RP4 implant-supported overdentures

Overview

In an RP4 prosthesis, the denture is primarily supported and stabilized by implants, a bar, or attachment systems, with little or no planned mucosal load. The prosthesis remains removable by the patient.

Within the RP4 category, multiple options are available: monolithic, with thimble, and full denture workflows.

This page describes the main DentalDB setup options relevant for RP4 overdenture workflows in DentalCAD. The exact setup may vary depending on the scan data, selected implant system, attachment system, material configuration, purchased modules, and user preferences.

Monolithic restoration on an offset substructure	Thimble structure with crowns on an offset substructure	Full denture over a bar

Step-by-step

A bar-supported RP4 overdenture can be designed as a two-stage workflow: first, the bar using the Bar Module, and then the suprastructure over the bar.

Offset substructure

The Offset substructure creates a defined-thickness secondary structure or shell over a scanned substructure, commonly an implant bar.

It can be designed to provide support, controlled fit, frictional retention, and stability between prosthetic components, such as a metal bar, a PEEK secondary/bar attachment, and a zirconia or acrylic denture superstructure.

• Open the DentalDB Application and create a new project. Then, define the job for individual teeth as usual. Select the tooth number and under Work Type, select Offset substructure. Click OK and apply the same selection to the other teeth.

Then, Save the project and click Design to open DentalCAD.

Monolithic restoration on an offset substructure

• After the offset substructure, you can either manufacture the part and scan it in the new project, or use the files generated previously. The monolithic option creates a full-contour restoration and does not create space for veneering material. The restoration is designed as a single-piece structure according to the selected workflow.

• Open the DentalDB Application and create a new project. Then, define the job for individual teeth as usual. Select the tooth number and under Work Type, you can select Anatomic waxup or Anatomic crown. Under, Implant-based? select the option On substructure scan (e.g. bar). Then, click OK and apply the same settings to the remaining teeth.

• Then, Save the project and click Design to open DentalCAD.

Thimble structure with crowns on an offset substructure

*After the offset substructure, you can either manufacture the part and scan it in the new project, or use the files generated previously. The thimble option creates reduced, preparation-like crown structures that serve as supporting geometry for a subsequent restoration. These thimble crowns are designed to receive separate single-unit crowns or a suprastructure, depending on the restoration concept.

TIP: The Thimble option is only available when the selected tooth library supports thimble reduction. Libraries that typically provide this option include Generic, Exofan, and Inspira.

If the option is unavailable, use Choose Library Tooth - exocad to select a compatible library.

• Open the DentalDB Application and create a new project. Then, define the job for individual teeth as usual. Select the tooth number and under Work Type, select Coping. Under, Implant-based? select the option On substructure scan (e.g. bar). Additional design steps in wizard? Select Virtual gingiva and Thimble crown. Then, click OK and apply the same settings to the remaining teeth.

• Select the antagonist teeth as well. Then, Save the project and click Design to open DentalCAD.

Full denture over a bar

After creating the bar, you can either manufacture and scan the part in a new project, or use the files generated previously. The full denture option creates a complete denture superstructure over the bar, including the denture base and teeth. The bar serves as the supporting structure and provides retention and stability according to the selected workflow.

• Open the DentalDB Application and create a new project. Then, define the job for individual teeth as usual. Select the tooth number and under Work Type, select Full Denture. Then, click OK and apply the same selection to the other teeth. Depending on the workflow, additional options may be available.

• Select the antagonist teeth as well. Then, Save the project and click Design to open DentalCAD.

Common questions

What if the bar/substructure is not aligned with the model?

• If the imported file or new scan is not positioned correctly in relation to the model, first check whether the bar/substructure and the scan data use the same orientation or coordinate system. If needed, use the Align Meshes tool to align the imported bar/substructure with the model. You can also use Add/Remove Mesh to load additional meshes from different locations, for example from a previously saved scene. This is useful when the bar/substructure was created in another project or when the generated file needs to be added manually. Both tools are available in DentalCAD by entering Expert Mode and clicking Tools.

If the scan has some holes, how should I manage them?

• Right-click the mesh and select Scan Data Editor. Use Mark triangles to outline the hole completely, then click Close Holes. The software fills the selected area with a smooth surface based on the surrounding mesh geometry. Check the result carefully before continuing, especially if the hole is located near relevant design areas such as the bar, attachment surfaces, margins, or contact areas. For further details, see 3D Data Editor.