title: Effect of recycling protocol on mechanical strength of used mini-implants.
abstract: 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.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492 Bairro Santana, 90035-003 Porto Alegre, RS, Brazil.
authors.forename: Sérgio
authors.initials: S
authors.lastname: Estelita
authors.affiliation: Department of Orthodontics, Bauru Dental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla, 9-75 Vila Universitária, 17012-901 Bauru, SP, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.affiliation: School of Dentistry, Sao Leopoldo Mandic, Rua Caiubi, 181 Perdizes, 05010-000 São Paulo, SP, Brazil.
authors.forename: Kelly
authors.initials: K
authors.lastname: Chiqueto
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492 Bairro Santana, 90035-003 Porto Alegre, RS, Brazil.
authors.forename: Eduardo Silveira
authors.initials: ES
authors.lastname: Ferreira