I began to work out a classification system for implant prosthetics based on their hygienic ability. It was published in this month’s RDH magazine but you can see the online version here. Essentially, there are three kinds of implant prosthetic contours:
Anatomical Emergence: There is a smooth contour extending from the implant platform through the transmucosal abutment and on to the crows contours. This is the most cleansable.
Modified Ridge Lap: There is an obtuse angle formed between the abutment and the crown. A bit harder to clean.
Full Ridge Lap: There is an acute angle formed between the abutment and the crown. This is the hardest to maintain hygienically.
This language is based on prosthodontic terms for pontics but is slightly modified. Check out the article for greater detail and illustrations. What I recently realized is that we need some terms for the soft tissue underneath these crown contours. After all, that is the area that we’re trying to keep healthy.
Here’s a cross-section of an implant in the central incisor region:
Using my definitions, we can identify this implant crown as being a full ridge lap restoration. The lingual aspect is fairly cleansable, but there is a buccal flange that extends gingivally and hinders hygienic access.
Okay, now let’s describe the soft tissue we’re trying to save. I see two types: peri-implant sulcus mucosa and underlying prosthetic mucosa.
Peri-Implant Sulcus Mucosa: The soft tissue in contact with the transmucosal abutment, implant platform, and any other implant surfaces along the depth of the sulcus.
Underlying Prosthetic Mucosa: The soft tissue that is covered by the implant crown or restorative superstructures (e.g. framework).
Here’s the same cross-section from above with these mucosal areas marked:
Blue: underlying prosthetic mucosa Red: peri-implant sulcus mucosa
Let’s look an area of a full-arch implant restoration for further comparison:
Left: Two of the implants supporting the hybrid restoration. Right: Corresponding area of the hybrid restoration. Note the accumulation of plaque and calculus.
See that plaque and calculus on the right? That’s the enemy. We must destroy it without mercy! Our war on peri-implantitis and peri-implant mucositis begins with being able to communicate with our team. Here’s the same picture highlighting the terms we’ve just created:
Blue: underlying prosthetic mucosa Red: peri-implant sulcus mucosa. On the right, the same colors are used to illustrate the corresponding parts of the hybrid that cause the trouble.
Know your enemy! With a common set of terms, dentists can better design prostheses with their lab technicians and better maintain them with their hygienists.
If you’d like to learn more about this and other implant complications, come out to Las Vegas in August to see me lecture with Dr. Scott Froum.
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