Comparative Evaluation of the Basic Physical Properties of a 3D Printed Experimental Soft Liner versus Conventional Soft Relining Materials

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Traditional liners, such as acrylic-based short-term and silicone-based long-term materials, are widely used. With the advent of additive manufacturing, 3D-printed materials have emerged as promising alternatives. However, their physical properties must be thoroughly evaluated before clinical implementation. Methods: This in vitro study compared the color stability, surface roughness, and Shore A hardness of an experimental 3D-printed soft liner with two conventional materials: GC (acrylic-based, short-term) and UP (silicone-based, long-term). Standardized specimens (n = 10 per group) were immersed in distilled water and coffee at 37°C for 1 week, 1 month, and 3 months. Color change (ΔE₀₀) was measured using a spectrophotometer, surface roughness (Ra) with a profilometer, and hardness with a Shore A durometer. Data were analyzed using one-way and repeated measures ANOVA followed by Bonferroni post hoc tests (p < 0.05). Results: The 3D-printed soft liner showed significantly higher Shore A hardness compared to both GC and UP materials across all time intervals. In terms of color stability, the 3D-printed material performed similarly to GC but was inferior to UP. Surface roughness analysis revealed that the 3D-printed liner was rougher than UP, which maintained the smoothest surface and greatest color stability overall throughout the testing period. Conclusions: While the 3D-printed experimental soft liner demonstrated clinically acceptable physical properties, particularly in hardness, its increased surface roughness and moderate color stability suggest that further formulation improvements are needed. Enhancements in softness and smoothness would be necessary for the material to become a viable alternative to conventional soft liners in routine prosthodontic practice. 3D-printed lining material soft denture liner tissue conditioner color stability surface roughness Shore A hardness Introduction Soft denture lining materials were first introduced for clinical use in 1943 ( 1 ). Since then, their use has become increasingly popular for enhancing the comfort of denture wearers, particularly for those using removable dentures who may not tolerate conventional hard denture bases, especially in cases of thin and non-resilient mucosa or severe alveolar resorption ( 2 ). This is because, during mastication, the thin mucosa becomes compressed between the rigid denture base and the underlying bone, leading to irritation in the affected area or the spread of pain ( 3 ). In such clinical situations, soft liner materials help protect the tissues from localized stresses during functional loading ( 2 ). Soft denture liners play a crucial role in distributing functional loads evenly across the denture-bearing area, preventing localized stress concentrations. They function as a cushioning layer between the rigid denture base and the underlying tissues, thereby reducing the risk of mucosal trauma. Moreover, by minimizing excessive pressure on the alveolar ridge, soft liner materials may contribute to the reduction of residual ridge resorption, thereby enhancing patient comfort. Simultaneously, their ability to adapt to undercut areas improves denture retention, offering both biological and mechanical advantages in prosthodontic rehabilitation ( 2 , 4 ). The effectiveness of these materials in providing cushioning largely depends on their resilience ( 4 ). According to ISO 10139 standards, soft relining materials are classified as long-term (more than 30 days) or short-term (a continuous period from 60 minutes up to 30 days). The second group, short-term materials, is clinically used as tissue conditioners and temporary soft lining materials ( 5 ). Three-dimensional (3D) printing is a rapidly advancing technology that fabricates physical objects by sequentially layering materials based on digital designs created through specialized software ( 6 ). 3D printing is expected to become the leading digital manufacturing technique in dentistry—especially in prosthodontics—due to its speed, accuracy, design versatility, and efficient use of materials. Recent years have seen a notable rise in the development of dental materials tailored for additive manufacturing ( 6 ). Although various printable resins have recently entered the market for both permanent and temporary prosthetic restorations, to the best of the authors' knowledge, a soft liner material produced using the 3D printing method has not yet been reported in the literature. Conventional soft lining materials belong to the group of polymeric dental materials; however, several issues associated with the use of soft liners have been reported, including hardening over time, color instability, microbial colonization, and detachment from the denture base ( 7 ). These clinical challenges necessitate a creative approach and the pursuit of new solutions to improve their properties. Such advancements may be achieved, as in other types of dental materials, through the development of composites incorporating a reinforcing phase that enhances the desired biofunctional characteristics combined with a rational design approach based on modern methodologies ( 5 , 8 ). The 3D-printed experimental soft liner material used in this study has the potential to be utilized in both removable prostheses for patients with thin mucosa and maxillofacial prostheses, allowing fabrication through digital impressions. This approach could enable a comfortable and pressure-free impression and relining process, benefiting both the patient and the clinician. The aim of this study is to compare the properties required for clinical application of a potentially novel soft liner material—designed to benefit from digital impression techniques and 3D printing technologies that enable pressure-free tissue registration—with those of conventional short- and long-term soft liner materials. The null hypothesis (H₀) of this study is that there is no significant difference in the clinically relevant properties—such as color change, surface roughness, and hardness—between the 3D printed experimental soft liner material and conventional short- and long-term soft denture liners. Materials and Methods This study evaluated three different soft denture relining materials. One of them was an experimental 3D printed soft liner (Group 3D), as outlined in Table 1. The other two were widely used, commercially available products: an acrylic-based short-term tissue conditioner (GC Tissue Conditioner, Tokyo, Japan) referred to as Group GC, and an autopolymerising silicone-based long-term reline material (Ufi Gel P, Voco GmbH, Cuxhaven, Germany), labelled as Group UP. Detailed formulations for all three materials are presented in Table 1. Table 1 Chemical Composition of the Soft Relining Materials Used in the Study Groups Manufacturer Composition Group 3D (Experimental 3D Printed Liner) Aliphatic urethane diacrylate, morpholine, acrylic acid ester, trimethylolpropane acrylate, monofunctional urethane acrylate Group GC GC Comporation, Tokyo, Japan (Tissue Treating and Conditioner) PEMA powder, liquid (composed of dibutyl sebacate and ethanol), and a coating agent (consisting of ethyl acetate and dissolved polymer) Group UP Voco GmbH, Cuxhaven, Germany (Ufi Gel P, Cold Curing, Silicone-based Soft lining Material) Modified polydimethyl siloxane and platinum catalyst Specimen Preparation For Group 3D, two types of specimens were prepared: square-shaped samples (10 × 10 × 2 mm) and cylindrical samples (15 mm in diameter and 10 mm in height). The experimental 3D printing resin was loaded into a DLP printer (Asiga Max UV–385 nm, Asiga Pty. Ltd., Australia). Specimens were printed layer by layer at a thickness of 50 µm and oriented at 0°, according to the pre-determined dimensions. After printing, the specimens were cleaned with isopropanol and then post-cured by immersion for 10 minutes in a post-curing oven (Lilivis Cure, 395 nm, Huvitz, South Korea) to ensure the complete polymerisation of any remaining monomers. For groups GC and UP, specimens were fabricated using custom-made metal molds in two shapes: square (10 × 10 × 2 mm) and cylindrical (15 mm in diameter and 10 mm in height). Each mold was placed on a glass slab coated with petroleum jelly to facilitate easy removal of the specimens. The soft denture liners were prepared according to the manufacturers’ instructions. For group GC, the material was mixed at a ratio of 2.2 g powder to 1.8 g liquid by weight (equivalent to the first graduation on the powder measure and four graduations of the liquid syringe by volume). Both components were combined in a glass jar and mixed for 30 seconds. For group UP, the base and catalyst were proportioned in a 1:1 ratio by weight and mixed thoroughly for 30 seconds. The prepared mixtures were then placed into the molds, which remained on the glass slab. Another glass slab, also coated with petroleum jelly, was placed on top. The two slabs were pressed firmly together to eliminate excess material and shape the specimens precisely according to the mold dimensions. After polymerisation, the specimens were carefully removed from the molds and trimmed using a sharp blade to ensure uniform edges. Specimens in group GC were additionally polished using the manufacturer-provided coating agent. All specimens were then stored in distilled water at 37°C for 24 hours prior to testing. Color Change Evaluation Square-shaped specimens (n = 10 per group) were used to assess color changes. Baseline color measurements were recorded before immersion. Based on the protocol by Güler et al. ( 9 ), which equates 24 hours of immersion to approximately one month of clinical aging, the specimens were immersed in a coffee solution at 37°C—renewed daily—for simulated aging periods: 5.5 hours (1 week), 24 hours (1 month), and 72 hours (3 months). To prevent contact or cross-contamination, each specimen was placed in an individually sectioned, water-permeable fabric during immersion ( 10 ). The granule coffee solution (Nescafe Classic, Nestlé, Switzerland) was prepared by dissolving 3.6 g of instant coffee in 300 mL of boiling distilled water, following the manufacturer’s guidelines. The mixture was stirred for 10 minutes and filtered through standard filter paper. After each immersion period, specimens were rinsed with distilled water, gently blotted dry with tissue paper, and air-dried at room temperature before taking color measurements. Color Measurement Protocol Initial color values (L*, a*, b*) of the specimens were measured using a spectrophotometer (VITA Easyshade V, VITA Zahnfabrik, Germany). The device was calibrated before each use according to the manufacturer's instructions. All measurements were conducted by a single researcher under standardized daylight conditions at a consistent time of day to ensure reliability. The same background color used by Costa et al. ( 10 ) was selected as the reference (L₀, a₀, b₀). To reduce the influence of ambient light and ensure consistent positioning, a custom-made silicone mold compatible with the spectrophotometer was fabricated. During measurements, the device was placed vertically in direct contact with the specimen through the mold on a flat surface. Color values (L*, a*, b*) were recorded across the entire surface of each specimen, and the average of these readings was defined as the baseline value (L₀, a₀, b₀). Following each immersion interval, the same protocol was applied. Three measurements were taken per specimen after aging, and the mean value was used for analysis. Color differences (ΔE₀₀) were then calculated using the recorded data. Color Stability (ΔE₀₀) Color differences were calculated according to the CIEDE2000 formula to determine color stability over time. Specifically, ΔE₀₀₇, ΔE₀₀₃₀, and ΔE₀₀₉₀ represent the color changes observed after 1 week, 1 month, and 3 months of