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The Field of View is the Holy Grail of Intra-Oral Scanners

The field of view of or scan area is probably the most important factor to keep in mind with ios. i don’t know of a single study that discusses this. Admittedly i don’t read any studies on digital dentistry because they are riddled with errors and nonsense here i demonstrate how a small field of view set deliberately affects our results and introduces errors. what happens when you scan an edentulous area, the buccal and lingual vestibule are out of focal distance which dramatically reduces the scan area.
This is precisely why ios can veer off track and introduce errors in your models. to drive the point home, if you scan the intaglio of a physical impression, the same vestibular areas provide solid landmarks and data that help keep the scanner on track

 

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Scanner Tip Dimensions and Their Impact on Accurate Scanning

An often overlooked characteristics of an intra-oral scanner is the scan area / window. The larger the area, the more likely it is that your scanner will stay on track and not derail and introduce errors. In this video, we demonstrate how a small scan area, rendered either digitally or by small sized tips, can readily introduce errors known as the Veersing Effect. We can overcome this easily just by holding the camera in a proper orientation.  Some scanners make this much easier because of their tip dimensions.  The Trios 5 is 19mm x 13mm, the Medit tip is 15 x 13, and the DEXIS 3800 Side Tip can capture up to 19.6 mms.  The 19 mm tip size makes these scanners the preferred ones for larger implant cases with extended edentulous spaces between the suprastructures.

In the video below, we will explain how the capture window size (field of view) affects the accuracy of intraoral scanning and provide tips on how to optimize the capture of data during scanning

Medit Tip Dimensions

DEXIS 3800 Tip Dimensions

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Setting Occlusal Plane and Vertical Midline in 3D

Download the 3D Occlusal Plane and Vertical Line
horizontal plane and Vertical line

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Here’s a tutorial on how to use tinkercad in more depth

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Self Guided Tours of CAD-Ray Facility and its Offerings

Are you interested in an office build out or incorporating technology into your practice?

feel free to visit us when we are conducting courses or sign up to take a self guided tour at your convenience when you come out to Las Vegas for a business trip. You can reach us by emailing support@cad-ray.com

 

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Full Mouth Rehab under Sedation

  the patient was sedated and intubated for the case so we could not keep track of the bite. Instead, we imaged all 30 prepared teeth and used medit compare / design to digitally mount them to the wax ups. In the link provided you can download the models and relate them to each other […]
To access this page and view the premium content and support, you must either be a customer of CAD-Ray or purchase CAD-Ray Membership.
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Fast and Easy Full Arch Temporary by Medit Design Software

Medit Compare, now called Medit Design, now has a boolean cut feature that lets you extract a temporary shell model from wax up or mock up model and prep model for easy and quick designs without painful margin marking on multiple units

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Top Reasons Why Restorations from Digital Impressions Don’t Fit

Much like conventional impressions, digital impressions can render ill-fitting restorations.  It is imperative to figure out the source of the problem and to understand if it is a scanning or manufacturing issue.  We have compiled the top reasons for such errors in this article:

    1. If the restoration is manufactured on printed models, you should be alarmed! There are so many variables that can be introduced in additive manufacturing process that can lead to less than desired results.  Printed models should only be used after restorations are milled to assess contacts or to dial back bulky material to the margin on they die.
    2. Translucent / transparent enamel can lead to inaccurate scans.  This is most magnified when we work on conservative preparations made on enamel.  See this article to understand the troubles that can be introduced while scanning glass. aa

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Comparing Intra-Oral Scan with Printed Model

3. We highly recommend that the clinician places his or her margins as soon as they image the preparation. Oftentimes, labs only work with STL models instead of color models and this leaves a lot of room for open interpretation and errors.  Labs can then print the models to finish work like contacts and reducing margins they have bulked out to protect the material whilst milling.

