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Effectiveness of lingual retainers bonded to thecanines in preventing mandibular incisorrelapseAnne-Marie Renkema, Samah Al-Assad, Ewald Bronkhorst, Sabine Weindel, Christos Katsaros,and Jörg A. Lisson

Nijmegen, The Netherlands, and Homburg/Saar, Germany

Introduction: A retainer bonded to the lingualsurfaces of the mandibular canines (3-3 retainer) is awidely used type of retention. Our aim in this study wasto assess the effectiveness of the 3-3 mandibular lingualstainless steel retainer to prevent relapse of the orth-odontic treatment in the mandibular anterior region.

Methods: The sample consisted of the dental castsof 235 consecutively treated patients (96 boys, 139girls) from the archives of the Department of Orthodon-tics and Oral Biology, Radboud University NijmegenMedical Center, The Netherlands, who received a 3-3mandibular lingual stainless steel retainer at the end ofactive orthodontic treatment. The casts were studiedbefore treatment (Ts), immediately after treatment (T0),and 2 years (T2), and 5 years (T5) posttreatment.

Results: The main irregularity index decreasedsignificantly from 7.2 mm (SD, 4.0) at Ts to 0.3 mm(SD, 0.5) at T0; it increased significantly during theposttreatment period to 0.7 mm (SD, 0.8) at T2 and 0.9mm (SD, 0.9) at T5. The irregularity index was stableduring the 5-year posttreatment period (T0-T5) in 141patients (60%) and increased by 0.4 mm (SD, 0.7) in 94patients (40%). The intercanine distance increased 1.3mm between Ts and T0 and remained stable during theposttreatment period.

Conclusions: The 3-3 mandibular lingual stainlesssteel retainer (bonded to the canines only) is effective inpreventing relapse in the mandibular anterior region inmost patients, but a relatively high percentage willexperience a small to moderate increase in mandibularincisor irregularity.

The full text of this article can be found at: www.ajodo.org.

Am J Orthod Dentofacial Orthop 2008;134:179-80

0889-5406/$34.00

Copyright © 2008 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2008.06.003

EDITOR’S SUMMARY

Even with prolonged retention combined with lightinterproximal enamel reduction, the mandibular frontteeth tend to relapse. As a result, fixed retainers are beingused more frequently, often for extended periods, tomaintain acceptable alignment. A Cochrane review in2006 found only 2 prospective randomized clinical trialsand 3 pseudo-randomized clinical trials that evaluated theeffectiveness of various retention strategies. In patientswhose retainers had failed, a greater increase in incisorirregularity could be measured. Other studies not includedin the Cochrane report indicated that the average increasein irregularity was rather small as long as the intercaninedistance remained stable.

The subjects for this study were obtained from theDepartment of Orthodontics and Oral Biology, RadboudUniversity Nijmegen Medical Center, The Netherlands.Patients were recalled at 3 months, 6 months, 1 year, 2years, 5 years, and 10 years posttreatment. Two years aftertreatment, the irregularity index was stable in 66% of thepatients; at 5 years posttreatment, it was stable in 60% ofthe patients. If long-term treatment results have any valueto us as the professionals who “fix” malocclusions, greaterattention must be paid to our patients in retention.

TAKE-HOME POINTS

● The bonding and maintenance of a mandibularcanine-to-canine retainer is effective in stabilizingthe orthodontic treatment results in most treatedpatients. However, a relatively high percentage ofpatients still experience a small to moderate increasein incisor irregularity in the long term.

● Because the stability of alignment was negativelyaffected by failures of a bonded retainer, it isimportant to stress the value of the periodic main-tenance of retainers bonded to the canines.

● These results will further enable clinicians to informtheir posttreatment patients about limitations inretaining the mandibular front teeth and give them

more realistic expectations.

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tion about the best retention strategy.

