Asunción Mendoza

Microstructural, mechanical and citotoxicity evaluation of different NiTi and NiTiCu shape memory alloys.

Transformation temperatures and mechanical properties such as transformation stresses at different temperatures and the superelasticity have been investigated in NiTiCu alloys with various Copper concentrations. The results have been compared with the conventional NiTi alloys. The addition of copper was effective to narrow the stress hysteresis and to stabilize the superelasticity characteristics. Moreover, it produced greater stability on both the transformation temperatures and the forces applied to the different tissues. However, the studies of cell cultured with human fibroblasts showed certain toxicity.

Inhibition of Ni release from NiTi and NiTiCu orthodontic archwires by nitrogen diffusion treatment

The effects of nickel (Ni) allergy from NiTi alloys were reduced due to the titanium nitrided coating obtained by nitrogen gas diffusion at different temperatures. The samples were immersed in artificial saliva at 37 degrees C for different periods demonstrating that the titanium nitride coating prevents biodegradation. In addition, the lack of low friction coefficient for the NiTi super-elastic archwires makes the optimal use of these materials in orthodontic applications difficult. In this study, the reduction in this friction coefficient was achieved by nitrogen diffusion heat treatments. (Journal of Applied Biomaterials & Biomechanics 2004; 2: 151-5).

Treatment and orthodontic movement of a root-fractured maxillary central incisor with an immature apex: 10-year follow-up

AIM To report a maxillary central incisor tooth with a horizontal root fracture and incomplete root development that healed and was then moved orthodontically some years after the traumatic injury. SUMMARY A 7-year-old girl attended following trauma to the maxillary anterior region. Radiologic examination revealed a horizontal root fracture in the middle third of the maxillary right central incisor tooth that had an immature apex. After early treatment, the fractured tooth healed and pulpal health was retained. Recall examination after 2years revealed complete root development. Orthodontic treatment was performed to correct an angle type I malocclusion. Clinical and radiologic controls were performed over 10years and confirmed both pulpal and periodontal health. KEY LEARNING POINT •  Orthodontic movements of teeth with previously fractured roots might be possible without adverse pulpal effects.