Using high-frequency vibration in orthodontic retention
Retention can be a frustrating process for orthodontists and patients alike. Relapse occurs for many reasons, ranging from patients who don’t replace their broken retainers to those who are simply noncompliant. Studies have shown that 40 percent to 90 percent of orthodontic patients have unacceptable dental alignment 10 years after treatment.1 Based on these statistics, there’s certainly room for improvement in this important aspect of orthodontic treatment. Therefore, when choosing our retention strategy and appliance, basing it on the individual and retention science can contribute to preserving a lasting and stable occlusion.
One of the reasons retention is difficult to maintain is because of the length of time it takes for the teeth to be adequately “settled” in their new positions. Pratt et al. noted that while retention varies based on tissue types, generally reorganization of the periodontal ligament occurs over three to four months, the gingival collagen–fiber network takes approximately four to six months to remodel, and the elastic supracrestal fibers remain deviated for more than seven months. The article notes that this reorganization phase is completed usually within a year of debonding.1
Bone-density changes occur during and after orthodontic treatment, as well. Yu et al. noted a 23 percent reduction in bone-mineral density around treated teeth after a seven-month period of active orthodontic treatment. After a two-year retention period, most patients’ alveolar bone density recovered; however, bone density around approximately 10 percent of teeth failed to recover to even 80 percent of its pretreatment state.2 This stresses the importance of the second phase: post-retention, lasting for the rest of the patient’s life.