American Journal of Orthodontics and Dentofacial OrthopedicsAugust 2008

180 Renkema et al

REVIEWER’S CRITIQUE

I liked this study and the way it was written, but Iwonder about the practice of bonding only mandibularcanines. The current gold standard for mandibular canine-to-canine fixed retention usually includes bonding a wireto each of the 6 anterior teeth. There are obviously somelimitations to this study when compared with a random-ized controlled trial. The design was retrospective, with norandomization and no control group. A comparison groupmight have consisted of patients retained with removablerather than fixed appliances. Confounders include variousstaff members and graduate students in the orthodonticdepartment where the treatment was provided. Theseparticipants might well have used varying techniques anddifferent bonding agents, and each had a unique skill levelwhen placing the fixed retainers. Of credit to the authors,some of these limitations are discussed.

In their discussion, the authors cited a study by Boese(Fiberotomy and reproximation without lower retention—nine years in retrospect: part II. Angle Orthod 1980;50:169-78) in which the author proposed combining a bondedcanine-to-canine retainer with interproximal enamel reduc-tion and circumferential supracrestal fiberotomy (CSF).There is some evidence that CSF leads to increased stabilityin both the maxillary and mandibular anterior segments.However, our readers might want to check out another articlefor a long-term view of the problem (Edwards JG. Along-term prospective evaluation of the CSF in alleviatingorthodontic relapse. Am J Orthod 1988;93:380-7). Edwardsfound CSF more effective in preventing pure rotationalrelapse than in reducing labiolingual relapse over the longterm, and more successful in the maxillary anterior segmentthan the mandible. Finally, in our recent article, Peter Miles,Jack Sheridan, and I found that significant and unpredictableindividual tooth movements were still observed after CSF(Rinchuse DJ, Miles P, Sheridan JJ. Orthodontic retentionand stability: a clinical perspective. J Clin Orthod 2007;41:125-32).

Daniel J. RinchuseGreenburg, Pa

Fig. Lingual retainer (0.0215 x 0.0027-in stainless steel

rounded rectangular wire) bonded to mandibular ca-

Q & AEditor: In an article in the December issue (KatsarosC, Livas C, Renkema, AM. Unexpected complicationsof bonded mandibular lingual retainers. Am J OrthodDentofacial Orthop 2007;132:838-41), you expresseddissatisfaction with a flexible spiral wire bonded to all6 mandibular front teeth for retention. Are you anyhappier with the results of the fixed retainer whenusing a heavier wire bonded only to the canines?

Katsaros: In that article, we were dealing only withpatients with unexpected complications during retentionwith a 3-strand twist-flex retainer. A new study that theNijmegen group will submit to the AJO-DO shows that,in most patients with no complications, twist-flex retain-ers are efficient in preventing relapse of the mandibularanterior teeth. However, since undetected complicationsusually lead to retreatment, I do not use twist-flex retain-ers anymore in the mandible. With a thick stainless steelretainer bonded only to the mandibular canines, accept-able alignment of the mandibular anterior teeth can bemaintained, but, when perfect alignment control is re-quired, I currently use a .016 � .022-in stainless-steelretainer bonded on all anterior teeth with the .022-in sidein contact with the tooth surface. However, this type ofretainer must still be evaluated.

Editor: What would you say to clinicians who routinelydismiss their patients after 6 to 12 months of retentionwith the advice to call the office if problems arise?

Katsaros: I know that many orthodontic practices havedifficulties in following retention patients because oflogistic problems; after some years in practice, the num-ber of these patients can be large. Patients with retainersbonded only to the canines will immediately notice aloose retainer. With retainers bonded to all mandibularteeth, however, loose sites are not always easy to beidentified. Furthermore, it is difficult for the patienttoidentify unexpected complications of these retainers.

My advice is to check the retainers once a year; thesefollow-ups could be also done by a general dentist as apart of the regular dental checkup, if dentists areinstructed accordingly.

Editor: Are you planning any other retention studies inthe future? If so, what type of study design will give usthe missing information?

Katsaros: With the experience of the retrospectivestudies on both canine-and-canine and canine-to-ca-nine lingual retainers, the Nijmegen group is planninga large-scale, multi-site, prospective clinical trial. Thistype of study can give more evidence-based informa-

nines only.