One of the greatest advantages of digital impressions and oral appliances is how there is very little post op adjustments to be made when you capture the vertical dimension correctly. Here, we deliver a Panthera OSA device with just an exam kit.
This article features the new Meditlink 2.3 software which has some advanced functionality. One of the greatest achievements is he ability to tell the scanner to avoid imaging certain colors like green and blue. This greatly facilitates the imaging of full arches as you can let your gloves / fingers guide the camera and displace all the soft tissue that impedes image capturing. We also feature how easy it is to launch CAD software to design the restoration and mill it out of lithium disilicate material
Case set up: here we enter the patients name and a simple tab appears where we chose the material and restoration tab. Once you image, you can place an order to the lab or you can advance to the CAD tab:
After the Rx has been filled out, you can launch the Medit Scan and image the upper and lower arches. Please note how we tell the camera to avoid the color blue and it ignores the clinicians fingers during imaging. The upper jaw and lower jaw were captured, then the bite registration even before the preparation was finished. This allows the verification of proper reduction and space for the ceramic material
Lower Arch Scan
The lower arch is the most difficult area to scan as you frequently have to battle the tongue, saliva, and the lips. The optragate can be of great help but notice how we use the color filter to hide the blue gloves while we advance the camera. It is a great aid in facilitating the capture of the lower arch
Upper Arch Scan
The same principle is applied to the upper arch. Notice that the software does not care if you start with the upper or lower arch. Here, you can visualize how the blue glove was used to displace the cheek and capture the pre-op condition of the upper second molar. The rest of the arch was easily imaged. It is not necessary to capture full arch impressions and this was done just for demonstration purposes. For a single unit case, generally imaging distal from the canine is adequate.
Checkingthe reduction and aquiiring the bite registration
We recommend that you capture the bite before you finish imaging the preparation. This gives you one last chance to verify that you have reduced enough to accommodate material thickness. You can see how we just take regular photos to document the lack of clearance and we continue to adjust the height of the preparation until we achieve the required space. We then activate the imaging process and capture the occlusal relationship between the upper jaw and the lower jaw
Image the preparation and place margin in native MeditScan Software that transfers to CAD Software
The preop condition is then transferred to the arch model and the tooth in question is cropped out. The rest of the arch is protected so no extra data is added unnecessarily to the equation. This protect feature is used for demonstration purposes and is subsequently removed. The prep in question is then highlighted and the local area is processed and the margins are placed. This margin line can be sent to the lab or it can be automatically carried to the design software
Launch CAD Software
The Meditlink software allow you to launch a variety of CAD programs that include 3shape, exocad, cerec, etc… Here we launch exocad which automatically imports and aligns the models and marks the margins. The restoration is then designed to completion.
Design of restoration
The CAD software allows you or the lab to alter the marked margins if necessary. The restoration is aligned in the arch for and the contacts are adapted to the adjacents and the oppising
You can take the designed restoration to ANY milling machine or printer
Milling of Lithium Disilicate with Imes Icore Coritec One
The final restoration design can be exported as an stl and taken to a variety of mills or printers. Here we designed it millbox and milled with the coritec One. The material used was Amber Mill and it was crystalized and seated
Final X-ray was taken to verify the fit and to make sure no excess resin was left behind
The following pictures depict the sequence of burs we recommend that you use to finish a preparation quickly. While patient is getting numb, take a quick look at the clearance you will need to reach proper material thickness. Once the quadrant is isolated with isolite and optragate, take an occlusal router bur and create a trough to gain the proper depth. Follow that with a flat disk, and you can quickly reduce the occlusal height.
A shoulder bur of .8 mm thickness can help you reduce the interproximal areas as well as the buccal and lingual margin lines. Before finishing the prep, place hemostatic agent like expasyl in the sulcus and place retraction cord. while it is setting, check your reduction. If you need more space, now is the time to reduce some more.
Once you have adequate clearance, retraction, and hemostatis, you can readily image and find your margins in the CAD software
A Medit i500 scan was taken and merged with a CT scan and the distance to bone was measured (5.5 mm’s) giving enough space for soft tissue contouring with a diode laser. The 3D X-ray must be captured with cotton rolls placed in the vestibule so that you can differentiate between the gingiva and the lip. Ideally you should not close the base of the digital model by the intra-oral scanner as it can make the merge of the data sets more difficult than it needs to be.
Comparison of Pre-Op Scan and Post Gingivectomy Scan with Medit i500
I am not one to place much faith in published articles from academicians. I usually draw my information from trusted colleagues and also a very reliable source, Mr. Andrew Sedler, from Advanced Technology Centers in Burbank California. He is in charge of manufacturing thousands of full arch restorations for clinicians and many other labs that outsource their manufacturing.
One of the things I always get a kick out of is whenever they do purchase technology or implement a process, they always have to do it with redundancy. What that means is that their machines can never go down for whatever reason, so they always purchase printers and mills by multiple sets. Interestingly, I was witness to them incorporating printers into the lab about 6-7 years ago and now they have a large wing dedicated to printing with over 20 machines for many different purposes.
