In a previous article, we discussed two etiologies of open gingival embrasures due to a short contact: root angulation and tooth shape. When the contact is not long enough we must determine the etiology before we can choose a solution.
If the roots are parallel, the papilla is at a normal level and an open embrasure exists, the etiology is most likely overly tapered tooth form. In order to change tooth shape it's helpful to know what your two options are.
Orthodontics: If the roots are divergent, then orthodontics is an easy choice to align the teeth and in doing so move the contact apically; however, even if the roots are parallel orthodontics can provide some improvement in correcting an overly tapered tooth form. The orthodontist can move the contact apically by stripping the interproximal contour, making a less tapered tooth form and creating a small diastema.
The teeth are then moved together closing the diastema and extending the contact to the papilla. Like most procedures, this approach does carry some risks. For instance, in order to do this you must have space occlusally and it may be necessary to strip the lower incisors to allow them to be moved creating excess overjet, allowing the maxillary teeth to be retracted. The other risk is potentially making the teeth too narrow. As the teeth are reshaped they are made narrower. It is possible with this technique to create teeth, which appear too long and narrow, typically staying above a 70 percent width to length ratio will still give a natural look.
Restoration: If you have a patient with reasonably well aligned teeth and an acceptable occlusion, restorative dentistry can help you achieve the correct crown contour and lengthen the contact. To understand the challenge of closing an open gingival embrasure restoratively, it helps to consider another restorative challenge: closing a diastema. Most restorative dentists have tried to close a diastema with composite. This seems like a simple and quick procedure, but after the composite is placed it is often nearly impossible to floss without getting caught on overhangs.
If you want a smooth contour the trick is to go subgingivally. What you'll want to do is extend the contact down to the papilla, then extend the restoration 1mm farther subgingivally to create a smooth contour. You can use a metal matrix band with the preferred contour already bent into it and placed 1mm below tissue, then adapt the matrix tightly against the lingual aspect of the tooth. This will allow you to etch, apply your bonding agent, and place the composite, extending the restoration below the gingiva resulting in a lengthened contact and closed gingival embrasure.