RESUMO
This paper evaluates the potential of diamond-like carbon (DLC) as a durable surface protection to replace the chromium (Cr) layer, which is traditionally applied to gravure print cylinders and other components through a galvanic electroplating process. The fabrication of DLC is more eco-friendly and could reduce the environmental hazard posed by hexavalent chromium in liquid form that is used in Cr application and better adhere to environmental regulations. This could encourage businesses to bring the DLC fabrication process in-house, sharing resources such as materials, labor, and equipment, to help reduce costs. Four DLC variants (standard DLC, A-DLC, S-DLC, and organic silica) and chrome were analyzed and tested for their surface properties and durability. Data suggest that both standard DLC and S-DLC had higher surface free energy, allowing for good ink wetting on the surface when compared to chrome. In addition, the standard DLC and S-DLC surfaces are generally smoother than the chrome, resulting in lower relative hydrophilicity and allowing for easier removal of ink in the nonimage regions with the doctor blade. The elcometer adhesion test demonstrated that the bond strength of the DLC variants to their base layer was comparable to the bond strength of chrome, indicating that the adhesion strength of the two materials was similar. Furthermore, in the abrasion test, the wear on the standard DLC surface and the corresponding wear on the lamella tip of the metal doctor blades were notably lower than that observed on chrome. This distinction is particularly evident in each of the test trials, specifically run 1, which involved 2,000,000 wiping actions of a metal doctor blade in the presence of abrasive TiO2 ink pigments. Statistical analysis on standard DLC versus chrome suggests that DLC fabrication is effective and durable on plain and patterned surfaces. Therefore, from a sustainable and eco-friendly perspective, standard DLC and S-DLC would be good alternative durable surfaces for print cylinders and other components used in various industries due to superior wear resistance properties.
RESUMO
PURPOSE: This investigation was conducted to obtain preliminary roughness data on a microtextured implant surface and to determine its ability to sustain a 1-stage surgical procedure and early full occlusal loading of single-tooth restorations in humans. MATERIALS AND METHODS: Three-dimensional (3D) vertical scanning interferometry was conducted on samples of the test surface (MTX) and 2 control surfaces (Osseotite and sandblasted/acid-etched [SLA]). Test implants were also placed in vivo, restored with fully occluding single-tooth restorations (n = 27) after 2 months of nonsubmerged healing, and clinically monitored for 48 months of follow-up. RESULTS: Microtexture was relatively uniform on the test surface and more random and irregular on the control surfaces. MTX and Osseotite were similar in some roughness parameters, but the MTX surface had a greater number of micropits that were spaced closer together (Stylus Y lambda q) and with higher slope values (Stylus Y delta q). Cumulative life table results were 100% for all MTX implants placed in maxillary and mandibular jaw locations, and no discernible marginal bone changes were observed. Overall implant success was 100% after 4 years of clinical functioning. DISCUSSION: The findings of this study appear promising but should be considered preliminary, because of the limitations in the number of locations measured on each product sample and the small number of implants clinically studied. CONCLUSION: Within the scope of the present study, MTX implants exhibited a uniform micropitted surface, as well as 100% survival and 100% clinical success after nonsubmerged placement, early loading with single-tooth restorations at 2 months, and 48 months of clinical functioning. (More than 50 references.)