The Effects of Diatomaceous Earth and Zinc Oxide on the Physical, Mechanical, Rheological and Antibacterial Properties of Condensation Silicone Impression Dental Materials

The Effects of Diatomaceous Earth and Zinc Oxide on the Physical, Mechanical, Rheological and Antibacterial Properties of Condensation Silicone Impression Dental Materials | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article The Effects of Diatomaceous Earth and Zinc Oxide on the Physical, Mechanical, Rheological and Antibacterial Properties of Condensation Silicone Impression Dental Materials Mohsen Fakoori, Saeed Hesaraki, Nader Nezafati, Majid ghiass This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6222021/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 13 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Condensation silicones are widely used for dental impressions because of their ease of handling and affordability but exhibit limitations, including shrinkage, suboptimal rheological properties, and potential for bacterial contamination. This study investigated the effects of incorporating microsized diatomaceous earth (DE) and zinc oxide (ZnO) on the properties of a condensed silicone dental impression material, including setting time, rheological behavior, dimensional stability, mechanical properties, wettability, and antibacterial activity. DE and ZnO powders were dry mixed with silica and calcium carbonate via a planetary ball mill. The resulting powder was mixed with PDMS-OH and TEOS. These pastes, along with a control group (silica and calcium carbonate fillers only), were evaluated for mixing, working and setting times and rheological properties. Cured materials were assessed for dimensional stability, tensile strength, hardness, wettability, and antibacterial activity against Escherichia coli and Streptococcus mutans . Microstructural analysis was conducted via SEM, EDAX, and XRD. Incorporating DE and ZnO extended the setting time and improved the flowability. ZnO significantly enhanced the dimensional stability, whereas DE did not. Both fillers slightly decreased the Shore A hardness and increased the hydrophilicity. The ZnO-containing samples had significantly greater antibacterial activity. Both DE and ZnO improved the flowability and enhanced the specific properties of condensed silicone impression materials. ZnO also exhibited significant antibacterial activity. These findings may lead to the development of impression materials with improved handling characteristics, dimensional accuracy, and antibacterial properties. Physical sciences/Materials science Physical sciences/Materials science/Biomaterials Condensation silicone Dental materials Diatomaceous earth Impression Zinc oxide Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 1. INTRODUCTION The accuracy of dental impressions is crucial in modern dentistry for achieving optimal results in prosthodontics, restorative dentistry, and orthodontics [ 1 ], [ 2 ]. Such impressions are the basis of a wide range of dental prosthesis-inlays, onlays, crowns, bridges, and orthodontic appliances [ 3 ]. The fidelity of the impression directly affects the fit, function, and longevity of these restorations and, therefore, has implications for patient satisfaction and oral health. Traditionally, impression materials have evolved from rigid materials to elastic materials, such as plaster, agar, and alginate, which have poor accuracy and detail capture. [ 4 ], [ 5 ]. The discovery of elastomeric impression materials has led to revolutionary changes in dentistry, where much better accuracy, dimensional stability, and minute anatomical detail reproduction could be achieved with far greater precision. [ 6 ], [ 7 ]. Among elastomers, condensation silicones, also called polysiloxanes, have reached great popularity owing to their very favorable properties of easy handling, hydrophobicity, excellent elastic recovery, and good dimensional stability [ 8 ], [ 9 ], [ 10 ]. These materials usually consist of a base polymer, which is normally a polydimethylsiloxane with terminal hydroxyl groups, and a cross-linking agent, which is more often an alkoxysilane, in addition to fillers, plasticizers, and catalysts, to properly control the setting reaction and final properties [ 11 ], [ 12 ], [ 13 ]. Despite the numerous advantages of condensation silicones, they have several disadvantages. One serious disadvantage is inherent; the very mechanism of polymerization involves the emission of a byproduct, in most cases ethanol. The volatile byproduct can cause changes in dimensions and a subsequent decrease in accuracy [ 14 ]. Another urgent problem is the optimal development of rheological and mechanical properties with satisfactory wettability for condensation silicone impression materials. These limitations point to the need for further research to improve the performance and clinical applicability of these materials [ 15 ]. These are further compounded by the need for effective disinfection protocols, which introduce dimensional changes on their own and thus affect the accuracy of the impression [ 16 ]. In this respect, modifications have been carried out in the formulation of impression silicones, mainly by the addition of various types of fillers [ 17 ], [ 18 ]. Fillers can have a great effect on the physical, mechanical and rheological properties of the impression material. Developments in the properties of impression materials can be achieved via the use of fillers with specific properties[ 18 ]. Diatomaceous earth (DE), a biogenic sedimentary rock primarily composed of fossilized diatom remains, is a promising biomaterial with diverse applications [ 19 ], [ 20 ], [ 21 ]. The unique physicochemical properties of DE stem from its high silica content (80–90% SiO2) coupled with the presence of other metal oxides, such as alumina (Al2O3) and iron oxide (Fe2O3) [ 22 ]. The intricate, porous structure of DE, resulting from the diverse shapes and sizes of diatom frustules, contributes to its high surface area, low density, and chemical inertness[ 23 ]. These characteristics, along with their inherent biocompatibility, have led to their widespread use in various fields, including filtration, absorption, drug delivery, and even as pesticide carriers[ 21 ], [ 24 ], [ 25 ]. The versatility of DE extends to its use as a filler in dental impression materials, such as alginates, which are widely used in dentistry for creating diagnostic and working casts[ 26 ]. Zinc oxide (ZnO) is a versatile inorganic compound that has established applications in a variety of dental materials, and its potential applications in impression materials are an area of growing interest[ 27 ]. ZnO is valued for its biocompatibility, affordability, ability to impart antimicrobial properties, and enhanced mechanical properties[ 28 ], [ 29 ], [ 30 ], [ 31 ]. ZnO is incorporated into a variety of dental materials to improve their properties[ 32 ], [ 33 ]. In restorative dentistry, ZnO is added to resin composites, glass ionomer cements, and dental amalgams to enhance their mechanical properties, durability, and antimicrobial activity[ 34 ]. The potential benefits of incorporating ZnO into impression materials, however, have received less attention. To date, research exploring the impact of fillers on condensation silicone impression materials has been limited. This study investigated the effects of two distinct filler types on a comprehensive suite of clinically relevant properties of these materials. Specifically, the mixing time, working time, setting time, rheological behavior, dimensional stability, tensile strength, hardness, wettability, and antibacterial activity were examined. This investigation seeks to provide crucial insights into how these fillers might improve the performance and clinical utility of condensation silicone impression materials. 2. MATERIALS AND METHOD 2.1 Sample preparation The pastes were prepared from the following materials: silica (SiO 2 ) with an average particle size of 25 µm and a density of 2.65 g/cm³ from Neutron® Pharmaceutical Chemical Company (Iran); calcium carbonate (CaCO 3 ) with a density of 2.71 g/cm³ and hydroxy-terminated polydimethylsiloxane (PDMS-OH) with a viscosity of 3500 cSt and a density of 0.97 g/cm³, both from Sigma‒Aldrich® (Germany); and diatomaceous earth with a particle size < 20 µm and zinc oxide (particle size: ~1 µm) with densities of 2.30 g/cm³ and 5.61 g/cm³, respectively, purchased from Neutron® Pharmaceutical Chemical Company (Iran); and tetraethyl orthosilicate (TEOS) with a density of 0.93 g/cm³ and absolute ethanol (99.99%) from Sigma‒Aldrich® (Germany). A series of condensation silicone pastes were formulated to investigate the effects of diatomaceous earth and zinc oxide on the physical, mechanical, rheological and antibacterial properties of dental impression materials. The detailed compositions of these pastes are presented in Table 1 . Table 1 Formulation of silicone pastes by volume (parts) Group Sample Name SiO2 (Vol%) CaCO3 (Vol%) ZnO (Vol%) DE (Vol%) PDMS-OH (Vol%) TEOS (Vol%) Total Volume (Vol%) Control Base Paste 54 6 0 0 39 1 100 Zn ZnO (0.5%) 53.5 6 0.5 0 39 1 100 ZnO (1%) 53 6 1 0 39 1 100 ZnO (2%) 52 6 2 0 39 1 100 ZnO (3%) 51 6 3 0 39 1 100 ZnO (4%) 50 6 4 0 39 1 100 DE DE (0.5%) 53.5 6 0 0.5 39 1 100 DE (1%) 53 6 0 1 39 1 100 DE (2%) 52 6 0 2 39 1 100 DE (3%) 51 6 0 3 39 1 100 DE (4%) 50 6 0 4 39 1 100 A control paste (Base Paste) was prepared using a mixture of silicon dioxide (SiO2) and calcium carbonate (CaCO3) fillers within a hydroxyl-terminated polydimethylsiloxane (PDMS-OH) matrix, along with tetraethyl orthosilicate (TEOS) as a crosslinking agent. The specific compositions of the control and experimental pastes, including the varying volume fractions of the ZnO and DE additives, are detailed in Table 1 . To achieve a homogeneous mixture with a desirable dispersion of microsized zinc oxide (ZnO) and diatomaceous earth (DE) particles within a silicone matrix, a planetary ball milling method was employed (Fig. 1 ). This technique, owing to the high-impact collisions and shear forces generated between the balls and the materials, facilitates a uniform distribution of particles. In each stage of paste preparation, a predetermined amount of ZnO or DE powder was weighed along with the silica and calcium carbonate powders via a high-precision balance. This mixture was then placed into the zirconia jar of a planetary ball mill (AS2-600 model, Bonyan Faragir Sanat Mehrbin Co.). To increase the milling efficiency and prevent contamination, zirconia balls were utilized. The mixture was subsequently rotated for 2 hours at a speed of 400 rpm. Following the milling process, the resulting powder was placed in an oven at 100°C for 24 hours to eliminate any potential moisture that could affect the mechanical and rheological properties of the paste. Moisture can hydrolyze TEOS, potentially disrupting the silicone matrix. To prepare the silicone paste, specific amounts of hydroxy-terminated polydimethylsiloxane (PDMS-OH) and tetraethyl orthosilicate (TEOS) were added to the dried powder. This step was carried out slowly via a mechanical stirrer (IKA® RW 20 digital) to prevent air entrapment within the mixture. The stirring process was continued for two hours to ensure a uniform dispersion of PDMS-OH within the resulting powder mixture. 2.2 Die preparation For tensile analysis, dumbbell-shaped samples (Die C dimensions, ASTM D412) were machined from stainless steel (Fig. 2a) and subsequently attached to a polished, high-density polyethylene (HDPE) sheet. The sample fabrication involved loading the die with the prepared pastes, utilizing an HDPE sheet as the upper platen. To assess the linear dimensional stability of the fabricated samples, a standardized ruled block and mold were constructed from polymethyl methacrylate (PMMA), ensuring a smooth and fine surface, in accordance with ANSI/ADA No. 19 and ISO 4823 standards (Fig. 2b). The pastes were loaded into the mold, and the ruled block was used to shape and compress the material. 