Aug 2008 AJO

1. ONLINE ONLY
Effectiveness of lingual retainers bonded to the
canines in preventing mandibular incisor
relapse
Anne-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 lingual EDITOR’S SUMMARY
surfaces of the mandibular canines (3-3 retainer) is a Even with prolonged retention combined with light
widely used type of retention. Our aim in this study was interproximal enamel reduction, the mandibular front
to assess the effectiveness of the 3-3 mandibular lingual teeth tend to relapse. As a result, fixed retainers are being
stainless steel retainer to prevent relapse of the orth- used more frequently, often for extended periods, to
odontic treatment in the mandibular anterior region. maintain acceptable alignment. A Cochrane review in
Methods: The sample consisted of the dental casts 2006 found only 2 prospective randomized clinical trials
of 235 consecutively treated patients (96 boys, 139 and 3 pseudo-randomized clinical trials that evaluated the
girls) from the archives of the Department of Orthodon- effectiveness of various retention strategies. In patients
tics and Oral Biology, Radboud University Nijmegen whose retainers had failed, a greater increase in incisor
Medical Center, The Netherlands, who received a 3-3 irregularity could be measured. Other studies not included
mandibular lingual stainless steel retainer at the end of in the Cochrane report indicated that the average increase
active orthodontic treatment. The casts were studied in irregularity was rather small as long as the intercanine
before treatment (Ts), immediately after treatment (T0), distance remained stable.
and 2 years (T2), and 5 years (T5) posttreatment. The subjects for this study were obtained from the
Results: The main irregularity index decreased Department of Orthodontics and Oral Biology, Radboud
significantly from 7.2 mm (SD, 4.0) at Ts to 0.3 mm University Nijmegen Medical Center, The Netherlands.
(SD, 0.5) at T0; it increased significantly during the Patients were recalled at 3 months, 6 months, 1 year, 2
years, 5 years, and 10 years posttreatment. Two years after
posttreatment period to 0.7 mm (SD, 0.8) at T2 and 0.9
treatment, the irregularity index was stable in 66% of the
mm (SD, 0.9) at T5. The irregularity index was stable
patients; at 5 years posttreatment, it was stable in 60% of
during the 5-year posttreatment period (T0-T5) in 141
the patients. If long-term treatment results have any value
patients (60%) and increased by 0.4 mm (SD, 0.7) in 94
to us as the professionals who “fix” malocclusions, greater
patients (40%). The intercanine distance increased 1.3 attention must be paid to our patients in retention.
mm between Ts and T0 and remained stable during the
posttreatment period. TAKE-HOME POINTS
Conclusions: The 3-3 mandibular lingual stainless
● The bonding and maintenance of a mandibular
steel retainer (bonded to the canines only) is effective in
canine-to-canine retainer is effective in stabilizing
preventing relapse in the mandibular anterior region in
the orthodontic treatment results in most treated
most patients, but a relatively high percentage will
patients. However, a relatively high percentage of
experience a small to moderate increase in mandibular
patients still experience a small to moderate increase
incisor irregularity. in incisor irregularity in the long term.
● Because the stability of alignment was negatively
The full text of this article can be found at: www.ajodo.org.
Am J Orthod Dentofacial Orthop 2008;134:179-80 affected by failures of a bonded retainer, it is
0889-5406/$34.00 important to stress the value of the periodic main-
Copyright © 2008 by the American Association of Orthodontists.
tenance of retainers bonded to the canines.
doi:10.1016/j.ajodo.2008.06.003
● These results will further enable clinicians to inform
their posttreatment patients about limitations in
retaining the mandibular front teeth and give them
more realistic expectations.