I trust his judgement and always follow his recommendation and tested methods. When he says “do not bypass verification jigs, no matter what scanner was used”, I don’t even question it. He sees all the cases many entities can’t manage and he can manufacture any screw, prosthetic, abutment, etc… with their high end milling machines. In fact, it was on his word alone we decided to distribute the ICam4d by imetric.
I thought it would be a good idea to revisit full arch implant restorations with him and see what the state of the industry is like today and what he would recommend for the end users and patients. A very good perspective for a clinician to keep is how a simple mistake or misunderstanding can wipe away all the profit margins for a lab and even for the clinician. A simple example is if you have to correct an angulation issue on an abutment which can dramatically impact the costs of the lab work.
Here is the Q/A session:
“Hi Andrew, I am writing an article on full arches and would appreciate some info”
- what % of the full arches that docs order from you are zirconia on tibases only at implant sites?
- what % are on titanium bars?
- what % are hybrids with acrylic?
- what % are MUA vs Implant level?
- what is the most prescribed full arch prosthesis now compared to 5 -10 years ago?
- what % are soft tissue level vs bone level / mua level?
- what would you do for yourself?
- which one has the most failure rate?
- how often does zirc framework break?
- how much damage do you think people do to zirconia frameworks while trying to mill it to sharp corners of tibases?
- MUA vs IMPLANT LEVEL : over 90% of upper arches will have MUA and 60 to 70 % of the lower arches will have MUA
- BONE LEVEL vs TISSUE: majority of implants (90% and up) bone level that requires MUA .
- The most failure rate in order is (all of these in respect to the material limitations ):
- the traditional acrylic hybrid
- composite hybrid next
- zirconia monolithic
- and the least breakage will be zirconia hybrid supported by metal frame
- Zirconia failure is around 4 to 5 % (adding the internal lab remakes – i would say another 3 to 4 %)
The damage caused by adjusting the zirconia could be very considerable, especially around the access hole since those areas are thinner than the full teeth . For myself i would restore zirconia over metal frame if my choice is hybrid, while removable bar overdenture will be a more predictable and more hygienic choice .
Shining3d has a projector and a single camera that takes photos of the surfaces it is scanning. at first, you may think this is a shortcoming, but in many ways, it dramatically reduces errors a new user can introduce.
in the early days of cerec, all you needed to do was capture the margins and the area above the height of contours of the adjacent teeth. This made the try-in and the contacts really easy as the design software just dropped straight a straight wall down to make contacts to. same concept here!
also, after you image and place margins, A SINGLE CLICK takes you to design software where you can finish the case and mill it right away.
if you want a fixture level impression vs MUA in those rare situations, you can still place a MUA and image that. The dess library can easily convert that information to the location of the fixture. you just need to make sure that you make note of the exact mua and collar height you used. the timing won’t matter as these are RP non-indexed abutments. that solves the number 1 request you folks make when looking at this.
we will have all the libraries of the abutment from the margin and up available to you so you can pop them into the medit scan and easily identify the MUA in the mouth.
for the process to work in the traditional way, you would have had to place the mua’s, place the scnflags, image with icam. take off scanflags, place cylinders, scan with ios. then take off cylinders and then place healing caps. NOW, you can place the MUA’s, place scanflags, image with icam. export the stl and import it into medit. take off scan flags, BYPASS the cylinders, and just start scanning MUA’s in the mouth. With the AI feature, you will readily identify the multi unit abutments no matter how bloody the field is and if parts of the margins are buried under tissue. Of course, in the situation where the implant is super deep and the mua can’t stick its neck out, you will still have the option of popping the cylinders on. you will know which route to go as soon as you seat the MUA after surgery or uncovery
Thanks to Justin Shafer who created a script for us that allows you to export an stl file to a specific directory, where you create a subfolder for each program you want to run. Once the file lands in a subfolder the program is launched and the models are important.
Justin did this at no cost. The more you donate to his work, the more programs he can add to the installer. Some programs like Rayware allow you to import multiple files into one program whereas others launch a single program for each file, like BlueSkyBio. Contact the software designers to easily add commands line to accommodate your needs
This molar’s suggested mill times with the MCXL are for either Size 12 or 14 blocks:
Sprue on distal in normal speed mode is 14:05 minutes, fast speed at 7:54
Sprue on buccal in normal speed is 13:48 minutes, fast speed at 7:46
This molar would only fit in a size 14 block of Amber Mill in Imes Icore Coritec
Sprue on distal in normal speed mode is 14:15 minutes, sprue on buccal in normal speed is 14:42 and speed crown is proosed at 13:23
For our advanced users who mill in house or what to speed up their digital impressions we advocate taking advantage of digital dentistry’s unique features that allow you to take impressions over a period of time and segments, building larger models over different sequences and time. In this particular case we have two molars in the lower left quadrant that warranted replacement. The traditional method would be to prep both, isolate both, retract both, and take your final impression, but we will approach this as if there are two separate patients involved
For the second molar, we will take advantage of the anesthesia time and capture the first bite, the opposing, the pre-existing situation and then crop out the preparation area digitally. Once the tooth is prepared, we will check for proper reduction. We will then take the second bite to verify the vertical dimension has not changed.