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Mark your own margins
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Full Arch Implant Planning Set Up with Medit i700

This used to be such a long process and we can bust them out in no time. take upper and lower scans in a minute. add lip…

Posted by Armen Mirzayan on Monday, October 11, 2021

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Download the Medit Case with live scans

 

Download the CT scan dcm’s to design along

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Distalized Second Molar During Temporary Stage

With second molars, you should always be on the look out for not just the jaw settling, if you remove the first point of contact, but also with the temporary step forcing the tooth to tip towards the distal, if there is no third molar to stop its tilting.

In this case, a doctor was trying to seat a second molar crown he had just prepped a few weeks prior.  There was an open contact and he could not ascertain the reason for this. He did take a second impression digitally so we had the chance to merge the two models and look for discreptancies between the preps. This video shows how the comparison of those two steps in Medit Compare

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Distalized Second Molar
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Meshwork in Local HD and RD Scanning

The Medit scanner has a feature where you can locally capture a preparation in HD mode.

This allows for more crisp visualization of tooth anatomy and morphology but most deem it clinically insignificant

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Scanned in HD and in RD

In this case a preparation was captured twice, once in regular definition mode and again in high definition mode

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Meshwork in Local HD and RD Scanning

The models were then rendered and compared and the differences were analyzed. You can import them into medit compare and see
For yourself

This crown was replaced along with multiple class 2 restorations approximating it. This last video shows the try-in of the amber mill block

HD vs RD local

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Fabrication of Lithium Disilicate Crown
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Measuring Intra-Oral Scanner Accuracy and How Accurate is the Medit Scanner?

Still not a single article published that says Medit ios is a good scanner ! its just been user driven for 3 years now.

 

it’s a good thing, because the world just changed. it is irresponsible to extrapolate research done outside the mouth on stone models or impressions into clinical significance with intra-oral scanning. There are parameters that are impossible to quantify like focal distance throughout the scan (unlike desktop scanners with known focal distances), the codes use to do the algorithms, the scan patterns, and also how light is treated by enamel, dentin, and restored materials.

 

i can’t believe people still use terms like trueness and accuracy when they really don’t even exist when you scan intra-orally. Like analog impressions, it is impossible to judge digital impression accuracy LIVE while it is happening.

 

Enter Medit! There are a few distinct ways to demonstrate an accurate scan live while it is happening. One way is to import a geometric shape that doesn’t alter its form while models are being rendered. That’s what’s demonstrated here. To my knowledge no one has ever studied this approach because no other camera lets you do this. i did see some publications where the authors attached objects like radiographic markers and after it was processed, they could measure that object and see if it distorted or not, but nothing at this level.

 

You can download the case and design along

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Translucent Enamel Is A MotherDoctor For All Intra-Oral Scanners And Their Accuracy

One of the most important lessons a digital dentist has to learn quickly is how to not introduce errors when scanning dentition.  The most likely area when s/he can introduce errors is in the anterior area where the incisor are not only narrower than molars but can also have translucent enamel.  Add just a little spacing between teeth with diastemas and you can quickly distort the accuracy of the model.  This is true of ALL intra-oral scanners in the market

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Incisal Translucency / Transparency Causing Model Distortion
There are a few ways you can overcome these issues and the second video highlights some of our preferred methods. The concept is easy- block the light from travelling through the tooth structure and you are set!  Watch the videos to learn how to do it

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The Problem With Light Travelling Through Enamel and Intra-Oral Scanners

Here are some examples of how light shinning through the enamel and /or ceramic instead of bouncing back resulting in errors in model accuracy. Lesson #1 for every ios user is to know when and where they are likely to introduce error. in dentate cases, it usually is right that the transition from premolar to canine to lateral. The surface area decreases dramatically and if you have translucent enamel and / or material and / or highly reflective surfaces you can “derail” the model building. Here is an exaggerated demonstration

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Same Issue May Arise While Scanning Translucent Ceramic and/or Shinny Surfaces

Translucent enamel can also play a role in distorting the cavosurface margins of a inlay or onlay restoration.  When imaging from the occlusal, the gingiva below the margins acts as a barrier to block light transmission through the enamel, but as soon as you start to roll the camera to the buccal or lingual, and you have enamel with no substrate behind it to block light transmission, you can introduce errors in the equation with any scanner.

