How to Diagnose a Gummy Smile with Crown-Length Problems

In a recent article, we revealed the seven possible etiologies that can cause a gummy smile. In patients with short anterior teeth, only three of those seven etiologies can be the actual culprit: Wear, altered active eruption or altered passive eruption.

While the presentation is still the same, these three etiologies have very different traits when it comes to making a diagnosis. There are certain steps you can take in order to evaluate their crown length and develop your treatment plan.

Wear: The first step you need to take is evaluating the wear on the patient's teeth – if there is any. We know that as teeth wear away and lose occlusal contact, they typically continue to erupt in the same pattern in order to maintain that contact. This eruption process encourages the bone and gingiva to follow the same pattern, resulting in a gummy smile. When examining the teeth, look at their length to width ratio; patient's teeth that look like perfect squares most likely have a wear issue.

Sulcus depth: If you rule out tooth wear as the cause, the next step you should take is probe the sulcus. We know that the normal amount of sulcus is anywhere between 1-2mm, anything above that indicates the gingiva is not migrating properly. However, if you discover the sulcus is too deep, you must refer to the CEJ and where it is relative to the bone.

CEJ location: If probing doesn't reveal the location of the CEJ, it's highly probable that there is an abnormality in the relationship between the bone and CEJ. During the diagnosis phase, you want to keep treatment as conservative as possible. Instead of anesthetizing the area and laying a flap for visualization, refer to the radiograph step below.

Radiograph: This step is necessary if all the prior steps did not reveal where the CEJ is located relative to the bone. This is the best chance at determining active eruption at this point in the diagnosis. The radiograph will not show you the facial, but it does allow you to make assumptions about it by looking interproximally. We can see where the interproximal bone is relative to the interproximal CEJ. Whatever is revealed interproximally, you can assume the same goes for the facial and you can begin your treatment planning.