Yueh-Tse Lee1,2,3, Eric Jein-Wein Liou4,5,6, Sinn-Wen Chen7. 1. Graduate Institute of Dental and Craniofacial Science, Chang Gung University, Taoyuan, Taiwan. 2. Craniofacial Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan. 3. Department of Craniofacial Orthodontics, Chang Gung Memorial Hospital, Linkou, 5, Fusing St., Gueishan District, Taoyuan, 333, Taiwan. 4. Graduate Institute of Dental and Craniofacial Science, Chang Gung University, Taoyuan, Taiwan. lioueric2042@gmail.com. 5. Craniofacial Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan. lioueric2042@gmail.com. 6. Department of Craniofacial Orthodontics, Chang Gung Memorial Hospital, Taipei, 199, Tung-Hwa North Rd., Taipei, 105, Taiwan. lioueric2042@gmail.com. 7. Department of Chemical Engineering, National Tsing Hua University, #101, Sec. 2, Kuang-Fu Rd., Hsin-Chu, 300, Taiwan.
Abstract
PURPOSE: Surface characteristics of orthodontic miniscrews might affect survival rates and removal torque values (RTVs). This experimental study aimed to clarify whether and why a microporous or nanoporous surface promotes higher survival rates and RTVs for orthodontic miniscrews. METHODS: Using a split-leg design, one set each of nonporous (sham control, n = 24) and microporous (control, n = 6), and three sets of nanoporous (experimental, n = 6 per set) miniscrews were implanted in the tibias of 12 New Zealand rabbits and immediately loaded with 1.5 N nickel-titanium coil springs for 12 weeks. The surface morphology, micropores, and nanotube diameters of the miniscrews were examined using scanning electron microscopy and field-emission scanning electron microscopy. The surface composition and thickness were determined using Auger electron spectroscopy. The survival rates and RTVs of each set were assessed. RESULTS: The nanoporous miniscrews had higher survival rates, RTVs (p < 0.001), and thicker nanotube oxide thicknesses (p < 0.001) than the nonporous and microporous miniscrews. The nonporous and microporous miniscrews had no nanotube structures. The surface oxide composition was titanium dioxide (TiO2). The threshold RTV, TiO2 thickness, and nanotube diameter of nanoporous miniscrews needed to promote the experimental survival rate to 100% was determined to be 6.6 ± 0.8 N-cm (p < 0.05), 22.5 ± 4.8 nm (p < 0.05), and 17.6 ± 2.3 nm or above, respectively. CONCLUSION: Nanoporous surfaces promoted higher survival rates and RTVs than microporous miniscrews. This could be due to TiO2 nanotube structures with thicker oxide layers in nanoporous miniscrews.
PURPOSE: Surface characteristics of orthodontic miniscrews might affect survival rates and removal torque values (RTVs). This experimental study aimed to clarify whether and why a microporous or nanoporous surface promotes higher survival rates and RTVs for orthodontic miniscrews. METHODS: Using a split-leg design, one set each of nonporous (sham control, n = 24) and microporous (control, n = 6), and three sets of nanoporous (experimental, n = 6 per set) miniscrews were implanted in the tibias of 12 New Zealand rabbits and immediately loaded with 1.5 N nickel-titanium coil springs for 12 weeks. The surface morphology, micropores, and nanotube diameters of the miniscrews were examined using scanning electron microscopy and field-emission scanning electron microscopy. The surface composition and thickness were determined using Auger electron spectroscopy. The survival rates and RTVs of each set were assessed. RESULTS: The nanoporous miniscrews had higher survival rates, RTVs (p < 0.001), and thicker nanotube oxide thicknesses (p < 0.001) than the nonporous and microporous miniscrews. The nonporous and microporous miniscrews had no nanotube structures. The surface oxide composition was titanium dioxide (TiO2). The threshold RTV, TiO2 thickness, and nanotube diameter of nanoporous miniscrews needed to promote the experimental survival rate to 100% was determined to be 6.6 ± 0.8 N-cm (p < 0.05), 22.5 ± 4.8 nm (p < 0.05), and 17.6 ± 2.3 nm or above, respectively. CONCLUSION: Nanoporous surfaces promoted higher survival rates and RTVs than microporous miniscrews. This could be due to TiO2 nanotube structures with thicker oxide layers in nanoporous miniscrews.
Authors: Glaucio Serra; Liliane S Morais; Carlos Nelson Elias; Marc A Meyers; Leonardo Andrade; Carlos Muller; Marcelo Muller Journal: Am J Orthod Dentofacial Orthop Date: 2008-07 Impact factor: 2.650
Authors: Glaucio Serra; Liliane S Morais; Carlos Nelson Elias; Marc A Meyers; Leonardo Andrade; Carlos A Müller; Marcelo Müller Journal: Am J Orthod Dentofacial Orthop Date: 2010-01 Impact factor: 2.650