Category: Digital Impressions

Same visit crowns can be a practice builder. We had a patient referred for in house fabrication of a restoration because she did not want to go through the procedure twice. A family member made the referral for a broken tooth.

After the tooth tested vital and the patient consented to treatment, she was anesthetized. While waiting for the onsite of anesthesia, the upper arch was imaged along with the lower arch and the bite in the occlusal one window box. The case was set up for just imaging the preparation. Most of this can be delegated to team members.

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fractured DL susp of lower second molar

two bites taken to verfiy proper vertical dimension

We highly recommend that you capture the final bite after you have finished preparing the most distal tooth. You can use your camera to visualize your clearance. You can keep reducing the occlusal surface until you have enough clearance.

In this particular case, when we took the second occlusion images, the models would not turn green. When this happens, you should immediately ascertain if you have captured the first or second bite correctly. Double check to see if the jaw settled or if the patient moved their jaw during this acquisition step.

You can watch how we troubleshoot the bite and manually choose the second bite to relate the arches together.

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Correcting the occlusal relationship with second bite

Once the bite is captured, the isolite is re-inserted and the tissue is displaced and isolation is achieved. Then the predation is captured.

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imaging the prep after enough clearance has been established

After the crown is seated a final bitewing is taken to verify seat and if any excess resin is left behind.

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post op bitewing to verify seat and resin clean up

At CAD-Ray we are constantly testing milling machines that can render ceramic or metal abutment restorations. In this particular case, we are testing the conelog line of tibases and utilizing the automated identification of the scanbody with the new Medit i500 V2.1 Artificial Intelligence program. Not only does the software identify the scanbody and locate the fixture but it also imports the whole complex into the cad software where the fixture and digital tibase are already identified and aligned.

We scanned the tibase as well on the model and merged it to the digital proposal to see how closely the digital proposals matched the physical model.

It is very important to properly identify the scanbodies and to label them accordingly. A single mis-step can result in ill fitting restorations and cause disappointment. If the nomenclature or the math doesn’t add up, it is always a good idea to contact the manufacturer of the scanbody to verify your findings.

In the first set of videos, we demonstrate how the scanbody is imaged with the Medit i500.  For this particular demonstration, we placed a tibase on a conelog 4.3 mm diameter fixture and then a peek scanbody on top of it. Indexing and making sure it is seated is of paramount importance. Once the software identifies the complex it can automatically import it into exocad software so you can proceed with the design.

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articial intellegence identification of tibase and scanbdoy

scan of tibase itself on model for verification of indexing

This test case is milled for record keeping and FDA compliance as we are distributors of multiple scanners and milling machines.  We are only concerned about the fit of the restoration.  After the design was completed it was then imported into milbox CAM software, nested, and the sprue was configured for the mill.

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autoimport and design hybrid abutment crown

Nesting and Sprue Design in Millbox

Milling Simulation

The first produced restoration did not seat completely and the internal was relieved in an analog manner.  It did finally seat but by then, it lost its anti-rotation mechanism.  The case was then reloaded in millbox and the internal relief was increased by – 0.05 mm.  That simple adjustment allowed for proper seating without any analog adjustments.  You can also appreciate some residual material that may keep you from seating.  Both the software and the carbon marks left on the intaglio of the restoration can be clear indications of what needs to be adjusted.

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provide relief

look of intaglio from relief

perfect fit of restoration to tibase

A common request when processing models is to create a plan that matches the occlusal plane of the arches. To keep it simple the algorithms of the Medit iScan will create a plane from the lowest data point on one side of the model to the highest point on the model on the contralateral side. You can control this plane by using the edit tool in the arches and crop out data so that you help the software to find this plane more easily.  The more discrepancy there is between these data points will render drastically different planes than the occlusal scheme as seen in the attached photo.  Besides, the less data you have to process, the faster the models will be rendered.

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How To Create A Flat Base In The Model That Is Parallel To The Occlusal Plane

We got a bat signal from a group of doctors who were having trouble with ill fitting restorations to tibases.  This can suck up a lot of time and energy to pinpoint the exact source of the issue, and you basically have to go through a pilot’s checklist before take off.  Here’s a list you can use for yourself to determine what the cause of the issue, after you understand what the issue really is.