aging, respectively. $$\:\varDelta\:{E}_{00}=\sqrt[2]{{\left(\frac{\varDelta\:{L}^{{\prime\:}}}{{K}_{L}{S}_{L}}\right)}^{2}+{\left(\frac{\varDelta\:{C}^{{\prime\:}}}{{K}_{c}{S}_{c}}\right)}^{2}+{\left(\frac{\varDelta\:{H}^{{\prime\:}}}{{K}_{H}{S}_{H}}\right)}^{2}+{R}_{T}\left(\frac{\varDelta\:{C}^{{\prime\:}}}{{K}_{c}{S}_{c}}\right)\left(\frac{\varDelta\:{H}^{{\prime\:}}}{{K}_{H}{S}_{H}}\right)}$$ The CIELAB values were converted into CIEDE2000 parameters: L′ (lightness), C′ (chroma), and h′ (hue). Within the CIEDE2000 uniform color space, the differences in these parameters—ΔL′, ΔC′, and ΔH′—were calculated as the metric differences between the corresponding values of each sample. To refine these values and reflect perceptual uniformity, three weighting functions were applied: SL, SC, and SH, adjusted by the empirical parametric factors KL, KC, and KH, respectively. In addition, the RT term was included to account for the interaction between chroma and hue differences, particularly to correct for perceptual distortions in the blue region of the color space. For this study, all parametric factors (KL, KC, and KH) were set to 1, in accordance with the standard conditions defined by the CIEDE2000 formula. As noted by Paravina et al. ( 11 ), a ΔE₀₀ value of 0.8 is considered the threshold for clinical perceptibility, while 1.8 is deemed the upper limit for clinical acceptability. This benchmark was adopted in our study to evaluate the clinical significance of the observed color changes. Surface Roughness Evaluation Surface roughness was evaluated on the basal surface of cylindrical specimens. A total of 20 specimens were used, with five specimens allocated for each time point. For each specimen, five measurements were taken using a surface roughness tester (Surftest SJ-210; Mitutoyo Corporation, Kanagawa, Japan), calibrated with a 0.8 mm cut-off value and a scanning speed of 0.5 mm/s, covering a total distance of 4.0 mm. The average surface roughness (Ra) was calculated for each specimen at every evaluation period. Water Immersion and Measurement Time Intervals Baseline surface roughness measurements (T0) were taken prior to immersion. The specimens were then stored in distilled water at 37°C to simulate oral conditions. Measurements were conducted after 7-day immersion period (T1), 30 days (T2) and 90 days (T3) of water storage at 37°C, in accordance with ISO 10139-1:2018 ( 12 ) and ISO 10139-2:2009 ( 13 ), which covers soft lining materials designed for extended clinical application. Hardness Measurement Shore A hardness was measured on the surface opposite to that used for surface roughness evaluation, using a durometer (Turonic, Shanghai, China). Initial measurements were performed one hour after specimen preparation. For each material, 20 cylindrical specimens were fabricated. At each time point, five specimens were randomly selected, and five hardness readings were taken on a single, flat surface of each specimen. The durometer was applied with a 1 kg-f load and a one-second dwell time to ensure consistent penetration and accurate measurement ( 14 ). Statistical analysis The sample size was calculated using G*Power 3.1.9.7 (Heinric-Heine-Universität Düsseldorf, Germany) based on data from a similar study by Kasuga et al. ( 3 ) Using a pooled standard deviation of 2.477, the effect size was determined as 2.21138. With 95% power and 5% significance, 9 samples were required for each of the 3 groups. As the initially calculated sample size was deemed insufficient, the final sample size was determined to be 30, with 10 samples allocated to each group. Statistical analyses were performed using SPSS version 22.0 (SPSS Inc., Chicago, IL, USA). Descriptive statistics, including the mean, standard deviation, minimum, and maximum values, were calculated for all variables. The normality of data distribution was assessed using the Shapiro–Wilk test, and the homogeneity of variances was evaluated using Levene’s test for color, surface roughness, and hardness measurements. Changes in color values over time were analyzed using repeated measures ANOVA. When the assumptions of normality and homogeneity of variances were met, comparisons between different materials were performed using one-way ANOVA. In cases where the assumption of homogeneity was violated, as indicated by Levene’s test (e.g., for surface roughness data), Welch’s ANOVA was used. Similarly, Shore A hardness values were compared between groups using one-way ANOVA, provided that the assumptions of normality and homogeneity were satisfied. Post hoc pairwise comparisons were conducted using either the Bonferroni or Tamhane’s T2 test, depending on the equality of variances. A significance level of 0.05 was set for all statistical tests. Results Evaluation of Color Change According to the results of the one-way ANOVA, which compared different groups at various time points, statistically significant differences were observed across all time points. Based on the Tamhane T2 post hoc test, the UP group exhibited significantly lower color change values compared to the other two groups, while the 3D group showed similar results to the GC group. Repeated measures ANOVA (Table 2), used for within-group comparisons over time, revealed a statistically significant increase in color change across all groups. According to the Bonferroni post hoc test, the 3D group showed a significant increase in color change at all time points. In contrast, In the GC group, no significant differences were observed between T0 and T1, and between T2 and T3. No significant difference was found between time points T0 and T1 in the UP group, whereas the increases at other time points were significant. Table 2 Repeated measures ANOVA results for Color Change Over Time Materials Test Statistics † Group GC Group 3D Group UP x̄± SD x̄± SD x̄± SD F p Time T0 5.80 ± 2.61 a,A 5.89 ± 0.65 a,A 1.78 ± 0.72 b,A 21.3215 < 0.001 T1 T2 T3 6.03 ± 1.98 a,A 8.86 ± 1.99 a,B 8.76 ± 1.62 a,B 7.51 ± 1.06 a,B 8.48 ± 0.95 a,C 9.78 ± 0.75 a,D 2.11 ± 0.47 b,A 2.71 ± 0.59 b,B 3.62 ± 0.62 b,C 44.5367 68.0688 91.5027 < 0.001 < 0.001 < 0.001 Test Statistics ‡ F 16.4532 126.3813 42.8801 p < 0.001 < 0.001 < 0.001 x̄: Mean, SD : Standard deviations, † : Intergroup comparisons for materials (One-way ANOVA, Tamhane T2 test results), The superscripts a and b indicate groups with statistically significant differences in each measurement. Groups with the same superscripts are statistically similar. ‡ : Intergroup comparisons of materials (Repeated measures ANOVA and Bonferroni test results) The superscripts A, B, C and D indicate groups with statistically significant differences in each time interval Evaluation of Roughness Data According to the results of the one-way ANOVA (Table 3) and Welch’s test, there were statistically significant differences among the groups at all time points. Pairwise comparisons using the Bonferroni and Tamhane post hoc tests revealed that all groups differed significantly from each other. The highest surface roughness values were observed in the GC group, while the lowest values were recorded in the UP group. Table 3 Welch’s ANOVA Results for Surface Roughness SURFACE ROUGHNESS TEST RESULTS N Mean Standart Deviations Minimum Maksimum Roughness T0 GC a 5 4,33 0,34 3,87 4,77 3D b 5 1,54 0,19 1,32 1,83 UP c 5 0,65 0,12 0,53 0,86 F/p F = 336,347/ p = 0.000 Roughness T1 GC a 5 3,75 0,15 3,50 3,89 3D b 5 1,39 0,10 1,27 1,51 UP c 5 0,49 0,09 0,36 0,59 F/p F = 1024,477/ p = 0.000 Roughness T2 GC a 5 4,29 0,42 3,76 4,76 3D b 5 1,50 0,16 1,34 1,70 UP c 5 0,79 0,12 0,71 1,01 WELCH’S F/p F = 156,578/ p = 0.000 Roughness T3 GC a 5 4,02 0,42 3,52 4,43 3D b 5 1,50 0,25 1,07 1,69 UP c 5 0,58 0,07 0,50 0,69 WELCH’S F/p F = 169,140/ p = 0.000 The superscripts a, b and c indicate groups with statistically significant differences in each measurement Shore A Hardness Test Results According to the one-way ANOVA (Table 4) results, there were statistically significant differences in Shore A hardness values among the groups at all time intervals. Pairwise comparisons using the Bonferroni test indicated that all groups differed significantly from each other. The highest Shore A Hardness value was observed in the 3D group at time point T0, whereas the lowest value was recorded in the GC group at time point T3. Table 4 One-way ANOVA results of Shore A Hardness Test Results SURFACE HARDNESS TEST RESULTS N Mean Standart deviations Minimum Maksimum Shore A T0 GC a 5 24,72 1,03 23,60 26,40 3D b 5 69,32 0,54 68,80 70,00 UP c 5 35,08 0,50 34,50 35,80 F/p F = 5136.49/ p = 0.000 Shore A T1 GC a 5 14,66 0,62 13,80 15,40 3D b 5 58,96 1,03 57,90 60,30 UP c 5 26,60 0,48 25,90 27,10 F/p F = 4688.02/ p = 0.000 Shore A T2 GC a 5 12,18 0,54 11,30 12,70 3D b 5 55,76 1,33 53,50 57,00 VOCO c 5 26,60 0,93 25,30 27,80 F/p F = 2536.41/ p = 0.000 Shore A T3 GC a 5 15,80 1,70 14,00 17,60 3D b 5 54,80 0,82 54,20 55,80 UP c 5 27,48 1,03 25,80 28,50 F/p F = 1298.79/ p = 0.000 The superscripts a, b and c indicate groups with statistically significant differences in each measurement Discussion Ideal soft lining materials should exhibit durable viscoelastic properties over time, minimal water sorption, resistance to discoloration, strong adhesion to the denture base, dimensional stability, ease of handling during processing, and excellent biocompatibility ( 3 ). In this study, an experimental soft relining resin was developed in collaboration with a manufacturer for potential use in 3D printing applications. The resin composition included monomers such as aliphatic urethane diacrylate, trimethylolpropane acrylate, and monofunctional urethane acrylate, imparting it with an acrylic nature. The rationale behind selecting this composition lies in the increasing reliability of digital impressions, which allow for pressure-free impression techniques. This is particularly advantageous in cases where soft lining materials are indicated, such as resorbed alveolar ridges or maxillofacial defects, where minimizing trauma is essential. Therefore, there is a clinical need for a soft lining material that is compatible with 3D printed acrylic denture bases. The chosen resin offers ease of application, chemical bonding capability to acrylic bases, and adjustable softness through plasticizer content. To determine the suitability of the experimental material for either long-term relining or short-term tissue conditioning, it was compared with two reference materials: tissue conditioner, representing short-term use, and soft-liner, which is indicated for long-term applications. Several studies have consistently demonstrated the superior color stability of silicone-based soft liners compared to acrylic-based materials. Canay et al. ( 4 ) reported that acrylic-based soft liners exhibited greater discoloration than silicone-based ones when immersed in food colorant solutions. Similarly, Saraç et al.( 15 ) found that silicone-based liners were more resistant to staining. In a related study, Mancuso et al. ( 16 ) evaluated the color change and hardness of soft liners composed of either acrylic resin (Trusoft) or silicone (Dentusil, Ufi Gel P, and Ufi Gel SC) after thermocycling. Their findings indicated that silicone-based liners exhibited significantly better color stability and that acrylic-based materials presented the lowest Shore A hardness values following thermocycling. The significant color changes were attributed to the inherent material characteristics. In agreement with these findings, our study revealed that the UP group (a silicone-based liner) exhibited the least color change, while the 3D and GC groups showed similar outcomes. These results further support the notion that silicone-based soft liners tend to be more color stable, demonstrating a consistent pattern across different studies and material types. When the effect of time intervals was considered in our study, the 3D group exhibited a significant increase in color change at all time points. In contrast, the GC group showed no significant difference between T0 and T1, or between T2 and T3. Similarly, in the UP group, no significant difference was observed between T0 and T1; however, the increases at subsequent time points were statistically significant. These findings may be related to the material composition. According to Ergün et al.,( 17 ) the UP group contains dimethylsiloxane as its primary component, which contributes to its color stability. In contrast, acrylic-based liners tend to contain higher concentrations of plasticizers and ethanol. The rapid release of ethanol from these materials is considered a contributing factor to the greater degree of color change observed in comparison to the UP group. Surface roughness is a critical property of polymeric materials, particularly due to its influence on microbial adhesion. In the context of denture base materials, the initial attachment of microorganisms serves as a key step in biofilm formation, which can subsequently lead to conditions such as denture-related stomatitis. To mitigate this risk, it is essential that these materials possess smooth surface characteristics, thereby reducing microbial adherence and minimizing the potential for biofilm development and the associated onset of oral mucositis.