The V- loop bonded lingual retainer is an innovative design that allows the patient to floss with ease. The interdental wire span of the V-loop design allows easier access for flossing as well as sufficient flexibility for independent tooth movement within the periodontal space. Patient acceptance of the V-loop bonded lingual retainer is excellent as most patients find the retainer to be comfortable and easy to floss. Bond failure rate for the V-loop retainer is no worse than for conventional straight wire bonded lingual retainers.
The prevention of relapse of crowding, rotations or spacing in the maxillary and mandibular anterior segments following orthodontic treatment often necessitates long-term retention. Fixed lingual retainers are frequently chosen for this purpose1,2,3,4,5 they are sometimes used as the sole retainer or in conjunction with removable retainers as an added precaution.5,6,7 There are many variants of the bonded lingual retainer system with the common denominator of placing a straight wire flush along the lingual surfaces of the anterior teeth, parallel with the incisal edges.
Although highly effective for retention, the major disadvantage of the straight wire bonded lingual retainer is the compromise in oral hygiene.8 This retainer tends to predispose to the accumulation of plaque and calculus.8,9,10,11 Stormann and Ehmer12 found that although regular oral hygiene instruction was given to patients with fixed retainers, they had increased plaque accumulation at each successive recall visit over a 24-month period.
rtun et al13 found that the presence of a bonded lingual retainer and the accumulation of plaque and calculus gingivally to the retainer wire after long-term use caused no apparent damage to the hard and soft tissues adjacent to the wire. Moreover, in another study, no signs of dental caries or carious white spot lesions were found in patients with direct-bonded lingual retainers; however, some patients with inadequate hygiene had moderate gingivitis.11 In addition, mandibular lingual retainers often were associated with considerable interdental calculus, particularly in patients with a tendency to develop calculus.11 Although the evidence for plaque and calculus as a result of the fixed retaining wire is not alarming, it is substantial and cannot be ignored. Attention is required to monitor for potential periodontal and caries involvement during the retention phase.
To address this issue and facilitate oral hygiene, Lew,14 in 1989, proposed an innovative design for the direct-bonded lingual retainer. He adapted a length of .0195″ spiral wire to a model so that the straight portion followed the middle or cervical third of the lingual surfaces and the “V” portions crossed the interdental papillae. This design allowed the patient to floss inteproximally without the need for an interdental cleansing aid (floss threader). Furthermore, the flexibility of the extended inter-adhesive spans of the V-loop wire permitted movement of the teeth within their physiologic range in the periodontal membrane space.
With the obvious flossing advantage of the V-looped bonded lingual retainer, the current authors were curious to determine if there was any downside to using this type of retainer. A retrospective study15 was conducted to determine if the V-looped bonded lingual retainers were more likely to fail than the conventional straight wire lingual retainers.
Failure of a fixed retainer happens in three ways: detachment of the retainer at the wire-composite interface, the composite-enamel interface8,16 or a stress fracture of the wire. Another important factor, which may contribute to detachment, is the thickness and rigidity of the retainer wire. Heavier gauge wires tend to be more susceptible to breakage than lighter, more flexible wires.17
We found no clinical or significant difference between V-looped and straight wire bonded lingual retainers when bond failure rates were compared.15 In a sample of 147 V-looped bonded lingual retainers and 153 straight wire lingual retainers, the detachment rates were 14.3% and 12.4% respectively. When comparing maxillary vs. mandibular fixed retainers, regardless of the design (straight wire or V-looped) more bond failures occurred in the maxilla (15.1% of 132 retainers) than in the mandible (10.8 % of 185 retainers).15
Bonded lingual retainer systems require precision in the fabrication and placement of the retainer to ensure stability of the teeth and to minimize failure of the retainer due to detachment or breakage. With regard to the technical difficulty of using the V-loop design compared to the straight wire design, the V-loop wire is slightly more intricate to bend to get the V-loops perfectly centered between the teeth and to make the entire wire flush and passive against the teeth. The actual bonding procedure is no different for the V-looped and straight wire retainers.
Our protocol for retainer fabrication and placement is as follows:
Alginate impressions are taken before the deband date. Retaining wires of .016″ Australian Black (GAC international, Bohemia, NY) wire are meticulously adapted to these models. Lingual retainers are bonded in place immediately before removal of the brackets. The lingual retainers are attached to each individual tooth in the anterior segment (4 to 6 teeth). The following technique is used for retainer placement:
1. The lingual surfaces of the teeth to be bonded are pumiced.
2. The teeth to be bonded are isolated with a mouth prop and/or cotton rolls.
3. The lingual tooth surfaces are dried prior to applying a 37% phosphoric acid etching solution for 60 seconds. The teeth are then rinsed thoroughly.
4. The tooth surfaces are dried and checked to ensure a chalky white appearance.
5. Transbond XT primer (3M Unitek, Monrovia, Calif) is then sparingly applied in the areas to be bonded and light cured for a total of 20 seconds.
