Very few. The best that can be said is that it holds the teeth statically in place as long as it is not bent, broken or comes loose, a not infrequent occurrence .They are generally difficult to clean, may cause damage to tooth structure and/or supporting bone and provide no protection against bruxing (night grinding) and clenching of teeth while sleeping. We all do that to some extent.
At some point, the patient will wish the permanent retainer removed, and the teeth will likely start relapse at that time. Patients need to accept some responsibility for their dental health and the success of their orthodontic treatment over the long haul. Making quality, comfortable removable retainers that are easy to wear at night protect the orthodontic result and lessen the damages from grinding and clenching at night. They may aid many temporomandibular joint (TMJ) issues by lessening the pressures one can exert on the jaw while sleeping.
David G. Haas, DDS, MS
View all answers to this question