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International Journal of Dentistry
Volume 2014, Article ID 424923, 5 pages
Research Article

Effect of Recycling Protocol on Mechanical Strength of Used Mini-Implants

1Department of Orthodontics, Faculty of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492 Bairro Santana, 90035-003 Porto Alegre, RS, Brazil
2Department of Orthodontics, Bauru Dental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla, 9-75 Vila Universitária, 17012-901 Bauru, SP, Brazil
3School of Dentistry, Sao Leopoldo Mandic, Rua Caiubi, 181 Perdizes, 05010-000 São Paulo, SP, Brazil

Received 18 May 2014; Accepted 12 July 2014; Published 17 July 2014

Academic Editor: Seong-Hun Kim

Copyright © 2014 Sérgio Estelita et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Purpose. This study evaluated the influence of recycling process on the torsional strength of mini-implants. Materials and Methods. Two hundred mini-implants were divided into 4 groups with 50 screws equally distributed in five diameters (1.3 to 1.7 mm): control group (CG): unused mini-implants, G1: mini-implants inserted in pig iliac bone and removed, G2: same protocol of group 1 followed by sonication for cleaning and autoclave sterilization, and G3: same insertion protocol of group 1 followed by sonication for cleaning before and after sandblasting (Al2O3-90 µ) and autoclave sterilization. G2 and G3 mini-implants were weighed after recycling process to evaluate weight loss (W). All the screws were broken to determine the fracture torque (FT). The influence of recycling process on FT and W was evaluated by ANOVA, Mann-Whitney, and multiple linear regression analysis. Results. FT was not influenced by recycling protocols even when sandblasting was added. Sandblasting caused weight loss due to abrasive mechanical stripping of screw surface. Screw diameter was the only variable that affected FT. Conclusions. Torsional strengths of screws that underwent the recycling protocols were not changed. Thus, screw diameter choice can be a more critical step to avoid screw fracture than recycling decision.