Dimensional Stability Research Articles

Impact of hydrocolloids on 3D meat analog printing and cooking

This study investigated the effects of hydrocolloid addition on three-dimensional (3D) printing and cooking of plant ingredients-based meat analog (MA). The MA inks were formulated with soy protein isolate, wheat gluten, canola oil, water, and hydrocolloids (xanthan gum, pectin, hydroxypropyl methylcellulose, guar gum, locust bean gum) at a ratio of 22:12:15:88:2. Formulated inks were used to create a specific 3D cylindrical model geometry and the printed structure were subjected to air frying (AF:180°C, 15 min) and infrared heating (IR:180°C, 15 min). Results showed that the MA ink’s viscosity (3871–5482 Pa. s), 3D printing rate (0.34–0.39 g.sec−1), printing error (2.51–10.37 %), and printing precision (81.97–97.27 %) were significantly (p<0.05) impacted by the incorporation of hydrocolloids. The dimensional stability (63.17–98.58 %), and cooking loss (6.70–17.41 %) were greatly impacted by both the hydrocolloids and post-printing cooking methods. Moisture (1.71 db) and fat (0.28 db) content of uncooked 3D printed MA were identical, whereas, differences in color attributes (L value:80.21–98.88, a value:0.01–0.13, b value:0.11–2.11) among the studied hydrocolloid added samples were observed. Moisture, fat, and color traits of 3D printed meat-analogs were significantly (p<0.05) impacted by post-printing cooking methods (AF, IR). During post-printing cooking, the loss of mass (moisture, fat) and changes in color tones were associated with the types of hydrocolloids incorporated in formulating the 3D printing ink. Surfaces and internal structure, mass loss, chemical profile, and glass-transition-temperature of 3D printed meat-analogs were significantly (p<0.05) impacted by both the type of incorporated hydrocolloids and post-printing cooking methods.

Investigations on ironing parameters in screw extrusion additive manufacturing (SEAM)

Additive Manufacturing (AM) is a novel manufacturing process that enables the physical realization of a given 3D model via layered deposition. Material extrusion (MEX) is one of the most widely used forms of the various AM techniques, in which the screw extrusion-based AM (SEAM) processing offers the most versatile characteristics, in terms of material handling and flow rate capacities. It involves continuous extrusion of the semi-solid material via an extruder screw. Ironing is a common practice in MEX techniques, to maintain z-height and improve the surface morphologies while deposition. Most commercially used nozzles for MEX are thin-walled, such that the ratio of the nozzle width to the diameter (w/d) is close to 1. In this research, investigations on the ironing effect during screw extrusion-based material deposition are explored using a set of wider nozzles (w/d as high as 40). Special emphasis is laid on the deposited surface finish, interlayer strength, and geometrical conformance of the extrusion. The nozzle diameter and the stand-off distance (SOD) are also independently varied. It is found that the best dimensional stability is achieved when the SOD is set between 75 % and 100 % of the nozzle diameter. Ironing improved the surface finish and the interlayer strength in all instances, with an average improvement of 50 % and 200 %, respectively.

Real-time monitoring and control of the layer height in laser metal deposition with coaxial wire feeding using optical coherence tomography

Laser metal deposition (LMD) with coaxial wire feeding is an additive manufacturing technology in which a metal wire is fed into a laser-induced melt pool. The repeated deposition of weld beads allows three-dimensional geometries to be created that can be used for manufacturing, repair, and modification of metal components. However, the process is highly sensitive to disturbances because the fed wire must always be fully melted, and no self-regulating effects as in powder-based LMD exist. The layer height is particularly important for process stability, as even small deviations accumulate over many layers and, ultimately, lead to the termination of the process. Therefore, monitoring and closed-loop control of the layer height during the deposition process are crucial. Due to process emissions, an interruption of the process is usually necessary for the accurate optical measurement of the layer height, which negatively affects the overall productivity. In order to overcome this drawback, an in-axis optical coherence tomography (OCT) sensor was employed in this work, which enabled real-time measurements of the layer height. It was found that positioning the OCT measurement spot as close as possible to the center of the wire provided the highest signal quality. Based on the real-time height data, a closed-loop layer height control was implemented, applying the wire feed rate as the manipulated variable. The experimental results showed that the proposed system was able to compensate for significant disturbances, ensuring dimensional accuracy and process stability.

