Expectations and Reality

More and more ‘ligature-free’ bracket systems have been introduced that claim to offer improved and more efficient treatment, particularly during leveling and alignment ( Table 1.1 ). Another proposed advantage is the ability to reduce the forces acting on the teeth, which supposedly improve patient safety by reducing adverse effects such as root resorption resulting from high force levels. Other advantages claimed include reduced patient discomfort.1 Previous in-vitro studies have shown that active systems are associated with slightly greater friction than passive ones. However, active self-ligating brackets are slightly better at dealing with rotation and torque.7 ^, 26 ^, 27 Further details comparing active and passive self-ligation brackets are provided in Chapter 2. The effectiveness of distalization for class II treatment due to reduced friction is another advantage that has been claimed for self-ligating systems.8 ^, 28 However, scientific proof that self-ligating brackets have improved friction characteristics in comparison with standard brackets is still lacking.3 ^, 4 An investigation by Fucket al.7 showed on the contrary that conventional twin brackets with “loose” steel ligatures are associated with the least friction in comparison to self-ligation. However, elastic elements and tight steel ligatures are routinely used for treatment with twin brackets, so that the friction characteristics of self-ligation can be expected to be beneficial for this type of treatment. Some clinical studies have shown that the overall treatment time is significantly shorter with self-ligating brackets.6 ^, 11 ^, 15 The locking mechanisms of self-ligating brackets are not subject to biological degradation, as elastomeric ligatures are, and in this case intervals between routine checkups can sometimes be increased. Most self-ligating brackets are very small, and this should make cleaning easier and hence reduce the risk of demineralization. Avoiding elastomeric ligatures may also further reduce the risk of plaque retention.21 Some authors have also claimed that patient comfort is improved, as there are fewer hooks and ligatures that irritate the lips or cheeks.

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