Notes on Masking Abutments [Part 1]

One of my earliest attempts to block a severely discolored abutment came back for a follow-up appointment today. The patient was a woman in her seventies, and had fractured her ceramic crown on tooth #11. She had visited Taipei VGH, and was referred to our clinic for one-visit restoration. After our consultation, she decided to redo both #11 and #21, which had visible secondary caries.

The fractured #11 and the rather ominous #21.

The real fun when re-doing crowns, of course, always comes after crown removal. It’s like opening presents; most of the time you’re happy to see what’s inside, but every once in a while… this was one of those whiles.

If you turn this picture upside down it’s almost like a big black middle-finger. That’s what it felt like anyway.

At the time I didn’t have too much experience with abutment coverage, and so I had to go by the numbers; with feldspathic ceramic, I was told that a minimum of 1.2 mm was needed to cover up this atrocity. Fortunately, the original crown allowed a pretty generous buccal real estate, so thickness of the ceramic wasn’t an issue. Still, the dark surface wouldn’t reflect light very well and can cause the entire restoration to lose light value, so I thought maybe a little resin boost would help.

Coverage with composite resin. Not the prettiest but it helped. Maybe.

The neighboring teeth weren’t exactly the most harmonious to begin with, so I had to play the hand I was dealt. Luckily, the patient didn’t at all mind her original alignment and occlusion.

Cemented restoration showing a mismatched hue in #21.

During the try-in I noticed that #21, while successfully masking the abutment, wasn’t the right hue. Even with repeated staining and glazing, we weren’t able to replicate #11’s color exactly. The apathy of the patient again saved the day, and I delivered the crown anyway. After a few month and a few other similar cases, I had a pretty good theory on why the material behaves like this. It’s more than just the abutment’s color leeching in, and has to do with crystalization change during glazing. Will need to confirm this with a study.

Six-month follow up.

Anyway, this is her six-month followup. The mismatched color is still there, but otherwise I think the crowns have held up fairly decently.

Obligatory pretentious artsy photo. And yes, she’s seventy.