179

2. 180 Renkema et al American Journal of Orthodontics and Dentofacial Orthopedics
August 2008
REVIEWER’S CRITIQUE
Q&A
Editor: In an article in the December issue (Katsaros I liked this study and the way it was written, but I
C, Livas C, Renkema, AM. Unexpected complications wonder about the practice of bonding only mandibular
of bonded mandibular lingual retainers. Am J Orthod canines. The current gold standard for mandibular canine-
Dentofacial Orthop 2007;132:838-41), you expressed to-canine fixed retention usually includes bonding a wire
dissatisfaction with a flexible spiral wire bonded to all to each of the 6 anterior teeth. There are obviously some
6 mandibular front teeth for retention. Are you any limitations to this study when compared with a random-
happier with the results of the fixed retainer when ized controlled trial. The design was retrospective, with no
using a heavier wire bonded only to the canines? randomization and no control group. A comparison group
might have consisted of patients retained with removable
Katsaros: In that article, we were dealing only with rather than fixed appliances. Confounders include various
patients with unexpected complications during retention staff members and graduate students in the orthodontic
with a 3-strand twist-flex retainer. A new study that the department where the treatment was provided. These
Nijmegen group will submit to the AJO-DO shows that, participants might well have used varying techniques and
in most patients with no complications, twist-flex retain- different bonding agents, and each had a unique skill level
ers are efficient in preventing relapse of the mandibular when placing the fixed retainers. Of credit to the authors,
anterior teeth. However, since undetected complications some of these limitations are discussed.
usually lead to retreatment, I do not use twist-flex retain- In their discussion, the authors cited a study by Boese
ers anymore in the mandible. With a thick stainless steel (Fiberotomy and reproximation without lower retention—
retainer bonded only to the mandibular canines, accept- nine years in retrospect: part II. Angle Orthod 1980;50:169-
able alignment of the mandibular anterior teeth can be 78) in which the author proposed combining a bonded
maintained, but, when perfect alignment control is re- canine-to-canine retainer with interproximal enamel reduc-
quired, I currently use a .016 .022-in stainless-steel tion and circumferential supracrestal fiberotomy (CSF).
retainer bonded on all anterior teeth with the .022-in side There is some evidence that CSF leads to increased stability
in contact with the tooth surface. However, this type of in both the maxillary and mandibular anterior segments.
retainer must still be evaluated. However, our readers might want to check out another article
Editor: What would you say to clinicians who routinely for a long-term view of the problem (Edwards JG. A
dismiss their patients after 6 to 12 months of retention long-term prospective evaluation of the CSF in alleviating
with the advice to call the office if problems arise? orthodontic relapse. Am J Orthod 1988;93:380-7). Edwards
found CSF more effective in preventing pure rotational
Katsaros: I know that many orthodontic practices have relapse than in reducing labiolingual relapse over the long
difficulties in following retention patients because of term, and more successful in the maxillary anterior segment
logistic problems; after some years in practice, the num- than the mandible. Finally, in our recent article, Peter Miles,
ber of these patients can be large. Patients with retainers Jack Sheridan, and I found that significant and unpredictable
bonded only to the canines will immediately notice a individual tooth movements were still observed after CSF
loose retainer. With retainers bonded to all mandibular (Rinchuse DJ, Miles P, Sheridan JJ. Orthodontic retention
teeth, however, loose sites are not always easy to be and stability: a clinical perspective. J Clin Orthod 2007;41:
identified. Furthermore, it is difficult for the patient 125-32).
toidentify unexpected complications of these retainers. Daniel J. Rinchuse
Greenburg, Pa
My advice is to check the retainers once a year; these
follow-ups could be also done by a general dentist as a
part of the regular dental checkup, if dentists are
instructed accordingly.
Editor: Are you planning any other retention studies in
the future? If so, what type of study design will give us
the missing information?
Katsaros: With the experience of the retrospective
studies on both canine-and-canine and canine-to-ca-
nine lingual retainers, the Nijmegen group is planning
a large-scale, multi-site, prospective clinical trial. This
type of study can give more evidence-based informa- Fig. Lingual retainer (0.0215 x 0.0027-in stainless steel
rounded rectangular wire) bonded to mandibular ca-
tion about the best retention strategy.
nines only.