Magnetic orthodontic extrusion restores the ferrule without sacrificing the periodontium

When the ferrule is missing and the tooth is not to be lost

Endodontically treated teeth with extensive loss of coronal tissue pose the same problem every time. Without a sufficient band of sound structure above the preparation margin, that is, without a ferrule, the post and crown work against biomechanics, and the remaining options are surgical crown lengthening, which consumes the supporting periodontium, or extraction.

Orthodontic extrusion is a third route: the tooth is slowly drawn out of the alveolus until enough supragingival structure emerges, while the periodontal support is preserved. The team led by Arturo Pineda-Lopez, writing in the Journal of Endodontics, describes a variant of this approach in which the force is delivered by magnets and the planning and control of the movement are guided digitally.

The patient was a 57-year-old man who presented because of a decemented metal-ceramic crown on the maxillary right first premolar. The endodontic diagnosis was previously treated tooth, and the periapical diagnosis was asymptomatic apical periodontitis. The procedure combined non-surgical endodontic retreatment with digitally guided magnetic extrusion in order to restore the ferrule before the definitive prosthetic restoration.

Limitations

This is a single case report, a design that permits no conclusions about the frequency of success and no comparison with surgical crown lengthening. Data on the length of follow-up and the final outcome are not available in the abstract, so they should be checked in the full paper.

For your practice

• Before declaring a tooth with an insufficient ferrule unusable, assess whether extrusion is an option: the criteria are the length and shape of the root and the condition of the periodontium, not only the height of the remaining coronal structure.
• In previously treated teeth with asymptomatic apical periodontitis the order matters. Endodontic retreatment comes before the prosthetic plan, not after it.
• Digital planning of the movement makes it possible to determine in advance how many millimetres of extrusion are needed and whether a correction of the gingival level will be required afterwards.