Have you ever heard of that unseen line on the earth that separates the two hemispheres? The equator? There are also mystical lines that delineate the notorious Bermuda Triangle, and to this day, ships even orientate themselves to avoid them for fear of disaster.
Well in the intraoral scan frontier you might be surprised to learn that there are also important lines that you will encounter. Albeit not so dramatic, you will be faced with them in every single scan you attempt. The way you navigate them can mean success or failure for your clinical indication when it relates to occlusal referencing and digital bite scan taking.
A few months back, I contacted a senior tech from 3Shape to gain a better understanding of how the bite scan technology works. I was hoping that the information might help me gain better and more precise clinical outcomes for my patients. We spoke for a long time and to be honest, most of the tech terminology flew miles over my head. As my layman brain understood it, the scanner is looking for common threads that it can image map and put into some semblance of organisation and order. If all the images line up to a degree that the device can measure and logically place, you will hear that sweet-sweet melody resonating from your computer and the Maxilla/Mandible relation (MMR) or for us, bite scan, will be secured.
Enter the Bermuda Midline. You might be saying to yourself, “Leif, bit of an exaggeration, that bite scan line isn’t scary at all,” and yet, when you are recording bite scans across full arch quadrants, crossing that magical midline might be more important than you think. When I take bite scans with very few opposing teeth, I have found from experience that unless I scan past the midline in one full bite scan I will not hear that delightful tune.
The reason scanning past the midline is so difficult to do in one go is as you approach that point, your body and hand position starts to get very cramped and tied up. You might be thinking: well why don’t you just perform the old ‘scanner spin’ move? Well with cords, hardware, and real life, it isn’t always so easy. I have learnt from over 2,500 patient scans that taking the scanner out of the mouth and then relocating in a reverse hand position is the easiest way to continue scanning past the Bermuda Midline.
The primary reason I go past the midline in complex full arch bite record taking, is that you need to collect as much data as possible to aid the system in putting all the pieces of the bite puzzle together. This might mean taking the scanner out of the mouth (don’t push the button to stop recording though), repositioning your body - hand and scanner - and then putting it back in the mouth for additional record taking by picking up where you left off. If you go past the midline in the first stage, finding a re-reference point to continue the bite into the next quadrant is much easier.
You’ll note that in addition to hand technique, clear instructions for the patient are critical.
Here are my steps in standard bite taking as well as a supplementary section on enhanced bite taking for cases when you need to cross the midline. Do this for every bite (even small quadrant bites):