Magnetic extrusion for restoring teeth with a negative ferrule effect: a 2-year follow-up case report

The restoration of severely damaged teeth with no coronal structure requires an adequate supracrestal tissue attachment (STA) and a distance of at least 3 mm between the crown margin and the alveolar crest. Management of a tooth with no walls and only subgingival tooth structure implies that the tooth has no ferrule. Ferrule preparation from 1.5 to 2.0 mm with a circumference greater than 75% is crucial for a good medium- and long-term prognosis (especially at the anterior segments) and increases survival probability by 5%. Three main options may be considered to create space for a ferrule: crown lengthening, orthodontic extrusion or surgical extrusion. Although extrusion is widely performed with fixed orthodontic appliances using arch wires or elastics attached to the tooth, the same outcome can also be achieved with magnets. This article reports on a 56-year-old male with a severely damaged tooth 23 with no ferrule, which was an abutment of an In-Ceram alumina fixed partial denture (FPD). The treatment plan consisted of a magnetic extrusion of tooth 23 using a provisional tooth-implant FPD made of polymethyl methacrylate (PMMA). The treatment lasted approximately 10 months, with the last clinical and radiographic control carried out 2 years post-extrusion. The present case report aims to demonstrate that magnetic extrusion with an FPD provides a friction-free system in which the direction and amount of force can be manipulated. This technique offers an excellent alternative for the restoration of teeth with insufficient ferrule, or even with no ferrule. Further prospective studies and randomized controlled trials are needed to demonstrate the feasibility of this treatment option.