In previous articles in this series, I have discussed what biologic width is, and described how I place restorative margins based upon the presenting sulcus depth and thickness of the gingiva.
This article will start to address how to diagnose inflammation around restorations that exists because the margins have been placed too deep, violating the attachment. When we see an anterior restoration particularly a full crown, that has significant gingival inflammation, a series of possible diagnoses exist:
- It could be plaque control, but if the adjacent teeth have healthy gingiva, that is unlikely.
- It could be marginal fit, which can be examined with an explorer and radiograph.
- It could be poor contour, preventing adequate hygiene again possible to examine.
- It could be an allergic response to the restorative material, especially if the restoration was done in the '80s or '90s using a nickel-containing alloy, and the patient is female.
- But it could be because the margin is placed too close to bone, violating the biologic width. (See Figures 1-4 below)
Ideally, if the existing restoration is removed, and a well-fitting temporary placed for at least three months without the return of any gingival inflammation, you would assume the margin location was not the problem, and one of the other etiologies applied. The reason for the three-month wait is that it is not unusual to damage the attachment apparatus when removing an old restoration and placing a temporary.
You may see perfectly healthy-looking tissue until it heals and matures, which is usually between eight to 12 weeks, and then the inflammation returns. Of course, not every patient wants you to take off their restoration to make a diagnosis, so here are some other options to assist in deciding whether or not the margin location is the problem:
- First, simply place a perio probe in the sulcus until it reaches the margin, do this circumferentially around the tooth. What you are looking for is pain: a margin in the sulcus will result in no response, a margin in the connective tissue attachment will be painful to probe.
- Next anesthetize the tooth you are concerned about. Place the perio probe on the restorative margin, and read the distance from there to the gingival margin. Keeping the probe against the root laterally, slide the probe down to bone, allowing you to compare the previous probe readings vs when the probe is on bone.
- Third, use a periapical radiograph; while it won’t let you see the margin location relative to bone on the facial, it will on the interproximal.
If the margin is painful to probe, is within two mm of the bone when measuring it, or on a radiograph, you probably have a biologic width violation, and the only thing you will be able to do to eliminate the inflammation is correct the problem. That will be topic of my next article – stay tuned for Part Eight!
(Click this link for more dentistry articles by Dr. Frank Spear.)