2.3 Characterization Mixing, Setting, and Working Times The mixing, working, and setting times were assessed for each freshly made paste according to ISO 4823, with five repetitions per test. The mixing time was determined at 25°C via direct observation via a stopwatch (accurate to 1 s over a 30 s period). A stopwatch with one-second accuracy over a 30-second interval was used to measure the mixing time at 25°C. This involved timing the period from the first contact of the base paste and activator until a uniform mixture was achieved through hand kneading, indicated by a consistent color and texture. The working time was measured similarly, beginning at the start of mixing and concluding when the material became less fluid and showed elastic features. To determine the setting time, a timer was initiated upon the first contact of the components. After mixing, the paste was placed in a ring-shaped mold (like the one used for dimensional stability), with a sealed polyethylene sheet at the bottom. A Gillmore needle was periodically dropped onto the paste surface every 15 seconds. The timer stopped when the needle no longer left a mark, indicating the final setting time. Scanning electron microscopy (SEM) A TESCAN VEGA3 scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDAX) detector was used to analyze the morphology and elemental composition of the samples. Elemental mapping was used to investigate the homogeneity of the samples. Rheology An Anton Paar Physica MCR 301 rheometer was employed to study the rheological properties of the prepared pastes (5 g each) at 25°C. This analysis, which uses both rotational and oscillatory modes, provides data on the flow behavior and viscoelastic characteristics of the materials. Dimensional Stability Dimensional stability was evaluated via impressions made with a standardized ruled block. Each impression was created by mixing the paste and activator at 25°C, loading the resulting paste into a ring-shaped mold, and shaping it with the ruled block. Five replicate impressions were made for each sample, adhering to ISO 4823 guidelines. Postsetting, the impressions were examined via an OLYMPUS DP72 optical microscope. The distances between parallel lines (a, b, c, d 1 , d 2 ) on the surface were measured at 30 minutes and 12 hours after setting to assess short-term and long-term dimensional changes (Fig. 2b). Tensile A SANTAM STM-20 universal testing machine (Iran) with a 2-ton capacity was used to evaluate the tensile properties of the materials, following the ASTM D412 standard. Five samples were prepared for each formula. Each sample underwent a 1-Newton preload at a crosshead speed of 5 mm/min, followed by an increase to 500 mm/min until rupture. Shore A Hardness Hardness was measured with a Shore A-type analog portable durometer (Model SHD, SANTAM, Iran), in line with ASTM D-2240. Three samples were prepared for each sample. Five hardness samples were taken at various points on each sample's flattest surface. All mechanical testing was conducted at 25°C. Wettability assessment The surface wettability of the set impression material was assessed by measuring the static contact angle. For each formula, contact angle measurements were taken on five samples via an MTN9.3‒2021 optical tensiometer (from the Wetting and Interface Laboratory, Materials and Energy Research Center) equipped with IrCA94 software for analysis and reporting. X-ray diffraction (XRD) To analyze the crystalline structure, X-ray diffraction (XRD) was performed via a Seifert 3003 pts diffractometer (Germany) with a copper anode and Cu Kα radiation (λ = 1.542 Å). This analysis provided insights into the phase changes, intensity variations, and degree of crystallinity within the samples. Antibacterial The antibacterial activity of the samples was evaluated quantitatively (by counting) against Escherichia coli (ATCC 25922, PTCC 1399) and Streptococcus mutans (IBRC-M 10682). A fresh bacterial culture, adjusted to a turbidity equivalent to 0.5 McFarland standard (1.5×108 CFU/ml) and diluted to 1.5×106 CFU/ml, was used. The samples were exposed to this bacterial suspension for 24 hours at 37°C. Viable bacteria (reported in CFU–colony forming units) were counted after incubation, with each test repeated three times for accuracy, and the average results are reported. The antibacterial activity was calculated via the following formula: $$\:Antibacterial\:activity\:\left(\%\right)\:=\:\frac{(C\:-\:T)\:}{C}\:*\:100$$ where C represents the number of bacteria in the control sample (CFU/ml) and T represents the number of bacteria in the test sample (CFU/ml). A positive control (pure culture) was included to ensure that the bacteria were viable. A negative control (no sample) was included to determine the initial bacterial concentration. 3. RESULTS AND DISCUSSION To investigate the effects of ZnO and DE on the key properties of condensation silicone impression dental materials, 1 vol% ZnO and 3 vol% DE were selected for detailed characterization. This selection was based on an initial exploration of concentrations ranging from 0.5 vol% to 4 vol% for both additives, which revealed significant concentration-dependent changes in mixing, workability, setting time, and dimensional stability. Compared with the control, 0.5 vol% ZnO had minimal effects on these properties. While 1 vol% showed potential benefits, which will be discussed in detail below, higher concentrations (2–4 vol%) led to a gradual increase in adhesiveness, negatively impacting mixing and workability. This became particularly problematic at 3 vol% and 4 vol%, where manual mixing became impossible. Thus, 1 vol% ZnO was chosen as the optimal concentration, balancing potential benefits with acceptable workability. In contrast, DE had minimal effects on mixing, workability, setting time, and dimensional stability at concentrations ranging from 0.5 vol% to 2 vol% compared with those of the control. However, at 4 vol%, DE significantly increased viscosity and altered viscoelastic behavior, severely hindering both mixing and workability. Despite these drawbacks, 3 vol% DE was chosen as the lowest concentration exhibiting significant changes to investigate its potential to enhance other material properties, as will be discussed subsequently. On the basis of these findings, two series of experimental pastes were designed to further characterize the effects of 1 vol% ZnO and 3 vol% DE. In each series, ZnO or DE was substituted for SiO2 while maintaining a constant 60:40 volume ratio of fillers to liquid components (PDMS-OH and TEOS) to assess their individual effects on the paste properties. The formulations were designed on the basis of a fixed total volume and were divided into 100 parts for ease of calculation. As shown in Table 1 (in the Materials and Methods section), increasing the volume fraction of either ZnO or DE ensures that the total filler volume remains constant. 3.1 Mixing, Setting and Working Times Figure 3 illustrates the setting time, working time, and mixing time of three distinct elastomeric impression material samples (a control, DE, and Zn) measured under standardized conditions as per ISO 4823. The analysis revealed significant differences in both setting and working times among the samples. Specifically, both DE and Zn samples exhibited significantly longer setting times compared to the control samples (p < 0.001). The Zn sample presented the most prolonged setting time, followed by the DE sample and then the control, with statistically significant differences observed among all three groups (p < 0.001 for all comparisons). Similarly, significant differences were identified in working times. The Zn sample demonstrated a significantly longer working time compared to both the control and DE samples (p < 0.001). Conversely, the DE sample presented a significantly shorter working time than the control (p 0.05), indicating similar mixing times across all samples. These findings highlight the distinct effects of sample compositions, particularly DE and Zn in comparison to the control, on the setting and working times of the impression pastes. Notably, the mixing time remained unaffected. The DE sample, in comparison to the control, exhibited a significantly shorter working time coupled with a longer setting time. This seemingly contradictory behavior can be attributed to the unique porous structure of DE. Diatomaceous earth is characterized by its high surface area and porosity, comprising frustules (the rigid, porous silica shells of diatoms), microtubules, and fragmented particles. This structure leads to significant surface adsorption and, notably, deep absorption of PDMS-OH oligomers [ 35 ], [ 36 ], which are crucial components in the condensation polymerization reaction. The absorption of PDMS-OH reduces the effective liquid‒to‒filler phase ratio, resulting in decreased workability of the paste and a shorter working time. This reduced workability may pose challenges for dentists, potentially hindering the accurate capture of details and increasing the likelihood of errors due to limited manipulation time before setting. Furthermore, the surface and deep absorption of PDMS-OH decreases the number of hydroxyl functional groups available for condensation polymerization, consequently prolonging the setting time [ 37 ]. Conversely, the Zn sample exhibited both a significantly extended working time and setting time compared with those of the control. This can be attributed to the interaction between ZnO and the hydroxyl groups in PDMS-OH. ZnO, a highly polar metal oxide due to the substantial electronegativity difference between oxygen (3.5 on the Pauling scale) and zinc (1.65 on the Pauling scale), exhibits amphoteric properties. The oxygen atom in ZnO, which possesses lone pairs of electrons, can function as a Lewis base. It can form a coordinate covalent bond with the silicon atom in PDMS-OH, which has vacant d orbitals. In this bond, the oxygen atom of ZnO acts as the electron donor, whereas the silicon atom of PDMS-OH acts as the electron acceptor. The formation of this bond prevents the silicon atom from readily participating in other reactions, such as cross-linking. Consequently, the curing reaction rate decreases, leading to an increase in both the working and setting times of the impression material [ 38 ]. Moreover, the oxygen atom in ZnO can form a hydrogen bond with the hydrogen atom in the hydroxyl (OH) group of PDMS-OH. The formation of coordinated covalent bonds and hydrogen bonds between ZnO and PDMS-OH reduces the availability of functional groups for the cross-linking reaction, thereby increasing the working and setting times. In essence, by occupying the hydroxyl groups of PDMS-OH, ZnO prevents them from participating in cross-linking and setting reactions [ 39 ]. The extended working time offered by the Zn-containing sample could be advantageous for dentists, particularly in complex cases, as it provides ample time to achieve a more precise impression. 3.2 Rheology The rheological properties of dental impression materials are critical to their clinical performance, dictating their ability to accurately capture intricate intraoral details while maintaining dimensional stability. These materials typically exhibit pseudoplastic shear-thinning behavior, characterized by a decrease in viscosity with increasing shear rate [ 40 ], [ 41 ]. This property facilitates easy flow and adaptation to oral tissues during impression, while ensuring sufficient viscosity at rest to preserve the impression shape[ 42 ]. Figure 4 shows the rheological properties of the control, DE, and Zn impression pastes. As shown in Fig. 4 a, all pastes exhibited shear-thinning behavior, with viscosity decreasing as shear rate increased. The control paste had a high initial viscosity (approximately 1000 Pa·s) at the start of the shear rate range, while the DE paste exhibited the lowest viscosity across all shear rates tested. Between approximately 1 s⁻¹ and 40 s⁻¹, the Zn and DE pastes showed a nearly constant decrease in viscosity, whereas the control paste exhibited a more gradual decrease. This difference in viscosity can be attributed to the morphology of the fillers and their influence on interparticle interactions. The higher initial viscosity of the control paste at low shear rates may limit its ability to fully capture fine details. This is likely due to increased interparticle interactions arising from the morphology of the silica (sharp edges) and calcium carbonate (irregular shape) fillers, which can increase friction and interparticle bonding (Fig. 9 ). The sharp edges of the silica particles and the irregular shape of the calcium carbonate particles may interlock or become entangled, hindering flow at low shear rates. Conversely, the Zn and DE pastes exhibited lower viscosities at low shear rates, indicating improved flow characteristics. This suggests that these materials may be better able to flow into and capture fine details within the oral cavity. SEM analysis (Fig. 9 ) revealed that DE paste, with its diverse range of particle shapes (irregular shards, spherical particles, and hollow tube-like structures), disrupts efficient packing and reduces interparticle contact[ 19 ]. Similarly, the needle-like structure of the ZnO particles in the Zn paste may also interfere with efficient packing, leading to lower viscosity. Furthermore, the alignment of these needle-like ZnO particles under shear could contribute to the lower viscosity by facilitating slippage and reducing resistance to flow [ 43 ], [ 44 ]. The torque-speed profiles shown in Fig. 4 b mirror the observed viscosity trends. Figure 4 c shows the storage modulus (G') of the pastes, where at ω = 1 s⁻¹, the control paste exhibited the highest storage modulus (G'), followed by the Zn paste and then the DE paste. In fact, G' increased with increasing ω for all pastes. The control paste also presented the highest G", followed by the Zn paste and then the DE paste, as shown in Fig. 4 d. Both G' and G" increased with increasing ω for all pastes. Figure 4 e illustrates the relationship between the complex viscosity (η*) and angular frequency. The control paste presented the highest complex viscosity, whereas the DE presented the lowest, which is consistent across the entire range of angular frequencies tested. The Zn paste maintains an intermediate η*. Analysis of the storage modulus (G') (Fig. 4 c) revealed frequency-dependent behavior. At an angular frequency (ω) of 1 s⁻¹, the control paste exhibited the highest G', followed by the Zn paste and then the DE paste. G' increased with increasing ω for all pastes. The control paste exhibited the highest G' across all frequencies, indicating a greater degree of elastic behavior and a stronger network structure within the paste. This is presumably due to greater hydrogen bonding and van der Waals forces between the polymer oligomers and increased particle-particle interactions [ 39 ]. Conversely, the lower G' of the DE paste suggests a less developed or more easily disrupted internal network, which may potentially lead to greater susceptibility to permanent deformation[ 24 ]. The Zn paste, which incorporated needle-like ZnO particles, presented intermediate G' values, indicating a balance between elastic and viscous responses. The loss modulus (G") (Fig. 4 d) followed a similar trend (Control > Zn > DE), providing further insight into the paste's dissipative properties. The control paste exhibited the highest G", reflecting greater energy dissipation during deformation, which is consistent with its more robust network structure. The significantly lower G" of the DE paste suggests reduced interparticle friction and lower energy dissipation[ 23 ]. The Zn paste, despite its intermediate G", displayed a lower complex viscosity (η*) than the control, suggesting enhanced flowability [ 45 ]. This could be attributed to the alignment of the needle-like ZnO particles under shear, potentially creating a lubricating effect that facilitates flow while maintaining a degree of structural integrity [ 46 ]. This trend is further supported by the complex viscosity data shown in Fig. 4 e, where the control paste presented