Purpose: Fixed retainers have been advocated for the prevention of anterior mandibular crowding after orthodontic treatment. However, limited data is available to help clinicians choose a retention protocol that is acceptable in terms of stability, emergencies, and side effects in the long term. It was the aim of this study to assess survival and alignment stability of the 0.016” x 0.022” stainless steel wire compared to more common protocols.
Keywords: adverse effects, bond failure, enamel adhesion, fixed retainers, relapse, retainer failure, retention, stability of orthodontic treatment
Materials and Methods: Three different mandibular fixed retention protocols were compared in 600 consecutive patients: 1. 0.0215” multistrand wire (MW) with separate curing of resin and composite; 2. 0.016” x 0.022” stainless-steel wire with simultaneous curing of resin and composite (SS1C); and 3. 0.016” x 0.022” stainless-steel wire with separate curing of resin and composite (SS2C). The hazard rate for detachment across wire groups was assessed with a Cox frailty model.
Results: Incisor alignment was maintained with all retention wires. One incisor with unexpected torque change was observed in group MW. The average annual emergency rate was below 2% for all three protocols. Fewer emergency visits were found in patients with solid steel wires than with multistrand wires. Detachment of the wire is the most common cause of emergency visits with no difference between wire types. Multistrand wires were more often damaged than were solid steel wires. There was no evidence that direct application of the composite on the uncured primer influenced retainer adhesion to the enamel.
Conclusions: The mandibular anterior teeth can be predictably stabilised with a 0.016” x 0.022” stainless steel wire.