17. Successful case of a denture with magnetic attachment replaced by cone crown telescope
Hasegawa N. 1, Fukuzawa R. 1, Syouji K. 1, Itou F. 2, Okada M. 2, Nakamura Y. 1 and Tanaka Y. 1
1The First Department of Prosthodontics, School of Dentistry , Aichi-Gakuin University
2Department of Dental Laboratory, Aichi-Gakuin University Dental Hospital
Introduction
Overcoping telescopic denture design is based upon the use of telescoping overcoping on domed crowns with coping full coverage crowns. This prosthetic removable design results in a very strong supporting structure, and has improved long-term postoperative prognosis compared to a clasp denture based upon an increased number of supporting abutments. Clinically this design is complex and complicated with a high requirement for good laboratory fit and processing. There may be difficulties in adjustment of the retentive force as well. Removable prosthetic devices with magnetic attachments embedded in and out of the crown have been widely applied in recent years. We report treatment of complications and successful repair and use of magnetic attachments in a denture treatment that specifically used the telescopic crown technique. This case report documents difficulties and the clinical problems that may be overcome.
Patient
Date of birth: 1931. 9 Sex: female
The
patient received a cone crown denture to replace the losses of 765｜2 at our university
hospital
in 1996. The abutment teeth were 4｜3 4 (Fig. 1). We subsequently
restored
several upper teeth. The follow-up course of the lower teeth was uneventful, and we regularly
followed up the patient with the Department of Periodontology.
a b c d
Fig.1:Intraoral picture in wearing cone crown denture
a Frontal view
b Occlusal view
c Inner cap of a cone crown
d Cone crown denture
The first trouble and treatment
In May 2006, the
tooth｜5 , an
abutment tooth for the bridge｜⑤ 6 ⑦ , had a root fracture, and was to be extracted (Fig. 2).
Fig. 2:｜5 root fracture
To add the abutment to address the increased tooth loss, the old denture was fixed with a MT
crown
placed on｜7 .
MT crown has a strong supporting structure and retentive force similar to
a cone crown (Fig. 3).
a b c d
Fig.3 Denture repair with MT crown
a Inner cap of a MT
b Outer cap of a MT
c Completion of repair
d Intraoral occlusal view in wearing denture
The second trouble and treatment
In February 2007, the second trouble occurred. The inner cap
of 4｜
was detached due to the secondary caries. The caries reached the
infrabony region, and it was difficult to preserve the tooth. We tried
root traction method using the attractive force of a magnet as an orthodontic
force. Magnetic assembly with a screw is attached into the outer cap of
the cone crown, and the root traction was performed by using the attractive
force of a magnet created in the space between the magnetic assembly and the
temporary root cap with a keeper by turning a screw. Fig. 4 shows the
fabrication procedure of a traction device.
 |
Fig. 4: Fabrication procedure of a traction device
a Placement of a temporary root cap with a keeper
b Placement of a magnetic assembly with a screw
c Cut-back of the occlusal surface of a cone crown outer cap, and the placement of the denture
d Securement of the traction space by silicone impression material
e fixation of a screw and outer cap of a cone crown with composite resin
f Rotation of a screw after removing the impression material to adjust the space between a keeper and a magnetic assembly.
The rate of traction was 0.5 mm/week and a total of 2 mm for 4 weeks. Fig. 5 shows the X-rays before and after the root traction.
a b
Fig. 5: X-ray of 4｜
a Before traction
b After traction
After the root traction, root cap with a keeper was attached, and the magnetic assembly used for the traction was fixed into the outer cap of a cone crown with composite resin to seal the occlusal surface, and completed the repair of a denture (Fig. 6). In general, applying the occlusal force on the tooth right after extrusive movement to the tooth is contraindicated. However, since the denture itself serves as a retainer in this case, it was considered that applying occlusal loads right after the root traction would not cause any problem, and thus, completed the treatment. The patient has been using the denture without any problems and has been regularly followed up.
a b
Fig. 6: Completion of the repair of a denture
a Attachment of a root cap with a keeper
b Occlusal view of the repaired denture
Consideration
We applied magnetic attachments to deal with two troubles of a cone crown denture, and achieved successful results. Cone crown and MT crown have different characteristics of frictional force and magnetic force, respectively, but have similar availabilities. Considering that the patient used the repaired denture without any problems right away, it is considered that the combination of cone crown and magnetic attachment is effective. As for the root traction that we performed at the second trouble, the following advantages are expected;
* The current denture can be used continuously.
* Excellent aesthetic appearance and hygiene since the device is localized in the tooth crown.
* Minor orthodontic force can be applied continuously.
* Easy to adjust the space at every visit.
* Magnet is reusable.
* No additional retainer is required.
Given these advantages, it was suggested that this method is very useful for cases of this kind.
References
1. Tanaka, Y.: Dental Magnetic Attachment - new prothodontic treatment used the magnet -, Ishiyaku Publishers, Inc. (Tokyo), 1992.
2. Tanaka, Y.: Dental Magnetic Attachment, Q＆A, Ishiyaku Publishers, Inc. (Tokyo), 1995.
3. Nakamura, Y.: Stress analysis of overlay denture and a magnetic attachment using finite element method. J Jpn Prosthodont Soc, 42: 234-245, 1998.