There are many ways to combat this which include powdering the tooth structure, using a rubber dam, or in Medit’s case, you can use the color subtraction filter.  You selectively tell  the scanner to ignore certain colors and you use that exact color (here, it is the color of the glove) to block light transmission through the enamel. So the software just ignores the blue, but the light is prevented from shining through reducing the errors you would introduce.

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Translucent Enamel in Class 2 Preparations

Here is another example of the distorted enamel margins on a conservative preparation and how blocking out the light from travelling through the tooth structure leads to crisp visualization of margins without any distortion or artifact

can you explain why we see blurred margins and artifact/distortion between the 2 centrals while in the second image the…

Posted by Armen Mirzayan on Sunday, March 6, 2022

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Using the CT as a Remount Jig If You Have Lost The Vertical Dimension For Some Reason or Another

At CAD-Ray, we have now designed over 20,000 implant cases since 2013. One of the most common requests we get is from doctors doing full arches and their desires to reduce the conversion time. A simple thought to keep in mind is that A LOT can be derived from the actual implant plan, even if you don’t do the surgery guided. You can extract the digital implant positions and fabricate temps and based on your level of experience, your conversion / temporary time can drastically reduce.

Another very helpful matter to keep in mind is a concept we preach a lot at our courses. It deals with relating models to each other, both automatically and manually. This can be a CT scan to an intra-oral scan, or a pre-op to a post op. You just have to find redundant landmarks for the software to merge the models together. One thing to keep in mind, particularly with the Medit i500 is that when you merge models to each other and process it, their relationship to each other is preserved.

There is a lot of benefit that can be derived from that. For example, in this video, we have the dicoms converted to surface STL’s which is very easy to do. We also have the intra-oral scan merged to that stl file. You can digitally extract the teeth and do bone reductions, and if you are ever in a bind where you lost track of the vertical dimension, you can use the jaws as the means to related the preop to post-op. Or you can even use the nose if you are really desperate.

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Relating Large Models to Each Other
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A Mix of All of the Medit Features Include Compare, Smile Design, Model Imports, CT scans, Image, Videos, etc…

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Compare and Smile Design Features

in this case we import multiple models, videos, CT scans, and Face Scans so that our users can utilize all of these features. Click here to enter the member’s section to download the whole case and design along

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How Medit’s AI Killed The Tibase Scanbody Star!

here is a list of why the Medit Artificial Intelligent Implant Suprastructure Identification System is significantly more advantageous over all other cadcam systems.

  1.  It s technically a crown and bridge case and the implant location or timing does not matter
  2. You can find margins outside the mouth!  See the first video to appreciate the significance of this
  3. You don’t have to deal with retraction or hemostatis at all
  4.  You don’t have to worry about sprue position. Many other systems force the placement of the sprue to a specific location often making the case more difficult to manage than necessary
  5.  you are not limited to just a few implant lines
  6.  you don’t have to worry about location of anti rotational notch
  7.  you can digitally alter the prep and get a virtual reduction coping in cad
  8.  Use any restorative block you want.  There is no need to order special blocks with pre-fabricated access channels and keep a large inventory of many colors. Your regular block inventory will suffice.  Just make sure the top of the tibase is wider than the diameter of the drill used to mill out the intaglio.  Also, the CAM and the milling machine determine the exact product and different settings maybe utilized to give you relief off the walls.  Some will even remove the antirotational notch because the adaptation is so tight, the restoration will not rotate due to the tall walls of the tibase
  9.  You can check the fit outside the mouth on the same tibase or a one you keep chairside for every case to let you know that if you are not seating, it is clearly a contact or contour issue as opposed to an intaglio issue.

 

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Digital Tibase - Medit's AI Feature

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Fit of Tibase to Milled Restoration

With Medit’s Crown Fit function, you can see exactly how much cement is required to seat the restoration and how well it is adapted to the tibase.

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Medit Crown Fit
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Prep Sequence for Easy Access

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

 

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Prep Sequence for Easy Access