( 18 ) In the present study, the surface roughness values of the experimental 3D-printed group showed no statistically significant differences across all measured time intervals over the three-month period. A marked decrease was observed in the surface roughness measurements of the GC and UP groups, particularly after the first week. This decrease was followed by a notable increase at the end of the first month in the same groups. The experimental 3D group remained stable throughout the study period, exhibiting a smoother surface compared to the GC group, but consistently rougher than the UP group at all time intervals. In the study conducted by Urban et al., in which they incorporated antimicrobial agents and evaluated Shore A hardness and surface roughness, a decrease in surface roughness values was observed in the one-week measurements of the control group, which included a tissue conditioner and an acrylic-based long-term resilient liner. This finding is consistent with the decrease observed in our study during the same time period.( 19 ) Additionally, the lowest surface roughness values were recorded in the UP group, while the experimental 3D group maintained values around 1.5 and did not exhibit statistically significant changes over time. One of the major challenges in the clinical use of soft denture liners is maintaining their hardness within acceptable limits, primarily due to their susceptibility to changes in the aqueous oral environment ( 20 ). During clinical use, these materials are continuously exposed to saliva, food, water, and oral hygiene products, leading to leaching of their components and increased water absorption ( 21 , 22 ). These effects are commonly associated with increased hardness, expansion, distortion, discoloration, unpleasant odor emission, and the enhanced adhesion and proliferation of microorganisms ( 21 ). Surface roughness of dental materials plays a critical role in biofilm accumulation, thereby facilitating the development and persistence of oral pathologies ( 19 ). While soft lining materials typically exhibit greater surface irregularities and higher roughness compared to denture base resins—thereby promoting more bacterial colonization—they are still used as long-term solutions, sometimes for several months or even years ( 23 ) In the present study, although the specimens were standardized by preparing them between two glass slabs, the initial surface roughness values varied among groups and exceeded 0.2 µm, which is recognized as the critical threshold for microbial adhesion ( 24 – 26 ). Among the tested groups, the highest roughness was observed in the GC group, while the lowest was recorded in the UP group; however, all groups exceeded the aforementioned threshold. In contrast to our findings Kutlu et al.( 26 ) evaluated the surface roughness of methacrylate- and silicone-based liners after applying a coating and storing them in various solutions. They reported that methacrylate-based liners exhibited a greater increase in surface roughness compared to silicone-based liners. According to ISO 10139-2:200 standards, the acceptable Shore A hardness values for soft lining materials range between 20 and 50. Although the initial Shore A value of the experimental 3D material investigated in this study was higher than this range, it was observed to approach the acceptable limits over the time intervals. This can be considered a favorable outcome when clinical and storage conditions are taken into account. Furthermore, it is anticipated that the Shore A value may remain within the expected range for a longer duration. Since a Shore A value that is too low may result in inadequate cushioning and insufficient protection of the oral tissues, achieving an optimal hardness is essential. Given that the material is experimental, modifying the type and ratio of plasticisers within its composition could help achieve more ideal Shore A values. In the literature, studies evaluating the hardness of soft lining materials have reported the addition of various agents to enhance their antimicrobial properties. In the study by Kasuga et al., ( 3 ) who incorporated fluoride, no significant changes were observed in the Shore A hardness values of acrylic-based and silicone-based soft lining materials after one week of water immersion. In the study by Urban et al.,( 19 ) which evaluated tissue conditioners and resilient liners with added antimicrobial agents, an increase in Shore A hardness was observed in the tissue conditioner, while no significant time-dependent changes were detected in the resilient liner. In contrast to our study, the Shore A hardness value in the experimental 3D group decreased over one week time. Kasuga et al.( 3 ) and Urban et al.( 19 ) conducted their studies with evaluation periods limited to one and two weeks. In contrast, our study extended the assessment periods to one and three months to more thoroughly evaluate the materials’ suitability for long-term clinical application. At the one-month evaluation, the experimental 3D group demonstrated Shore A values comparable to those recorded at one week, whereas the GC and UP groups exhibited a decline. At three months, the experimental 3D group continued to maintain Shore A values similar to the initial measurement, while the GC group showed a further decrease and the UP group exhibited an increase. These variations are likely attributable to differences in material composition especially regarding the type and quantity of plasticizers. ( 19 , 21 ) It is important to note that the GC group is recommended primarily for short-term use. This study has several limitations that should be acknowledged. Firstly, although the experimental period extended to three months—longer than many previous studies—it may still not fully represent the long-term clinical performance of soft lining materials, particularly for applications intended to last several months or years. Secondly, the in vitro nature of the study limits the generalizability of the results to clinical conditions, where factors such as salivary enzymes, mechanical forces from mastication, and patient-specific hygiene habits can significantly influence material behavior. Additionally, while color stability, surface roughness, and Shore A hardness were comprehensively evaluated, other important properties such as tensile strength, bond strength to denture base materials, microbial colonization resistance, and patient comfort were not assessed in this phase of the research. Finally, the experimental material was tested in its current formulation only; further studies are required to explore the impact of varying the plasticizer content and other compositional modifications to optimize clinical performance. Conclusion The experimental 3D-printed soft liner demonstrated promising results in terms of surface roughness and Shore A hardness stability over time, with color stability comparable to conventional materials. While its initial Shore A hardness was slightly above the ideal range, it gradually approached acceptable limits, suggesting potential for long-term clinical application. Given the growing reliability and accessibility of 3D printing technologies, this material may offer clinicians a valuable alternative for soft denture relining, particularly in cases requiring minimally traumatic solutions. Future studies should focus on optimizing its softness characteristics and investigating key properties such as bacterial adhesion and water sorption to enhance its clinical performance. As 3D technology continues to evolve, this type of material could become a viable and efficient option in prosthodontic practice. Declarations Acknowledgements The authors would like to thank Arma Dental Üretim Sistemleri Sanayi ve Ticaret Ltd. Şti. (Kocaeli, Türkiye) and Sinan Günüç for their valuable support in the production and provision of the experimental 3D-printed soft liner material used in this study. Author Contributions Conceptualization, Göknil Alkan Demetoğlu and Osman Kaya; Methodology, Göknil Alkan Demetoğlu and Osman Kaya; Investigation, Göknil Alkan Demetoğlu;, Osman Kaya Formal analysis, Esra Talay Çevlik, Pınar Yıldız; Writing – Original Draft Preparation, Göknil Alkan Demetoğlu; and Esra Talay Çevlik, and Pınar Yıldız Writing – Review & Editing, Göknil Alkan Demetoğlu;, Esra Talay Çevlik, Pınar Yıldız; Supervision, Göknil Alkan Demetoğlu. All authors have read and agreed to the published version of the manuscript. Funding This study is self-funded. The authors do not have any financial interest in the companies whose materials are included in this article. Data availability The original contributions presented in this study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author(s). Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests. References Tylman S. The use of elastic and resilient synthetic resins and their copolymer in oral, dental and facial prostheses. Dent Digest 1943;49:167–9. Oguz S, Mutluay MM, Dogan OM, Bek B. Color change evaluation of denture soft lining materials in coffee and tea. Dent Mater J 2007;26(2):209–16. Kasuga Y, Takahashi H, Akiba N, Minakuchi S, Matsushita N, Hishimoto M. Basic evaluation on physical properties of experimental fluorinated soft lining materials. Dent Mater J 2011;30(1):45–51. Canay Ş, Hersek N, Tulunoğlu I, Uzun G. Evaluation of colour and hardness changes of soft lining materials in food colorant solutions. J Oral Rehabil 1999;26(10):821–9. Chladek G, Kalamarz I, Pakieła W, Barszczewska-Rybarek I, Czuba Z, Mertas A. A temporary acrylic soft denture lining material enriched with silver-releasing filler—cytotoxicity, mechanical and antifungal properties. Materials 2024;17(4):902. Tian Y, Chen C, Xu X, Wang J, Hou X, Li K, et al. A review of 3D printing in dentistry: Technologies, affecting factors, and applications. Scanning 2021;2021(1):9950131. Alsaggaf A, Fenlon MR. A case control study to investigate the effects of denture wear on residual alveolar ridge resorption in edentulous patients. J Dent 2020;98:103373. Yadav R, Meena A, Lee H-H, Lee S-Y, Park S-J. Tribological behavior of dental resin composites: A comprehensive review. Tribol Int 2023;190:109017. Guler AU, Yilmaz F, Kulunk T, Guler E, Kurt S. Effects of different drinks on stainability of resin composite provisional restorative materials. J Prosthet Dent 2005;94(2):118–24. Costa B, Neves CB, Roque JC, Anes V, Santos V. Influence of food pigments and thermal aging on the color stability of denture base resins. Appl Sci 2025;15(3):1503. Paravina RD, Ghinea R, Herrera LJ, Bona AD, Igiel C, Linninger M, et al. Color difference thresholds in dentistry. J Esthet Restor Dent 2015;27\:S1–9. ISO 10139-1:2018. Dentistry—Soft lining materials for removable dentures—Part 1: Materials for short-term use. ISO 10139-2:2009. Dentistry—Soft lining materials for removable dentures—Part 2: Materials for long-term use. Kiat‐Amnuay S, Gettleman L, Mekayarajjananonth T, Khan Z, Goldsmith LJ. The influence of water storage on durometer hardness of five soft denture liners over time. J Prosthodont 2005;14(1):19–24. Saraç D, Saraç YŞ, Kurt M, Yüzbaşioğlu E. The effectiveness of denture cleansers on soft denture liners colored by food colorant solutions. J Prosthodont 2007;16(3):185–91. Mancuso DN, Goiato MC, Zuccolotti BCR, Moreno A, dos Santos DM, Pesqueira