Mani Alikhani1, Michelle Y Chou2, Edmund Khoo3, Sarah Alansari3, Rachel Kwal4, Tali Elfersi5, Abdullah Almansour6, Chinapa Sangsuwon7, Mohammed Al Jearah6, Jeanne M Nervina7, Cristina C Teixeira8. 1. Advanced Graduate Education Program in Orthodontics, Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Mass; Forsyth Institute, Cambridge, Mass; Consortium for Translational Orthodontic Research, Hoboken, NJ. 2. Advanced Graduate Education Program in Orthodontics, Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Mass. 3. Consortium for Translational Orthodontic Research, Hoboken, NJ. 4. Private practice, Merrick, NY. 5. Private practice, Beverly Hills, CA. 6. Department of Orthodontics, College of Dentistry, New York University, New York, NY. 7. Consortium for Translational Orthodontic Research, Hoboken, NJ; Department of Orthodontics, College of Dentistry, New York University, New York, NY. 8. Consortium for Translational Orthodontic Research, Hoboken, NJ; Department of Orthodontics, College of Dentistry, New York University, New York, NY. Electronic address: cristina.teixeira@nyu.edu.
Abstract
INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.