RESUMO
The ability to utilize extrusion-based, direct ink write (DIW) 3D printing to create silica-reinforced silicones with complex structures could expand their utility in industrial and biomedical applications. Sylgard 184, a common Pt-cure silicone, lacks the thixotropic behavior necessary for effective printing and its hydrophobicity renders cured structures susceptible to biofouling. Herein, we evaluated the efficacy of various PEO-silane amphiphiles (PEO-SAs) as thixotropic and surface modifying additives in Sylgard 184. Eight amphiphilic PEO-SAs of varying architecture (e.g. linear, star, and graft), crosslinkability, and PEO content were evaluated. Modified formulations were also prepared with additional amounts of silica filler, both hexamethyldisilazane (HMDS)-treated and dimethyldichlorosilane (DiMeDi)-treated types. Numerous PEO-SA modified silicone formulations demonstrated effective water-driven surface hydrophilicity that was generally diminished with the addition of HMDS-treated silica filler. While increased yield stress was observed for PEO-SA modified silicones with added HMDS-treated filler, none achieved the initial target for 3D printing (>1000 Pa). Only the formulations containing the DiMeDi-treated filler (17.3 wt%) were able to surpass this value. These formulations were then tested for their thixotropic properties and all surpassed the targets for recovered storage modulus (G') (>1000 Pa) and loss factor (<0.8). In particular, the triblock linear PEO-SA produced exceptionally high recovered G', low loss factor, and substantial water-driven restructuring to form a hydrophilic surface. Combined, these results demonstrate the potential of silicones modified with PEO-SA surface-modifying additives (SMAs) for extrusion-based, DIW 3D printing applications.
RESUMO
Background: The study aims to develop a data-driven methodology to assess bone drilling in preparation for future clinical trials in residency training. The existing assessment methods are either subjective or do not consider the interdependence among individual skill factors, such as time and accuracy. This study uses quantitative data and radar plots to visualize the balance of the selected skill factors. Methods: In the experiment, straight vertical drilling was assessed across 3 skill levels: expert surgeons (N = 10), intermediate residents (postgraduate year-2-5, N = 5), and novice residents (postgraduate year-1, N = 10). Motion and force were measured for each drilling trial, and data from multiple trials were then converted into 5 performance indicators, including overshoot, drilling time, overshoot consistency, time consistency, and force fluctuation. Each indicator was then scored between 0 and 10, with 10 being the best, and plotted into a radar plot. Results: Statistical difference (p < 0.05) was confirmed among 3 skill levels in force, time, and overshoot data. The radar plots revealed that the novice group exhibited the most distorted pentagons compared with the well-formed pentagons observed in the case of expert participants. The intermediate group showed slight distortion that was between the expert and novice groups. Conclusion/Clinical Relevance: This research shows the utility of radar plots in drilling assessment in a comprehensive manner and lays the groundwork for a data-driven training scheme to prepare novice residents for clinical practice.
RESUMO
The purpose of this study is to propose a quantitative assessment scheme to help with surgical bone drilling training. This pilot study gathered and compared motion and force data from expert surgeons (n = 3) and novice residents (n = 6). The experiment used three-dimensional printed bone simulants of young bone (YB) and osteoporotic bone (OB), and drilling overshoot, time, and force were measured. There was no statistically significant difference in overshoot between the two groups (p = 0.217 for YB and 0.215 for OB). The results, however, show that the experts took less time (mean = 4.01 s) than the novices (mean = 9.98 s), with a statistical difference (p = 0.003 for YB and 0.0001 for OB). In addition, the expert group performed more consistently than the novices. The force analysis further revealed that experts used a higher force to drill the first cortical section and a noticeably lower force in the second cortex to control the overshoot (approximate reduction of 5.5 N). Finally, when drilling time and overshoot distance were combined, the motion data distinguished the skill gap between expert and novice drilling; the force data provided insight into the drilling mechanism and performance outcomes. This study lays the groundwork for a data-driven training scheme to prepare novice residents for clinical practice.