AA. Effect of thermocycling on hardness, absorption, solubility and colour change of soft liners. Gerodontology 2012;29(2)\:e215–9. Ergun G, Ataol AS, Şahin Z, Altürk RG. The impact of adding nano zirconium dioxide fillers on color change, water sorption and solubility for denture liners. Acta Odontol Turc 2022;39(2):26–31. Felemban NH, Ebrahim MI. The influence of adding modified zirconium oxide–titanium dioxide nanoparticles on mechanical properties of orthodontic adhesive: an in vitro study. BMC Oral Health 2017;17:1–8. Urban VM, Lima TF, Bueno MG, Giannini M, Arioli Filho JN, de Almeida ALP, et al. Effect of the addition of antimicrobial agents on Shore A hardness and roughness of soft lining materials. J Prosthodont 2015;24(3):207–14. Pisani MX, Silva‐Lovato CH, Malheiros‐Segundo AdL, Macedo AP, Paranhos HFO. Bond strength and degree of infiltration between acrylic resin denture liner after immersion in effervescent denture cleanser. J Prosthodont 2009;18(2):123–9. Parr GR, Rueggeberg FA. In vitro hardness, water sorption, and resin solubility of laboratory-processed and autopolymerized long-term resilient denture liners over one year of water storage. J Prosthet Dent 2002;88(2):139–44. Parker S, Martin D, Braden M. Soft acrylic resin materials containing a polymerisable plasticiser. II: Water absorption characteristics. Biomaterials 1999;20(1):55–60. Pisani MX, da Silva CHL, Paranhos HFO, Souza RF, Macedo AP. Evaluation of experimental cleanser solution of *Ricinus communis*: effect on soft denture liner properties. Gerodontology 2012;29(2)\:e179–85. Pavan S, Dos Santos PH, Filho JNA, Spolidorio DMP. Colonisation of soft lining materials by micro‐organisms. Gerodontology 2010;27(3):211–6. Hong G, Li Y, Maeda T, Mizumachi W, Sadamori S, Hamada T, et al. Influence of storage methods on the surface roughness of tissue conditioners. Dent Mater J 2008;27(2):153–8. Kutlu IU, Yanikoğlu ND, Kul E, Duymuş ZY, Sağsöz NP. Effect of sealer coating and storage methods on the surface roughness of soft liners. J Prosthet Dent 2016;115(3):371–6. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 31 Oct, 2025 Read the published version in BMC Oral Health → Version 1 posted Editorial decision: Revision requested 29 Sep, 2025 Reviews received at journal 28 Sep, 2025 Reviews received at journal 15 Sep, 2025 Reviewers agreed at journal 10 Sep, 2025 Reviews received at journal 26 Aug, 2025 Reviewers agreed at journal 25 Aug, 2025 Reviewers agreed at journal 21 Aug, 2025 Reviewers agreed at journal 18 Aug, 2025 Reviewers invited by journal 18 Aug, 2025 Editor invited by journal 11 Aug, 2025 Editor assigned by journal 11 Aug, 2025 Submission checks completed at journal 11 Aug, 2025 First submitted to journal 28 Jul, 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. 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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-7234810","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":505852213,"identity":"088481ed-d2a5-4b23-9056-eba046fa72f8","order_by":0,"name":"ALKAN DEMETOĞLU Göknil","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+0lEQVRIiWNgGAWjYFACNgaGhAIGBj4eIPsDAzNIyIAILUA1bEAtjDPgWhIIaGGAamHmIUaLvHtb2oMHBgzybDyHnz22qbFObGBv3ibB+OMeTi2GZ44dNwA6zLCNt83cOOdYemIDz7EyCYaEYtxaZqS3SQC1MLbxM5hJ57AdTmyQyDEDasHtMpgW+zZ+9m/SFv+AWuTf4NciL5F2DKQlsY23x0yasQ1kCw9+LQY8x9KAWiSS23jOlEn29qUbt/GkFVskpOGxpb3NTPJHhY1tP0/6Nokf36xl+9kPb7zxwQaPLQfAlARCBBRPeGNSvgGP5CgYBaNgFIwCMAAAZ5hHzXiGcGkAAAAASUVORK5CYII=","orcid":"","institution":"Adnan Menderes University","correspondingAuthor":true,"prefix":"","firstName":"ALKAN","middleName":"DEMETOĞLU","lastName":"Göknil","suffix":""},{"id":505852214,"identity":"337d01f3-256a-4314-bc9e-47d57b1752ba","order_by":1,"name":"TALAY ÇEVLİK Esra","email":"","orcid":"","institution":"Adnan Menderes University","correspondingAuthor":false,"prefix":"","firstName":"TALAY","middleName":"ÇEVLİK","lastName":"Esra","suffix":""},{"id":505852215,"identity":"09b7b29d-64b0-473c-a969-f00825699ae6","order_by":2,"name":"Osman KAYA","email":"","orcid":"","institution":"Adnan Menderes University","correspondingAuthor":false,"prefix":"","firstName":"Osman","middleName":"","lastName":"KAYA","suffix":""},{"id":505852216,"identity":"44cbe5e5-1d32-49c2-be33-7430e7676a32","order_by":3,"name":"Pınar YILDIZ","email":"","orcid":"","institution":"Nimet Bayraktar ADSM","correspondingAuthor":false,"prefix":"","firstName":"Pınar","middleName":"","lastName":"YILDIZ","suffix":""}],"badges":[],"createdAt":"2025-07-28 14:08:47","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7234810/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7234810/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12903-025-07259-6","type":"published","date":"2025-10-31T15:57:59+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":95039988,"identity":"0960f130-0ee4-4507-af13-1be6ed46ae8b","added_by":"auto","created_at":"2025-11-03 16:07:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":981784,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7234810/v1/2ffd0254-d84b-4cc6-8893-6a574f9ddb23.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparative Evaluation of the Basic Physical Properties of a 3D Printed Experimental Soft Liner versus Conventional Soft Relining Materials","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSoft denture lining materials were first introduced for clinical use in 1943 (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Since then, their use has become increasingly popular for enhancing the comfort of denture wearers, particularly for those using removable dentures who may not tolerate conventional hard denture bases, especially in cases of thin and non-resilient mucosa or severe alveolar resorption (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThis is because, during mastication, the thin mucosa becomes compressed between the rigid denture base and the underlying bone, leading to irritation in the affected area or the spread of pain (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn such clinical situations, soft liner materials help protect the tissues from localized stresses during functional loading (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Soft denture liners play a crucial role in distributing functional loads evenly across the denture-bearing area, preventing localized stress concentrations. They function as a cushioning layer between the rigid denture base and the underlying tissues, thereby reducing the risk of mucosal trauma. Moreover, by minimizing excessive pressure on the alveolar ridge, soft liner materials may contribute to the reduction of residual ridge resorption, thereby enhancing patient comfort. Simultaneously, their ability to adapt to undercut areas improves denture retention, offering both biological and mechanical advantages in prosthodontic rehabilitation (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). The effectiveness of these materials in providing cushioning largely depends on their resilience (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAccording to ISO 10139 standards, soft relining materials are classified as long-term (more than 30 days) or short-term (a continuous period from 60 minutes up to 30 days). The second group, short-term materials, is clinically used as tissue conditioners and temporary soft lining materials (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThree-dimensional (3D) printing is a rapidly advancing technology that fabricates physical objects by sequentially layering materials based on digital designs created through specialized software (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). 3D printing is expected to become the leading digital manufacturing technique in dentistry\u0026mdash;especially in prosthodontics\u0026mdash;due to its speed, accuracy, design versatility, and efficient use of materials. Recent years have seen a notable rise in the development of dental materials tailored for additive manufacturing (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAlthough various printable resins have recently entered the market for both permanent and temporary prosthetic restorations, to the best of the authors' knowledge, a soft liner material produced using the 3D printing method has not yet been reported in the literature.\u003c/p\u003e\u003cp\u003eConventional soft lining materials belong to the group of polymeric dental materials; however, several issues associated with the use of soft liners have been reported, including hardening over time, color instability, microbial colonization, and detachment from the denture base (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). These clinical challenges necessitate a creative approach and the pursuit of new solutions to improve their properties. Such advancements may be achieved, as in other types of dental materials, through the development of composites incorporating a reinforcing phase that enhances the desired biofunctional characteristics combined with a rational design approach based on modern methodologies (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe 3D-printed experimental soft liner material used in this study has the potential to be utilized in both removable prostheses for patients with thin mucosa and maxillofacial prostheses, allowing fabrication through digital impressions. This approach could enable a comfortable and pressure-free impression and relining process, benefiting both the patient and the clinician.\u003c/p\u003e\u003cp\u003eThe aim of this study is to compare the properties required for clinical application of a potentially novel soft liner material\u0026mdash;designed to benefit from digital impression techniques and 3D printing technologies that enable pressure-free tissue registration\u0026mdash;with those of conventional short- and long-term soft liner materials.\u003c/p\u003e\u003cp\u003eThe null hypothesis (H₀) of this study is that there is no significant difference in the clinically relevant properties\u0026mdash;such as color change, surface roughness, and hardness\u0026mdash;between the 3D printed experimental soft liner material and conventional short- and long-term soft denture liners.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThis study evaluated three different soft denture relining materials. One of them was an experimental 3D printed soft liner (Group 3D), as outlined in Table\u0026nbsp;1. The other two were widely used, commercially available products: an acrylic-based short-term tissue conditioner (GC Tissue Conditioner, Tokyo, Japan) referred to as Group GC, and an autopolymerising silicone-based long-term reline material (Ufi Gel P, Voco GmbH, Cuxhaven, Germany), labelled as Group UP. Detailed formulations for all three materials are presented in Table\u0026nbsp;1.\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\u003eChemical Composition of the Soft Relining Materials Used in the Study\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroups\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eManufacturer\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eComposition\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup 3D\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(Experimental 3D Printed Liner)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAliphatic urethane diacrylate, morpholine, acrylic acid ester, trimethylolpropane acrylate, monofunctional urethane acrylate\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup GC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGC Comporation, Tokyo, Japan\u003c/p\u003e\u003cp\u003e(Tissue Treating and Conditioner)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePEMA powder, liquid (composed of dibutyl sebacate and ethanol), and a coating agent (consisting of ethyl acetate and dissolved polymer)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup UP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVoco GmbH, Cuxhaven, Germany\u003c/p\u003e\u003cp\u003e(Ufi Gel P, Cold Curing, Silicone-based Soft lining Material)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eModified polydimethyl siloxane and platinum catalyst\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eSpecimen Preparation\u003c/h2\u003e\u003cp\u003eFor Group 3D, two types of specimens were prepared: square-shaped samples (10 \u0026times; 10 \u0026times; 2 mm) and cylindrical samples (15 mm in diameter and 10 mm in height). The experimental 3D printing resin was loaded into a DLP printer (Asiga Max UV\u0026ndash;385 nm, Asiga Pty. Ltd., Australia). Specimens were printed layer by layer at a thickness of 50 \u0026micro;m and oriented at 0\u0026deg;, according to the pre-determined dimensions. After printing, the specimens were cleaned with isopropanol and then post-cured by immersion for 10 minutes in a post-curing oven (Lilivis Cure, 395 nm, Huvitz, South Korea) to ensure the complete polymerisation of any remaining monomers.