A comparative study on the bonding performance of an admixed repair mortar and high-strength flowable micro-concrete with substrate: Considerations on the physico-mechanical compatibility

The physical and mechanical properties of repair mortar (RM), incorporating a multipurpose hybrid admixture and a high-strength concrete matrix phase known as micro-concrete (MiC), have been experimentally investigated. The flexural and compressive strengths, as well as the modulus of elasticity of each mixture, were tested at 7 and 28 days. The dimensional stability of prismatic bar specimens under dry and water-saturated conditions was monitored over a period of 56 days. The thermal coefficient of expansion for each repair material was determined, and the risk of thermal cracking was evaluated. Additionally, the bonding performance of admixed repair mortar and micro-concrete with substrate mortar (SM) was assessed using a modified slant shear test setup. The influence of surface roughness on slant shear strength was also studied. The compatibility of each mix design with substrate mortar was quantified and compared using a “physico-mechanical compatibility” based proximity comparison criterion. The proposed methodology can be used to monitor the compatibility and bonding potential of a repair material for a given substrate. Test results and analysis indicated that the admixed RM, with lower compressive/tensile strength ratio, performed better than MiC in terms of substrate compatibility.

Bonding of Beech Wood to Mortar with a Novel Epoxy Hybrid-Adhesive: Performance in Dry and Wet Conditions

Composites made of timber and cementitious materials require a rigid connection to exploit their full composite action, which can be achieved by using full-surface adhesive bonding. In this work, we investigated a novel hybrid-adhesive system consisting of a silane-terminated polyurethane (STP) and epoxy resin for the bonding of beech wood timber to fresh mortar for use in timber-mortar composites (TMC). The mechanical performance and the influence of moisture on TMC produced by the wet-in-wet process (fresh mortar) was investigated and compared to the bonding of prefabricated mortar (prefab process). The STP-epoxy hybrid-adhesive showed a suitable bonding performance of beech wood to both, fresh mortar and precured mortar with median compression shear strengths of 4.57 MPa and 6.07 MPa, respectively. The fracture pattern showed the strength of the near-surface layer in the mortar, close to the adhesive, being often decisive for the bond performance. The same failure mode predominated in TMC beams after 3-point bending tests. The stability of the composite upon the influence of moisture is especially challenging when using beech wood due to its low dimensional stability. Thus, the moisture stability of the bond was investigated by compression shear tests after water immersion. It showed superior water stability compared to composites bonded with a pure epoxy resin. Nonetheless, a clear reduction in bond strength compared to the dry state was observed, with delamination of 25% of the wet-in-wet and 17 % of the prefab specimens during water immersion. Furthermore, it was seen that the adhesive waiting time played a decisive role in the wet-in-wet produced specimens influencing both, dry and wet shear strength.

“Mortise and Tenon Joint” Technique to Improve the Stability of Three-Dimensional Costal Cartilage Framework in Fully Expansion Ear Reconstruction

Objective: For full expansion of ear reconstruction, the stability of a cartilage framework is very important. However, most techniques for framework fabrication focus on three-dimensional structure and adequate projection. Few studies are available on improving the stability of the reconstructed framework. This study introduces a new “mortise and tenon joint” technique to create a more stable framework in fully expansion ear reconstruction. Methods: A total of 137 patients with microtia underwent full expansion ear reconstruction with the “mortise and tenon joint” technique from January 2018 to July 2022. Results: Hematoma was found in 2 patients after the expander was implanted and evacuated timely to save the flap. Ear cartilage framework exposure occurred in 3 patients after the second stage of surgery. The wounds were debridement and covered by a retroauricular fascia flap with a skin graft. No other complications, such as infection, expander exposure, or rupture, were observed. All patients were followed up for 6 to 12 months after ear reconstruction and asked to fill in a form anonymously about their satisfaction with the reconstructed ear. One hundred thirty-four patients (97.8%) were satisfied with the results. Conclusions: In fully expansion ear reconstruction, the “mortise and tenon joint” technique improves not only the stability of the cartilage framework but also the stereoperception of the reconstructed ear. Most patients who underwent the new technique were satisfied with clear contour and delicate substructures of the reconstructed ear, matched skin color, and long-term dimensional stability.

