Digital Dental Impressions with Intra-Oral and Desktop Scanners
Same visit restorations are a great way to measure accuracy of an iOS and cad software and milling machines
One thing that I highly recommend is to take the bite before imaging the prep itself. It forces you to check for clearance and to keep reducing until you have the appropriate space for a ceramic restoration
You have to be comfortable with different workflows you may be accustomed to
Emax Try- in before bonding with NX3 resin cement
Immediate post op
Don’t be mislead; it is much easier to scan the upper edentulous jaw than the lower, as you don’t have to deal with the tongue or saliva. With the Medit i500 we have a feature called the model display mode, where you can see how the meshwork is being formed by turning red areas to green. When scanning, you can image at the rate of “red colors turning green” so you can produce global accuracy across the arch without distortion or double images forming like you see with all intra oral scanners when they try and scan edentulous ridges on a flat plane
You can download the meshwork for this case by clicking here (Note that the gold caps were omitted on purpose)
In this particular case, we demonstrate an emax restoration fabricated with the Z4 milling machine by VHF. In the first video, you can see how the case was set up initially within the software. You will notice how we image the preop, image the opposing and can even image the bite out of sequence, all while the patient is being anesthetized.
Once the preparation is captured, we place the margins and design a crown in exocad. The emax is milled, tried in, and them placed in the oven for crystallization. It is then delivered to the patient. Note how the decay at the contacts of the adjacent teeth was drilled out and restored, while the crown was milling / crystalizing. An immediate post op x-ray was taken to make sure there was no resin left behin
The Z4 Milling Machine can drill emax, zirconia and metal abutments. You can use a scanbody, identify the location of the fixture, design the abutment and mill our either ceramic or metal as the abutment.
Metal abutments in the posterior molar areas, tibases in canine and premolar regions, and angled abutments in incisor area is the general consensus for restoration of choice
One of the greatest advantages of the Z4 is that it can start milling while it is doing the calculation for milling. Furthermore, you can load multiple designs in preparation of continuous milling. In the picture attached, the CAM software is shown which operates in the background. Most users don’t usually see this interface.
Here you can see how there are 5 drills for the machine. The top tier, consisting of 3 drills, labeled G240, G100, and G060 are all labeled as R. The G120-T and G060-T are used only for a screw access holes
The following case demonstrates how a symptomatic cracked tooth was treated with an emax restoration that was fabricated / seated during the same appointment as it was prepared. The patient had a heavy gag reflex and the preparation and access were difficult. The medit i500 was utilized and the restoration was designed with CAD-Ray’s design software, powered by exocad, and then milled with the Z4 milling machine by VHF
In this pre-op of video, trans-illumination was utilized to highlight the lack of light propagation at the crack line. Moreover, the patient was percussion sensitive on the lingual cusps for over 5 days where he initially developed symptoms
The Medit i500 software was launched while the patient was anesthetized. The appropriate job definition was defined where we identified that a pre-op scan would be taken. We also identified the spacer parameters and the marked the opposing dentition. All of these items define the image catalog that will be launched when we capture the optical impression (there will be a preparation model, a pre-op model, the opposing, and minimally one bite registration)
While anesthetic was taking affect, salt on the tongue was used to suppress the gag reflex, and the opposing arch was imaged. Then the lower arch was scanned and the bite was captured. The software then was set to the mandibular arch where the tooth in question was cropped out of the equation.
A great benefit to this approach is that you can analyze if you have taken the bite registration correctly before you even image the preparation. Sine the medit i500 can capture color, you can can the patient bite down on articulating paper and pick up the color renderings while imaging. You can then compare the digital occlusal stamps to the ones left behind by articulating paper. This is a great way to gauge if you or the patient has introduced errors in the capturing the correct occlusal relationship between the upper arch and the lower arch
Since the patient was very sensitive while taking impressions of the tongue, the model of the preparation was built in multiple segments and steps. With the medit i500, the initial part of the preparation was imaged, certain areas were cropped out, then the tip of the camera was used to displace the tongue so the lingual margins could be captured. The image itself was capture in the local HD mode. The attached video demonstrates how areas were protected with the software so that we did not inadvertently introduce errors to areas that already had accurate data captured
Once the image was captured, it was processed and directly launched into CAD software. the pre-existing condition was replicated in the design of the crown and minor adjustments were made to its morphology while taking the opposing dentition into consideration
Once the restoration was designed it was automatically transmitted to the milling machine for fabrication. After it was milled, the restoration was checked for fit and contacts while in its blue stage and then crystalized in an oven. Once cooled it was seated with resin cement.
