An in vitro comparison between a bonded retainer system and a directly bonded flexible spiral wire retainer.

Bonded lingual retainers are becoming more popular to stabilize the results of orthodontic treatment. The in vitro shear strength of a flexible spiral wire (FSW) retainer (Zachrisson, 1977, 1983) bonded with Prisma Fil was compared to the 'A'-Company bonded lingual retainer system, bonded with either Concise or Right-On, to human enamel. Statistical analysis of the results showed no significant differences between the 'A'-Company system when bonded with Concise or Right On, Concise having a greater mean bond strength, but also a greater range of bond strength values. All the materials tested gave bond strengths that were adequate for clinical practice and it is concluded that the choice of bonded retainer system can be made upon grounds of clinical convenience or cost.