Magnet 30(in Unerupted Teeth)

International Journal of Paediatric Dentistry

2003;

13:

204–207

204

© 2003 BSPD and IAPD

Blackwell Publishing Ltd.

The role of magnets in the management of unerupted teeth in children and adolescents

B. O. I. COLE

1

, A. J. SHAW

1

, R. S. HOBSON

1

, J. H. NUNN

1

, R. R. WELBURY

1

, J. G. MEECHAN

2

& N. J. A. JEPSON

3

1

Department of Child Dental Health,

2

Department of Oral Surgery, and

3

Department

of Restorative Dentistry, Dental School & Hospital, Richardson Road, Newcastle upon

Tyne, UK

Summary.

This case report describes the use of magnets in the management of teeththat fail to erupt. Eight children aged between 10 and 15 years were treated. Magnetictraction was applied to two premolars and six molars. Seven teeth (one premolar and sixmolars) erupted successfully (mean treatment time with magnetic traction: 7·5 months).One premolar failed to erupt; serial radiographic assessment over a 9-month periodrevealed no evidence of movement and so the magnetic fixture was removed. Histologicalevaluation of tissue samples taken from around the fixture revealed no evidence ofabnormal pathology.

Introduction

Magnets have been used in dentistry to retain dentures[1–3] and maxillofacial prostheses [4]. Developmentand availability of rare earth magnetic alloys (cobalt-samarium alloys or neodymium-iron-boron) haveled to their increased use in orthodontics [5,6].Several clinical applications have been described,including the treatment of unerupted teeth [7,8], archexpansion [9], fixed retention [10] and anterior openbite correction [11].

This case report describes the use of magnets inthe management of unerupted premolars and molarsand considers the advantages and limitations of thetechnique.

Case report

Eight children, mean age 11·5 years (range 10–15years), were selected. Each child had a single tooththat had failed to erupt and that was consideredbeyond the scope of conventional orthodontic techniques.Treatment was undertaken in a Hospital Paediatric

Dental Unit following a standard clinical protocol(illustrated in Figs 1–5).

Clinical protocol

1

Radiographs (panoramic or periapical views) weretaken to ascertain the cause of eruption failure andseverity of tooth impaction (Fig. 1).

2

A removable appliance was fitted prior to surgicaltooth exposure (magnet placement) to ensure that

Correspondence: B. O. I. Cole, Department of Child DentalHealth, Dental School & Hospital, Richardson Road, Newcastleupon Tyne NE2 4AZ, UK. E-mail: [email protected]

Fig. 1. Panoramic view showing distally inclined and uneruptedUR7 prior to treatment.

Moving impacted teeth with magnets

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© 2003 BSPD and IAPD,


13:

204–207

patients had the necessary compliance to undergotheir postoperative orthodontic treatment (Fig. 2).

3

Paralene coated NdFeB magnets (Magnet Devel-opments Ltd, Swindon, UK) were encased in ortho-dontic composite (Transbond, 3M, Unitek, Monrovia,CA, USA).

4

Teeth were surgically exposed and encasedmagnets (3 mm

×

3 mm

×

2 mm) were cementedin place using orthodontic adhesive (Transbond, 3M,Unitek) (Fig. 3).

5

Patients were reviewed 1–2 weeks after surgeryand their removable appliances modified to acceptan encased magnet (5 mm

×

5 mm

×

3 mm). Themagnet was carefully orientated to ensure the flatattractive surface was as near parallel as possibleto the first magnet bonded to the tooth.

6

Post-operative radiographs (panoramic or peri-apicalviews) were taken to confirm correct magnet orientationand as a baseline reference for monitoring toothmovement.

7

Patients were seen for a further review at 1 monthand then at 3-monthly intervals until the magnetswere removed or, between these reviews if problemsoccurred.

8

Final arch alignment was undertaken with fixedappliances if necessary (Fig. 5).

Results

Seven teeth (one premolar and six molars) eruptedsuccessfully over a 6-month period. The meantreatment time with magnetic traction was 7·5 months(range 3–12 months). One premolar failed to erupt.Serial radiographic assessment over a 9-month periodrevealed no evidence of tooth movement and so themagnetic fixture was removed. Histological assessmentof soft tissue samples taken from around the fixture,at the time of removal, identified the presence ofgranulation tissue with no evidence of abnormalpathology.

Fig. 2. A lower removable appliance demonstrating embeddedopposing magnet.