\u003c/p\u003e\u003cp\u003eFor groups GC and UP, specimens were fabricated using custom-made metal molds in two shapes: square (10 \u0026times; 10 \u0026times; 2 mm) and cylindrical (15 mm in diameter and 10 mm in height). Each mold was placed on a glass slab coated with petroleum jelly to facilitate easy removal of the specimens.\u003c/p\u003e\u003cp\u003eThe soft denture liners were prepared according to the manufacturers\u0026rsquo; instructions. For group GC, the material was mixed at a ratio of 2.2 g powder to 1.8 g liquid by weight (equivalent to the first graduation on the powder measure and four graduations of the liquid syringe by volume). Both components were combined in a glass jar and mixed for 30 seconds.\u003c/p\u003e\u003cp\u003eFor group UP, the base and catalyst were proportioned in a 1:1 ratio by weight and mixed thoroughly for 30 seconds. The prepared mixtures were then placed into the molds, which remained on the glass slab. Another glass slab, also coated with petroleum jelly, was placed on top. The two slabs were pressed firmly together to eliminate excess material and shape the specimens precisely according to the mold dimensions.\u003c/p\u003e\u003cp\u003eAfter polymerisation, the specimens were carefully removed from the molds and trimmed using a sharp blade to ensure uniform edges. Specimens in group GC were additionally polished using the manufacturer-provided coating agent. All specimens were then stored in distilled water at 37\u0026deg;C for 24 hours prior to testing.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eColor Change Evaluation\u003c/h3\u003e\n\u003cp\u003eSquare-shaped specimens (n\u0026thinsp;=\u0026thinsp;10 per group) were used to assess color changes. Baseline color measurements were recorded before immersion. Based on the protocol by G\u0026uuml;ler et al. (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e), which equates 24 hours of immersion to approximately one month of clinical aging, the specimens were immersed in a coffee solution at 37\u0026deg;C\u0026mdash;renewed daily\u0026mdash;for simulated aging periods: 5.5 hours (1 week), 24 hours (1 month), and 72 hours (3 months).\u003c/p\u003e\u003cp\u003eTo prevent contact or cross-contamination, each specimen was placed in an individually sectioned, water-permeable fabric during immersion (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe granule coffee solution (Nescafe Classic, Nestl\u0026eacute;, Switzerland) was prepared by dissolving 3.6 g of instant coffee in 300 mL of boiling distilled water, following the manufacturer\u0026rsquo;s guidelines. The mixture was stirred for 10 minutes and filtered through standard filter paper.\u003c/p\u003e\u003cp\u003eAfter each immersion period, specimens were rinsed with distilled water, gently blotted dry with tissue paper, and air-dried at room temperature before taking color measurements.\u003c/p\u003e\n\u003ch3\u003eColor Measurement Protocol\u003c/h3\u003e\n\u003cp\u003eInitial color values (L*, a*, b*) of the specimens were measured using a spectrophotometer (VITA Easyshade V, VITA Zahnfabrik, Germany). The device was calibrated before each use according to the manufacturer's instructions. All measurements were conducted by a single researcher under standardized daylight conditions at a consistent time of day to ensure reliability. The same background color used by Costa et al. (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e) was selected as the reference (L₀, a₀, b₀).\u003c/p\u003e\u003cp\u003eTo reduce the influence of ambient light and ensure consistent positioning, a custom-made silicone mold compatible with the spectrophotometer was fabricated. During measurements, the device was placed vertically in direct contact with the specimen through the mold on a flat surface.\u003c/p\u003e\u003cp\u003eColor values (L*, a*, b*) were recorded across the entire surface of each specimen, and the average of these readings was defined as the baseline value (L₀, a₀, b₀). Following each immersion interval, the same protocol was applied. Three measurements were taken per specimen after aging, and the mean value was used for analysis. Color differences (ΔE₀₀) were then calculated using the recorded data.\u003c/p\u003e\n\u003ch3\u003eColor Stability (ΔE₀₀)\u003c/h3\u003e\n\u003cp\u003eColor differences were calculated according to the CIEDE2000 formula to determine color stability over time. Specifically, ΔE₀₀₇, ΔE₀₀₃₀, and ΔE₀₀₉₀ represent the color changes observed after 1 week, 1 month, and 3 months of aging, respectively.\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:\\varDelta\\:{E}_{00}=\\sqrt[2]{{\\left(\\frac{\\varDelta\\:{L}^{{\\prime\\:}}}{{K}_{L}{S}_{L}}\\right)}^{2}+{\\left(\\frac{\\varDelta\\:{C}^{{\\prime\\:}}}{{K}_{c}{S}_{c}}\\right)}^{2}+{\\left(\\frac{\\varDelta\\:{H}^{{\\prime\\:}}}{{K}_{H}{S}_{H}}\\right)}^{2}+{R}_{T}\\left(\\frac{\\varDelta\\:{C}^{{\\prime\\:}}}{{K}_{c}{S}_{c}}\\right)\\left(\\frac{\\varDelta\\:{H}^{{\\prime\\:}}}{{K}_{H}{S}_{H}}\\right)}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe CIELAB values were converted into CIEDE2000 parameters: L\u0026prime; (lightness), C\u0026prime; (chroma), and h\u0026prime; (hue). Within the CIEDE2000 uniform color space, the differences in these parameters\u0026mdash;ΔL\u0026prime;, ΔC\u0026prime;, and ΔH\u0026prime;\u0026mdash;were calculated as the metric differences between the corresponding values of each sample. To refine these values and reflect perceptual uniformity, three weighting functions were applied: SL, SC, and SH, adjusted by the empirical parametric factors KL, KC, and KH, respectively.\u003c/p\u003e\u003cp\u003eIn addition, the RT term was included to account for the interaction between chroma and hue differences, particularly to correct for perceptual distortions in the blue region of the color space. For this study, all parametric factors (KL, KC, and KH) were set to 1, in accordance with the standard conditions defined by the CIEDE2000 formula. As noted by Paravina et al. (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), a ΔE₀₀ value of 0.8 is considered the threshold for clinical perceptibility, while 1.8 is deemed the upper limit for clinical acceptability. This benchmark was adopted in our study to evaluate the clinical significance of the observed color changes.\u003c/p\u003e\n\u003ch3\u003eSurface Roughness Evaluation\u003c/h3\u003e\n\u003cp\u003eSurface roughness was evaluated on the basal surface of cylindrical specimens. A total of 20 specimens were used, with five specimens allocated for each time point. For each specimen, five measurements were taken using a surface roughness tester (Surftest SJ-210; Mitutoyo Corporation, Kanagawa, Japan), calibrated with a 0.8 mm cut-off value and a scanning speed of 0.5 mm/s, covering a total distance of 4.0 mm. The average surface roughness (Ra) was calculated for each specimen at every evaluation period.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eWater Immersion and Measurement Time Intervals\u003c/h2\u003e\u003cp\u003eBaseline surface roughness measurements (T0) were taken prior to immersion. The specimens were then stored in distilled water at 37\u0026deg;C to simulate oral conditions.\u003c/p\u003e\u003cp\u003eMeasurements were conducted after 7-day immersion period (T1), 30 days (T2) and 90 days (T3) of water storage at 37\u0026deg;C, in accordance with ISO 10139-1:2018 (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e) and ISO 10139-2:2009 (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e), which covers soft lining materials designed for extended clinical application.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eHardness Measurement\u003c/h3\u003e\n\u003cp\u003eShore A hardness was measured on the surface opposite to that used for surface roughness evaluation, using a durometer (Turonic, Shanghai, China). Initial measurements were performed one hour after specimen preparation. For each material, 20 cylindrical specimens were fabricated. At each time point, five specimens were randomly selected, and five hardness readings were taken on a single, flat surface of each specimen. The durometer was applied with a 1 kg-f load and a one-second dwell time to ensure consistent penetration and accurate measurement (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e).\u003c/p\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eThe sample size was calculated using G*Power 3.1.9.7 (Heinric-Heine-Universit\u0026auml;t D\u0026uuml;sseldorf, Germany) based on data from a similar study by Kasuga et al. (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) Using a pooled standard deviation of 2.477, the effect size was determined as 2.21138. With 95% power and 5% significance, 9 samples were required for each of the 3 groups. As the initially calculated sample size was deemed insufficient, the final sample size was determined to be 30, with 10 samples allocated to each group.\u003c/p\u003e\u003cp\u003eStatistical analyses were performed using SPSS version 22.0 (SPSS Inc., Chicago, IL, USA). Descriptive statistics, including the mean, standard deviation, minimum, and maximum values, were calculated for all variables. The normality of data distribution was assessed using the Shapiro\u0026ndash;Wilk test, and the homogeneity of variances was evaluated using Levene\u0026rsquo;s test for color, surface roughness, and hardness measurements. Changes in color values over time were analyzed using repeated measures ANOVA. When the assumptions of normality and homogeneity of variances were met, comparisons between different materials were performed using one-way ANOVA. In cases where the assumption of homogeneity was violated, as indicated by Levene\u0026rsquo;s test (e.g., for surface roughness data), Welch\u0026rsquo;s ANOVA was used. Similarly, Shore A hardness values were compared between groups using one-way ANOVA, provided that the assumptions of normality and homogeneity were satisfied. Post hoc pairwise comparisons were conducted using either the Bonferroni or Tamhane\u0026rsquo;s T2 test, depending on the equality of variances. A significance level of 0.05 was set for all statistical tests.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eEvaluation of Color Change\u003c/h2\u003e\u003cp\u003eAccording to the results of the one-way ANOVA, which compared different groups at various time points, statistically significant differences were observed across all time points. Based on the Tamhane T2 post hoc test, the UP group exhibited significantly lower color change values compared to the other two groups, while the 3D group showed similar results to the GC group.\u003c/p\u003e\u003cp\u003eRepeated measures ANOVA (Table\u0026nbsp;2), used for within-group comparisons over time, revealed a statistically significant increase in color change across all groups. According to the Bonferroni post hoc test, the 3D group showed a significant increase in color change at all time points. In contrast, In the GC group, no significant differences were observed between T0 and T1, and between T2 and T3. No significant difference was found between time points T0 and T1 in the UP group, whereas the increases at other time points were significant.