• Take a picture of the scanbody and a picture of the tibase and then pictures of their packaging material and verify you ordered the right parts
• Do not mix scanbody from company A to image implant fixture from company B and then mill a restoration to a tibase manufactured by company C even though they all say they are compatible with company D.
• Verify that you have the latest library of scanbodies
• Verify that you correctly chose the right scanbody from the large list of implant possibilities on the market
• Verify that you have the correct height as a lot of companies have the multiple height scanbodies for same diameter fixture
• When starting a case, you select either Custom Abutment for the implant restoration if there is no screw access hole and Screw Retained Abutment if you do have a screw access channel
• Understand that the decision for custom titanium abutment is made when you identify the scanbody in the design step, not in the job definition step
• You will not be able to verify seat / index until you fire and shrink material like zirconia
• The smallest drill in your milling machine will determine if you can carve out that much detail

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Milling Internal for Tibases

Retrofit Designs to Tibase

Desinged In Millbox and Milled in CORiTEC ONE

Designed and Millled in VHF Z4

We took the case file from our users and directly imported their design case into a few of the CAM systems we have at CAD-Ray. We used Celtra Duo burner blocks to verify the fit. The screw-mentable restorations were binding on the walls of the tibase so it took a few adjustments to seat it completely. The good part is that the carbon on the titanium abutment leaves metal marks on the internal intaglio, so it is easy to know where to adjust

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The restoration still needed some adjustments so we played around with some of the spacer settings, screw access holes, and other parameters to get it to seat all the way.

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Changing Manufacturing Parameters to Aid in Seating

Could Screw Access Space Provide Relief?

Fit to Tibase Still Too Tight

Perhaps Internal Relief with Spacer Could be the Answer

Quick Way to Guage if Spacer / Adhesive Gap Have and Effect on Internal

Even with these adjustments of the parameters a little analog milling helped get the restoration seated. The CAM software can give you plenty of hints on where it will bind. We recommend that you don’t change your spacer settings and understand that you will likely bind on the walls of the tibase and/or restorations as it is difficult for any machine to mill out all the detail you need to have NO adjustments. The good news is that the indexing and anti-rotation mechanism work properly.

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Minor Adjustment at Seat

Minor Adjustment at Seat

Hints of Areas that Still May Bind

In conclusion, it is physically impossible to mill the intaglio of a ceramic restoration to perfectly retrofit most tibases as they have too much detail that even 5 axis milling machines cannot reach. The choices are to increase the space between the walls of the tibase and the restoration providing enough relief to allow you to seat the restoration, but that comes at the risk of losing your antirotation mechanism. Alternatively you can mill them out knowing full well that they will bind and using the sophisticated CAM to pinpoint the areas that need adjustment.

When imaging and designing a restoration in exocad, with models captured by the Medit i500 intra-oral scanner, you will produce an stl file of the restoration along with the construction file.

The stl file alone carries enough information for most CAM software to instantly mill the restoration.  The CEREC cam software gives you the ability to either import the project file or the stl file.

In this demonstration we showcase how you have to redraw the margins in the CEREC inlab software so you can mill the restoration when you only import the stl file.

Alternatively, if you imported the construction file, you could have skipped the margination step.

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Imaging A Second Molar With The Medit i500

Image in Medit, Design in exocad, Mill with CEREC

Design in exocad

Import and Nest to Mill in Inlab 18.1

Mill eMax with CEREC MCXL

Our advanced users can appreciate “the lip” at the margin of the restoration. This is a function of the minimum parameter thickness in exocad.

Most people set this setting to 0.4 mm or less which adds material to the margins so they are protected during the milling process.  This thickness is invisible to the naked eye and produce desirable results with lithium dissilicate

A lot of our users are migrating to SSD Drives which greatly speeds up processing and graphics rendering in intense software applications. When you are capturing scans with the Medit i500 you can quickly fill up your hard drive with law videos (which is technically a series of thousands of images) and when you process the case, the data is converted into small 30-50 MB size digital models

In previous versions of the software that data was only stored on your local machine, which meant you could not log into another computer to add or edit your live video images. You now can sync the data through the cloud so you can access it anywhere, or you can delete the raw footage from the preview screen. In previous versions you would have to search hidden folders to find this data, but now it is readily available and you can dump the data with one click. You do not delete your models in this situation.

Titanium blanks are the hottest topic in digital dentistry in 2019. A lot of new milling machines can mill emax, zirconia, and custom metal abutments.

One of the parameters to keep in mind when milling them is the diameter of the screw access channel. Most CAM will carve them out but leave a lot of finishing processes remaining.

We’ve tested quite a lot of mills with the imes icore coritec one and the milbox cam software. If you set the settings to 2.5 mm’s , you can pee off the excess sprue material with just finger pressure, dramatically reducing the free hand work that you would have to do.

The pin diameter at object and at material under 2.5 mm’s will give you inconsistent results.

Most scanners will export the jaw model and the scanbody model separately but a new feature on the Medit upcoming software will let you export them as individual models or as a single merged model.

There are design advantages to both scenarios based on the practitioners skill level!

There are numerous ways to quickly check a model before taking it to a design software. Windows comes with at least 3 such free software. Another one to have handy is called 3dviewer.net to let you verify models really quickly