which is difficult and time consuming if not impossible to replicate by contouring prefabricated denture teeth.

    Traditional hand-built techniques for constructing a custom resin-based crown are time consuming and generally cost prohibitive when used in combination with most RPDs. The evolution of digital CAD/CAM in restorative dentistry has made it feasible to construct custom resin crowns to be used in combination with a flexible or metal based RPD. This set of flexible RPDs will be constructed in just two patient appointments — the first to acquire digital final impressions and maxillo-mandibular relationship records, and the second to deliver the prostheses.

    Case study

    A young male who presented with partially edentulous spans on the maxillary and mandibular arches and in need of Kennedy Fig. 2Fig. 2Class I (maxillary) and Kennedy Class I Mod. I (mandibular) removable partial dentures (Fig. 1). The bilateral distal extension situation present in both arches made the patient a suitable candidate for flexible RPDs. This will incorporate stressbreaking function and the snowshoe principle into the dentures in an attempt to alleviate stress and torque on the distal abutments.

    Final impressions and the jaw relationship record are taken at a single appointment in full color using the Trios Intraoral Scanner (3Shape A/S, Fig. 2). The scanner records color information and captures all tooth and tissue areas with ease, and transmits the scans electronically to the lab within minutes after being taken.

    Cornelius Yen, DDS
    Dr. Cornelius Yen is the owner of Yen Dentistry and Implantology in Flushing, New York. He obtained his DDS at the NYU College of ...

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