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\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\u003eRepeated measures ANOVA results for Color Change Over Time\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eMaterials\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c6\" namest=\"c5\" rowspan=\"2\"\u003e\u003cp\u003eTest Statistics\u003csup\u003e\u0026dagger;\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup GC\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGroup 3D\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eGroup UP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ex̄\u0026plusmn; \u003cem\u003eSD\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ex̄\u0026plusmn; \u003cem\u003eSD\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ex̄\u0026plusmn; \u003cem\u003eSD\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003eTime\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.80\u0026thinsp;\u0026plusmn;\u0026thinsp;2.61\u003csup\u003ea,A\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003csup\u003ea,A\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72\u003csup\u003eb,A\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e21.3215\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT1\u003c/p\u003e\u003cp\u003eT2\u003c/p\u003e\u003cp\u003eT3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.98\u003csup\u003ea,A\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e8.86\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99\u003csup\u003ea,B\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e8.76\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62\u003csup\u003ea,B\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.06\u003csup\u003ea,B\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e8.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.95\u003csup\u003ea,C\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e9.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.75\u003csup\u003ea,D\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47\u003csup\u003eb,A\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e2.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003csup\u003eb,B\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003csup\u003eb,C\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e44.5367\u003c/p\u003e\u003cp\u003e68.0688\u003c/p\u003e\u003cp\u003e91.5027\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTest Statistics\u003c/b\u003e\u003csup\u003e\u003cb\u003e\u0026Dagger;\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16.4532\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e126.3813\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e42.8801\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003ex̄: Mean, \u003cem\u003eSD\u003c/em\u003e: Standard deviations,\u0026nbsp;\u003csup\u003e\u0026dagger;\u003c/sup\u003e: Intergroup comparisons for materials (One-way ANOVA, Tamhane T2 test results), The superscripts a and b indicate groups with statistically significant differences in each measurement. Groups with the same superscripts are statistically similar. \u003csup\u003e\u0026Dagger;\u003c/sup\u003e: Intergroup comparisons of materials (Repeated measures ANOVA and Bonferroni test results) The superscripts A, B, C and D indicate groups with statistically significant differences in each time interval\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eEvaluation of Roughness Data\u003c/h2\u003e\u003cp\u003eAccording to the results of the one-way ANOVA (Table\u0026nbsp;3) and Welch\u0026rsquo;s test, there were statistically significant differences among the groups at all time points. Pairwise comparisons using the Bonferroni and Tamhane post hoc tests revealed that all groups differed significantly from each other. The highest surface roughness values were observed in the GC group, while the lowest values were recorded in the UP group.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\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\u003eWelch\u0026rsquo;s ANOVA Results for Surface Roughness\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003eSURFACE ROUGHNESS TEST RESULTS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMean\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eStandart Deviations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMinimum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMaksimum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eRoughness T0\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e4,33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3,87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4,77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e1,54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1,32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1,83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e0,65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0,53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0,86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eF/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;336,347/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eRoughness T1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e3,75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3,89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e1,39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1,27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1,51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e0,49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0,36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0,59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eF/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;1024,477/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eRoughness T2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e4,29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3,76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4,76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e1,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1,34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1,70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e0,79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0,71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1,01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWELCH\u0026rsquo;S F/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;156,578/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eRoughness T3\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e4,02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3,52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4,43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e1,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1,07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1,69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e0,58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0,69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWELCH\u0026rsquo;S F/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;169,140/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eThe superscripts a, b and c indicate groups with statistically significant differences in each measurement\u003c/h2\u003e\u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\u003ch2\u003eShore A Hardness Test Results\u003c/h2\u003e\u003cp\u003eAccording to the one-way ANOVA (Table\u0026nbsp;4) results, there were statistically significant differences in Shore A hardness values among the groups at all time intervals. Pairwise comparisons using the Bonferroni test indicated that all groups differed significantly from each other. The highest Shore A Hardness value was observed in the 3D group at time point T0, whereas the lowest value was recorded in the GC group at time point T3.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\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\u003eOne-way ANOVA results of Shore A Hardness Test Results\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003eSURFACE HARDNESS TEST RESULTS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMean\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eStandart deviations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMinimum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMaksimum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eShore A T0\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e24,72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1,03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e23,60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e26,40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e69,32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e68,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e70,00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e35,08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e34,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e35,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eF/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;5136.49/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eShore A T1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e14,66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e15,40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e58,96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1,03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e57,90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e60,30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e26,60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e25,90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e27,10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eF/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;4688.02/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eShore A T2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e12,18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11,30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e12,70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e55,76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1,33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e53,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e57,00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eVOCO\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e26,60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e25,30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e27,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eF/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;2536.41/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eShore A T3\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eGC\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\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\u003e15,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1,70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e14,00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e17,60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e3D\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\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\u003e54,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0,82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e54,20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e55,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eUP\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\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\u003e27,48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1,03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e25,80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e28,50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eF/p\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eF\u0026thinsp;=\u0026thinsp;1298.79/ p\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003cp\u003eThe superscripts a, b and c indicate groups with statistically significant differences in each measurement\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIdeal soft lining materials should exhibit durable viscoelastic properties over time, minimal water sorption, resistance to discoloration, strong adhesion to the denture base, dimensional stability, ease of handling during processing, and excellent biocompatibility (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn this study, an experimental soft relining resin was developed in collaboration with a manufacturer for potential use in 3D printing applications. The resin composition included monomers such as aliphatic urethane diacrylate, trimethylolpropane acrylate, and monofunctional urethane acrylate, imparting it with an acrylic nature. The rationale behind selecting this composition lies in the increasing reliability of digital impressions, which allow for pressure-free impression techniques. This is particularly advantageous in cases where soft lining materials are indicated, such as resorbed alveolar ridges or maxillofacial defects, where minimizing trauma is essential. Therefore, there is a clinical need for a soft lining material that is compatible with 3D printed acrylic denture bases. The chosen resin offers ease of application, chemical bonding capability to acrylic bases, and adjustable softness through plasticizer content. To determine the suitability of the experimental material for either long-term relining or short-term tissue conditioning, it was compared with two reference materials: tissue conditioner, representing short-term use, and soft-liner, which is indicated for long-term applications.\u003c/p\u003e\u003cp\u003eSeveral studies have consistently demonstrated the superior color stability of silicone-based soft liners compared to acrylic-based materials. Canay et al. (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) reported that acrylic-based soft liners exhibited greater discoloration than silicone-based ones when immersed in food colorant solutions. Similarly, Sara\u0026ccedil; et al.(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e) found that silicone-based liners were more resistant to staining. In a related study, Mancuso et al. (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e) evaluated the color change and hardness of soft liners composed of either acrylic resin (Trusoft) or silicone (Dentusil, Ufi Gel P, and Ufi Gel SC) after thermocycling. Their findings indicated that silicone-based liners exhibited significantly better color stability and that acrylic-based materials presented the lowest Shore A hardness values following thermocycling. The significant color changes were attributed to the inherent material characteristics. In agreement with these findings, our study revealed that the UP group (a silicone-based liner) exhibited the least color change, while the 3D and GC groups showed similar outcomes. These results further support the notion that silicone-based soft liners tend to be more color stable, demonstrating a consistent pattern across different studies and material types.\u003c/p\u003e\u003cp\u003eWhen the effect of time intervals was considered in our study, the 3D group exhibited a significant increase in color change at all time points. In contrast, the GC group showed no significant difference between T0 and T1, or between T2 and T3. Similarly, in the UP group, no significant difference was observed between T0 and T1; however, the increases at subsequent time points were statistically significant.\u003c/p\u003e\u003cp\u003eThese findings may be related to the material composition. According to Erg\u0026uuml;n et al.,(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e) the UP group contains dimethylsiloxane as its primary component, which contributes to its color stability. In contrast, acrylic-based liners tend to contain higher concentrations of plasticizers and ethanol. The rapid release of ethanol from these materials is considered a contributing factor to the greater degree of color change observed in comparison to the UP group.\u003c/p\u003e\u003cp\u003eSurface roughness is a critical property of polymeric materials, particularly due to its influence on microbial adhesion. In the context of denture base materials, the initial attachment of microorganisms serves as a key step in biofilm formation, which can subsequently lead to conditions such as denture-related stomatitis. To mitigate this risk, it is essential that these materials possess smooth surface characteristics, thereby reducing microbial adherence and minimizing the potential for biofilm development and the associated onset of oral mucositis.(\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eIn the present study, the surface roughness values of the experimental 3D-printed group showed no statistically significant differences across all measured time intervals over the three-month period. A marked decrease was observed in the surface roughness measurements of the GC and UP groups, particularly after the first week. This decrease was followed by a notable increase at the end of the first month in the same groups. The experimental 3D group remained stable throughout the study period, exhibiting a smoother surface compared to the GC group, but consistently rougher than the UP group at all time intervals.\u003c/p\u003e\u003cp\u003eIn the study conducted by Urban et al., in which they incorporated antimicrobial agents and evaluated Shore A hardness and surface roughness, a decrease in surface roughness values was observed in the one-week measurements of the control group, which included a tissue conditioner and an acrylic-based long-term resilient liner. This finding is consistent with the decrease observed in our study during the same time period.(\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) Additionally, the lowest surface roughness values were recorded in the UP group, while the experimental 3D group maintained values around 1.5 and did not exhibit statistically significant changes over time.\u003c/p\u003e\u003cp\u003eOne of the major challenges in the clinical use of soft denture liners is maintaining their hardness within acceptable limits, primarily due to their susceptibility to changes in the aqueous oral environment (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). During clinical use, these materials are continuously exposed to saliva, food, water, and oral hygiene products, leading to leaching of their components and increased water absorption (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). These effects are commonly associated with increased hardness, expansion, distortion, discoloration, unpleasant odor emission, and the enhanced adhesion and proliferation of microorganisms (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSurface roughness of dental materials plays a critical role in biofilm accumulation, thereby facilitating the development and persistence of oral pathologies (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWhile soft lining materials typically exhibit greater surface irregularities and higher roughness compared to denture base resins\u0026mdash;thereby promoting more bacterial colonization\u0026mdash;they are still used as long-term solutions, sometimes for several months or even years (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eIn the present study, although the specimens were standardized by preparing them between two glass slabs, the initial surface roughness values varied among groups and exceeded 0.2 \u0026micro;m, which is recognized as the critical threshold for microbial adhesion (\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAmong the tested groups, the highest roughness was observed in the GC group, while the lowest was recorded in the UP group; however, all groups exceeded the aforementioned threshold.\u003c/p\u003e\u003cp\u003eIn contrast to our findings Kutlu et al.(\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e) evaluated the surface roughness of methacrylate- and silicone-based liners after applying a coating and storing them in various solutions. They reported that methacrylate-based liners exhibited a greater increase in surface roughness compared to silicone-based liners.\u003c/p\u003e\u003cp\u003eAccording to ISO 10139-2:200 standards, the acceptable Shore A hardness values for soft lining materials range between 20 and 50. Although the initial Shore A value of the experimental 3D material investigated in this study was higher than this range, it was observed to approach the acceptable limits over the time intervals. This can be considered a favorable outcome when clinical and storage conditions are taken into account. Furthermore, it is anticipated that the Shore A value may remain within the expected range for a longer duration. Since a Shore A value that is too low may result in inadequate cushioning and insufficient protection of the oral tissues, achieving an optimal hardness is essential. Given that the material is experimental, modifying the type and ratio of plasticisers within its composition could help achieve more ideal Shore A values.\u003c/p\u003e\u003cp\u003eIn the literature, studies evaluating the hardness of soft lining materials have reported the addition of various agents to enhance their antimicrobial properties. In the study by Kasuga et al., (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) who incorporated fluoride, no significant changes were observed in the Shore A hardness values of acrylic-based and silicone-based soft lining materials after one week of water immersion.\u003c/p\u003e\u003cp\u003eIn the study by Urban et al.,(\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) which evaluated tissue conditioners and resilient liners with added antimicrobial agents, an increase in Shore A hardness was observed in the tissue conditioner, while no significant time-dependent changes were detected in the resilient liner. In contrast to our study, the Shore A hardness value in the experimental 3D group decreased over one week time.\u003c/p\u003e\u003cp\u003eKasuga et al.(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) and Urban et al.(\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) conducted their studies with evaluation periods limited to one and two weeks. In contrast, our study extended the assessment periods to one and three months to more thoroughly evaluate the materials\u0026rsquo; suitability for long-term clinical application. At the one-month evaluation, the experimental 3D group demonstrated Shore A values comparable to those recorded at one week, whereas the GC and UP groups exhibited a decline. At three months, the experimental 3D group continued to maintain Shore A values similar to the initial measurement, while the GC group showed a further decrease and the UP group exhibited an increase. These variations are likely attributable to differences in material composition especially regarding the type and quantity of plasticizers. (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e) It is important to note that the GC group is recommended primarily for short-term use.\u003c/p\u003e\u003cp\u003eThis study has several limitations that should be acknowledged. Firstly, although the experimental period extended to three months\u0026mdash;longer than many previous studies\u0026mdash;it may still not fully represent the long-term clinical performance of soft lining materials, particularly for applications intended to last several months or years. Secondly, the in vitro nature of the study limits the generalizability of the results to clinical conditions, where factors such as salivary enzymes, mechanical forces from mastication, and patient-specific hygiene habits can significantly influence material behavior. Additionally, while color stability, surface roughness, and Shore A hardness were comprehensively evaluated, other important properties such as tensile strength, bond strength to denture base materials, microbial colonization resistance, and patient comfort were not assessed in this phase of the research. Finally, the experimental material was tested in its current formulation only; further studies are required to explore the impact of varying the plasticizer content and other compositional modifications to optimize clinical performance.