OBJECTIVE: To compare the effect of clockwise and counterclockwise torque on the primary stability of a mini-implant with a lever-arm-shaped upper structure. MATERIALS AND METHODS: Twenty-four white rabbits were used for this study. Two screw-type mini-implants were placed in each tibia. In all, 96 screws were inserted. Two weeks later, a 2-N force was applied to the mini-implants without an upper structure in eight rabbits (control group). The mini-implants of the other 16 rabbits were loaded with an upper structure (experimental group). In the experimental group, the two left mini-implants were loaded in a clockwise direction (CW group) and the two right implants were loaded in a counterclockwise direction (CCW group). The rabbits were sacrificed at 1 week or 8 weeks after loading in both control and experimental groups. The removal torque value (RTV) was measured in 15 of 16 mini-implants in each group and the remaining implant was processed for histologic examination. RESULTS: At 1 week there were no significant differences in the mean RTV between the control, CW, and CCW groups. At 8 weeks, the RTV was higher in the control and experimental groups than in the respective 1-week groups. At 8 weeks, there were no significant differences in the RTV between the control and CW groups, but the CCW group showed a lower RTV. CONCLUSIONS: CCW torque can decrease the stability of a mini-implant, whereas a CW torque has no effect.
OBJECTIVE: To compare the effect of clockwise and counterclockwise torque on the primary stability of a mini-implant with a lever-arm-shaped upper structure. MATERIALS AND METHODS: Twenty-four white rabbits were used for this study. Two screw-type mini-implants were placed in each tibia. In all, 96 screws were inserted. Two weeks later, a 2-N force was applied to the mini-implants without an upper structure in eight rabbits (control group). The mini-implants of the other 16 rabbits were loaded with an upper structure (experimental group). In the experimental group, the two left mini-implants were loaded in a clockwise direction (CW group) and the two right implants were loaded in a counterclockwise direction (CCW group). The rabbits were sacrificed at 1 week or 8 weeks after loading in both control and experimental groups. The removal torque value (RTV) was measured in 15 of 16 mini-implants in each group and the remaining implant was processed for histologic examination. RESULTS: At 1 week there were no significant differences in the mean RTV between the control, CW, and CCW groups. At 8 weeks, the RTV was higher in the control and experimental groups than in the respective 1-week groups. At 8 weeks, there were no significant differences in the RTV between the control and CW groups, but the CCW group showed a lower RTV. CONCLUSIONS: CCW torque can decrease the stability of a mini-implant, whereas a CW torque has no effect.
Authors: André Büchter; Dirk Wiechmann; Stefan Koerdt; Hans Peter Wiesmann; Josef Piffko; Ulrich Meyer Journal: Clin Oral Implants Res Date: 2005-08 Impact factor: 5.977
Authors: Sarandeep S Huja; Alan S Litsky; F Mike Beck; Kenneth A Johnson; Peter E Larsen Journal: Am J Orthod Dentofacial Orthop Date: 2005-03 Impact factor: 2.650
Authors: S Saito; N Sugimoto; T Morohashi; M Ozeki; H Kurabayashi; H Shimizu; K Yamasaki; A Shiba; S Yamada; Y Shibasaki Journal: Am J Orthod Dentofacial Orthop Date: 2000-12 Impact factor: 2.650