6. A small amount of Transbond LR adhesive (3M Unitek) is placed on the most distal teeth of the bonded retainer.
7. Using cotton pliers, the lingual retainer is then maneuvered into place and the adhesive is cured on either end of the wire using an Ortholux light emitting diode curing light (3M Unitek).
8. Additional adhesive is added to embed the ends of the wire retainer and also to cover the wire where it contacts the cingulum area of each tooth. All areas of cement are then fully cured.
9. Excess composite material is removed with a high speed finishing bur.
10. The patient is then allowed to rinse and given instruction in brushing and flossing, ensuring that all contacts are free of excess cement and sealant.
A difference in the detachment frequency for maxillary and mandibular bonded lingual retainers is expected because a maxillary lingual retainer is subject to more forces during mastication. It is important to prevent occlusal contacts from the mandibular incisors on the upper bonded lingual retaining wire. This risk can be minimized by appropriate adaptation and placement of the wire on the lingual of the maxillary anterior teeth. Using hand-articulated stone casts, the contact level of the mandibular incisors should be visualized and marked on the lingual aspect of the teeth on the maxillary model prior to fabrication of the lingual retainer. The proper location of the lingual retainer may also be verified clinically by marking the interincisal contact zone with articulating paper prior to preparation of the tooth surfaces for insertion of the lingual retainer.
In conclusion, the cleaning advantage of the V-looped bonded lingual retainer outweighs any additional complexity in fabrication. Bond failure rates are comparable to conventional bonded lingual retainers. Patient acceptance of the V-looped bonded lingual retainer
has been excellent. Furthermore feedback from referring dentists and periodontists has also been positive, expressing approval for the V-looped design because of its obvious flossing advantage. When properly adapted, the V-looped extensions interproximally do not result in any gingival irritation. Tongue and speech adaptation routinely occurs in one to two days. Food trapping is not found to be any more of a problem than with the conventional straight wire retainers. Although one might expect that the increased interdental span of wire in the V-looped retainers would be subject to distortion, no evidence of this has been found.
Critical factors for the clinical success of a bonded lingual retainer utilized as long-term retention are cleanability and physiologic adaptability.3 The V-looped retainer system addresses both of these factors, by permitting normal flossing and sufficient flexibility for independent tooth movement within the periodontal space. OH
Dr. Krista Lee recently graduated from the Advanced Education Program in Orthodontics and Dentofacial Orthopedics at New York University and is looking forward to a career in private practice in Canada.
Dr. Christine Mills has recently retired after 33 years in private practice as a certified specialist in orthodontics in Vancouver. She is currently a part-time clinical assistant professor at the University of British Columbia, Faculty of Dentistry.
Oral Health welcomes this original article.
1. Bearn DR. Bonded orthodontic retainers: a review. Am J Orthod Dentofacial Orthop. 1995 Aug;108(2):207-13.
2. Lee RT. The lower incisor bonded retainer in clinical practice: a three-year study. Br J Orthod. 1981;8(1):15-8.
3. Sperry TP, Abdulla A. Physiologic permanent retention following space closure. Am J Orthod. 1982;82(1):42-4.
4. Zachrisson BJ. Third-generation mandibular bonded lingual 3-3 retainer. J Clin Orthod 1995; 29(1):39-48.
5. Lang G, Alfter G, Goz G, Lang GH. Retention and stability — taking various treatment parameters into account. J Orofac Orthop. 2002;63(1):26-41.
6. Corti AF. An indirect-bonded lingual retainer. J Clin Orthod. 1991;25(10):631-2.
7. Krause FW. Bonded maxillary custom lingual retainer. J Clin Orthod. 1984;18(10):734-7.
8. Butler J, Dowling P. Orthodontic bonded retainers. J Ir Dent Assoc. 2005;51(1):29-32.
9. Heier EE, De Smit AA, Wijgaerts IA, Adriaens PA. Periodontal implications of bonded versus removable retainers. Am J Orthod Dentofacial Orthop. 1997;112(6):607-16.
10. rtun J. Caries and periodontal reactions associated with long-term use of different types of bonded lingual retainers. Am J Orthod. 1984;86(2):112-8.
11. Dahl EH, Zachrisson BU. Long-term experience with direct-bonded lingual retainers. J Clin Orthod. 1991;25(10):619-30.
12. Stormann I, Ehmer U. A prospective randomized study of different retainer types, J Orofac Orthop. 2002;63(1):42-50.
13. rtun J, Spadafora AT, Shapiro PA. A 3-year follow-up study of various types of orthodontic canine-to-canine retainers. Eur J Orthod. 1997;19(5):501-9.
14. Lew KK. Direct-bonded lingual retainer. J Clin Orthod. 1989;23(7):490-1.
15. Lee KD, Mills CM. Bond failure rates for V-loop vs. straight wire lingual retainers. Am J Orthod Dentofacial Orthop 2009;135:502-6
16. Radlanski RJ, Zain ND. Stability of the bonded lingual wire retainer-a study of the initial bond strength. J Orofac Orthop. 2004;65(4):321-35.
17. Zachrisson, B.J.: The bonded lingual retainer and multiple spacing of anterior teeth, J.Clin. Orthod. 17(12):838-844,1983.