Conductivity-enhanced Poly(biphenyl piperidine) anion exchange membranes with organic tubes

Anion exchange membrane fuel cells (AEMFCs) present an economically efficient alternative to proton exchange membrane fuel cells because of the use of non-precious metals. The development of high-performance and durable AEMFCs necessitates the use of highly conductive and robust anion exchange membranes (AEMs). In this study, a novel organic-organic composite AEM was synthesized by preparing poly(arylene piperidinium) polymer through Friedel-Crafts acid condensation and incorporating one-dimensional organic tubes as reinforcing materials. The composite AEM exhibits high conductivity (235 mS cm−1 at 80 °C) due to the chain orientation within the organic tubes and the availability of abundant transport sites. Furthermore, in contrast to the incompatibility of inorganic materials with polymers, the flexible nature of organic tubes enhanced polymer entanglement, significantly boosting the mechanical strength (120 MPa) of the AEM. Crosslinking the polymer backbone with the organic tubes facilitated simultaneous swelling, effectively mitigating interfacial compatibility issues, result in high dimensional stability. The H2–O2 fuel cell employing the developed AEM demonstrated a peak power density of 1018 mW cm−2 at 80 °C. This study provides a comprehensive synthetic strategy for producing stable AEMs with high hydroxide ion conductivity and outstanding mechanical properties tailored for alkaline membrane fuel cell applications.

Effect of dimensional stabilization treatment on mechanical properties of 45% SiCp/Al composites

Abstract With 14μm SiC particles and 2024Al alloy as raw materials, 45% SiCp/Al composites were prepared by hot isostatic pressing method to study the effect of dimensional stabilization treatments on the mechanical properties of composites. The dimensional stabilization treatments used were divided into annealing heat treatment and cold and thermal cycle treatments, and the research method found that the primary annealing treatment decreased the bending strength from 694MPa to 639MPa, and the secondary annealing treatment decreased the bending strength from 863.69MPa to 605MPa. The bending strength decreased from 694 MPa to 639 MPa after the second annealing treatment, and further to 605 MPa after the second annealing treatment. The bending strength of the composites also decreased from 863.69 MPa to 836.16 MPa, and then to 855.54 MPa after solution aging due to the cold and thermal cycle treatments of 120°C to −20°C and 190°C to −196°C, respectively. The micro yield strength increased from 356.57 MPa to 402.66 MPa, and then to 476.03 MPa. The dimensional stabilization treatments included heat treatment, as well as cold and thermal cycle treatments. The cold and thermal cycle treatments further increased the brittleness of the composites after solution aging. Both annealing and cold and thermal cycling reduce the density of the composite, with the annealing resulting in a smaller reduction than the cold and thermal cycling.

Wearing Quality of Ribbed Knits Made from Viscose and Lyocell Fibers for Underwear

As an alternative to cotton, viscose and lyocell fibers are suitable for the production of knitted next-to-skin underwear. Despite the advantages of a more environmentally friendly production process and valuable properties, the consumption of lyocell fibers is significantly lower compared to viscose fibers. The applicability of viscose and lyocell fibers in the production of ribbed knits for underwear is insufficiently researched, as is the influence of unconventionally spun yarns on their wearing properties. This study, therefore, investigates the possibilities of using lyocell fibers in the production of novel knitwear with improved properties compared to viscose and conventional cotton knitwear and determines their wearing quality. In this context, two sets of circular 1 × 1 rib jersey fabrics were produced from three types of differently spun viscose and lyocell yarns. The quality of the dry relaxed and wet processed knitted fabrics was evaluated by determining their structure, absorbency, air permeability, and dimensional stability, as well as their tensile, abrasion, and pilling properties, all in comparison to cotton knitted fabric produced under the same conditions. The results showed that lyocell rib knits have better structural uniformity, tensile properties, dimensional stability, air permeability, lower abrasion resistance, and comparable moisture absorbency and pilling propensity compared to viscose knits.

