In a perfect world, you would never need to use an implant abutment that corrects for angulation.
Also, in a perfect world I would live here.
But we don’t live in a perfect world and sometimes we have to deal with complications. One of the minor complications I routinely encounter is imperfect implant angulation.
The two main reasons for implant angulation to be off are:
(1) Iatrogenic. The implant surgeon was off the mark by a little or a lot.
(2) Lack of bone. If a patient refuses bone augmentation to correct a defect, the implant surgeon may have no choice but to place the implant off-axis so that it will be fully encased in bone.
Whether you are a fan of screw-retained or cementable implant crowns, you’ll need select an abutment that can compensate for the implant’s imperfect position.
Take an implant-level impression and have the lab fabricate the model. Don’t order any parts and pieces just yet!
If you’re taking an impression of a single implant that is at a very extreme angle, say more than 45 degrees or so, you will likely have to take an open tray impression. If you use a closed tray technique in this case, you will likely lock in the tray around the undercut introduced by the impression coping. The open tray technique picks up the impression coping with the tray, so no worries there.
If you’re taking an impression of two or more implants that have divergent angles from one another, the same precaution should be taken.
Review the implant catalog to see what your options are. Surprisingly, not every implant company provides a full array of angled abutment options. This is especially true of screw-retained, angled abutments. Some companies just don’t make them.
I used to measure the angulations by eye, but that leads to error. Frustrating, time-wasting error.
For most systems, I use a simple technique.
Go online, find an image of a protractor and print it. Here’s a link to a site with all the steps.
Now mark some lines on the paper for your implant angulation options.
Instant protractor! Note lines at 15 and 30 degrees for angled abutment options.
Place impression copings or just the pins into the implant replicas in the model. Hold up your fancy new protractor.
Now visualize your final restoration. In this case I’m using an angled, screw-retained abutment so I want the access hole to emerge through the cingulum area of the tooth.
The 15 degree angled abutment should work nicely.
Finally just measure the tissue collar height and select your angled abutment.
Now here’s something really cool. Neoss is an excellent dental implant company that makes ingenious components that make my life easier. Here is one of their nifty inventions:
Neoss Angulation Guage
It measures angulation and tissue height all in one little toy. The hole is for floss in case you want to use it intra-orally.
What a great little gadget!
The red line indicates the original angulation of the implant. There is a pin in the adjacent implant to serve as a reference. As you can see, I’ll need a 20 degree angled abutment with a 3 mm collar height. Done and done.