the highest η* and the DE paste the lowest across the entire range of angular frequencies tested. Dimensional Stability The dimensional stability of control, DE, and Zn-filled condensation silicone impression materials was evaluated by measuring linear dimensional changes at 30 minutes and 12 hours after setting (Fig. 5 and Fig. 6 ). Across all measured dimensions (a-b, b-c, a-c, and d1-d2) and at both time points, the Zn filler exhibited significantly less shrinkage compared to the control (p < 0.05, p < 0.01, or p < 0.001), highlighting its positive impact on dimensional stability. Conversely, the DE filler did not improve dimensional stability. At 30 minutes, the b-c and a-c measurements for the DE filler showed significantly greater shrinkage than the control (p < 0.05 and p < 0.01, respectively), with a similar level of significance observed at 12 hours (p < 0.01). While other DE filler measurements were not significantly different from the control, the overall data indicates that the DE filler did not offer any improvement and even exacerbated shrinkage in certain dimensions. Condensation silicone impression materials shrink due to the release of volatile byproducts during the condensation reaction [ 47 ]. Minimizing this shrinkage and achieving isotropic shrinkage are critical for accurate dental impressions [ 48 ]. Isotropic shrinkage minimizes distortion and improves the fit of dental prosthetics and appliances [ 49 ]. The present study demonstrates the significant influence of filler type on the dimensional stability of these silicones. The consistent reduction in shrinkage observed with the ZnO filler aligns with its established reinforcing properties [ 28 ]. SEM analysis (Fig. 11 ) revealed a homogeneous distribution of needle-like ZnO particles, approximately 1 µm in size, within the silicone matrix. This uniform dispersion likely contributes to the observed reduction in shrinkage, as the ZnO particles may effectively occupy potential voids within the silicone matrix, restricting polymer chain movement during polymerization and consequently mitigating shrinkage [ 50 ]. Tensile Figure 7 and Table 2 present the stress‒strain curves and corresponding tensile test data for the control, Zn, and DE samples, highlighting key differences in their mechanical behavior. The control and DE samples exhibit similar initial slopes in the elastic region, confirmed by their comparable elastic moduli (4.27 ± 1.02 MPa and 4.31 ± 1.12 MPa, respectively), indicating similar stiffness. This similarity in elastic moduli, however, appears to contradict the rheological analysis (Fig. 4 a), where the control paste exhibited a significantly higher storage modulus (G') than the DE paste across all frequencies. This discrepancy likely arises from the different testing conditions: the tensile test is static, while the rheological measurements are dynamic, and these different loading regimes can influence material response [ 51 ]. Table 2 Tensile test results for the control, DE, and Zn samples. The values are presented as the means ± standard deviations. Sample Force (N) Extension (mm) Elongation (%) Elastic Modulus (MPa) Control 25.00 +/- 1.21 12.52 +/- 1.09 37.94 +/- 1.26 4.27 +/- 1.02 DE 27.46 +/- 0.98 15.01 +/- 0.99 45.48 +/- 1.07 4.31 +/- 1.12 Zn 24.03 +/- 1.09 21.17 +/- 0.93 64.16 +/- 1.21 2.35 +/- 1.14 In contrast to the control and DE samples, the Zn sample displays a visibly lower initial slope and a lower elastic modulus (2.35 ± 1.14 MPa), suggesting greater flexibility. This lower modulus, while potentially advantageous for adapting to complex dental structures (consistent with its lower viscosity and enhanced flow properties), surprisingly did not compromise dimensional stability. This can likely be attributed to the homogeneous distribution of needle-like ZnO particles (observed via SEM), which effectively reinforce the silicone matrix and restrict polymer chain movement during polymerization, as previously discussed [ 52 ]. The Zn sample also exhibits high elongation at break (64.16 ± 1.21%), indicating good ductility but potentially lower ultimate tensile strength. While this lower ultimate tensile strength raised concerns about its ability to withstand stress without permanent deformation [ 58 ], the Zn sample demonstrated the highest dimensional stability, suggesting its suitability for applications where dimensional accuracy is critical. The DE sample's stress-strain curve reveals a pronounced yield point, followed by plastic deformation before failure. This distinct yield point and greater ductility likely contribute to its ability to withstand deformation during removal without tearing. This behavior may be attributed to the specific surface area, hollow structure, and low density of the DE particles, which can promote interparticle bonding and energy dissipation [ 50 ], [ 53 ], [ 54 ]. Shore A Hardness Test Table 3 Shore A Hardness of Control, DE, and Zn 95% Confidence Interval for Mean Samples N Mean Std. Deviation Std. Error Lower Bound Upper Bound Minimum Maximum Control 5 62 1.41 0.63 59.17 64.83 61 64 DE 5 56 1 0.45 54 58 55 57 Zn 5 55 1 0.45 53 57 54 56 Shore A hardness, a measure of a material's resistance to indentation, is a crucial property in dental impression materials, influencing their ability to capture fine details, withstand stress, and support the casting process [ 57 ], [ 59 ]. Hardness measurements, performed according to ASTM D-2240 (Table 3 ), revealed that the control exhibited the highest Shore A hardness (62), while DE and Zn had lower values (56 and 55, respectively). The low standard deviations for all three materials indicate consistent hardness within each sample set. While the control higher hardness suggests superior resistance to deformation, this must be considered alongside other mechanical properties. Interestingly, despite its lower hardness, the Zn-incorporated paste demonstrated the highest dimensional stability. This suggests that factors beyond simple hardness, such as inherent elasticity and recovery from deformation, are crucial for dimensional accuracy. This observation aligns with the tensile test results, where Zn exhibited the highest ductility, indicating a greater capacity for elastic deformation than the DE and control pastes. The lower hardness of the DE and Zn pastes suggests greater flexibility, potentially advantageous for patient comfort and improved detail capture, particularly in undercut areas, as suggested by their lower viscosity and enhanced flow properties. However, their lower hardness necessitates careful handling to avoid distortion during impression removal [ 60 ]. Finally, the observed differences in hardness may be related to variations in the elemental composition of the samples, particularly the concentration of calcium [ 59 ], [ 61 ]. Wettability The wettability of dental impression materials is crucial for accurately capturing the fine details of oral tissues, ensuring precise replicas for restorations. Our results (Table 4 and Fig. 8 ) demonstrate the impact of incorporating DE and ZnO on this property. The control sample exhibited the highest contact angle (108.32° ± 2.37°), indicating the lowest wettability and potentially limiting its adaptation to moist oral tissues. This is consistent with its higher viscosity at low shear rates, which could further hinder flow and wetting of intricate surfaces. In contrast, incorporating DE significantly enhanced wettability, resulting in the lowest contact angle (102.37° ± 1.45°). This improvement likely stems from the porous structure of DE, which facilitates the release of low-molecular-weight components onto the material's surface in contact with water droplets, effectively increasing hydrophilicity [ 15 ]. The addition of ZnO also moderately improved wettability (106.24° ± 1.39°), likely due to the increased surface area provided by the microsized filler, leading to greater adsorption [ 54 ]. Furthermore, the wurtzite structure of ZnO, confirmed by XRD analysis, may contribute to increased wettability by promoting interactions with water molecules [ 56 ]. While the improvement with ZnO was less pronounced than with DE, it still contributed to the enhanced flow and detail capture observed in the ZnO paste. Overall, both DE and ZnO improved the wettability of the impression material, with DE demonstrating a more substantial effect. Table 4 Contact angle measurements of water droplets on control, DE, and Zn samples. Samples N Mean[°] Control 5 108.32 +/- 2.37 DE 5 102.37 +/- 1.45 Zn 5 106.24 +/- 1.39 scanning electron microscopy (SEM) Scanning electron microscopy (SEM) analysis revealed the distinct morphologies of the different powders. CaCO 3 consisted of particles with irregular shapes and a rough surface texture (Fig. 9 a), while SiO 2 quartz had angular particles with sharp edges and a smoother surface (Fig. 9 b). ZnO exhibited a predominantly needle-like morphology (Fig. 9 c), and the DE powder had a heterogeneous microstructure with a wide variety of diatom frustule morphologies, including elongated, cylindrical forms, disc-like forms, and fragmented frustules (Fig. 9 d). EDAX analysis (Fig. 10 ) confirmed the presence of key elements in each sample. The control primarily comprised carbon, oxygen, silicon, and calcium. The DE additionally showed peaks for aluminum and iron, confirming the incorporation of diatomaceous earth. Zn exhibited a prominent zinc peak. The gold (Au) peak, originating from the sputter coating applied to enhance sample conductivity, was disregarded in the analysis. The elemental maps (Fig. 11 ) provided a visual representation of the elemental distribution within the samples. These maps clearly showed the uniform distribution of carbon and silicon, the base elements of the condensation silicone impression matrix. Calcium was dispersed relatively evenly in the control sample. The DE sample showed a distinct localization of aluminum within the larger surface aggregates, and the Zn sample exhibited a homogeneous dispersion of zinc. The observed microstructures provide insights into the material properties. The heterogeneous and porous microstructure of DE powder is expected to disrupt efficient packing and reduce interparticle contact within the composite material, leading to a reduction in density and an increase in porosity. [ 19 ]. The needle-like morphology of the ZnO particles observed via SEM suggests a potential reinforcing effect within the matrix, including elongation percentage and tear strength[ 52 ]. The needle-like morphology of the ZnO particles suggests a potential reinforcing effect within the matrix [ 54 ], potentially contributing to the enhanced flow properties observed in the Zn paste [ 62 ]. The higher calcium concentration in the control sample (EDAX results) provides a possible explanation for its higher Shore A hardness value. This finding highlights the interconnectedness of material composition, microstructure, and mechanical properties [ 63 ], [ 64 ]. Finally, the uniform distribution of elements observed in the elemental maps (Fig. 11 ) confirms the successful incorporation of ZnO and DE powder into the silicone matrix while maintaining the stability of the base polymer material. X-ray Diffraction Test (XRD) X-ray diffraction (XRD) analysis was performed on the DE and ZnO powders, as well as on the Zn, DE, and control samples. As shown in Fig. 12 , the control sample displayed diffraction peaks corresponding to both quartz (α-quartz) and calcite. The ZnO powder exhibited a series of sharp, well-defined peaks indicative of a highly crystalline structure, aligning with the hexagonal wurtzite structure of ZnO. The Zn sample retained characteristic ZnO peaks but with a reduced intensity. The XRD patterns of both DE powder and the DE sample revealed the presence of cristobalite, a crystalline form of silica. Each sample displayed distinct crystalline phases and structural characteristics, highlighting the effects of the ZnO and DE powders as additives. In the Zn sample, the retention of ZnO peaks with reduced intensity indicates the successful incorporation of ZnO into the composite. This observation is consistent with the enhanced dimensional stability observed for the Zn sample, which exhibited the least shrinkage among the three materials. The reinforcing effect of ZnO, attributed to its high modulus of elasticity, strong particle-matrix interaction, and ability to restrict polymer chain movement, contributes to its ability to limit shrinkage and maintain dimensional accuracy [ 30 ]. The presence of cristobalite in the DE sample, alongside quartz [ 19 ], further confirms the successful incorporation of DE. The relative intensities of the peaks in the DE sample were slightly lower than those in the DE powder pattern, which is expected because of the lower concentration of diatomaceous earth in the composite matrix. Antibacterial The antibacterial activity of dental impression materials containing diatomaceous earth (DE) and zinc oxide (ZnO) was evaluated against E. coli and S. mutans , two common oral bacteria. As shown in Table 5 and Fig. 13 , the Zn-containing material exhibited potent antibacterial activity, reducing the colony-forming units (CFU) of E. coli by 80% and S. mutans by 48% compared to the control. In contrast, the DE-containing material showed minimal antibacterial effects (5% reduction in CFU for E. coli and 5.5% for S. mutans ), similar to the negligible activity observed in the control sample. This superior antibacterial efficacy of the Zn-containing material aligns with the well-established antimicrobial properties of zinc ions [ 65 ]. Zn 2+ ions exert bactericidal effects by disrupting bacterial cell membrane integrity, interfering with enzyme activity, and inducing oxidative stress[ 27 ], [ 33 ], [ 66 ]. Conversely, the negligible antibacterial activity of the DE-containing material is consistent with the inherent lack of antimicrobial properties associated with diatomaceous earth [ 22 ]. Table 5 Antibacterial activity of impression materials containing ZnO and DE against E. coli and S. mutans after 24 hours of incubation. Sample E. coli