Bonding Fiber-Reinforced Lingual Retainers with Color-Reactivating Flowable Composite
Fiber-reinforced composites (FRCs) have beendeveloped as esthetic and metal-free alternativesfor various dental materials, includingprosthodontic bridges and crowns, periodontalsplints, and orthodontic retainers.1-4 In orthodontics,Burstone and Kuhlberg have advocated theuse of FRCs for both passive and active applications.5
The first attempts to make FRC retainersinvolved using long, continuous fibers that weresaturated with resin and bonded to the teeth.These first-generation retainers were too rigid toallow tooth movement, however, and the fibersand bonding adhesives were technically unsatisfactory.
Recent developments have solved theseproblems. EverStick Ortho is a glass fiber bundlethat is pre-impregnated with a polymethylmethacrylatepolymer. The surface of the fiberframework is partially dissolved with resin, providingboth micromechanical and chemicaladhesion. Studies have demonstrated adequatebonding of the fiber to the composite resin.6
Both the retainer material and the compositeappear to be critical in successful bonding oflingual retainers.7 Flexible wires have the highestfailure rate among common materials, with manybond failures due to fracture of the wires themselves.7,8 A reinforced polyethylene fiber materialis just as difficult to cover completely withresin. Using light-cured, color-reactivating composite(Tetric Flow Chroma) rather than atooth-colored composite gives the clinician a betteropportunity to monitor cracks, failures, andinadequate interface between the adhesive andthe tooth surface. Another advantage of thisflowable resin is that there is no need for finishingor polishing, which saves chairtime.9-12
1. After debonding the fixed appliance, pumicethe lingual tooth surfaces to be bonded, using afluoride-free paste.
2. Measure the correct length for the everStickOrtho with dental floss.
3. Open the foil package and slide out the siliconesleeve containing the fiber bundle (Fig. 1).Cut the fiber to the measured length, keeping itaway from light exposure.
4. Etch the enamel surfaces with 37% phosphoricacid for 60 seconds, then rinse and air-dry.
5. Apply a light-cured adhesive to the lingualsurfaces, followed by a thin layer of Tetric FlowChroma.
6. Holding the fiber bundle with a tweezer, dipone end into the Tetric Flow Chroma.
7. Adapt this end to the appropriate tooth surface,and light-cure it for five seconds, shieldingthe rest of the bundle from the curing light.
8. Continue adapting and curing the fiber retainertooth by tooth.
9. After this initial tacking, cover the interproximalportions of the fiber with a thin layer of TetricFlow Chroma, and light-cure it for 40 seconds(Fig. 2). The light-activated composite will havea dark green color, making it easy to identify.
Compared to conventional retainer materials,everStick Ortho is easy to place, with noneed to adapt it to the study casts beforehand. Itis suitable for use in patients with metal allergies.
A light-cured, color-reactivating compositefacilitates visual monitoring for removal ofexcess adhesive, thus avoiding undue thickness,which can cause plaque retention and gingivalinflammation. Since only the essential area ofenamel is bonded, this technique also limits thepotential for damaging the lingual enamel whenthe retainer and adhesive are removed.