3D Imaging

If you could see what I see…

A patient came in today for a simple implant assessment. Take a 3D scan, determine bone thickness and density for implants on 5 and 12, and send the pictures and CD to the referring doctor. I glanced at the pano (first image below) and thought it would be easy. I thought wrong.

 

Click on one of the pictures below and use the arrow (far right side of the picture) to navigate your own cone beam slide show. I highlighted the more interesting pathologies and concern areas. When you’re done look at the pano and ask how much you would have seen originally.

           

This guy looked great and was completely asymptomatic. Just like most of the patients who walk in each day. My New Years Resolution (along with hide sharp objects from Aimee) is to take a long look outside of the prescribed implant areas, just in case.

 

 

Monday Morning Mystery Case

I begin my races visualizing the finish line and what I need to get there. With marathons, I usually need a cab. With implants, the finish line is the final restoration. You will make your referring GPs’ Christmas, Hanukkah, Tet, Eid, Kwanzaa, and Groundhog Day gift lists by placing implants within the quadrants’ curve of spee and minimizing the need for custom abutments or cantilever crowns. Some CBCT software packages (including our Anatomage) enable you to virtually place the final crown and view the abutment as you’re determining implant placement. By maneuvering the final crown into position between the neighboring teeth, implant planning with cone beam moves from an educated guess to a very precise determination.

 

What should be done when there are no neighboring teeth to determine final crown placement? In other words, what is your first implant planning step when the finish line is extremely murky? (If you answered “refer it out,” you’re wise. Wisdom and honesty and humility are all closely related.)

    

In this case a young man in his 20s suffered trauma that knocked out 7-10 and left insufficient bone for implants on 7 and 10. The GP and oral surgeon decided to place implants on 8 and 9 and, depending on insurance and the patient’s decision, revisit the laterals later.

 

First we virtually placed implants on 8 and 9. The software shows their emergence profile angles (see the long thin white lines), and to confirm we were in the ballpark we placed implants on 6 and 11. After the angle was correct (near parallel) we deleted the unneeded 6 and 11 “reference” implants. This mirrored the rotation and a slight facial tilt in line with the rest of the anteriors, even though the neighboring teeth (7 and 10) are absent.

 

 

Next we placed restorations on the virtual 8 and 9 implants. We measured the total edentulous area to determine the approximate width of each central. Although these will not be the final restorations, we wanted a close approximation because we wanted to place the implants as close to dead-center as possible. The implant abutments are shown in orange outlines and clearly show if they need to be custom (not in this case). We were also able to use the incisal foramen as an approximate midline. (This shouldn’t be standard practice as the incisal canal doesn’t necessarily follow the true midline; we just got lucky in this case.)

     

With this information Reveal Diagnostics ordered a surgical guide, which arrived at 8am the following day at the oral surgeon’s office (again, thanks Anatomage). If the patient elects to have implants placed on 7 and 10 (presumably after some bone augmentation) and we take another cone beam 3d x-ray scan, we’ll post the after CBCT pictures!

 

 

Monday Morning Mystery Case (priceless)

When this patient called to reserve a 3D scan, I thought it was a creative joke. When the patient arrived, I thought it was just creative. Actually the patient didn’t phone. The patient wasn’t alive.

 

A representative from the international auction agency Bonhams arrived with a 12″ x 12″ x 4″ sealed wooden box that hopefully contained a rare and snazzy Winston Churchill edition Montblanc pen. How snazzy? The barrel is crafted of 18 karat pink gold, inlaid with black and brown tortoise shell lacquer bands. The captop is ringed with 53 diamonds (to commemorate the year in which Churchill was both knighted and bestowed the Nobel Prize for Literature), and the Montblanc star is of mother-of-pearl. Really similar to the Reveal Diagnostics pens I give away to 3D dental imaging clients…

   

 

The pen is valued at $25,000 if it’s still in the sealed box. However, Bonhams needed to confirm the right pen was actually inside the box to ensure their seller was honest and their buyer would remain honest after taking the box home.

 

We tied the box to the chin rest of our CBCT and took a 3D x-ray scan. The cone beam image revealed a mint condition Winston Churchill Montblanc. The Bonhams agent was happy.

 

I wasn’t.

 

The 3D scan showed a pen that looked a lot different than the dozen Montblanc pen collection I’d purchased for three monthly installments of $19.95, plus shipping and handling. Still, the rare Montblanc pales (in utility and value) in comparison to my James Bond pen!

 

Monday Morning Mystery Case

Even before the 3d cone beam scan, this problem wasn’t much of a mystery… but treatment options were.

 

If you guessed the patient has a periapical lesion on ECT #2, you’re a winner! The bonus question is whether to retreat and keep the tooth, or extract it. The patient really wanted to keep her tooth and the doctor really wanted to see what he was dealing with, so they both showed up at Reveal Diagnostics. After a quick 15-second 3D dental imaging scan we had the below sagital (buccal) view.

 

This view only shows one dimension of the area of interest. True, the CBCT image bisected the buccal roots and allowed a better view of the abscess, and the cone beam image revealed previously hidden pathology in the maxillary sinus. We have more data than when we started with a 2D pano. However, one plane does not tell the whole story or answer the main question. Namely, can this ECT tooth be re-treated with a reasonable expectation of success? Before you pounce on the slippery definition of “success,” look at the 3D image from all three angles below.

 

The coronal (cross-section) and axial (top-down) views show the patient has no cortical bone on the buccal side of #2, not even at the root apex. In addition, only about 1mm of bone remains lingually and to the maxillary sinus cavity. Upon seeing these 3D cone beam images, the referring doctor decided to extract the infected tooth. I won’t judge if it was the right or wrong decision, but I will say the doctor’s judgement was based on as much 3D diagnostic information as possible.

Monday Morning Mystery Case

This Frankenstein of a patient is near and dear to me; she is my business partner Aimee. She suffered late mandibular bone growth in her mid-20′s, especially on her right side. Her surgery included, among other procedures, the filing down of her right mandible to reach better symmetry.

 

Post surgery she experienced periodic numbness and shooting pain down the right side of her neck. The above left photo shows Aimee’s post-op 3D scan. The above right photo shows that her beauty isn’t just bone-deep.

Now for the cause of that recurrent pain… if you clicked on the above 3D image to enlarge it, you probably saw the culprit. However, we prefer to show these cases from different angles to make it obvious and for patient education.

 

In reshaping the right mandible (done before 3D cone beam scans were invented), the alveolar nerve canal was actually bisected and the nerve is now exposed. When this nerve rolls outside of the remaining half-canal, the stretching/pinching effect causes the numbness and pain.

I told Aimee that she’ll be pain-free if she just stops talking. Now instead of verbally abusing me she throws things!

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