Age-dependent biologic response to orthodontic forces

• Published in: American journal of orthodontics and dentofacial orthopedics 2018-05, Vol.153 (5), p.632-644
• Main Authors: Alikhani, Mani, Chou, Michelle Y., Khoo, Edmund, Alansari, Sarah, Kwal, Rachel, Elfersi, Tali, Almansour, Abdullah, Sangsuwon, Chinapa, Al Jearah, Mohammed, Nervina, Jeanne M., Teixeira, Cristina C.
• Format: Article
• Language: English
• Subjects: Dentistry
• ISSN: 0889-5406; 1097-6752
• DOI: 10.1016/j.ajodo.2017.09.016

Orthodontic tooth movement results from increased inflammation and osteoclast activation. Since patients of all ages now routinely seek orthodontics treatment, we investigated whether age-dependent biologic responses to orthodontic force correlate with the rate of tooth movement. We studied 18 healthy subjects, adolescents (11-14 years) and adults (21-45 years), with Class II Division 1 malocclusion requiring 4 first premolar extractions. Canines were retracted with a constant force of 50 cN. Gingival crevicular fluid was collected before orthodontic treatment and at days 1, 7, 14, and 28 after the canine retraction. Cytokine (IL-1β, CCL2, TNF-α) and osteoclast markers (RANKL and MMP-9) were measured using antibody-based protein assays. Pain and discomfort were monitored with a numeric rating scale. The canine retraction rate was measured from study models taken at days 28 and 56. Although the cytokine and osteoclast markers increased significantly in both age groups at days 1, 7, and 14, the increases were greater in adults than in adolescents. Interestingly, the rate of tooth movement in adults was significantly slower than in adolescents over the 56-day study period. Adults also reported significantly more discomfort and pain. Age is a significant variable contributing to the biologic response to orthodontic tooth movement. Adults exhibited a significantly higher level of cytokine and osteoclasts activity but, counterintuitively, had a significantly slower rate of tooth movement. •Age is an important factor in the biologic response to orthodontic forces.•Cytokine and osteoclast markers increased significantly in adolescents and adults in the first weeks of orthodontic force application.•Increases in cytokine and osteoclast markers are greater in adults than in adolescents in response to the same orthodontic force level.•The rate of tooth movement in adults is slower than in adolescents.•Adults report more pain and discomfort than adolescents in response to same force level.