Fig. 3. Surgically exposed UR7 with magnet cemented on themesial surface.

Fig. 4. Partially erupted UR7 four months post magnetic traction.

Fig. 5. Final alignment of UR7 with fixed appliance.

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et al.



13:

204–207

Discussion

Treatment options available to clinicians for themanagement of teeth that fail to erupt include extrac-tion, transplantation and application of conventionalorthodontic traction [12–14]. An alternative optioninvolves the use of magnetic traction, which is lesstraumatic than extraction and transplantation and avoidsthe need for direct application of traction forcesthrough gold chain, ligatures and elastics [13,14].Case reports have shown the technique to be effectivein the management of unerupted canines and premolars[7,8]. This case report confirms that magnetic tractioncan also be used to treat unerupted molars where theapplication of direct traction forces is frequentlyrestricted.

The failure of one premolar to erupt was attrib-uted to its unfavourable position. Correct orientationof magnetic fixtures proved difficult and the 10 mmintermagnet distance achieved for this tooth wasconsidered too large to generate sufficient attractiveforce to produce tooth movement. Previous reportsconfirmed that attractive forces generated betweenintraoral magnets fall rapidly as intermagneticdistances increase [7,15] and this can be explainedas the force generated between magnets is inverselyproportional to the square of the distance betweenthem. In the seven successful cases, the intermagnetdistances did not exceed 8 mm, suggesting thatdistances up to this magnitude can produce sufficientforce to induce tooth movement.

The safety and biological properties of magnetshave been thoroughly investigated and currentevidence indicates that coated NdFeB magnets areacceptable for clinical use [16,17]. Magnets usedin this series were Paralene coated and encased inorthodontic composite to prevent degeneration inthe oral environment. Failure of one premolar toerupt gave the opportunity to take soft tissuebiopsies adjacent to the fixture at the time of itsremoval. No histological evidence of abnormalpathology was noted in agreement with previouswork [17].

This case report confirms that magnetic traction canbe used in the management of unerupted premolarsand molars and merits further investigation.

Acknowledgements

We are grateful to all the practitioners who contributedpatients to this series.

Résumé.

Cette série de cas décrit l’utilisation d’aim-ants dans le traitement de dents n’ayant pu faire leuréruption. Huit enfants ont été traités, âgés de 10 à15 ans. La traction magnétique a été appliquée àdeux prémolaires et six molaires. Sept dents (uneprémolaire et six molaires) ont pu faire leur éruption(temps moyen de traction magnétique 7,5 mois).Une prémolaire est restée bloquée. L’évaluationradiographique sur une période de 9 mois n’a montréaucune preuve de mouvement. Le système mag-nétique a été déposée. L’évaluation des échantillonsde tissus pris autour du système n’ont révélé aucunepathologie.

Zusammenfassung.

Diese Fallserie schildert den Ein-satz von Magneten in der Behandlung von Zähnenmit Eruptionsstörungen. Acht Kinder im Alter von10 bis 15 Jahren wurden behandelt. MagnetischeBefestigungselemente wurden an zwei Prämolarenund sechs Molaren angebracht. Sieben Zähne (einPrämolar und sechs Molaren) konnten daraufhin zurEruption gebracht werden (mittlerer Behandlungszeitmit Magnetzug: 7.5 Monate). Ein Prämolar konnte nichtmobilisiert werden: Eine Serie von Röntgenaufnahmenüber einen Zeitraum von 9 Monaten ergab keinerleiHinweise auf eine Bewegung, so dass die mag-netische Apparatur entfernt wurde.

Die histologische Untersuchung von Gewebe ausder Umgebung der magnetischen Apparatur ergabkeine pathologischen Veränderungen.

Resumen.

Esta serie de casos describe el uso deimanes en el tratamiento de dientes que presentanun fracaso en la erupción. Se trataron ocho niñosque tenían entre 10 y 15 años. La tracción magnéticafue aplicada en dos premolares y seis molares. Sietedientes (un premolar y seis molares) erupcionaronexitosamente (tiempo promedio con tracción mag-nética: 7,5 meses). Un premolar no erupcionó y laserie radiográfica durante un periodo de 9 meses,reveló la falta de movimiento eruptivo por lo quese retiró la fijación magnética. La evaluación his-tológica obtenida del tejido circundante a la fijación,reveló la ausencia de patología.

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Documents

Magnet 30(in Unerupted Teeth)