L R Iwasaki1,2, Y Liu3, H Liu2, J C Nickel1,2. 1. Department of Orthodontics and Dentofacial Orthopedics, University of Missouri-Kansas City, Kansas City, MO, USA. 2. Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA. 3. Department of Biostatistics and Epidemiology, East Tennessee State University, Johnson City, TN, USA.
Abstract
OBJECTIVES: To test that the speed of tooth translation is not affected by stress magnitude and growth status. SETTING AND SAMPLE POPULATION: Advanced Education Orthodontic clinics at the Universities of Nebraska Medical Center and Missouri-Kansas City. Forty-six consenting subjects with orthodontic treatment plans involving maxillary first premolar extractions. MATERIALS AND METHODS: This randomized split-mouth study used segmental mechanics with definitive posterior anchorage and individual vertical-loop maxillary canine retraction appliances and measured three-dimensional tooth movements. Height and cephalometric superimposition changes determined growing (G) and non-growing (NG) subjects. Subjects were appointed for 9-11 visits over 84 days for maxillary dental impressions to measure three-dimensional tooth movement and to ensure retraction forces were continuously applied via calibrated nitinol coil springs. Springs were custom selected to apply two different stresses of 4, 13, 26, 52 or 78 kPa to maxillary canines in each subject. Statistical analyses (α=0.050) included ANOVA, effect size (partial η2 ) and Tukey's Honest Significant Difference (HSD) and two-group t tests. RESULTS:Distolateral translation speeds were 0.034±0.015, 0.047±0.019, 0.066±0.025, 0.068±0.016 and 0.079±0.030 mm/d for 4, 13, 26, 52 and 78 kPa, respectively. Stress significantly affected speed and partial η2 =0.376. Overall, more distopalatal rotation was shown by teeth moved by 78 kPa (18.03±9.50º) compared to other stresses (3.86±6.83º), and speeds were significantly higher (P=.001) in G (0.062±0.026 mm/d) than NG subjects (0.041±0.019 mm/d). CONCLUSIONS: Stress magnitude and growth status significantly affected the speed of tooth translation. Optimal applied stresses were 26-52 kPa, and overall speeds were 1.5-fold faster in G compared to NG subjects.
RCT Entities:
OBJECTIVES: To test that the speed of tooth translation is not affected by stress magnitude and growth status. SETTING AND SAMPLE POPULATION: Advanced Education Orthodontic clinics at the Universities of Nebraska Medical Center and Missouri-Kansas City. Forty-six consenting subjects with orthodontic treatment plans involving maxillary first premolar extractions. MATERIALS AND METHODS: This randomized split-mouth study used segmental mechanics with definitive posterior anchorage and individual vertical-loop maxillary canine retraction appliances and measured three-dimensional tooth movements. Height and cephalometric superimposition changes determined growing (G) and non-growing (NG) subjects. Subjects were appointed for 9-11 visits over 84 days for maxillary dental impressions to measure three-dimensional tooth movement and to ensure retraction forces were continuously applied via calibrated nitinol coil springs. Springs were custom selected to apply two different stresses of 4, 13, 26, 52 or 78 kPa to maxillary canines in each subject. Statistical analyses (α=0.050) included ANOVA, effect size (partial η2 ) and Tukey's Honest Significant Difference (HSD) and two-group t tests. RESULTS: Distolateral translation speeds were 0.034±0.015, 0.047±0.019, 0.066±0.025, 0.068±0.016 and 0.079±0.030 mm/d for 4, 13, 26, 52 and 78 kPa, respectively. Stress significantly affected speed and partial η2 =0.376. Overall, more distopalatal rotation was shown by teeth moved by 78 kPa (18.03±9.50º) compared to other stresses (3.86±6.83º), and speeds were significantly higher (P=.001) in G (0.062±0.026 mm/d) than NG subjects (0.041±0.019 mm/d). CONCLUSIONS:Stress magnitude and growth status significantly affected the speed of tooth translation. Optimal applied stresses were 26-52 kPa, and overall speeds were 1.5-fold faster in G compared to NG subjects.
Authors: Harsimrat Kaur; Brandon Owen; Bill Tran; Raymond Guan; Jeramy Luo; Alexander Granley; Jason P Carey; Paul W Major; Dan L Romanyk Journal: Angle Orthod Date: 2020-09-01 Impact factor: 2.079