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Poorly Contoured Dental Restorations / Dental Overhang

An example of poorly contoured dental restorations: Dental x-ray of overcontoured crown on tooth with plaque trap caused perio pocket.

Figure 1a: Here, a crown was placed over an overhanging silver filling without removing the overhang (1). The result is the same—difficulty cleaning under the ledge can lead to secondary (recurrent) tooth decay, and damage to the gums and bone (2) adjacent to the poorly contoured dental restoration.

Dental restorations (fillings, inlays, crowns, etc.) are ideally made to blend smoothly with the contours of the natural tooth being restored. Ideally, the margins should close down tightly against the tooth, providing a hermetic seal against bacterial invasion.

If the restoration is built too large, or the margins overhang the edge of the tooth, food and bacterial plaque can accumulate along the margins, leading to inflammation and tooth decay (caries). Plaque accumulation in such areas can produce a bad taste and bad breath (halitosis).

Poorly contoured dental restorations do not always reflect a low skill level or lack of attention to details. In some situations, establishing ideal tooth contours is complicated by poor visibility, decay that extends well below the gum level, restricted ability of a patient to open their mouth adequately, and other factors.

Dental x-ray shows overcontoured silver filling in tooth causing periodontal pocket.

Figure 1b: A silver filling with a large overhang. Arrows show where an overhanging silver filling (1) has led to early bone loss (2). This is because food and bacterial plaque accumulate under the ledge, and are difficult or impossible for the patient to remove.

Sometimes, in an effort to be conservative, a well-meaning dentist may try to avoid crown-lengthening a tooth (a surgical periodontal procedure), and the restoration contours may be compromised as a result. However, if the tooth is to be maintained long term, restoring its ideal contours is typically recommended. Otherwise, even a well motivated patient may not be able to prevent problems from arising around the tooth over time.

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Author: Thomas J. Greany, D.D.S. / Editor: Ken Lambrecht

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