As early as 1920 one of the most respected orthodontists, Calvin Case, MD, DDS, stated that "if there is one part of orthodontia more than another that is absolutely indispensable to the success of this specialty and its establishment upon a firm foundation as one of the arts and sciences, it is the permanent retention of regulated [orthodontically moved] teeth."(1)

As a result of extensive research at the University of Washington, Little et al.(2) concluded that the orthodontist should not assume that stability will occur, but should assume instability will likely be the pattern. They stated that the only way to ensure continued satisfactory alignment post treatment is retention for life. Vandardall,(3) University of Pennsylvania, reinforced this belief when he said, "if patients desire no irregularity or dental changes post treatment, only long-term retention can prevent them."

In a recent, extensive review of the orthodontic literature regarding relapse, Shah(4) found that the mandibular anterior segment during the postretention period is perhaps the most predictable and frustrating of all orthodontic relapses. This type of relapse is sometimes erroneously construed as a sign of inappropriate treatment or evidence of misdiagnosis or incorrect mechanics. However, mandibular incisor relapse is almost inevitable, regardless of orthodontic techniques and timing of orthodontic treatment. The main reason for this development of relapse, or crowding is the dental arch perimeter/length, and intercanine width is decreasing, constricting over time in treated and untreated subjects. In 1959 Moorrees(5) published his findings at Harvard University, which demonstrated this pattern of dental arch constriction.

Blake and Bibby(6) made six suggestions in regards to increasing stability of orthodontic cases, which we also incorporate into our treatment planning except point number 5: