Designing Toronto bridges with iBar in Blender for Dental

A Toronto bridge is a full-arch, screw-retained prosthesis in which the teeth and gingiva sit on a rigid bar connected to the implants. It can be designed as a single piece, but splitting it into a bar and a separate superstructure gives more control over strength, aesthetics and later repairs. iBar, a set of tools in Blender for Dental, was built around that split.

I teach this workflow as a Blender for Dental Accredited Instructor. This post explains the logic of the design sequence. The individual tools are easier to learn hands-on, on a real case.

Why bar and superstructure are separate parts

The bar connects the implants and carries the load, so it is made in metal with a section sized for that job. The superstructure is the part the patient and the clinician see, and its material is chosen for appearance and for the opposing dentition.

Keeping them separate also helps with maintenance. A chipped or worn superstructure can be remade without touching the bar and its passive fit. In production the two parts often go to different machines, sometimes to different partners.

What you need before designing

Start with the upper and lower scans taken with scan bodies, the antagonist, and the implant or multi-unit library that matches those scan bodies.

You also need a tooth setup approved by the clinician. It can come from a wax-up, from a scan of the existing denture or from a digital setup, and the bar is always designed inside that volume.

Finally, know how and in which material the bar will be produced. The manufacturing method sets the minimum sections and the access for the milling tools.

The iBar design sequence

Check the implant positions

Import the scans, align the scan bodies to the library and verify each implant position and screw axis. An error here is carried into every later step, so each connection gets checked before anything is drawn.

Protect the screw channels

Around each implant the tools create the tubes and cones that keep the screw channel open along the screw axis. Look at where each channel emerges relative to the tooth setup. In the anterior region a channel that exits through a buccal surface ruins the aesthetics and has to be solved at this stage.

Trace the bar

Draw the bar path between the implants, following the arch inside the volume of the teeth. The bar should sit under the occlusal load and stay away from the buccal surface, where it would show through the superstructure or leave it too thin.

Shape the profile

Set the height and thickness of the bar profile. Tapering or angling the upper part leaves more room for the superstructure while the base keeps its section. Leave space under the bar so the patient can clean it with the aids the clinician recommends.

Set clearance and fit space

Define the clearance between bar and superstructure and the fit or cement space. Take these values from the material and the production method, because milled titanium, laser-melted cobalt-chrome and the superstructure material each have their own requirements.

Design the superstructure

With the bar finished, adapt the teeth and gingiva over it as a separate part, with the screw channels running through. Run a thickness check on the whole superstructure and look closely at the connectors and at the areas around the channels.

Export both parts

Export bar and superstructure as separate closed meshes with clear file names, and send the implant information to the production partner together with the files.

Materials for bar and superstructure

Part	Common options	Notes
Bar	Titanium, cobalt-chrome	Milled or laser-melted, depending on the partner
Definitive superstructure	Zirconia, high-performance polymers, composite on a suitable framework	Respect the material’s minimum thickness
Provisional or try-in	PMMA, printable resins	Used to test aesthetics, phonetics and function

The clinician chooses the materials within each manufacturer’s indications. As the designer, I make sure the geometry respects the minimum values of the chosen material.

Where Toronto bridge designs usually go wrong

The most frequent problem is designing the bar before the tooth setup exists. The bar ends up too high or too buccal, and the superstructure over it becomes thin. Other common errors are screw channels that emerge through visible surfaces, thicknesses judged by eye instead of measured on both parts, and bars that leave no room for cleaning underneath.

Learning iBar

A free iBar demo file is on the download page, and the complete workflow from scan bodies to export is part of my Blender for Dental training. If you work in exocad instead, the exocad Bar Module guide covers the same kind of case. For the component side, see choosing implant abutments.

Frequently asked questions

What is iBar in Blender for Dental?

A set of Blender for Dental tools for implant-supported bars. You build the bar around the implant connections and design the tooth superstructure as a separate part, which is the Toronto bridge concept.

Which material is used for the bar of a Toronto bridge?

Titanium and cobalt-chrome are the usual choices, milled or laser-melted depending on the production partner. The final choice follows the clinician's plan and the manufacturer's indications.

Can the superstructure be 3D printed?

Provisionals and try-ins can be printed with suitable resins. Definitive superstructures are usually milled from materials such as zirconia or high-performance polymers, following the material manufacturer's indications.

Is there a course on iBar?

Yes. I teach iBar and advanced Blender for Dental functions one-to-one and in an online masterclass, with demo files to practice on.