Sir, a 29-year-old woman was referred to her local oral surgery department for the extraction of her lower right six due to it being extensively broken down and unrestorable. On examination the tooth was grossly broken down with minimal clinical crown visible above the gingival margin. As part of the pre-operative assessment a DPT radiograph was taken, the findings of which were interesting and serve to illustrate the importance of using the utmost care and diligence when placing posts to restore teeth.

The DPT radiograph is shown in Figure 1 and clearly shows a post perforating through the furcation of the lower right six. This post is very long and does not even come close to being inside either one of the roots of the tooth. It is without doubt that the misplaced post has led to this young woman requiring this tooth to be extracted.

Figure 1
figure 1

DPT radiograph

Full size image

On examination the post had totally separated the roots of the tooth. The extraction was uneventful, with the roots and the post being extracted as three separate elements, and full healing is anticipated. A photograph of the extracted tooth and the post can be seen in Figure 2 which nicely illustrated exactly how long the post is compared to the roots.

Figure 2
figure 2

Photograph of extracted tooth and post

Full size image

It is generally accepted that the length of a post should be two thirds of the length of the root, with a crown-length to post-length ration of at least 1:1, and that the diameter of the post should allow for a minimum of 1 mm of dentine around the post.1

This case nicely illustrates the importance of using the correct size posts and how careful post placement is essential if a post is going to help a patient retain their tooth. If these principles are not followed and if posts are not diligently placed the exact opposite can happen, as in this case, resulting in the patient losing their tooth.