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe experimental 3D-printed soft liner demonstrated promising results in terms of surface roughness and Shore A hardness stability over time, with color stability comparable to conventional materials. While its initial Shore A hardness was slightly above the ideal range, it gradually approached acceptable limits, suggesting potential for long-term clinical application. Given the growing reliability and accessibility of 3D printing technologies, this material may offer clinicians a valuable alternative for soft denture relining, particularly in cases requiring minimally traumatic solutions. Future studies should focus on optimizing its softness characteristics and investigating key properties such as bacterial adhesion and water sorption to enhance its clinical performance. As 3D technology continues to evolve, this type of material could become a viable and efficient option in prosthodontic practice.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank Arma Dental Üretim Sistemleri Sanayi ve Ticaret Ltd. Şti. (Kocaeli, Türkiye) and Sinan Günüç for their valuable support in the production and provision of the experimental 3D-printed soft liner material used in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization, Göknil Alkan Demetoğlu and Osman Kaya; Methodology, Göknil Alkan Demetoğlu and Osman Kaya; Investigation, Göknil Alkan Demetoğlu;, Osman Kaya Formal analysis, Esra Talay Çevlik, Pınar Yıldız; Writing – Original Draft Preparation, Göknil Alkan Demetoğlu; and Esra Talay Çevlik, and Pınar Yıldız Writing – Review \u0026amp; Editing, Göknil Alkan Demetoğlu;, Esra Talay Çevlik, Pınar Yıldız; Supervision, Göknil Alkan Demetoğlu. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study is self-funded. The authors do not have any financial interest in the companies whose materials are included in this article.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe original contributions presented in this study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author(s).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTylman S. The use of elastic and resilient synthetic resins and their copolymer in oral, dental and facial prostheses. Dent Digest 1943;49:167\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eOguz S, Mutluay MM, Dogan OM, Bek B. Color change evaluation of denture soft lining materials in coffee and tea. Dent Mater J 2007;26(2):209\u0026ndash;16.\u003c/li\u003e\n\u003cli\u003eKasuga Y, Takahashi H, Akiba N, Minakuchi S, Matsushita N, Hishimoto M. Basic evaluation on physical properties of experimental fluorinated soft lining materials. Dent Mater J 2011;30(1):45\u0026ndash;51.\u003c/li\u003e\n\u003cli\u003eCanay Ş, Hersek N, Tulunoğlu I, Uzun G. Evaluation of colour and hardness changes of soft lining materials in food colorant solutions. J Oral Rehabil 1999;26(10):821\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eChladek G, Kalamarz I, Pakieła W, Barszczewska-Rybarek I, Czuba Z, Mertas A. A temporary acrylic soft denture lining material enriched with silver-releasing filler\u0026mdash;cytotoxicity, mechanical and antifungal properties. Materials 2024;17(4):902.\u003c/li\u003e\n\u003cli\u003eTian Y, Chen C, Xu X, Wang J, Hou X, Li K, et al. A review of 3D printing in dentistry: Technologies, affecting factors, and applications. Scanning 2021;2021(1):9950131.\u003c/li\u003e\n\u003cli\u003eAlsaggaf A, Fenlon MR. A case control study to investigate the effects of denture wear on residual alveolar ridge resorption in edentulous patients. J Dent 2020;98:103373.\u003c/li\u003e\n\u003cli\u003eYadav R, Meena A, Lee H-H, Lee S-Y, Park S-J. Tribological behavior of dental resin composites: A comprehensive review. Tribol Int 2023;190:109017.\u003c/li\u003e\n\u003cli\u003eGuler AU, Yilmaz F, Kulunk T, Guler E, Kurt S. Effects of different drinks on stainability of resin composite provisional restorative materials. J Prosthet Dent 2005;94(2):118\u0026ndash;24.\u003c/li\u003e\n\u003cli\u003eCosta B, Neves CB, Roque JC, Anes V, Santos V. Influence of food pigments and thermal aging on the color stability of denture base resins. Appl Sci 2025;15(3):1503.\u003c/li\u003e\n\u003cli\u003eParavina RD, Ghinea R, Herrera LJ, Bona AD, Igiel C, Linninger M, et al. Color difference thresholds in dentistry. J Esthet Restor Dent 2015;27\\:S1\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eISO 10139-1:2018. Dentistry\u0026mdash;Soft lining materials for removable dentures\u0026mdash;Part 1: Materials for short-term use.\u003c/li\u003e\n\u003cli\u003eISO 10139-2:2009. Dentistry\u0026mdash;Soft lining materials for removable dentures\u0026mdash;Part 2: Materials for long-term use.\u003c/li\u003e\n\u003cli\u003eKiat‐Amnuay S, Gettleman L, Mekayarajjananonth T, Khan Z, Goldsmith LJ. The influence of water storage on durometer hardness of five soft denture liners over time. J Prosthodont 2005;14(1):19\u0026ndash;24.\u003c/li\u003e\n\u003cli\u003eSara\u0026ccedil; D, Sara\u0026ccedil; YŞ, Kurt M, Y\u0026uuml;zbaşioğlu E. The effectiveness of denture cleansers on soft denture liners colored by food colorant solutions. J Prosthodont 2007;16(3):185\u0026ndash;91.\u003c/li\u003e\n\u003cli\u003eMancuso DN, Goiato MC, Zuccolotti BCR, Moreno A, dos Santos DM, Pesqueira AA. Effect of thermocycling on hardness, absorption, solubility and colour change of soft liners. Gerodontology 2012;29(2)\\:e215\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eErgun G, Ataol AS, Şahin Z, Alt\u0026uuml;rk RG. The impact of adding nano zirconium dioxide fillers on color change, water sorption and solubility for denture liners. Acta Odontol Turc 2022;39(2):26\u0026ndash;31.\u003c/li\u003e\n\u003cli\u003eFelemban NH, Ebrahim MI. The influence of adding modified zirconium oxide\u0026ndash;titanium dioxide nanoparticles on mechanical properties of orthodontic adhesive: an in vitro study. BMC Oral Health 2017;17:1\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eUrban VM, Lima TF, Bueno MG, Giannini M, Arioli Filho JN, de Almeida ALP, et al. Effect of the addition of antimicrobial agents on Shore A hardness and roughness of soft lining materials. J Prosthodont 2015;24(3):207\u0026ndash;14.\u003c/li\u003e\n\u003cli\u003ePisani MX, Silva‐Lovato CH, Malheiros‐Segundo AdL, Macedo AP, Paranhos HFO. Bond strength and degree of infiltration between acrylic resin denture liner after immersion in effervescent denture cleanser. J Prosthodont 2009;18(2):123\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eParr GR, Rueggeberg FA. In vitro hardness, water sorption, and resin solubility of laboratory-processed and autopolymerized long-term resilient denture liners over one year of water storage. J Prosthet Dent 2002;88(2):139\u0026ndash;44.\u003c/li\u003e\n\u003cli\u003eParker S, Martin D, Braden M. Soft acrylic resin materials containing a polymerisable plasticiser. II: Water absorption characteristics. Biomaterials 1999;20(1):55\u0026ndash;60.\u003c/li\u003e\n\u003cli\u003ePisani MX, da Silva CHL, Paranhos HFO, Souza RF, Macedo AP. Evaluation of experimental cleanser solution of *Ricinus communis*: effect on soft denture liner properties. Gerodontology 2012;29(2)\\:e179\u0026ndash;85.\u003c/li\u003e\n\u003cli\u003ePavan S, Dos Santos PH, Filho JNA, Spolidorio DMP. Colonisation of soft lining materials by micro‐organisms. Gerodontology 2010;27(3):211\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eHong G, Li Y, Maeda T, Mizumachi W, Sadamori S, Hamada T, et al. Influence of storage methods on the surface roughness of tissue conditioners. Dent Mater J 2008;27(2):153\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eKutlu IU, Yanikoğlu ND, Kul E, Duymuş ZY, Sağs\u0026ouml;z NP. Effect of sealer coating and storage methods on the surface roughness of soft liners. J Prosthet Dent 2016;115(3):371\u0026ndash;6.\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":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"3D-printed lining material, soft denture liner, tissue conditioner, color stability, surface roughness, Shore A hardness","lastPublishedDoi":"10.21203/rs.3.rs-7234810/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7234810/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e\u003cp\u003eSoft denture liners are essential in prosthodontics for cushioning masticatory forces and enhancing patient comfort. Traditional liners, such as acrylic-based short-term and silicone-based long-term materials, are widely used. With the advent of additive manufacturing, 3D-printed materials have emerged as promising alternatives. However, their physical properties must be thoroughly evaluated before clinical implementation.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e\u003cp\u003eThis in vitro study compared the color stability, surface roughness, and Shore A hardness of an experimental 3D-printed soft liner with two conventional materials: GC (acrylic-based, short-term) and UP (silicone-based, long-term). Standardized specimens (n\u0026thinsp;=\u0026thinsp;10 per group) were immersed in distilled water and coffee at 37\u0026deg;C for 1 week, 1 month, and 3 months. Color change (ΔE₀₀) was measured using a spectrophotometer, surface roughness (Ra) with a profilometer, and hardness with a Shore A durometer. Data were analyzed using one-way and repeated measures ANOVA followed by Bonferroni post hoc tests (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e\u003cp\u003eThe 3D-printed soft liner showed significantly higher Shore A hardness compared to both GC and UP materials across all time intervals. In terms of color stability, the 3D-printed material performed similarly to GC but was inferior to UP. Surface roughness analysis revealed that the 3D-printed liner was rougher than UP, which maintained the smoothest surface and greatest color stability overall throughout the testing period.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e\u003cp\u003eWhile the 3D-printed experimental soft liner demonstrated clinically acceptable physical properties, particularly in hardness, its increased surface roughness and moderate color stability suggest that further formulation improvements are needed. Enhancements in softness and smoothness would be necessary for the material to become a viable alternative to conventional soft liners in routine prosthodontic practice.\u003c/p\u003e","manuscriptTitle":"Comparative Evaluation of the Basic Physical Properties of a 3D Printed Experimental Soft Liner versus Conventional Soft Relining Materials","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-27 06:24:38","doi":"10.21203/rs.3.rs-7234810/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-29T07:03:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-28T06:54:11+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-15T16:36:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"326562816863378077323850953607494031531","date":"2025-09-10T13:40:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-26T13:05:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"309347075252596107653899853794684933518","date":"2025-08-25T14:34:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"169493895029573235523703920778050621763","date":"2025-08-21T12:18:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"204277653833242694540277321573402672295","date":"2025-08-19T03:21:05+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-19T03:18:23+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-08-11T17:53:11+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-11T06:15:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-11T06:15:40+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-07-28T14:06:05+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"51c683df-7a4d-4553-9534-1d2f9896bfc9","owner":[],"postedDate":"August 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-03T16:02:04+00:00","versionOfRecord":{"articleIdentity":"rs-7234810","link":"https://doi.org/10.1186/s12903-025-07259-6","journal":{"identity":"bmc-oral-health","isVorOnly":false,"title":"BMC Oral Health"},"publishedOn":"2025-10-31 15:57:59","publishedOnDateReadable":"October 31st, 2025"},"versionCreatedAt":"2025-08-27 06:24:38","video":"","vorDoi":"10.1186/s12903-025-07259-6","vorDoiUrl":"https://doi.org/10.1186/s12903-025-07259-6","workflowStages":[]},"version":"v1","identity":"rs-7234810","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7234810","identity":"rs-7234810","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}