Denture repair by applying a magnetic attachment after extracting theabutment tooth of a cone crown telescope: A case report
A.izumida
Department of Comprehensive Dentistry, Tohoku University Hospital

Abstract
In this case report, a denture was repaired by applying a magnetic attachment after extracting theabutment tooth of a cone crown telescope. The patient was a 76-year-old female. She wore a denturewith a cone crown telescope for three missing teeth: the left central incisor, the lateral incisor, and thecanine. The second premolar on the left side of the maxilla, one of the abutment teeth, was extracted
due to root fracture. Subsequently, a full metal crown with an extracoronal magnetic attachment wasaffixed to the maxillary left first molar behind the defect. Denture repair was performed by adding amagnetic attachment to the inner surface of the outer crown of the second premolar on the left side of
the maxilla to match the keeper of the extracoronal magnetic attachment. The patient was satisfied
with using the repaired denture. In addition, by adopting an extra-crown attachment, it was possible
to reduce the burden on the abutment tooth.

Introduction
In recent years, dental magnetic attachments have become easier to handle in general clinicalpractice due to their miniaturization, retentive force, improved corrosion resistance, and the fact thatthey can also be applied to extracoronal magnetic attachments. Another advantage is that, with a littleingenuity, there are various ways to use them.
In this case, one of the abutment teeth of the removable partial denture was extracted. The full metalcrown of the existing tooth at the extraction site was made into a full metal crown equipped with an
extracoronal magnetic attachment, and the denture was repaired by affixing a magnetic attachment to
the inner surface of the denture so as to fit the keeper.

Outline of the case
The condition of the prosthetic device in the oral cavity at this patient's first visit was shown in theprevious report, 1) but the basics are given below.
The patient was a 77-year-old female. On June 12, 2020, she came to the hospital complaining ofupper left pain during occlusion. Intraoral views and the denture are shown in Figure 1. As a generalmedical history, the patient was being treated for hypertension.

Fig.1 Intraoral views and the denture at thebeginning of prosthetic treatment
Her current dental history is as follows. In December 2000, inner crowns of the cone crowntelescope on the maxillary right central incisor, left first premolar, and left second premolar wereproduced for three tooth defects. A removable partial denture equipped with outer crowns conforming
to those inner crowns was then set. In November 2014, the inner crown of the maxillary right central
incisor, one of the abutment teeth, was removed for root canal treatment due to acute apicalperiodontitis. In July 2015, after endodontic treatment, the maxillary right central incisor was repairedby fitting a magnotelescopic crown (MT crown) with a magnetic attachment to fit the existing outercrown.
The current disease is as follows. The second premolar on the left side of the maxilla, which was
the focus of the main complaint, had occlusal pain for about 3 weeks; additionally, red swelling wasobserved in the buccal gingiva, the tooth mobility was second grade, and the periodontal pocket depth
was 9 mm at the deepest point. A dental photograph of the second premolar on the left side of themaxilla is shown in Figure 2. A root fracture extending to the apex was found, and the tooth was judged
to be unsavable, so it was extracted on June 30.

Fig. 2. Dental radiograph
Clinical procedure
In planning the prosthetic treatment, the following factors were considered: The denture had beenused for a long time, but the fit of the denture was good, and the patient could use the denture
comfortably. Therefore, the prosthetic treatment plan after tooth extraction was shown as follows andwas accepted by the patient:(1) Fabricate a provisional crown with an extracoronal attachment after removing the full metalcrown of the maxillary left first molar.
(2) Produce a full metal crown with an extracoronal magnetic attachment keeper after the residual
ridge being stable.
(3) Mount the magnetic assembly on the inner surface of the outer crown of the second premolar
on the left side of the maxilla.
(4) Maintain and recall.
Treatments were performed as follows.
A provisional crown with extracoronal attachment to the maxillary left first molar was made byapplying a bent ready-made rest wire to the outside of the crown. The extracoronal attachment wasfitted to the inner surface of the outer crown of the second premolar on the left side of the maxilla(Fig.3).