CFU/ml E. coli Antibacterial Activity (%) S. mutans CFU/ml S. mutans Antibacterial Activity (%) Zn 3.00E + 05 80 7.80E + 05 48 DE 1.40E + 06 5 1.40E + 06 5.5 Control 1.40E + 06 6 1.40E + 06 6.66 Blank 1.50E + 06 * 1.50E + 06 * Conclusion This study investigated the effects of incorporating diatomaceous earth (DE) and zinc oxide (ZnO) fillers into a condensation silicone impression material compared with a control group containing only silica and calcium carbonate fillers. Both fillers significantly altered the material's properties. ZnO enhanced the dimensional stability, extended the working and setting times, improved the flowability, and moderately enhanced the wettability. The lower elastic modulus and increased flexibility of the ZnO-filled material could improve patient comfort. DE significantly improved wettability and flowability while decreasing Shore A hardness, potentially increasing patient comfort. However, DE did not significantly affect dimensional stability and resulted in a shorter working time. The DE-filled samples also exhibited greater ductility. Importantly, ZnO imparted significant antibacterial activity against E. coli and S. mutans , whereas DE had little effect in this regard. In conclusion, both DE and ZnO offer distinct advantages. ZnO may be preferred when dimensional stability, longer working time, flexibility, and antibacterial properties are paramount, whereas DE may be preferred when enhanced wettability and moderate flexibility are desired. Declarations Acknowledgments Not applicable. Funding Not applicable. Author contributions SH contributed to the conception and design of the study, interpretation of the analyzed data, data checking and validation, and critical review of the manuscript. MF contributed to the conception and design of the study, data collection, interpretation of the analyzed data, data checking and validation, and writing of the manuscript and critically reviewed the manuscript. NN & MG contributed to the conception and design of the study and data collection. All the authors read and approved the final manuscript. Competing interests The authors declare that they have no competing interests. Ethical approval Not applicable. Data availability Data will be made available on request. Requests for data access should be directed to the corresponding author, Saeed Hesaraki, at [email protected] . References V. Bennani, G. Inglesias, and J. Samson, “Accuracy of intraoral digital impressions for fixed prosthodontics: A systematic review,” J Prosthet Dent , vol. 125, no. 1, pp. 34–42, 2021. F. A. Alshehri, F. A. AlHarbi, A. S. 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Cite Share Download PDF Status: Published Journal Publication published 13 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 08 Apr, 2025 Reviews received at journal 07 Apr, 2025 Reviews received at journal 03 Apr, 2025 Reviewers agreed at journal 23 Mar, 2025 Reviewers agreed at journal 18 Mar, 2025 Reviewers invited by journal 18 Mar, 2025 Editor assigned by journal 17 Mar, 2025 Editor invited by journal 17 Mar, 2025 Submission checks completed at journal 14 Mar, 2025 First submitted to journal 13 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6222021","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":430719039,"identity":"5fe476d1-d0cc-4630-b63d-943a00458c20","order_by":0,"name":"Mohsen Fakoori","email":"","orcid":"","institution":"Materials and Energy Research Center","correspondingAuthor":false,"prefix":"","firstName":"Mohsen","middleName":"","lastName":"Fakoori","suffix":""},{"id":430719040,"identity":"dbf2746f-dffc-489e-9c68-25f6f8f9e1e5","order_by":1,"name":"Saeed Hesaraki","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIiWNgGAWjYBAC+QYeCEOCmfkAXPQAVrVQYHAAroUtgUgtDDAtDDwGxDnMgIH34MMfNffkJdt5vm74uMeOgb/9AOPhCjxa5Bv4ko15jhUbzmbm3XZzxrNkBokzCQwHz+Cz5v4bM2kGtgTGeUAtt3kOAH1xg4HhYAM+LQd4zH/++JdgP4+Z59ntP0At8kRoMWPgbUtInM3Mw3abAajFgJAWYCAbS/P2JSTPbGYzu9lzIJnH8ExiA14twKg0/PjjW4LtjPOHn934ccBOTu744cMf8ToMHQCjiZEkDaNgFIyCUTAKsAAAGwpODvbfoA0AAAAASUVORK5CYII=","orcid":"","institution":"Materials and Energy Research Center","correspondingAuthor":true,"prefix":"","firstName":"Saeed","middleName":"","lastName":"Hesaraki","suffix":""},{"id":430719042,"identity":"8c788317-1fd3-446f-9c21-f0ff810fbf9e","order_by":2,"name":"Nader Nezafati","email":"","orcid":"","institution":"Materials and Energy Research Center","correspondingAuthor":false,"prefix":"","firstName":"Nader","middleName":"","lastName":"Nezafati","suffix":""},{"id":430719043,"identity":"72d83256-f706-4dae-8f87-b789e2d4837b","order_by":3,"name":"Majid ghiass","email":"","orcid":"","institution":"Iran Polymer and Petrochemical Institute (IPPI)","correspondingAuthor":false,"prefix":"","firstName":"Majid","middleName":"","lastName":"ghiass","suffix":""}],"badges":[],"createdAt":"2025-03-13 17:23:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6222021/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6222021/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-11026-6","type":"published","date":"2025-07-13T15:57:13+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":78810922,"identity":"75bcebb2-a1b8-44e3-afbb-bdc4399b4fab","added_by":"auto","created_at":"2025-03-19 09:05:17","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":137741,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of the silicone paste preparation process\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/a678ac4cfd90313344be1f76.png"},{"id":78810729,"identity":"a410ff97-38b3-4c82-9258-a4c1cebb58a4","added_by":"auto","created_at":"2025-03-19 08:57:17","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":71703,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic of a standard tensile test sample (ASTM D412). (b) Schematic of a ruled block for linear dimensional change measurements (ISO 4823).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/c443a54c8c211f463bb0322d.png"},{"id":78810727,"identity":"3330c93f-77a9-4799-b39f-1e3b4d35e5ae","added_by":"auto","created_at":"2025-03-19 08:57:17","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":62507,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Setting time, (b) working time, and (c) mixing time of the control, DE, and Zn impression material samples. The error bars represent the standard deviation. Statistical significance: ns (not significant) p \u0026gt; 0.05, ** p \u0026lt; 0.01, *** p \u0026lt; 0.001.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/3e8d71ec6c2a0c4b5f98483f.png"},{"id":78810923,"identity":"81b8c135-ab10-4623-a6c4-c41fe8d5b690","added_by":"auto","created_at":"2025-03-19 09:05:17","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":281735,"visible":true,"origin":"","legend":"\u003cp\u003eRheological properties of control, DE, and Zn impression pastes. (a) Viscosity as a function of shear rate. (b) Torque as a function of rotational speed. (c) Storage modulus (G') as a function of angular frequency (ω). (d) Loss modulus (G\") as a function of angular frequency (ω). (e) Complex viscosity (η*) as a function of angular frequency.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/3b659d6f9b85e2b7e00771c8.png"},{"id":78810924,"identity":"50701be5-cf71-454d-9378-f93d09fc3f8a","added_by":"auto","created_at":"2025-03-19 09:05:17","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":245581,"visible":true,"origin":"","legend":"\u003cp\u003eDimensional stability of Zn, DE, and control samples. Top row: Samples 30 min postfabrication. Bottom row: Optical microscope images of the lines used to measure dimensional changes (scale bars = 500 µm). Measured distances: Zn = 2436 µm, DE = 2391 µm, control = 2401 µm\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/d435d3fd84cf0c420092d647.png"},{"id":78811690,"identity":"efc3bb01-67ce-4e28-89fc-6034573691ef","added_by":"auto","created_at":"2025-03-19 09:13:17","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":107972,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of filler type and time on the dimensional stability of samples. Charts represent the mean distance (µm) between lines for different filler types (Control, DE, and Zn) at 30 minutes (blue bars) and 12 hours (green bars) for four different measurement sets: (a) a-b, (b) b-c, (c) a-c, and (d) d1-d2. The error bars represent the standard deviations. Statistical significance compared with the control at each time point is indicated: ns (not significant) p \u0026gt; 0.05, * p \u0026lt; 0.05, ** p \u0026lt; 0.01, *** p \u0026lt; 0.001.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/1a3137bab2de7e7a301b091f.png"},{"id":78810730,"identity":"4f5d4540-5b23-4e93-87f9-53c3b96b9915","added_by":"auto","created_at":"2025-03-19 08:57:17","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":62460,"visible":true,"origin":"","legend":"\u003cp\u003eStress‒strain curves of three samples: control, Zn and DE\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/95421e832c5b0bc549102114.png"},{"id":78810733,"identity":"2efd2731-e2b2-4fce-8074-345524cae76f","added_by":"auto","created_at":"2025-03-19 08:57:17","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":178699,"visible":true,"origin":"","legend":"\u003cp\u003eWettability of the (a) control, (b) Zn, and (c) DE samples.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/8b7edbd6f14f9aeda6129ac6.png"},{"id":78811692,"identity":"4ab5e1c1-83c2-4b75-963f-e658a0ff21ca","added_by":"auto","created_at":"2025-03-19 09:13:17","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":1162414,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of (a) CaCO\u003csub\u003e3\u003c/sub\u003e, (b) SiO\u003csub\u003e2\u003c/sub\u003e quartz, (c) ZnO powder and (d) DE powder\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/04f794fff458ad7aa4cf8728.png"},{"id":78811693,"identity":"3347ae94-6ef3-4ada-81a5-20e4ad01bf91","added_by":"auto","created_at":"2025-03-19 09:13:18","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":619706,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images and corresponding EDAX spectra of the (a) control, (b) DE, and (c) Zn samples.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/37c9d1c707027c674d49fd26.png"},{"id":78810742,"identity":"77ab5061-fef5-4969-9021-01332259d16c","added_by":"auto","created_at":"2025-03-19 08:57:17","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":1665406,"visible":true,"origin":"","legend":"\u003cp\u003eSEM micrographs and corresponding elemental maps of (a) the control, (b) DE, and (c) Zn\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/661fa05ce0df191664de9e00.png"},{"id":78810933,"identity":"9f0581ef-6aee-4083-b0f9-cc46364ad35b","added_by":"auto","created_at":"2025-03-19 09:05:17","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":200076,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray diffraction patterns of DE, DE powder, Zn, ZnO powder and the control\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/47bab9a879c7de27b29ff32d.png"},{"id":78810942,"identity":"e886c3b4-9a3f-4079-8cfd-b3dd0344c5db","added_by":"auto","created_at":"2025-03-19 09:05:18","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":262450,"visible":true,"origin":"","legend":"\u003cp\u003eAntibacterial activity of impression materials incorporating ZnO and DE against Escherichia coli and Streptococcus mutans. Agar plates showing bacterial growth after 24 hours of incubation.\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/267d45acd1ffec4833396afb.png"},{"id":86699568,"identity":"73d496c9-6457-4254-836b-b8b476720c10","added_by":"auto","created_at":"2025-07-14 16:11:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5855956,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6222021/v1/6c9adf91-d421-41f3-9f22-56753e293641.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Effects of Diatomaceous Earth and Zinc Oxide on the Physical, Mechanical, Rheological and Antibacterial Properties of Condensation Silicone Impression Dental Materials","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eThe accuracy of dental impressions is crucial in modern dentistry for achieving optimal results in prosthodontics, restorative dentistry, and orthodontics [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Such impressions are the basis of a wide range of dental prosthesis-inlays, onlays, crowns, bridges, and orthodontic appliances [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The fidelity of the impression directly affects the fit, function, and longevity of these restorations and, therefore, has implications for patient satisfaction and oral health. Traditionally, impression materials have evolved from rigid materials to elastic materials, such as plaster, agar, and alginate, which have poor accuracy and detail capture. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The discovery of elastomeric impression materials has led to revolutionary changes in dentistry, where much better accuracy, dimensional stability, and minute anatomical detail reproduction could be achieved with far greater precision. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Among elastomers, condensation silicones, also called polysiloxanes, have reached great popularity owing to their very favorable properties of easy handling, hydrophobicity, excellent elastic recovery, and good dimensional stability [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. These materials usually consist of a base polymer, which is normally a polydimethylsiloxane with terminal hydroxyl groups, and a cross-linking agent, which is more often an alkoxysilane, in addition to fillers, plasticizers, and catalysts, to properly control the setting reaction and final properties [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the numerous advantages of condensation silicones, they have several disadvantages. One serious disadvantage is inherent; the very mechanism of polymerization involves the emission of a byproduct, in most cases ethanol. The volatile byproduct can cause changes in dimensions and a subsequent decrease in accuracy [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Another urgent problem is the optimal development of rheological and mechanical properties with satisfactory wettability for condensation silicone impression materials. These limitations point to the need for further research to improve the performance and clinical applicability of these materials [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. These are further compounded by the need for effective disinfection protocols, which introduce dimensional changes on their own and thus affect the accuracy of the impression [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In this respect, modifications have been carried out in the formulation of impression silicones, mainly by the addition of various types of fillers [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Fillers can have a great effect on the physical, mechanical and rheological properties of the impression material. Developments in the properties of impression materials can be achieved via the use of fillers with specific properties[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDiatomaceous earth (DE), a biogenic sedimentary rock primarily composed of fossilized diatom remains, is a promising biomaterial with diverse applications [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The unique physicochemical properties of DE stem from its high silica content (80\u0026ndash;90% SiO2) coupled with the presence of other metal oxides, such as alumina (Al2O3) and iron oxide (Fe2O3) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The intricate, porous structure of DE, resulting from the diverse shapes and sizes of diatom frustules, contributes to its high surface area, low density, and chemical inertness[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. These characteristics, along with their inherent biocompatibility, have led to their widespread use in various fields, including filtration, absorption, drug delivery, and even as pesticide carriers[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The versatility of DE extends to its use as a filler in dental impression materials, such as alginates, which are widely used in dentistry for creating diagnostic and working casts[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eZinc oxide (ZnO) is a versatile inorganic compound that has established applications in a variety of dental materials, and its potential applications in impression materials are an area of growing interest[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. ZnO is valued for its biocompatibility, affordability, ability to impart antimicrobial properties, and enhanced mechanical properties[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. ZnO is incorporated into a variety of dental materials to improve their properties[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. In restorative dentistry, ZnO is added to resin composites, glass ionomer cements, and dental amalgams to enhance their mechanical properties, durability, and antimicrobial activity[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The potential benefits of incorporating ZnO into impression materials, however, have received less attention.\u003c/p\u003e \u003cp\u003eTo date, research exploring the impact of fillers on condensation silicone impression materials has been limited. This study investigated the effects of two distinct filler types on a comprehensive suite of clinically relevant properties of these materials. Specifically, the mixing time, working time, setting time, rheological behavior, dimensional stability, tensile strength, hardness, wettability, and antibacterial activity were examined. This investigation seeks to provide crucial insights into how these fillers might improve the performance and clinical utility of condensation silicone impression materials.\u003c/p\u003e"},{"header":"2. MATERIALS AND METHOD","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Sample preparation\u003c/h2\u003e \u003cp\u003eThe pastes were prepared from the following materials: silica (SiO\u003csub\u003e2\u003c/sub\u003e) with an average particle size of 25 \u0026micro;m and a density of 2.65 g/cm\u0026sup3; from Neutron\u0026reg; Pharmaceutical Chemical Company (Iran); calcium carbonate (CaCO\u003csub\u003e3\u003c/sub\u003e) with a density of 2.71 g/cm\u0026sup3; and hydroxy-terminated polydimethylsiloxane (PDMS-OH) with a viscosity of 3500 cSt and a density of 0.97 g/cm\u0026sup3;, both from Sigma‒Aldrich\u0026reg; (Germany); and diatomaceous earth with a particle size\u0026thinsp;\u0026lt;\u0026thinsp;20 \u0026micro;m and zinc oxide (particle size: ~1 \u0026micro;m) with densities of 2.30 g/cm\u0026sup3; and 5.61 g/cm\u0026sup3;, respectively, purchased from Neutron\u0026reg; Pharmaceutical Chemical Company (Iran); and tetraethyl orthosilicate (TEOS) with a density of 0.93 g/cm\u0026sup3; and absolute ethanol (99.99%) from Sigma‒Aldrich\u0026reg; (Germany). A series of condensation silicone pastes were formulated to investigate the effects of diatomaceous earth and zinc oxide on the physical, mechanical, rheological and antibacterial properties of dental impression materials. The detailed compositions of these pastes are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFormulation of silicone pastes by volume (parts)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSample Name\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSiO2 (Vol%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCaCO3 (Vol%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZnO (Vol%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDE (Vol%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePDMS-OH (Vol%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTEOS (Vol%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eTotal Volume (Vol%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBase Paste\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eZn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZnO (0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZnO (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZnO (2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZnO (3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZnO (4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eDE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDE (0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDE (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDE (2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDE (3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDE (4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eA control paste (Base Paste) was prepared using a mixture of silicon dioxide (SiO2) and calcium carbonate (CaCO3) fillers within a hydroxyl-terminated polydimethylsiloxane (PDMS-OH) matrix, along with tetraethyl orthosilicate (TEOS) as a crosslinking agent. The specific compositions of the control and experimental pastes, including the varying volume fractions of the ZnO and DE additives, are detailed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo achieve a homogeneous mixture with a desirable dispersion of microsized zinc oxide (ZnO) and diatomaceous earth (DE) particles within a silicone matrix, a planetary ball milling method was employed (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This technique, owing to the high-impact collisions and shear forces generated between the balls and the materials, facilitates a uniform distribution of particles. In each stage of paste preparation, a predetermined amount of ZnO or DE powder was weighed along with the silica and calcium carbonate powders via a high-precision balance. This mixture was then placed into the zirconia jar of a planetary ball mill (AS2-600 model, Bonyan Faragir Sanat Mehrbin Co.). To increase the milling efficiency and prevent contamination, zirconia balls were utilized. The mixture was subsequently rotated for 2 hours at a speed of 400 rpm. Following the milling process, the resulting powder was placed in an oven at 100\u0026deg;C for 24 hours to eliminate any potential moisture that could affect the mechanical and rheological properties of the paste. Moisture can hydrolyze TEOS, potentially disrupting the silicone matrix. To prepare the silicone paste, specific amounts of hydroxy-terminated polydimethylsiloxane (PDMS-OH) and tetraethyl orthosilicate (TEOS) were added to the dried powder. This step was carried out slowly via a mechanical stirrer (IKA\u0026reg; RW 20 digital) to prevent air entrapment within the mixture. The stirring process was continued for two hours to ensure a uniform dispersion of PDMS-OH within the resulting powder mixture.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Die preparation\u003c/h2\u003e \u003cp\u003eFor tensile analysis, dumbbell-shaped samples (Die C dimensions, ASTM D412) were machined from stainless steel (Fig.\u0026nbsp;2a) and subsequently attached to a polished, high-density polyethylene (HDPE) sheet. The sample fabrication involved loading the die with the prepared pastes, utilizing an HDPE sheet as the upper platen. To assess the linear dimensional stability of the fabricated samples, a standardized ruled block and mold were constructed from polymethyl methacrylate (PMMA), ensuring a smooth and fine surface, in accordance with ANSI/ADA No. 19 and ISO 4823 standards (Fig.\u0026nbsp;2b). The pastes were loaded into the mold, and the ruled block was used to shape and compress the material.\u003c/p\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Characterization\u003c/h2\u003e \u003cp\u003e \u003cb\u003eMixing, Setting, and Working Times\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe mixing, working, and setting times were assessed for each freshly made paste according to ISO 4823, with five repetitions per test. The mixing time was determined at 25\u0026deg;C via direct observation via a stopwatch (accurate to 1 s over a 30 s period). A stopwatch with one-second accuracy over a 30-second interval was used to measure the mixing time at 25\u0026deg;C. This involved timing the period from the first contact of the base paste and activator until a uniform mixture was achieved through hand kneading, indicated by a consistent color and texture. The working time was measured similarly, beginning at the start of mixing and concluding when the material became less fluid and showed elastic features. To determine the setting time, a timer was initiated upon the first contact of the components. After mixing, the paste was placed in a ring-shaped mold (like the one used for dimensional stability), with a sealed polyethylene sheet at the bottom. A Gillmore needle was periodically dropped onto the paste surface every 15 seconds. The timer stopped when the needle no longer left a mark, indicating the final setting time.\u003c/p\u003e \u003cp\u003e \u003cb\u003eScanning electron microscopy (SEM)\u003c/b\u003e \u003c/p\u003e \u003cp\u003eA TESCAN VEGA3 scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDAX) detector was used to analyze the morphology and elemental composition of the samples. Elemental mapping was used to investigate the homogeneity of the samples.\u003c/p\u003e \u003cp\u003e \u003cb\u003eRheology\u003c/b\u003e \u003c/p\u003e \u003cp\u003eAn Anton Paar Physica MCR 301 rheometer was employed to study the rheological properties of the prepared pastes (5 g each) at 25\u0026deg;C. This analysis, which uses both rotational and oscillatory modes, provides data on the flow behavior and viscoelastic characteristics of the materials.\u003c/p\u003e \u003cp\u003e \u003cb\u003eDimensional Stability\u003c/b\u003e \u003c/p\u003e \u003cp\u003eDimensional stability was evaluated via impressions made with a standardized ruled block. Each impression was created by mixing the paste and activator at 25\u0026deg;C, loading the resulting paste into a ring-shaped mold, and shaping it with the ruled block. Five replicate impressions were made for each sample, adhering to ISO 4823 guidelines. Postsetting, the impressions were examined via an OLYMPUS DP72 optical microscope. The distances between parallel lines (a, b, c, d\u003csub\u003e1\u003c/sub\u003e, d\u003csub\u003e2\u003c/sub\u003e) on the surface were measured at 30 minutes and 12 hours after setting to assess short-term and long-term dimensional changes (Fig.\u0026nbsp;2b).\u003c/p\u003e \u003cp\u003e \u003cb\u003eTensile\u003c/b\u003e \u003c/p\u003e \u003cp\u003eA SANTAM STM-20 universal testing machine (Iran) with a 2-ton capacity was used to evaluate the tensile properties of the materials, following the ASTM D412 standard. Five samples were prepared for each formula. Each sample underwent a 1-Newton preload at a crosshead speed of 5 mm/min, followed by an increase to 500 mm/min until rupture.\u003c/p\u003e \u003cp\u003e \u003cb\u003eShore A Hardness\u003c/b\u003e \u003c/p\u003e \u003cp\u003eHardness was measured with a Shore A-type analog portable durometer (Model SHD, SANTAM, Iran), in line with ASTM D-2240. Three samples were prepared for each sample. Five hardness samples were taken at various points on each sample's flattest surface. All mechanical testing was conducted at 25\u0026deg;C.\u003c/p\u003e \u003cp\u003e \u003cb\u003eWettability assessment\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe surface wettability of the set impression material was assessed by measuring the static contact angle. For each formula, contact angle measurements were taken on five samples via an MTN9.3‒2021 optical tensiometer (from the Wetting and Interface Laboratory, Materials and Energy Research Center) equipped with IrCA94 software for analysis and reporting.\u003c/p\u003e \u003cp\u003e \u003cb\u003eX-ray diffraction (XRD)\u003c/b\u003e \u003c/p\u003e \u003cp\u003eTo analyze the crystalline structure, X-ray diffraction (XRD) was performed via a Seifert 3003 pts diffractometer (Germany) with a copper anode and Cu Kα radiation (λ\u0026thinsp;=\u0026thinsp;1.542 \u0026Aring;). This analysis provided insights into the phase changes, intensity variations, and degree of crystallinity within the samples.