Aortic regurgitation in left ventricular assist device patients - Does aortic root dilatation contribute to valve incompetence?

Aortic regurgitation (AR) is a known complication after left ventricular assist device (LVAD) implantation potentially leading to recurrent heart failure. Possible pathomechanisms include valvular pathologies and aortic root dilatation. We assessed aortic root dimensions in a group of consecutive LVAD patients who received HeartMate 3. Since 11/2015, we identified 68 patients with no or mild AR at the time of HeartMate 3 implantation who underwent serial echocardiography to assess AR and aortic root dimensions (annulus, sinus, and sinotubular junction). Median follow-up was 40 months (2-94 months). Results were correlated with clinical outcomes. Patients were 60 ± 10 years old, predominantly male (88%) and 35% presented in preoperative critical condition as defined by INTERMACS levels 1 and 2. During follow-up, 23 patients developed AR ≥ II (34%). Actuarial incidence was 8% at 1 year, 29% at 3 years and 41% at 5 years. Echocardiography revealed practically stable root dimensions at the latest follow-up compared to the preoperative state (annulus: 23 ± 3 mm vs. 23 ± 2 mm, sinus: 32 ± 4 mm vs. 33 ± 3 mm, sinotubular junction: 27 ± 3 mm vs. 28 ± 3 mm), irrespective of the development of AR. Serial CT angiograms were performed in 13 patients to confirm echocardiographic findings. Twenty-one patients died during LVAD support leading to a 5-year survival of 71%, showing no difference between patients with and without AR ≥ II (p = 0.573). At least moderate AR develops over time in a substantial fraction of patients (one-third over 3 years). The mechanism does not seem to be related to dilatation of the aortic annulus or root.

Hybrid panels produced with particles and veneers of pine wood in different compositions

Hybrid wood panels can be produced with different particle or veneer sizes, forest species or even mixtures of synthetic materials, with the aim of reusing wood particles and generating new products. The present study aimed to verify the production process of hybrid panels formed with particles and veneers of Pinus taeda wood and urea‒formaldehyde resin. The panels were produced in four different compositions, with a nominal density of 0.65 g/cm³, and their quality was evaluated through their physical and mechanical properties. The addition of veneers in the traditional particleboard system increased the density of the hybrid panels and improved the mechanical properties. The properties of the MOR and MOE in static bending and screw withdrawal were favored using veneers on the panel faces. The internal bonding of the panels was not affected by their composition. The addition of veneers to the particleboard improved the dimensional stability of the panel.

Development of a Superior Anion Exchange Membrane with Hyperbranched Polymer for Anion Exchange Membrane Water Electrolysis

The production of hydrogen using membrane-based electrolyzersposes significant advantages and benefits compared to traditionalelectrolysis methods. Among the electrolyzers, anion exchangemembrane water electrolysis (AEMWE) has emerged as one of thepromising technologies owing to its unique advantages. However,the development of efficient AEMs for water electrolysis presentssignificant challenges, particularly in achieving enhanceddimensional stability and conductivity. In this study, ahyperbranched polyesteramide (HPEA) was synthesized andblended with poly(ether sulfone) (PES) to address the challenges.The resulting QPES-HPEA blend membrane exhibited a lowswelling ratio and high water uptake, which are critical formaintaining dimensional stability and enhancing the hydroxide iontransport efficiency of AEM. The enhanced physical properties andoptimized structure of the membrane make it a promising candidatefor next-generation AEMs in water electrolysis systems.