Fig. 3. Intraoral views, the denture and theprovisional crown
Working casts without the denture (Fig.4①) and with the denture (Fig.4②) were prepared for theproduction of a full metal crown with the extracoronal attachment. In this case, since it was used on
the inner surface of the outer crown of the second premolar on the left side of the maxilla, GIGAUSSC400® (GC, Japan) was used as the magnetic attachment, and the extracoronal attachment wasmanufactured by the keeper bonding method.
The crown morphology was waxed up in consideration of the following points (Fig.4③). The mesial
surface was adapted to the distal surface of the second premolar on the left side of the maxilla of themodel with denture. The part of the extracoronal attachment in contact with the mucosal surface wasfitted with a dentureless model. For the pedestal to which the keeper of the extracoronal attachment isaffixed, a model with denture was used, and wax-up was performed on the model in which the occlusal
surface was ground, leaving the axial surface of the second premolar on the left side of the maxilla.
The wax pattern was buried and cast according to the conventional method, and then the cast bodywas adjusted and polished (Fig.4④).

①②

③④

Fig. 4. Fabrication process from the wax-up of the firstmolar tooth to the completion of the full metal crownwith an extracoronal magnetic attachment
The full metal crown with an extracoronal attachment was set in the oral cavity. At the next visit, amagnetic attachment was fitted to the inner surface of the outer crown of the second premolar on theleft side of the maxilla (Fig.5).

Fig. 5. Intraoral views and the denture at the wearingof the magnetic attachment

Discussion
In this case, by extracting the second premolar on the left side of the maxilla, the Kennedy
classification is type 1 of Class III, and the Eichner classification is B-1. Including the maxillary rightsecond molar that had already been missing, 5 teeth were missing. Since there was no defect in themandible, the number of teeth decreased from 24 to 23, and the number of occlusal supports decreased
from 10 to 9. In Miyachi's occlusal triangle, the area changed from the first area to the second.2)
However, the patient had 9 occlusal supports and 23 teeth, had no tooth loss for the past 21 years, andshe had more teeth and occlusal supports than other people of her generation. As a result of considering
these factors, it was judged that the minimum prosthetic treatment was possible in this case.
Regarding the maxillary left first molar, the periodontium was generally good, and the pocket depth
was about 3 mm, although the margins of the full metal crown were incompatible.
The patient was using the denture well and strongly hoped to continue using it. Therefore, she wasrelatively reluctant to make new dentures. In this case, the purpose of prosthetic treatment was to use
the existing denture as much as possible while not placing an excessive burden on the abutment teeth.
When she was presented a treatment plan using a full metal crown with an extracoronal attachment,
she gave her consent to the treatment plan. 3)

Conclusions
As a prosthetic treatment after tooth extraction, the existing full metal crown of the existing tooth
was remade into a full metal crown with an extracoronal attachment. The existing denture was repairedby setting a magnetic attachment on the inner surface of the outer crown of the denture to fit the keeper.
By using the existing denture, we enabled the patient to use the repaired denture without discomfort
and with high satisfaction. In addition, the use of a magnetic attachment could reduce the burden onthe abutment teeth.

References
1) A. Izumida. Denture repair with the application of a magnetic attachment to the inner crown of atelescopic crown: A three-year follow-up case. J J Mag Dent 2019;28:9–13.
2) T. Miyachi. Clinical Evaluation and risk analysis for partially edentulous arch —Imbalance of thenumber of teeth between maxilla and mandible as a risk factor—. Ann Jpn Prosthodont Soc
2013;5:21–27.
3) T. Ohyama, T. Ishigami, S. Sakaguchi, E. Nagai, K. Ohtani, T. Fujimoto, Y. Katakura, M.
Takamura, and A. Magima. The Extracoronal magnetic attachment using ready-made patterns. JJ Mag Dent 2006;15:28–32.