3D Modeling Bites!

What is this?! Jesse Sprague badmouthing 3D Modeling? What has this world come to?

Oh contraire, my fair readers. Read On. On this day I am more impressed with 3D Modeling than ever. It is the way of the present but it is also the way of the future. While the SOLIDWORKS system of tools is not the hero of this particular story, its brothers and sisters in the CAD/CAM family certainly are.

The story begins on a cold winter night with some friends back in town from afar. It is a disturbing tale and not one for the squeamish or faint of heart.

It was unusually dark that night as we huddled around the open door of their backyard pizza oven. I couldn’t quite make out the peak of the oven’s roof against the sky, but the joists underneath were brightly lit by the fire. The wind was bitter but we hardly took notice with a drink in hand, good company, and radiant heat spilling out of the glowing oven. With the last of the pies baked to a perfect crisp, we closed up the oven and headed off to enjoy them indoors.

If you’ve never enjoyed fresh wood-fired pizza, I pity you. This stuff is surely what Marco Polo had in mind when he returned home to Italy with the goods. Lurking in this delicious treat however, was a threat to my oral health. Somewhere over the course of the evening I bit down on a grain of corn meal. A warm flash of pain shot down through my tooth and into my jaw. “That can’t be good” I thought to myself, “I should probably get that checked out”. Later that evening I realized I had cracked a tooth. Several days later I discovered that the damage was inevitable. A significant section of the side of my tooth departed revealing that trouble had been brewing under an old filling. As it turns out, most of my tooth was a goner. I tried to warn you this was a gruesome tale…

At this point, I did what any self-respecting engineer would do. I googled it. I had not been to the dentist in quite a while, mainly, because I am terrified of the dentist. I’m sure they’re all perfect ladies and gentlemen, but as far as I’m concerned, they’re one “bone stretcher” away from medieval torture. Take one look at that adjustable tray-of-death they slide around. You know what I mean. Picks and drills and grinders and needles… bah! It gives me the shivers just writing it. In an attempt to spare myself as much as possible, I scoured for good reviews and landed on a dentist near my office. Fortunately (or unfortunately), they were able to get me in just a few hours after I called. I sat nervously tapping my knees in the waiting room. I was called in for initial prognosis.

Filling? Maybe.

Crown? Maybe.

Root Canal? Maybe.

Extraction? Maybe.

The skies darkened. Until it was ground out there was no way to tell. So grind he did. I popped in my headphones and put on one of my favorite albums to get immersed into (Jerseyband - Lung Punch Fantasy). To be honest, it wasn’t too bad! Now here’s where things get cool. To my delight, there was just enough tooth left to do something with. But what? Most of the tooth was gone so there was nothing to fill and a crown would require removing most of what was left of the tooth. Little did I know, I was to be saved by my digital friend: the CAD/CAM system. Here’s how it went.

It turns out my dentist John trains other dentists across the country on how to use the German CAD/CAM system he uses. The first step is to stick a wand into my mouth to 3D scan the remaining tooth after it has been processed. It is a small unit no bigger than a TV remote. On its tip is a set of sensors, cameras, and mirrors to allow the unit to see around the tooth. John scans my tooth as well as the surrounding teeth and bite at about 18 frames per second. This is enough to allow the computer to stitch the scan together and build a model of my jaw. Just like using a library feature in SOLIDWORKS, John then pulls a digital tooth from the library on his system that best matches what used to be in its place. It looks like the system does some wizardry to figure out the new tooth segment’s orientation and does a Boolean operation to subtract out the nub left in my mouth. Apparently, the scan is accurate within the tolerance of the layer thickness of the bonding concrete.

So now we’ve got a model of a tooth that looks like what I had, and it nestles perfectly into what’s left. Before anything is created, John flips to a SOLIDWORKS Simulation-like contact pressure plot which indicates where my top molar will contact this new piece of hardware in my mouth. He selects a point near where a contact would occur and a directional arrow appears normal to the tooth surface much like SOLIDWORKS Industrial Design or the SOLIDWORKS Freeform tool. From there, he can adjust the topology of the tooth to match my bite. He uses a depth brush similar to those found in artist’s 3D modeling tools to pull out a couple of wrinkles in the shape and it’s ready to go.

“Would you like to watch it cut?” he asks. You bet I do. We walked down the hallway to a tidy looking desktop machining unit with a small block of material loaded. It is a dual-head grinding unit with the heads facing each other like the spindles of a Swiss Machine. I watched as the coolant fired up and it started grinding away on the top and bottom simultaneously. Not much more than 5 minutes had passed and my new “tooth” popped out. John bonded it into my mouth and I was on my way.

Here’s the stock in the machine getting ready to cut.

And here’s how it turned out before being bonded into my mouth (not my best photographic work but I blame the numbness in my face).

And that’s the story of how Jesse got a new tooth courtesy of a talented dental staff and seamless integration between 3D scanning, 3D modeling, and Computer Aided Manufacturing. Sure it wasn’t a SOLIDWORKS application, but we’re part of the movement aren’t we? Imagine where our 3D world will take us next.

P.S. I told John that I probably wouldn’t let another tooth rot to see the process again but I certainly was impressed! If you’re in the Rochester area and are in need of a good dentist, I would give a thumbs up to White Spruce Dental. If you scroll down on their website you can see a video showing the CEREC process I described in this article. http://whitesprucedental.com/

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