\u003c/p\u003e \u003cp\u003e \u003cb\u003eAntibacterial\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe antibacterial activity of the samples was evaluated quantitatively (by counting) against \u003cem\u003eEscherichia coli\u003c/em\u003e (ATCC 25922, PTCC 1399) and \u003cem\u003eStreptococcus mutans\u003c/em\u003e (IBRC-M 10682). A fresh bacterial culture, adjusted to a turbidity equivalent to 0.5 McFarland standard (1.5\u0026times;108 CFU/ml) and diluted to 1.5\u0026times;106 CFU/ml, was used. The samples were exposed to this bacterial suspension for 24 hours at 37\u0026deg;C. Viable bacteria (reported in CFU\u0026ndash;colony forming units) were counted after incubation, with each test repeated three times for accuracy, and the average results are reported. The antibacterial activity was calculated via the following formula:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:Antibacterial\\:activity\\:\\left(\\%\\right)\\:=\\:\\frac{(C\\:-\\:T)\\:}{C}\\:*\\:100$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere C represents the number of bacteria in the control sample (CFU/ml) and T represents the number of bacteria in the test sample (CFU/ml). A positive control (pure culture) was included to ensure that the bacteria were viable. A negative control (no sample) was included to determine the initial bacterial concentration.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. RESULTS AND DISCUSSION","content":"\u003cp\u003eTo investigate the effects of ZnO and DE on the key properties of condensation silicone impression dental materials, 1 vol% ZnO and 3 vol% DE were selected for detailed characterization. This selection was based on an initial exploration of concentrations ranging from 0.5 vol% to 4 vol% for both additives, which revealed significant concentration-dependent changes in mixing, workability, setting time, and dimensional stability. Compared with the control, 0.5 vol% ZnO had minimal effects on these properties. While 1 vol% showed potential benefits, which will be discussed in detail below, higher concentrations (2–4 vol%) led to a gradual increase in adhesiveness, negatively impacting mixing and workability. This became particularly problematic at 3 vol% and 4 vol%, where manual mixing became impossible. Thus, 1 vol% ZnO was chosen as the optimal concentration, balancing potential benefits with acceptable workability. In contrast, DE had minimal effects on mixing, workability, setting time, and dimensional stability at concentrations ranging from 0.5 vol% to 2 vol% compared with those of the control. However, at 4 vol%, DE significantly increased viscosity and altered viscoelastic behavior, severely hindering both mixing and workability. Despite these drawbacks, 3 vol% DE was chosen as the lowest concentration exhibiting significant changes to investigate its potential to enhance other material properties, as will be discussed subsequently. On the basis of these findings, two series of experimental pastes were designed to further characterize the effects of 1 vol% ZnO and 3 vol% DE. In each series, ZnO or DE was substituted for SiO2 while maintaining a constant 60:40 volume ratio of fillers to liquid components (PDMS-OH and TEOS) to assess their individual effects on the paste properties. The formulations were designed on the basis of a fixed total volume and were divided into 100 parts for ease of calculation. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (in the Materials and Methods section), increasing the volume fraction of either ZnO or DE ensures that the total filler volume remains constant.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Mixing, Setting and Working Times\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates the setting time, working time, and mixing time of three distinct elastomeric impression material samples (a control, DE, and Zn) measured under standardized conditions as per ISO 4823. The analysis revealed significant differences in both setting and working times among the samples. Specifically, both DE and Zn samples exhibited significantly longer setting times compared to the control samples (p \u0026lt; 0.001). The Zn sample presented the most prolonged setting time, followed by the DE sample and then the control, with statistically significant differences observed among all three groups (p \u0026lt; 0.001 for all comparisons).\u003c/p\u003e \u003cp\u003eSimilarly, significant differences were identified in working times. The Zn sample demonstrated a significantly longer working time compared to both the control and DE samples (p \u0026lt; 0.001). Conversely, the DE sample presented a significantly shorter working time than the control (p \u0026lt; 0.01). In contrast to the setting and working times, no significant differences were found in the mixing times among the three samples (p \u0026gt; 0.05), indicating similar mixing times across all samples. These findings highlight the distinct effects of sample compositions, particularly DE and Zn in comparison to the control, on the setting and working times of the impression pastes. Notably, the mixing time remained unaffected. The DE sample, in comparison to the control, exhibited a significantly shorter working time coupled with a longer setting time. This seemingly contradictory behavior can be attributed to the unique porous structure of DE.\u003c/p\u003e \u003cp\u003eDiatomaceous earth is characterized by its high surface area and porosity, comprising frustules (the rigid, porous silica shells of diatoms), microtubules, and fragmented particles. This structure leads to significant surface adsorption and, notably, deep absorption of PDMS-OH oligomers [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], which are crucial components in the condensation polymerization reaction. The absorption of PDMS-OH reduces the effective liquid‒to‒filler phase ratio, resulting in decreased workability of the paste and a shorter working time. This reduced workability may pose challenges for dentists, potentially hindering the accurate capture of details and increasing the likelihood of errors due to limited manipulation time before setting. Furthermore, the surface and deep absorption of PDMS-OH decreases the number of hydroxyl functional groups available for condensation polymerization, consequently prolonging the setting time [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConversely, the Zn sample exhibited both a significantly extended working time and setting time compared with those of the control. This can be attributed to the interaction between ZnO and the hydroxyl groups in PDMS-OH. ZnO, a highly polar metal oxide due to the substantial electronegativity difference between oxygen (3.5 on the Pauling scale) and zinc (1.65 on the Pauling scale), exhibits amphoteric properties. The oxygen atom in ZnO, which possesses lone pairs of electrons, can function as a Lewis base. It can form a coordinate covalent bond with the silicon atom in PDMS-OH, which has vacant d orbitals. In this bond, the oxygen atom of ZnO acts as the electron donor, whereas the silicon atom of PDMS-OH acts as the electron acceptor. The formation of this bond prevents the silicon atom from readily participating in other reactions, such as cross-linking. Consequently, the curing reaction rate decreases, leading to an increase in both the working and setting times of the impression material [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Moreover, the oxygen atom in ZnO can form a hydrogen bond with the hydrogen atom in the hydroxyl (OH) group of PDMS-OH. The formation of coordinated covalent bonds and hydrogen bonds between ZnO and PDMS-OH reduces the availability of functional groups for the cross-linking reaction, thereby increasing the working and setting times. In essence, by occupying the hydroxyl groups of PDMS-OH, ZnO prevents them from participating in cross-linking and setting reactions [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The extended working time offered by the Zn-containing sample could be advantageous for dentists, particularly in complex cases, as it provides ample time to achieve a more precise impression.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Rheology\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe rheological properties of dental impression materials are critical to their clinical performance, dictating their ability to accurately capture intricate intraoral details while maintaining dimensional stability. These materials typically exhibit pseudoplastic shear-thinning behavior, characterized by a decrease in viscosity with increasing shear rate [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e], [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. This property facilitates easy flow and adaptation to oral tissues during impression, while ensuring sufficient viscosity at rest to preserve the impression shape[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the rheological properties of the control, DE, and Zn impression pastes. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, all pastes exhibited shear-thinning behavior, with viscosity decreasing as shear rate increased. The control paste had a high initial viscosity (approximately 1000 Pa·s) at the start of the shear rate range, while the DE paste exhibited the lowest viscosity across all shear rates tested. Between approximately 1 s⁻¹ and 40 s⁻¹, the Zn and DE pastes showed a nearly constant decrease in viscosity, whereas the control paste exhibited a more gradual decrease.\u003c/p\u003e \u003cp\u003eThis difference in viscosity can be attributed to the morphology of the fillers and their influence on interparticle interactions. The higher initial viscosity of the control paste at low shear rates may limit its ability to fully capture fine details. This is likely due to increased interparticle interactions arising from the morphology of the silica (sharp edges) and calcium carbonate (irregular shape) fillers, which can increase friction and interparticle bonding (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003e). The sharp edges of the silica particles and the irregular shape of the calcium carbonate particles may interlock or become entangled, hindering flow at low shear rates. Conversely, the Zn and DE pastes exhibited lower viscosities at low shear rates, indicating improved flow characteristics. This suggests that these materials may be better able to flow into and capture fine details within the oral cavity. SEM analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003e) revealed that DE paste, with its diverse range of particle shapes (irregular shards, spherical particles, and hollow tube-like structures), disrupts efficient packing and reduces interparticle contact[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Similarly, the needle-like structure of the ZnO particles in the Zn paste may also interfere with efficient packing, leading to lower viscosity. Furthermore, the alignment of these needle-like ZnO particles under shear could contribute to the lower viscosity by facilitating slippage and reducing resistance to flow [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. The torque-speed profiles shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003eb mirror the observed viscosity trends.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ec shows the storage modulus (G') of the pastes, where at ω = 1 s⁻¹, the control paste exhibited the highest storage modulus (G'), followed by the Zn paste and then the DE paste. In fact, G' increased with increasing ω for all pastes. The control paste also presented the highest G\", followed by the Zn paste and then the DE paste, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ed. Both G' and G\" increased with increasing ω for all pastes. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ee illustrates the relationship between the complex viscosity (η*) and angular frequency. The control paste presented the highest complex viscosity, whereas the DE presented the lowest, which is consistent across the entire range of angular frequencies tested. The Zn paste maintains an intermediate η*.\u003c/p\u003e \u003cp\u003eAnalysis of the storage modulus (G') (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ec) revealed frequency-dependent behavior. At an angular frequency (ω) of 1 s⁻¹, the control paste exhibited the highest G', followed by the Zn paste and then the DE paste. G' increased with increasing ω for all pastes. The control paste exhibited the highest G' across all frequencies, indicating a greater degree of elastic behavior and a stronger network structure within the paste. This is presumably due to greater hydrogen bonding and van der Waals forces between the polymer oligomers and increased particle-particle interactions [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Conversely, the lower G' of the DE paste suggests a less developed or more easily disrupted internal network, which may potentially lead to greater susceptibility to permanent deformation[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The Zn paste, which incorporated needle-like ZnO particles, presented intermediate G' values, indicating a balance between elastic and viscous responses.\u003c/p\u003e \u003cp\u003eThe loss modulus (G\") (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ed) followed a similar trend (Control \u0026gt; Zn \u0026gt; DE), providing further insight into the paste's dissipative properties. The control paste exhibited the highest G\", reflecting greater energy dissipation during deformation, which is consistent with its more robust network structure. The significantly lower G\" of the DE paste suggests reduced interparticle friction and lower energy dissipation[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The Zn paste, despite its intermediate G\", displayed a lower complex viscosity (η*) than the control, suggesting enhanced flowability [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. This could be attributed to the alignment of the needle-like ZnO particles under shear, potentially creating a lubricating effect that facilitates flow while maintaining a degree of structural integrity [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. This trend is further supported by the complex viscosity data shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ee, where the control paste presented the highest η* and the DE paste the lowest across the entire range of angular frequencies tested.