Effect of aging on dimensional accuracy and color stability of CAD-CAM milled and 3D-printed denture base resins: a comparative in-vitro study

BackgroundThere is a lack of studies comparing the dimensional accuracy and color stability of denture base resins made using computer-aided design and computer-aided manufacturing (CAD-CAM) milling, 3-dimensional (3D) printing, and conventional denture processing techniques. This makes it challenging to determine the best method to fabricate complete dentures. The objective of this in vitro investigation was to assess and contrast the color stability and dimensional accuracy of denture base resins that were 3D printed and CAD-CAM milled, both before and after aging by thermocycling using digital surface matching technology and a benchtop laser scanner without using a spray, to optimize adaptation of the denture base and cast to minimize any imperfections and to evaluate the impact of the denture cleansing solution on the stability of color.MethodsEvaluation of the dimensional accuracy (n = 27) was completed on a sectional maxillary stone cast using a digital 3D-surface matching software before and after 5000 thermocycles. A spectrophotometer was used to measure the color change (△E00) of all disc specimens (N = 54) before and after 500 thermocycles and immersion in denture cleansing solution for 30 cycles (3 min each) daily for 6 days. The Kruskal Wallis test, Dunn’s post hoc test, Tukey’s test with Bonferroni adjustment, one sample t test and independent t test were used to statistically analyze the data (α < 0.05).ResultsThermocycling decreased the dimensional accuracy of the heat polymerized group at all 5 locations and the 3D-printed group at locations 1, 3 and 5 (P > .05), while it had no significant difference on the CAD-CAM milled group at all locations (P < .05). The color change (△E00) was lowest in the CAD-CAM milled group, moderate in the heat-polymerized group and highest in the 3D-printed group. After immersion in denture cleanser, the color change (△E00) was significantly higher in the 3 groups compared with after thermocycling (P > .001).ConclusionsCAD-CAM milled resins had the highest dimensional accuracy and the best color stability, conventional heat polymerized acrylic resins showed moderate change in dimensional accuracy and color stability, while the 3D- printed resin had the lowest dimensional accuracy and color stability after aging by thermocycling.

Precise cell wall modification of bamboo through two-step furfurylation via solution quantitative adsorption

Improving the dimensional stability of bamboo for construction and engineering use through furfurylation is crucial. Traditional methods like impregnation and soaking furfurylation are hindered by high modifier consumption and waste disposal issues. In this study, we propose a novel technique called solution quantitative adsorption furfurylation (SQAF) to enhance bamboo's dimensional stability and overcome these challenges. Our findings indicate that SQAF achieves enhanced dimensional stability (anti-swelling efficiency (ASE) up to 53.02 %) and reduced hygroscopicity (EMC down to 4.11 %) with approximately 12.50 % weight percentage gain (WPG), and a high furfuryl alcohol (FA) utilization efficiency (SR > 85 %). Analysis using SEM and nanoindentation reveals precise modification of the cell walls without FA resin accumulating in cell cavities. Additionally, SQAF allows for a graded distribution of FA resin, thereby improving the physical properties of bamboo while maintaining its mechanical integrity, especially as the decline in toughness of bamboo is reduced by more than 40 % compared to traditional methods.

Robust branched Poly(p-terphenyl isatin) anion exchange membranes with enhanced microphase separation structure for fuel cells

