THE CORROSION RESISTANCE OF A TITANIUM ALLOY DENTAL IMPLANT

After their introduction into the human body, the dental biomaterials are exposed to the corrosive environment. In our study, we evaluated the experimental corrosion resistance of a dental implant made by titanium alloy, immersed in artificial saliva at body temperature at pH = 5.2. The analysis of the main parameters of the corrosion process confirmed the good resistance of the titanium alloy subjected to corrosion

Exploring a Novel Material and Approach in 3D-Printed Wrist-Hand Orthoses

This article proposes the integration of two novel aspects into the production of 3D-printed customized wrist-hand orthoses. One aspect involves the material, particularly Colorfabb varioShore thermoplastic polyurethane (TPU) filament with an active foaming agent, which allows adjusting the 3D-printed orthoses’ mechanical properties via process parameters such as printing temperature. Consequently, within the same printing process, by using a single extrusion nozzle, orthoses with varying stiffness levels can be produced, aiming at both immobilization rigidity and skin-comfortable softness. This capability is harnessed by 3D-printing the orthosis in a flat shape via material extrusion-based additive manufacturing, which represents the other novel aspect. Subsequently, the orthosis conforms to the user’s upper limb shape after secure attachment, or by thermoforming in the case of a bi-material solution. A dedicated design web app, which relies on key patient hand measurement input, is also proposed, differing from the 3D scanning and modeling approach that requires engineering expertise and 3D scan data processing. The evaluation of varioShore TPU orthoses with diverse designs was conducted considering printing time, cost, maximum flexion angle, comfort, and perceived wrist stability as criteria. As some of the produced TPU orthoses lacked the necessary stiffness around the wrist or did not properly fit the palm shape, bi-material orthoses including polylactic acid (PLA) inserts of varying sizes were 3D-printed and assessed, showing an improved stiffness around the wrist and a better hand shape conformity. The findings demonstrated the potential of this innovative approach in creating bi-material upper limb orthoses, capitalizing on various characteristics such as varioShore properties, PLA thermoforming capabilities, and the design flexibility provided by additive manufacturing technology

COMPARATIVE STUDY ON THE CORROSION OF ALLOYS IN ARTIFICIAL SALIVA

Four types of dental alloys used in metal-ceramic technology, two NiCr-based and two CoCr-based, were studied for corrosion resistance. Of the 4 types of alloys, circular samples of 14 mm in diameter and 4 mm thickness were poured into the dental laboratory which were subsequently processed and subjected to corrosion in artificial saliva at the temperature of the human body (37 ± 0.5°C) and at pH = 5.2. In corrosion resistance testing performed, one of the CoCr-based alloys was shown to have the lowest corrosion current density, the lowest corrosion rate and a high polarization resistance

Electrochemical behaviour of ternary Ni-Zn-P thin films deposition on steel substrate

572-577Ternary Ni-Zn-P alloy thin films  with a thickness of 15-20 μm are considered as a replacement for cadmium sacrificial coatings for anticorrosive protection of steel parts working in highly corrosive media. Anticorrosive Ni-Zn-P thin films has been electrochemically deposited from aqueous sulphate solutions on carbon steel substrate. The influence of bath composition (variable ZnSO4·7H2O contents) and electrodeposition type (potentiostatic or galvanostatic) on physical-chemical and corrosion characteristics of obtained films have been studied. Films are characterized by energy dispersive analysis (EDAX) and scanning electron microscopy (SEM). The corrosion tests are performed in 3% NaCl solution with optimal resulting values of -916.2 mV vs. saturated calomel electrode (SCE) for the corrosion potential and 13.4 μA·cm-2 for the corrosion current density. The calculated value for the corrosive attack protection efficiency is 67.7%