The Meditlink software has a Work File List that is maintained after you have finished your design. It hold the arches, the occlusion, the restoration stil file and the dentalCAD file that you can relaunch to either continue with a previous design or launch a whole new design
There are many ways to capture the upper and lower jaw digitally and mount them correctly in a protrusive and open bite for obstructive sleep apnea devices. In this videos, we feature how to digitize conventional impressions with the Medit i500 and mount them with a model creator so that that you order printed models and/or oral appliances.
Desktop scanners accomplish this much more readily, but it is a snap with intra-oral scanners. The key is to know how to pick up hidden and deep areas, which you can often correct by trimming away excess flash of impression material with a scalpel
One of the greatest challenges in oral appliances for obstructive sleep apnea therapy is to capture the bite in the protrusive and open position in such a fashion so that you reduce or eliminate any adjustments after delivery
One of the greatest benefits to capturing the arches digitally and relating to each other before production is that you eliminate most of these adjustments. Proper scans and proper prints of model for appliance manufacturing make delivery appointments just a few minutes long. We hardly ever open the exam kit anymore
A very important principle to keep in mind with intra-oral scanners is how that data is printed. There are too many reasons to list what can constitute a mis-print. One method to verify accuracy of your printed models is to scan them and take that digital model and merge them with your intra-oral scan model. You pick some common data points and manually align them.
Once that is performed, you can do “best fit matching” and the more green and blue you see in the color profile, the more accurately your meshwork or data points match each other. Once you do that you can take your slice tool and look at the contours of the data and see how well they relate to each other. In this case, we scanned the upper printed model and then merged it with the intra-oral scan used to fabricate the device. There was not a single adjustment made to the appliance for occlusion or for fit
The following case is a 4 unit splinted bridge where the upper central incisors where root canal treated. The laterals remained vital after trauma to the upper maxilla fracture a pre-existing bridge. In this single appointment procedure, the case was set up by imaging the pre-existing temporaries, the opposing and the bite.
After the preparation were made, the tissue was retracted and hemostasis was achieved. The preps were imaged in HD mode with the Medit i500 intra-oral scanner. The restorations were designed in exocad and the final prosthesis was milled with the Z4 VHF Milling Machine. A size 40 block was used to mill the splinted units of eMax.
The fixed bridge was seated with NX3 resin cement and the excess was removed. Cord, packed in the sulcus, allowed for easy identification of the margins in the design step and aided in cement clean up. The patient will return for post op photos once the tissue has healed. The following video depict the steps the milling machine goes through as it carves out the four unit bridge, starting with the 2.4 mm drill, then the 1 mm drill, and the 0.6 diameter drill. Milling time was under 40 minutes
Look at that contact area! A dentist’s and lab tech’s dream, but you still get some crowns that are way too tight and you adjust like crazy until it seats and if you were too aggressive, you likely blew right through the contact. Here is what is happening:
When you image what is happening is that you are imaging below the height of contours of the adjacent teeth / contacts. A designer just sees a big contact area with lots of colors and s/he is happy, not realizing that they actually made contact with material BELOW the height of contour of the adjacent teeth. This is a VERY common error. It will sound strange, but if you are an advanced user, consider NOT taking scans below the HOC and let the software drop a straight wall down to the gumline and your seat issues will disappear! You can also recognize this issue and communicate it to the lab so they can address it
This a case that was done in a single appointment, where the second molar was restored with a class 2 composite restoration and the first molar was replaced using the copy mode in exocad. An initial scan was taken copying capturing the outline form of the pre-existing restoration, the crown was then removed, the tissue was retracted and the preparation was modified
After the decay was removed the Medit i500 was used to capture the prep and the restoration was designed in our CAD software. The eMax restoration was milled and crystallized and then delivered with NX3 resin cement
This restoration was milled in the regular mode without using the 060 drill. This speeds up milling but does not provide for detailed anatomy, which you can accentuate with a handpiece. It is your decision to select fine mode, regular, or fast mode.
