How to 360° intraoral scan fixed and removable appliances?

In the world of skateboarding, Tony Hawk's gravity-defying 360-degree spins were a mesmerizing spectacle that captivated my youthful imagination. Little did I know that over two decades later, the concept of 360-degree movement would resurface in an entirely unexpected realm: digital dentistry!

Let's embark on a journey where we explore the fascinating parallels between Hawk's iconic skateboard move and the art of capturing precise dental records.

With 4,000 IO scans under my belt, I've honed a repertoire of tips and tricks that can elevate your dental scanning game, revolutionizing the way your scanner assists you across various treatment indications. Strap in as we roll into the world of precision dentistry and explore the possibilities of 360-degree capture.

The ‘why’ of a 360 degree dental scan for digital dentures

Where to start, you might ask? Well, the most common applications for 360-degree intraoral scans generally fall into two categories: Removable full appliances and fixed full appliances. We'll delve into both digital denture types shortly, but before we do, let me provide you with a few guiding principles to steer you toward accurate 360-degree intraoral scans.

Firstly, the "why?" Why do you need to perform a 360-degree scan? The primary purpose of this scan technique is to capture several critical pieces of information in a single scan file that would otherwise be impossible to obtain digitally in separate case files. It is also a way of referencing and linking back the appliance to the patient's anatomy for a whole manner of technical reasons, which are generally most appreciated at a lab level.

So, what are the surfaces of appliances that we will be capturing in a 360 scan:

• Fitting surfaces (approach differs for upper and lower appliance captures if upper has full palate)
• Buccal peripheries
• Buccal aspect of the appliance (facial aspect of the teeth and flanges)
• Incisal and occlusal aspects of the appliance (of the prosthetic teeth)
• Lingual flanges
• Lingual periphery on lower appliances (and uppers without palates)
• Distal borders on full upper removable appliances (with palate)
• Scan devices affixed to implant prosthetics

Avoid stitching misalignments in your digital scan

Why, you might ask, does it matter in which order? Well, when completing a 360 degree scan, it can be quite easy to have some stitching misalignments as you close off the 360-scan loop. By capturing the most critical surfaces first, these will be the most accurate for you to use in the construction of your new appliances.

To determine where this join mark will be from where you started the capture to where you finish can place the demarcation in a place that may not affect scan quality if anything goes amiss along the process.

These are my steps that I go through for every 360 scan I approach, whether fixed or removable.

• What surface is most critical to the accuracy of the appliance?
• Is it possible to capture the most critical record first in the scan sequence (think fixed appliances in situ, which we will discuss more later)? If not, can I complete the most important surface second?
• What is the least important surface or aspect to capture? It's important to understand which is the least important part of the capture. This is generally a part of the scan that will have little to no bearing on the integrity of the final prosthetic you are working on. It will also mean this will be the place you will be planning your scan strategy as an endpoint. I can’t overstate it. It is super important.
• What is the second, third, fourth, and so on, most critical features so that these can be placed into the scan strategy order?

When to use these scanning techniques in full arch implantology?

Now let's have a chat about when you would use 360° scanning techniques as part of full arch implantology. Generally, the time you will need to use these techniques is when implants have integrated, and it's come time to convert the temporary bridge into the final.

Nowadays, there are some great reverse scan bodies that can be brought into your workflows. In short, these are scan bodies that you will place into the underside of your bridge and fix from the occlusal. I've been using these for some time now, and there are a few great ones out there from different manufacturers.

The latest I have been road-testing is the RevEx product by Straumann, which is very good as it has some good non-congruent head structures that intraoral scanners seem to digest very well. I would invite you to get acquainted with them and invest in them as a critical part of your repertoire.

It should also be noted that the 360 scans should be accompanied by a strong abutment level scan body system that can get you the required precision and scan assist when you complete your capture. But that discussion is for another occasion.

Example of the 360 degree scan steps for F/F fixed temp conversion to a final

Let’s dive into the Full Upper and Lower Fixed bridge conversions:

• Record occlusal/incisal, buccal, and lingual aspects of the temporary for both upper and lower (as per standard TRIOS dentate scan protocol).
• Record the bite.
• Crop any anatomy that is also captured in addition to your prosthetic (unless you are, of course, using this as an orientation piece where you might use landmarks sequentially captured).
• Remove bridges from the mouth.
• Fix posterior reverse scan bodies and orientate the unique feature (a trough or other identifying mark towards the mesial direction).
• Fix your anterior reverse scan bodies and orientate the unique feature distally toward the posterior scan bodies' unique features.
• With a rolling motion start your scan on the buccal aspect of the bridge and roll over the periphery toward the fitting surface, attempt to capture the unique geometry of the scan body as you roll along the periphery. Once you have captured part of the scan body continue a roll to complete the full record of the scan body.
• Move back to the buccal and scan along till you come to the next scan body then capture the unique geometry and complete a full roll around the scan body. Tip: You are using the buccal anatomy of the teeth as you bridge to get accurately to each scan body so always come back to that part of the scan as you move along.
• As you move along the buccal border continue this movement with the goal of capturing the fitting surface and scan device simultaneously.
• For these devices I would aim to have my final join and close the loop halfway between the lingual flange extension and the incisal/occlusal.

Precision scanning for amazing and functional smiles

In the realm of digital dentistry, the concept of 360-degree precision scanning is nothing short of revolutionary, much like Tony Hawk's mastery of gravity-defying 360-degree spins on a skateboard.

This technique allows us to capture critical information in a single case file, forging a vital link between the appliance and the patient's anatomy.

As we embark on this exhilarating journey of precision, remember that the order in which we capture surfaces holds the key to achieving the best possible scans. Prioritizing the most crucial aspects ensures that we lay a solid foundation for crafting amazing and functional smiles, which is indeed the main point after all.

Whether you're grinding through a full denture scan or diving into the complexities of full arch implantology, the pursuit of 360-degree precision in intraoral scanning is a captivating voyage. Welcome to a realm where precision and innovation converge, opening doors to endless possibilities for simplifying and achieving digital dental excellence.