Anion exchange membrane fuel cells (AEMFCs) are gradually becoming the focus of sustainable hydrogen energy research due to the advantages of clean by-products, faster oxidation-reduction dynamics and allowing cheap platinum-free base materials. As the key components of AEMFCs, anion exchange membranes (AEMs) are required to have high ionic conductivity and dimensional stability. This study focused on the design and preparation of branched AEMs for AEMFCs. The b-PTIN-x membranes were generated by incorporating 1,3,5-triphenylbenzene (TPB) units into rigid poly(p-terphenyl isatin) (PTI) polymer backbones. This innovative approach aimed to induce microphase separation structures by exploiting TPB with high FFV, as well as to enhance the tensile strength of AEMs with the help of branched structures. SAXS and AFM images revealed that the AEMs achieved enhanced microphase separation structures, resulting in the formation of ion transport channels with dimensions in the range of a few nanometers (3.36–3.70 nm). The branched b-PTIN-11 membranes displayed significant OH− conductivity (153.9 mS cm−1 at 80 °C) while having a low ion exchange capacity (IEC) (1.73 mmol g−1). The b-PTIN-11 membranes displayed improved tensile strength (56.69 MPa) and exceptional dimensional stability, with swelling ratio (SR) of 18.5 % at 80 °C. They also showed great chemical stability with 89.64 % conductivity remaining, lasting for more than 1200 h in 3 M NaOH solution at 80 °C. Ultimately, the b-PTIN-11 membrane underwent testing to evaluate its performance in a fuel cell using H2–O2. It demonstrated a peak power density (PPD) of 566 mW cm−2 when subjected to a current density of 1339 mA cm−2.

Effect of Storage Conditions and Time on the Dimensional Stability of 3D Printed Surgical Guides: An InVitro Study.

To evaluate the dimensional stability over time of additively manufactured surgical templates, fabricated by different resins, and stored by different methods. Using a 3D printer with DLS technology and two different resins (Surgical Guide (SG)-WhipMix and Key Guide (KG)-KeystoneIndustries), 96 surgical guides were additively manufactured. The guides were stored in three different environments: directly exposed to sunlight (S1), in normal interior room conditions (S2), and in darkness (S3). The guides were digitally scanned immediately after fabrication and post-processing, and after 1, 3, and 6 months of storage. For each group, the mean deviation of the root mean square (RMS) between guide's intaglio surface, as well as the axial deviation between sleeves' housings were calculated. The mean axial variations of angular axis deviation of sleeves' housings ranged between 0.09° and 3.99°. The mean deviation of the RMS discrepancy in guide's intaglio ranged from 0.1 to 0.18 mm. Variations were significant (p < 0.001) only for the S1 group and only for SG material. After 3 months, an additional storage time of 3 months did not have any further effect on dimensional stability. Within the limitations of the present study, storage time of a surgical guide for up to 3 months after manufacturing, as well as printing material can significantly affect surgical guide's dimensional stability, when they are exposed to direct or indirect sunlight conditions. Storage of guides in a dark environment is recommended in order to avoid an additional source of error in computer-guided surgery workflows.

Three-Dimensionally Printed Ternary Composites of Polyamide: Effect of Gradient Structure on Dimensional Stability and Mechanical Properties

Fused deposition modeling (FDM) 3D printing has the advantages of a simple molding principle, convenient operation, and low cost, making it suitable for the production and fabrication of complex structural parts. Moving forward to mass production using 3D printing, the major hurdle to overcome is the achievement of high dimensional stability and adequate mechanical properties. In particular, engineering plastics require precise dimensional accuracy. In this study, we overcame the issues of FDM 3D printing in terms of ternary material compounds for polyamides with gradient structures. Using multi-walled carbon nanotubes (MWCNTs) and boron nitride (BN) as fillers, polyamide 6 (PA6)-based 3D-printed parts with high dimensional stability were prepared using a single-nozzle, two-component composite fused deposition modeling (FDM) 3D printing technology to construct a gradient structure. The ternary composites were characterized via DSC and XRD to determine the optimal crystallinity. The warpage and shrinkage of the printed samples were measured to ensure the dimensional properties. The mechanical properties were analyzed to determine the influence of the gradient structures on the composites. The experimental results show that the warpage of pure polymer 3D-printed parts is as high as 72.64%, and the introduction of a gradient structure can reduce the warpage to 3.40% by offsetting the shrinkage internal stress between layers. In addition, the tensile strength of the gradient material reaches up to 42.91 MPa, and the increasing filler content improves the interlayer bonding of the composites, with the bending strength reaching up to 60.91 MPa and the interlayer shear strength reaching up to 10.23 MPa. Therefore, gradient structure design can be used to produce PA6 3D-printed composites with high dimensional stability without sacrificing the mechanical properties of PA6 composites.