Immediate post-op bitewing X-ray was taken to verify fit and to remove any excess resin that may have been left behind
Since July, we have imaged and milled many restorations with at least 4 different milling machines, including lab fabricated restorations. The margins and fit have been impeccable even with my terrible preps :). I love seeing the post op bitewings and the adaptation of the restorations. One thing I love having control over is the spacer settings; both the amount of space and also the distance I want the gap to end from my margins.
The following case is a lower first molar with the distobuccal cusp fractured and recurrent decay underneath the pre-existing composite restoration, warranting full cuspal coverage. The case was managed with the CAD-Ray workflow, where the medit software is launched and all the imaging is done in that platform.
Directly from meditlink, exocad software is launched and the margins are placed. Once the restoration designed, it nested in the block and sent off to the milling machine. The total time from final design to end of mill was about 18 minutes, and the last 4 or so minutes, the milling machine refined the sprue size and location. One can easily stop the milling process and remove the sprue manually.
Once the restoration was assessed for fit and proper contours, it was chrystalized and then bonded in with Kerr NX3 material. A final post op bitewing was taken to assess if any excess cement was left behind.
Time Stamps:
This video is sped up at some points, but from the time the design was finished and it was sent to production, it tool less than 90 seconds for the milling machine to start milling. It took a total of 9 minutes and 20 seconds from the time the first water is sprayed to the time the water stops.
The Meditlink software allows you to log in as a clinician or a laboratory. There are quite a few benefits to logging in as a lab, one of them is to have control over the whole process from imaging to design to fabrication
Here, we demonstrate how the case is set up in the job definition. We have linked the exocad CS CADapp as the design software of choice. You have many other options including manually exporting the models.
Once you define the job, you can directly launch the Medit scanner and start imaging. Once you are finished with imaging, you can start marking margins and complete the design of the restoration in the CAD software.
Once designed completely, you have a number of ways to submit it tofabrication. One big advantage here is how you can start milling as soon the calculations start, with the VHF Z4 milling machine. As opposed to milling machines that must have the calculation completed before they start milling, which oftentimes puts the procedure outside the realm of single visit dentistry
Imaging highly reflective surfaces can be challenging. In this particular situation, every tooth had either a pfm or a gold crown restoration. The video playback feature of the medit software allows you to see exactly how these areas are managed and captured. in the live preview box in the lower right corner, you can see the purple silhouette which shows areas that cannot be seen. Just angle the camera and moving its focal length and angulation allows all the areas to be captured. Not retraction besides a mirror was used. No isolation, air, or suction was used. Both arches were captured for an obstructive sleep apnea device with the Medit i500
Scanning highly reflective surfaces can be a challenge with every intra-oral scanner. Here’s a pointer that can help: don’t start by trying to scan the metal or highly reflective surface. Get your purchase point on material that is easy to scan, like gum tissue or tooth structure. Once the model starts to form, you can then build on your desired material.
In this example, we are scanning a metal framework for a hybrid. Notice how the scanner does not recognize the metal at first, until it starts to image the thumb holding it. Once you start building the metal model and then remove the thumb and image over that area, the fingers are removed from the equation
One of the most popular design techniques in digital dentistry is copying the pre-existing morphology of a restoration. When it is in occlusion and has desirable contours, you can image the pre-op condition before removing the crown.
Once the crown is removed, the preparation can be modified and new images can be taken. Placing margins is immediately followed by a great proposal that takes very little effort to finalize.
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