\u003c/p\u003e \u003cp\u003e \u003cb\u003eDimensional Stability\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe dimensional stability of control, DE, and Zn-filled condensation silicone impression materials was evaluated by measuring linear dimensional changes at 30 minutes and 12 hours after setting (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Across all measured dimensions (a-b, b-c, a-c, and d1-d2) and at both time points, the Zn filler exhibited significantly less shrinkage compared to the control (p \u0026lt; 0.05, p \u0026lt; 0.01, or p \u0026lt; 0.001), highlighting its positive impact on dimensional stability. Conversely, the DE filler did not improve dimensional stability. At 30 minutes, the b-c and a-c measurements for the DE filler showed significantly greater shrinkage than the control (p \u0026lt; 0.05 and p \u0026lt; 0.01, respectively), with a similar level of significance observed at 12 hours (p \u0026lt; 0.01). While other DE filler measurements were not significantly different from the control, the overall data indicates that the DE filler did not offer any improvement and even exacerbated shrinkage in certain dimensions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCondensation silicone impression materials shrink due to the release of volatile byproducts during the condensation reaction [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. Minimizing this shrinkage and achieving isotropic shrinkage are critical for accurate dental impressions [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Isotropic shrinkage minimizes distortion and improves the fit of dental prosthetics and appliances [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. The present study demonstrates the significant influence of filler type on the dimensional stability of these silicones. The consistent reduction in shrinkage observed with the ZnO filler aligns with its established reinforcing properties [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. SEM analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e11\u003c/span\u003e) revealed a homogeneous distribution of needle-like ZnO particles, approximately 1 µm in size, within the silicone matrix. This uniform dispersion likely contributes to the observed reduction in shrinkage, as the ZnO particles may effectively occupy potential voids within the silicone matrix, restricting polymer chain movement during polymerization and consequently mitigating shrinkage [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eTensile\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e present the stress‒strain curves and corresponding tensile test data for the control, Zn, and DE samples, highlighting key differences in their mechanical behavior. The control and DE samples exhibit similar initial slopes in the elastic region, confirmed by their comparable elastic moduli (4.27 ± 1.02 MPa and 4.31 ± 1.12 MPa, respectively), indicating similar stiffness. This similarity in elastic moduli, however, appears to contradict the rheological analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea), where the control paste exhibited a significantly higher storage modulus (G') than the DE paste across all frequencies. This discrepancy likely arises from the different testing conditions: the tensile test is static, while the rheological measurements are dynamic, and these different loading regimes can influence material response [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"−\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"−\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"−\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"−\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTensile test results for the control, DE, and Zn samples. The values are presented as the means ± standard deviations.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eForce (N)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtension (mm)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eElongation (%)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eElastic Modulus (MPa)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c2\"\u003e \u003cp\u003e25.00 +/- 1.21\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c3\"\u003e \u003cp\u003e12.52 +/- 1.09\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c4\"\u003e \u003cp\u003e37.94 +/- 1.26\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c5\"\u003e \u003cp\u003e4.27 +/- 1.02\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDE\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c2\"\u003e \u003cp\u003e27.46 +/- 0.98\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c3\"\u003e \u003cp\u003e15.01 +/- 0.99\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c4\"\u003e \u003cp\u003e45.48 +/- 1.07\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c5\"\u003e \u003cp\u003e4.31 +/- 1.12\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZn\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c2\"\u003e \u003cp\u003e24.03 +/- 1.09\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c3\"\u003e \u003cp\u003e21.17 +/- 0.93\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c4\"\u003e \u003cp\u003e64.16 +/- 1.21\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c5\"\u003e \u003cp\u003e2.35 +/- 1.14\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eIn contrast to the control and DE samples, the Zn sample displays a visibly lower initial slope and a lower elastic modulus (2.35 ± 1.14 MPa), suggesting greater flexibility. This lower modulus, while potentially advantageous for adapting to complex dental structures (consistent with its lower viscosity and enhanced flow properties), surprisingly did not compromise dimensional stability. This can likely be attributed to the homogeneous distribution of needle-like ZnO particles (observed via SEM), which effectively reinforce the silicone matrix and restrict polymer chain movement during polymerization, as previously discussed [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. The Zn sample also exhibits high elongation at break (64.16 ± 1.21%), indicating good ductility but potentially lower ultimate tensile strength. While this lower ultimate tensile strength raised concerns about its ability to withstand stress without permanent deformation [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e], the Zn sample demonstrated the highest dimensional stability, suggesting its suitability for applications where dimensional accuracy is critical. The DE sample's stress-strain curve reveals a pronounced yield point, followed by plastic deformation before failure. This distinct yield point and greater ductility likely contribute to its ability to withstand deformation during removal without tearing. This behavior may be attributed to the specific surface area, hollow structure, and low density of the DE particles, which can promote interparticle bonding and energy dissipation [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e], [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e], [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eShore A Hardness Test\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eShore A Hardness of Control, DE, and Zn\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e95% Confidence Interval for Mean\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSamples\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eMean\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eStd. Deviation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eStd. Error\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eLower Bound\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eUpper Bound\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003eMinimum\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003eMaximum\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.41\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e59.17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e64.83\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e61\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDE\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZn\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eShore A hardness, a measure of a material's resistance to indentation, is a crucial property in dental impression materials, influencing their ability to capture fine details, withstand stress, and support the casting process [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e], [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e]. Hardness measurements, performed according to ASTM D-2240 (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), revealed that the control exhibited the highest Shore A hardness (62), while DE and Zn had lower values (56 and 55, respectively). The low standard deviations for all three materials indicate consistent hardness within each sample set.\u003c/p\u003e \u003cp\u003eWhile the control higher hardness suggests superior resistance to deformation, this must be considered alongside other mechanical properties. Interestingly, despite its lower hardness, the Zn-incorporated paste demonstrated the highest dimensional stability. This suggests that factors beyond simple hardness, such as inherent elasticity and recovery from deformation, are crucial for dimensional accuracy. This observation aligns with the tensile test results, where Zn exhibited the highest ductility, indicating a greater capacity for elastic deformation than the DE and control pastes. The lower hardness of the DE and Zn pastes suggests greater flexibility, potentially advantageous for patient comfort and improved detail capture, particularly in undercut areas, as suggested by their lower viscosity and enhanced flow properties. However, their lower hardness necessitates careful handling to avoid distortion during impression removal [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. Finally, the observed differences in hardness may be related to variations in the elemental composition of the samples, particularly the concentration of calcium [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e], [\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eWettability\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe wettability of dental impression materials is crucial for accurately capturing the fine details of oral tissues, ensuring precise replicas for restorations. Our results (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e ) demonstrate the impact of incorporating DE and ZnO on this property. The control sample exhibited the highest contact angle (108.32° ± 2.37°), indicating the lowest wettability and potentially limiting its adaptation to moist oral tissues. This is consistent with its higher viscosity at low shear rates, which could further hinder flow and wetting of intricate surfaces.\u003c/p\u003e \u003cp\u003eIn contrast, incorporating DE significantly enhanced wettability, resulting in the lowest contact angle (102.37° ± 1.45°). This improvement likely stems from the porous structure of DE, which facilitates the release of low-molecular-weight components onto the material's surface in contact with water droplets, effectively increasing hydrophilicity [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The addition of ZnO also moderately improved wettability (106.24° ± 1.39°), likely due to the increased surface area provided by the microsized filler, leading to greater adsorption [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. Furthermore, the wurtzite structure of ZnO, confirmed by XRD analysis, may contribute to increased wettability by promoting interactions with water molecules [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. While the improvement with ZnO was less pronounced than with DE, it still contributed to the enhanced flow and detail capture observed in the ZnO paste. Overall, both DE and ZnO improved the wettability of the impression material, with DE demonstrating a more substantial effect.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"−\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eContact angle measurements of water droplets on control, DE, and Zn samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSamples\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean[°]\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c3\"\u003e \u003cp\u003e108.32 +/- 2.37\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDE\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c3\"\u003e \u003cp\u003e102.37 +/- 1.45\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZn\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"−\" colname=\"c3\"\u003e \u003cp\u003e106.24 +/- 1.39\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003escanning electron microscopy (SEM)\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eScanning electron microscopy (SEM) analysis revealed the distinct morphologies of the different powders. CaCO\u003csub\u003e3\u003c/sub\u003e consisted of particles with irregular shapes and a rough surface texture (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003ea), while SiO\u003csub\u003e2\u003c/sub\u003e quartz had angular particles with sharp edges and a smoother surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003eb). ZnO exhibited a predominantly needle-like morphology (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003ec), and the DE powder had a heterogeneous microstructure with a wide variety of diatom frustule morphologies, including elongated, cylindrical forms, disc-like forms, and fragmented frustules (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eEDAX analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e10\u003c/span\u003e) confirmed the presence of key elements in each sample. The control primarily comprised carbon, oxygen, silicon, and calcium. The DE additionally showed peaks for aluminum and iron, confirming the incorporation of diatomaceous earth. Zn exhibited a prominent zinc peak. The gold (Au) peak, originating from the sputter coating applied to enhance sample conductivity, was disregarded in the analysis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe elemental maps (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e11\u003c/span\u003e) provided a visual representation of the elemental distribution within the samples. These maps clearly showed the uniform distribution of carbon and silicon, the base elements of the condensation silicone impression matrix. Calcium was dispersed relatively evenly in the control sample. The DE sample showed a distinct localization of aluminum within the larger surface aggregates, and the Zn sample exhibited a homogeneous dispersion of zinc.