The Effect of Residence Time on the Tensile Properties of Superelastic and Thermal Activated Ni-Ti Orthodontic Wires

Since the 1980s, different devices based on superelastic alloys have been developed to fulfill orthodontic applications. Particularly in the last decades several researches have been carried out to evaluate the mechanical behavior of Ni-Ti alloys, including their tensile, torsion and fatigue properties. However, studies regarding the dependence of elastic properties on residence time of Ni-Ti wires in the oral cavity are scarce. Such approach is essential since metallic alloys are submitted to mechanical stresses during orthodontic treatment as well as pH and temperature fluctuations. The goal of the present contribution is to provide elastic stress-strain results to guide the orthodontic choice between martensitic thermal activated and austenitic superelastic Ni-Ti alloys. From the point of view of an orthodontist, the selection of appropriate materials and the correct maintenance of the orthodontic apparatus are essential needs during clinical treatment. The present work evaluated the elastic behavior of Ni-Ti alloy wires with diameters varying from 0.014 to 0.020 inches, submitted to hysteresis tensile tests with 8% strain. Tensile tests were performed after periods of use of 1, 2 and 3 months in the oral cavity of patients submitted to orthodontic treatment. The results from the hysteresis tests allowed to exam the strain range covered by isostress lines upon loading and unloading, as well as the residual strain after unloading for both superelastic and thermal activated Ni-Ti wires. Superelastic Ni-Ti wires exhibited higher load isostress values compared to thermal activated wires. It was found that such differences in the load isostress values can increase with increasing residence time.

Residência multiprofissional, desafios e compromissos na reorientação da formação para o SUS: um estudo na atenção primária

The Health Multiprofessional Residency Program of the Federal University of Rio Grande do Norte (PRMS/UFRN) adopts as guiding keystones the learning process of in-service teaching, the interdisciplinary multiprofessional work and the compliance with the principles and guidelines of the Brazilian Unified Health System (SUS). Although PRMS/UFRN have been idealized with a focus on hospital care, the training process in the insertion of residents in the Primary Health Care (PHC) has an important role because they need to experience all levels of care, taking into account that the educational process through work proposed by the Residence is based on the comprehensiveness of health care. In light of the foregoing, the present research has sought to elucidate the insertion of these residents in PHC services, through a qualitative approach of case study, where data collection was held in two different moments: firstly, a questionnaire was accomplished, through an semi-structured script, with the residents of PRMS/UFRN, Natal Campus; subsequently, the focus group technique was accomplished with a group of nine residents, and data were analyzed from the categorical thematic content analysis. From the process of empirical categorization, categories and subcategories were raised, among which, the positive aspects and potentialities of insertion of residents in PHC. We detected the articulation of actions for promoting, preventing and recovering health; training in comprehensiveness of health care, multiprofessional activities and activities aimed at doing the integration among teaching-service-community. Regarding the difficulties found in this experience, we dealt with the organization and planning of rotation activities, the preceptorship, the process of work found in the Basic Health Units (BHU), in addition to factors external to educational practice, such as the issue of safety within these communities. Accordingly, with this situational diagnosis, we became able to realize that residents have identified the importance of this rotation for their vocational training, since these are inserted in post-graduate programs in hospital care. As an immediate product of this study, we will present a report that will provide a space for discussion and assessment of this rotation by the coordination bodies of PRMS/UFRN, in order to seek organizational and pedagogical adaptations, besides the proposition of qualification courses for the actors involved with this process, aiming the implementation of improvements in the rotation of PHC toward the qualified training of professionals for SUS.

The Effect of Residence Time on the Tensile Properties of Superelastic and Thermal Activated Ni-Ti Orthodontic Wires

Since the 1980s, different devices based on superelastic alloys have been developed to fulfill orthodontic applications. Particularly in the last decades several researches have been carried out to evaluate the mechanical behavior of Ni-Ti alloys, including their tensile, torsion and fatigue properties. However, studies regarding the dependence of elastic properties on residence time of Ni-Ti wires in the oral cavity are scarce. Such approach is essential since metallic alloys are submitted to mechanical stresses during orthodontic treatment as well as pH and temperature fluctuations. The goal of the present contribution is to provide elastic stress-strain results to guide the orthodontic choice between martensitic thermal activated and austenitic superelastic Ni-Ti alloys. From the point of view of an orthodontist, the selection of appropriate materials and the correct maintenance of the orthodontic apparatus are essential needs during clinical treatment. The present work evaluated the elastic behavior of Ni-Ti alloy wires with diameters varying from 0.014 to 0.020 inches, submitted to hysteresis tensile tests with 8% strain. Tensile tests were performed after periods of use of 1, 2 and 3 months in the oral cavity of patients submitted to orthodontic treatment. The results from the hysteresis tests allowed to exam the strain range covered by isostress lines upon loading and unloading, as well as the residual strain after unloading for both superelastic and thermal activated Ni-Ti wires. Superelastic Ni-Ti wires exhibited higher load isostress values compared to thermal activated wires. It was found that such differences in the load isostress values can increase with increasing residence time.