While the second molar is being designed and milled in the first case, we will launch a second window by cloning the first case. All the data remains the same and this time we crop out the first molar digitally and protect the rest of the arch. Once the first molar is isolated, it is digitally captured and then designed and milled.
To manage the contact between the two crowns, there are many advanced applications. Here is a simple explanation of how we use the prep model from case 1 as the pre-op model for case two. Since the second molar in case 1 made contact with the distal wall of the first molar, when we design the crown for the first molar in case 2, all we have to do is make sure the distal wall is flush to the pre-op. This guarantees us a contact between the two. There are lots of shortcuts to this puzzle once you get the basics of digital impressions under your belt.
We quickly printed these same models and crowns just for demonstration purposes
One of the big limitations of CEREC (a registered trademark of denstply sirona) with tibases and implant crowns is that it is limited to very few implant lines and the antirotational notch can just ruin your day as it needs to go into a specific location. You also have to deal with making sure the tibase is seated all the way and the scanbody is properly indexed. The one benefit is that you are dealing with just crown and bridge and you do not need to know implant position or timing at all when doing the design.
In this case, we demonstrate how we utilize the Medit i500 to capture a Tibase from Blueskybio, Biomax NP Conical Connection. Once the tibase is seated, we simply start scanning and then use the artificial intelligent implant suprastructure identification system to identify the location of the tibase. This in essence allows you to capture your margins OUTSIDE the mouth and you don’t have to bother with imaging the tibase, which is highly reflective in the patient’s mouth.
Once processed, you can then modify the tissue digitally and gain access to the tibase margins. You can print the model if you want and manufacture the restoration. In this particular case, we took the design to the CEREC mcxl inlab cam, nested it, and milled it out to demonstrate how we can image with one device from one manufacturer and fabricate a restoration by another company’s manufacturing machine. But the single greatest benefit is that you can place the sprue wherever you want.
IMPORTANT NOTE: The Tibase that you use MUST be wider than the drill milling the intaglio and the sprue must be thick enough to handle the milling process.
Once you understand how the digital workflow goes, you can image with one device, design in another, and then either print or manufacture with yet another device. Here we mill a sectional stent with the cerec that was designed in Blueskybio plan, although printing makes more sense because it is less wear and tear on your drills
PRODUCTS USED IN THIS CASE:
For our coritec users: new users often mislabel restorations in the Rx form that leads to a lot of trouble. like calling a crown and onlay or vice versa. this can lead to all kinds of trouble
first sign of trouble is if the two purple lines don’t define the borders of the the restoration. sometimes it is missing, other times it is off the restoration. so always double check this step and usually the missed nomenclature is what causes the trouble.
the next problem people have is that the default setting for the sprue design is poor. it makes the sprue thicker at the mandrel than the restoration. this creates a crevice that the drill can’t get to. this leads to quick drill breakage as it tries to drill into that space (red circle). it is easy to set change these settings so the drill “flows” with the design of the sprue and you get a lot of use out of it. it’s annoying to do this manually so a subsequent video shows you how to change this by default.
another problem is the offset. the last video shows the distance from the restoration to the mandrel as 2mm. the drill is 2.5 in diameter. if you set it at 2, the calculation doesn’t allow enough space for the drill that also breaks it off. set it at 2.7 or 3 and it will last you a long time.
two subsequent videos will show you how to create your own blocks and change their orientation, so you can fit a taller design into a smaller size block
If you place enough implants, you may find yourself in need of a prosthetic part that just isn’t manufactured by anyone. For example, you may have a hybrid case on Bicons and for some reason you wanted to restored them with Multi Unit Abutments (MUA) and photogrammetry, yet there are no parts manufactured for such an endeavor. The problem is complex because a manufacturer needs to mass produce these parts and get them past regulatory matters.
Some have found a simple solution, which is to have the parts custom made specifically for the implant. If they need the MUA part before the procedure, they just send a digital or physical model into a lab that can custom make the part. The lab itself needs a prescription form on the lab analog. Since it is custom made, you have direct input on how tall you want the height of the margin, how much you want to displace the tissue, how much would want the restorative head angled, etc..
Most people will order a variety of them to address any situation on the same model and keep it in stock. What’s important to realize is that from the restorative standpoint, all your CAD software needs to know is the location of your abutment margins. It doesn’t care where fixture is and how the timing is lined up in the arch form. As long as it knows where the margins are, you can proceed with the design of the prosthesis.
Contact Andrew Seddler to send a digital or physical model and an Rx to get your custom made MUA’s
A dentist from Australia named demonstrates in this video how you can scan with the Medit i500 and import the stl file into CEREC Inlab18, design a restoration, and fabricate a restoration.
This is a great option for CEREC users who want a second intraoral scanner or want to upgrade from bluecam to a color scanner, even though you can’t design in color