\u003c/p\u003e \u003cp\u003eThe observed microstructures provide insights into the material properties. The heterogeneous and porous microstructure of DE powder is expected to disrupt efficient packing and reduce interparticle contact within the composite material, leading to a reduction in density and an increase in porosity. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The needle-like morphology of the ZnO particles observed via SEM suggests a potential reinforcing effect within the matrix, including elongation percentage and tear strength[\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. The needle-like morphology of the ZnO particles suggests a potential reinforcing effect within the matrix [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e], potentially contributing to the enhanced flow properties observed in the Zn paste [\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e]. The higher calcium concentration in the control sample (EDAX results) provides a possible explanation for its higher Shore A hardness value. This finding highlights the interconnectedness of material composition, microstructure, and mechanical properties [\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e], [\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e]. Finally, the uniform distribution of elements observed in the elemental maps (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e11\u003c/span\u003e) confirms the successful incorporation of ZnO and DE powder into the silicone matrix while maintaining the stability of the base polymer material.\u003c/p\u003e \u003cp\u003e \u003cb\u003eX-ray Diffraction Test (XRD)\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eX-ray diffraction (XRD) analysis was performed on the DE and ZnO powders, as well as on the Zn, DE, and control samples. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e12\u003c/span\u003e, the control sample displayed diffraction peaks corresponding to both quartz (α-quartz) and calcite. The ZnO powder exhibited a series of sharp, well-defined peaks indicative of a highly crystalline structure, aligning with the hexagonal wurtzite structure of ZnO. The Zn sample retained characteristic ZnO peaks but with a reduced intensity. The XRD patterns of both DE powder and the DE sample revealed the presence of cristobalite, a crystalline form of silica.\u003c/p\u003e \u003cp\u003eEach sample displayed distinct crystalline phases and structural characteristics, highlighting the effects of the ZnO and DE powders as additives. In the Zn sample, the retention of ZnO peaks with reduced intensity indicates the successful incorporation of ZnO into the composite. This observation is consistent with the enhanced dimensional stability observed for the Zn sample, which exhibited the least shrinkage among the three materials. The reinforcing effect of ZnO, attributed to its high modulus of elasticity, strong particle-matrix interaction, and ability to restrict polymer chain movement, contributes to its ability to limit shrinkage and maintain dimensional accuracy [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The presence of cristobalite in the DE sample, alongside quartz [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], further confirms the successful incorporation of DE. The relative intensities of the peaks in the DE sample were slightly lower than those in the DE powder pattern, which is expected because of the lower concentration of diatomaceous earth in the composite matrix.\u003c/p\u003e \u003cp\u003e \u003cb\u003eAntibacterial\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe antibacterial activity of dental impression materials containing diatomaceous earth (DE) and zinc oxide (ZnO) was evaluated against \u003cem\u003eE. coli\u003c/em\u003e and \u003cem\u003eS. mutans\u003c/em\u003e, two common oral bacteria. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e13\u003c/span\u003e, the Zn-containing material exhibited potent antibacterial activity, reducing the colony-forming units (CFU) of \u003cem\u003eE. coli\u003c/em\u003e by 80% and \u003cem\u003eS. mutans\u003c/em\u003e by 48% compared to the control. In contrast, the DE-containing material showed minimal antibacterial effects (5% reduction in CFU for \u003cem\u003eE. coli\u003c/em\u003e and 5.5% for \u003cem\u003eS. mutans\u003c/em\u003e), similar to the negligible activity observed in the control sample.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThis superior antibacterial efficacy of the Zn-containing material aligns with the well-established antimicrobial properties of zinc ions [\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e]. Zn\u003csup\u003e2+\u003c/sup\u003e ions exert bactericidal effects by disrupting bacterial cell membrane integrity, interfering with enzyme activity, and inducing oxidative stress[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], [\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e]. Conversely, the negligible antibacterial activity of the DE-containing material is consistent with the inherent lack of antimicrobial properties associated with diatomaceous earth [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAntibacterial activity of impression materials containing ZnO and DE against E. coli and S. mutans after 24 hours of incubation.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eE. coli\u003c/em\u003e CFU/ml\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eE. coli\u003c/em\u003e Antibacterial Activity (%)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eS. mutans\u003c/em\u003e CFU/ml\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eS. mutans\u003c/em\u003e Antibacterial Activity (%)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eZn\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.00E + 05\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.80E + 05\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.40E + 06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.40E + 06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eControl\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.40E + 06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.40E + 06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.66\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBlank\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.50E + 06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e*\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.50E + 06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e*\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study investigated the effects of incorporating diatomaceous earth (DE) and zinc oxide (ZnO) fillers into a condensation silicone impression material compared with a control group containing only silica and calcium carbonate fillers. Both fillers significantly altered the material's properties. ZnO enhanced the dimensional stability, extended the working and setting times, improved the flowability, and moderately enhanced the wettability. The lower elastic modulus and increased flexibility of the ZnO-filled material could improve patient comfort. DE significantly improved wettability and flowability while decreasing Shore A hardness, potentially increasing patient comfort. However, DE did not significantly affect dimensional stability and resulted in a shorter working time. The DE-filled samples also exhibited greater ductility. Importantly, ZnO imparted significant antibacterial activity against \u003cem\u003eE. coli\u003c/em\u003e and \u003cem\u003eS. mutans\u003c/em\u003e, whereas DE had little effect in this regard. In conclusion, both DE and ZnO offer distinct advantages. ZnO may be preferred when dimensional stability, longer working time, flexibility, and antibacterial properties are paramount, whereas DE may be preferred when enhanced wettability and moderate flexibility are desired.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSH contributed to the conception and design of the study, interpretation of the analyzed data, data checking and validation, and critical review of the manuscript. MF contributed to the conception and design of the study, data collection, interpretation of the analyzed data, data checking and validation, and writing of the manuscript and critically reviewed the manuscript. NN \u0026amp; MG contributed to the conception and design of the study and data collection.\u0026nbsp;All the authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available on request. Requests for data access should be directed to the corresponding author, Saeed Hesaraki, at [email protected].\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eV. Bennani, G. Inglesias, and J. 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Alizadeh, \u0026ldquo;Evaluating antimicrobial activity and cytotoxicity of silver nanoparticles incorporated into reinforced zinc oxide eugenol: an in vitro study,\u0026rdquo; \u003cem\u003eEuropean Archives of Pediatric Dentistry\u003c/em\u003e, vol. 25, no. 3, pp. 443\u0026ndash;450, 2024, doi: 10.1007/s40368-024-00905-7.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Condensation silicone, Dental materials, Diatomaceous earth, Impression, Zinc oxide","lastPublishedDoi":"10.21203/rs.3.rs-6222021/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6222021/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCondensation silicones are widely used for dental impressions because of their ease of handling and affordability but exhibit limitations, including shrinkage, suboptimal rheological properties, and potential for bacterial contamination. This study investigated the effects of incorporating microsized diatomaceous earth (DE) and zinc oxide (ZnO) on the properties of a condensed silicone dental impression material, including setting time, rheological behavior, dimensional stability, mechanical properties, wettability, and antibacterial activity. DE and ZnO powders were dry mixed with silica and calcium carbonate via a planetary ball mill. The resulting powder was mixed with PDMS-OH and TEOS. These pastes, along with a control group (silica and calcium carbonate fillers only), were evaluated for mixing, working and setting times and rheological properties. Cured materials were assessed for dimensional stability, tensile strength, hardness, wettability, and antibacterial activity against \u003cem\u003eEscherichia coli\u003c/em\u003e and \u003cem\u003eStreptococcus mutans\u003c/em\u003e. Microstructural analysis was conducted via SEM, EDAX, and XRD. Incorporating DE and ZnO extended the setting time and improved the flowability. ZnO significantly enhanced the dimensional stability, whereas DE did not. Both fillers slightly decreased the Shore A hardness and increased the hydrophilicity. The ZnO-containing samples had significantly greater antibacterial activity. Both DE and ZnO improved the flowability and enhanced the specific properties of condensed silicone impression materials. ZnO also exhibited significant antibacterial activity. These findings may lead to the development of impression materials with improved handling characteristics, dimensional accuracy, and antibacterial properties.\u003c/p\u003e","manuscriptTitle":"The Effects of Diatomaceous Earth and Zinc Oxide on the Physical, Mechanical, Rheological and Antibacterial Properties of Condensation Silicone Impression Dental Materials","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-19 08:57:12","doi":"10.21203/rs.3.rs-6222021/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-08T08:12:51+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-07T20:15:22+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-03T18:49:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"336149997248477670594278935174616339799","date":"2025-03-24T03:14:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"42471572536901571402708757012882948195","date":"2025-03-18T05:27:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-18T04:17:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-18T03:58:41+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-03-17T12:58:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-15T03:00:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-03-13T17:14:14+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0a6b36e4-9f81-4d75-b017-80967699c64c","owner":[],"postedDate":"March 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":45874679,"name":"Physical sciences/Materials science"},{"id":45874680,"name":"Physical sciences/Materials science/Biomaterials"}],"tags":[],"updatedAt":"2025-07-14T16:07:51+00:00","versionOfRecord":{"articleIdentity":"rs-6222021","link":"https://doi.org/10.1038/s41598-025-11026-6","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-07-13 15:57:13","publishedOnDateReadable":"July 13th, 2025"},"versionCreatedAt":"2025-03-19 08:57:12","video":"","vorDoi":"10.1038/s41598-025-11026-6","vorDoiUrl":"https://doi.org/10.1038/s41598-025-11026-6","workflowStages":[]},"version":"v1","identity":"rs-6222021","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6222021","identity":"rs-6222021","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}