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Effectiveness of lingual bonded retainers bonded only to the canines


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Aug 2008 AJO

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Effectiveness of lingual bonded retainers bonded only to the canines

  1. 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: 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. 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.