Reaction of β‐Ketoester and 1,3‐Diol to Access Chemically Recyclable and Mechanically Robust Poly(vinyl alcohol) Thermosets through Incorporation of β‐(1,3‐dioxane)ester

AbstractThe development of mechanically robust, chemically stable, and yet recyclable polymers represents an essential undertaking in the context of advancing a circular economy for plastics. Here, we introduce a novel cleavable β‐(1,3‐dioxane)ester (DXE) linkage, synthesized through the catalyst‐free reaction of β‐ketoester and 1,3‐diol, to cross‐link poly(vinyl alcohol) (PVA) for the formation of high‐performance thermosets with inherent chemical recyclability. PVA, modified with β‐ketoester groups through the transesterification reaction with excess tert‐butyl acetoacetate, undergoes cross‐linking reactions with the unmodified 1,3‐diols within PVA itself upon thermal treatment. The cross‐linking architecture improves PVA’s mechanical properties, with Young's modulus and toughness that can reach up to 656 MPa and 84 MJ cm−3, i.e. approximately 3‐ and 12‐fold those of linear PVA, respectively. Thermal treatment of the cross‐linked PVA polymers under acid conditions leads to deconstruction of the networks, enabling the excellent recovery (&gt;90 %) of PVA. In the absence of either thermal or acidic treatment, the cross‐linked PVA maintains its dimensional stability. We show that the recovery of PVA is also possible when the treatment is performed in the presence of other plastics commonly found in recycling mixtures. Furthermore, PVA‐based composites comprising carbon fibers and activated charcoal cross‐linked by the DXE linkages are also shown to be recyclable with recovery of the PVA and the fillers.

Effect of Ultraviolet-C Light Exposure Time on the Dimensional Stability of Addition Silicone Dental Impressions: An In Vitro Study.

To compare the effect of different ultraviolet-C (UV-C) light exposure times on the dimensional stability of addition silicone dental impressions. The dimensional stability of the addition silicone dental impressions was assessed by measuring specific dimensions on dental casts that were recovered from an upper acrylic resin model of dental implants. The impressions were reproduced using a customized tray adapted in a three-point simplex dental articulator permitting only opening and closing movements. Addition silicone dental impressions were divided into five groups (N = 12) according to the UV-C light exposure time. Group A was untreated; group B received 10 minutes; group C, 20 minutes; group D, 30 minutes; and group E, 40 minutes. All the impressions were poured with type IV dental stone and the internal edges of the upper silicone retainers of impression copings were used as five reference points (E, D, C, B, and A) to determine six linear measurements between ED, CB, EA, AD, EB, and CD points using a traveling microscope of 0.001 mm accuracy. One-way analysis of variance (ANOVA) was used for the statistical analysis (p < 0.05). Expansion and contraction were noted among ED, CB, EA, and EB measurements, whereas only expansion was noted among AD and CD measurements. The ANOVA analysis showed there was no significant difference in the arithmetic means for the measurements between and within group A and the other groups (p > 0.05). The UV-C light exposure time of 10, 20, 30, and 40 minutes did not have any negative effect on the dimensional stability of the addition silicone dental impressions evaluated. In the daily routine dental practice, dental impressions need to be washed and disinfected immediately after making to prevent cross-infections. The UV-C light has been proposed as a promising method for disinfection, but only a few studies have been published about its effect on the dimensional stability of dental silicones. How to cite this article: Bravo-Cueto AG, Tinedo-López PL, Malpartida-Carrillo V. Effect of Ultraviolet-C Light Exposure Time on the Dimensional Stability of Addition Silicone Dental Impressions: An In Vitro Study. J Contemp Dent Pract 2024;25(6):507-513.

Metal-organic polyhedra as dynamic cross-linker for recyclable mixed matrix membranes with promising dimension stability

Metal-organic polyhedra as dynamic cross-linker for recyclable mixed matrix membranes with promising dimension stability