Comparative Analysis of Fit, Mechanical Properties, and Surface Characteristics in Subtractive and Additive Manufactured Zirconia Crowns

Comparative Analysis of Fit, Mechanical Properties, and Surface Characteristics in Subtractive and Additive Manufactured Zirconia Crowns | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparative Analysis of Fit, Mechanical Properties, and Surface Characteristics in Subtractive and Additive Manufactured Zirconia Crowns Su-Min Cho, Hye-Min Chung, Ji-Man Park, Ryan Jin Young Kim, Alexis Ioannidis This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6273991/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Aug, 2025 Read the published version in BMC Oral Health → Version 1 posted 12 You are reading this latest preprint version Abstract Background: This study aims to present different zirconia 3D printing materials and technologies, and to evaluate the fit, hardness and shear bond strength of crowns produced by additive (AM) and subtractive (SM) manufacturing methods, along with an assessment of surface characteristics. Methods: Zirconia crowns fabricated using one 5-axis SM and five AM approaches, including four different digital light processing (DLP) principles and one stereolithography (SLA) technique, each with varying slurry delivery and light-curing mechanisms. The marginal and internal gaps (axial, line angle, occlusal) between crowns and abutments were measured using the replica technique. Vickers hardness and shear bond strength between the crowns and resin cement was evaluated. Surface characteristics were analyzed with scanning electron microscopy (SEM) after printing and sandblasting. Results: Marginal fit analysis revealed that the marginal fit was 48.45 µm for the milling group and ranged from 42.83 to 81.95 µm for the additive manufacturing groups, with significant differences between groups (<0.001), but all within the clinical acceptance range (120 µm). Vickers hardness measurements showed the milling group had a hardness of 1473.87 HV, while the additive manufacturing groups ranged from 1441.94 to 1532.53 HV, with statistically significant differences (P<0.001). Shear bond strength measurements showed 7.97 MPa for the milling group and 6.97 to 8.97 MPa for the additive manufacturing groups, with no significant differences between groups. SEM analysis of crown surfaces revealed agglomerated zirconia particles, with various grooves observed after sandblasting. Conclusions: Zirconia crowns produced by both AM and SM methods demonstrated clinically acceptable marginal fit and ideal hardness above 1200 HV. Some additive manufacturing groups exhibited higher hardness and shear bond strength compared to the milling group. The diverse physical and mechanical properties of various zirconia 3D printing technologies suggest their selective use based on specific clinical situations. Zirconia 3D-printed crown Dental prosthesis fit Physical properties Mechanical properties Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Background Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is a widely used dental restorative material for fixed dental prostheses (FDPs), valued for its mechanical strength, biocompatibility, and aesthetic qualities ( 1 , 2 ). They are typically fabricated using computer-aided design and manufacturing (CAD-CAM) technology, in which the prosthesis is digitally designed (CAD) and then produced via subtractive manufacturing (SM) methods within the CAM process, followed by sintering to achieve full density ( 3 , 4 )The subtractive nature of the SM process has inherent drawbacks, including challenges in creating thin internal structures due to toolpath constraints, excessive material waste, and frequent maintenance requirements resulting from tool wear( 5 , 6 ). To address these limitations, additive manufacturing (AM), commonly known as 3D printing, has emerged as an alternative. AM enables for the precise fabrication of complex internal structures by building material layer by layer. This approach reduces material consumption and provides greater design flexibility than SM ( 6 , 7 ). The main AM-technologies for zirconia fabrication are digital light processing (DLP) and stereolithography (SLA) ( 8 ). Both methods use a light-curable resin within a vat (VAT) for fabrication. DLP controls ultraviolet (UV) light exposure patterns through a digital micromirror device, curing resin layer by layer ( 9 ). Since it uses a projector to cure an entire layer at once, DLP offers relatively fast printing speeds. In contrast, SLA selectively cures cross-sections of the object using a laser beam, allowing for the production of highly intricate patterns in an automated manner ( 10 ). Previous studies on the mechanical properties of zirconia ceramics reported that AM zirconia exhibits lower mechanical strength compared to SM zirconia ( 11 – 13 ). However, recent advancements in materials and printing technologies have enhanced the mechanical properties of AM zirconia ( 14 – 18 ). Zirconia 3D printing technology however still faces challenges due to the high viscosity of the slurry, a mix of curable liquid and ceramic particles. To facilitate material delivery and deposition, techniques such as blade spreading and tank polymerization have been introduced ( 19 ). Consequently, differing technologies and material compositions 3D-printed zirconia could result in varied hardness, bonding strength, and surface characteristics ( 20 ). Additionally, for definitive FDPs, the fit between the restoration and the abutment tooth is crucial, as poor marginal fit can lead to periodontal disease, making it a clinically significant factor ( 21 – 23 ). This study therefore aims to introduce the various materials and technologies currently employed and to evaluate the fit, microhardness, shear bond strength, and surface properties of zirconia FDPs fabricated using AM compared to those produced through conventional SM processes. These properties are all critical indicators for assessing the clinical accuracy, mechanical performance, and physical characteristics of zirconia FDPs. The study hypotheses are: ( 1 ) there will be no significant differences between additively and subtractively manufactured zirconia crowns in these characteristics, and ( 2 ) no significant differences will be observed among zirconia crowns produced using different AM methods. 2. Materials and methods 2.1 Group Classification For ths study, six groups of zirconia crowns were formed, each containing 10 specimens (n = 10), resulting in a total of 60 crowns fabricated using both SM (1 control group) and AM (5 test groups). The test groups, applying AM technologies for crown fabrication included four digital light processing (DLP) groups and one stereolithography (SLA) group. The DLP groups differed in slurry delivery techniques, shading approaches, and platform movements (Table 1 ). The DLP Circular Spreading method employed an downward approach with the platform moving from above to bellow, whereas all other groups used a upward approach. Table 1 Processing methods and characteristics in this study Group Manufacturing Method Machines Number of Specimens SM CON Fabricated using a 5-axis milling machine with SM techniques. M1 (Zirkonzahn SRL, Italy) 10 AM DLP DLP spreading Used a rectangular table and blade for slurry delivery in a uniform color shade. Veltz-Cera90 (Hephzibah Co., Korea) 10 DLP spreading gradation Used a rectangular table and blade for slurry delivery with different shades applied layer by layer to create a shade-gradation effect. Veltz-Cera90 (Hephzibah Co., Korea) 10 DLP vat Employed a vat-based slurry supply. ZIPRO Dental (Aon Co., Korea) 10 DLP circular spreading Used a circular table and blade for slurry delivery. CeraFab System S65 Medical (Lithoz GmbH, Austria) 10 SLA SLA spreading used a rectangular table and blade for slurry delivery. CERAMAKER C900 Flex (3D CERAM SINTO, France) 10 Total 60 2.1.1. Design of geometric abutment and crown Abutments and crowns were designed using a CAD software (Rhino 7, Robert McNeel & Associates, USA). The dimensions of the abutment were set at 8mm length, 8mm width, and 6mm height, with a 5.5-degree taper starting 1mm above the margin—defined as the internal boundary of the crown-abutment interface. The abutment was specifically designed for the purpose of evaluating the fit using the replica technique, as the slight gap at the margin and the tapering shape were intended to provide a reliable fit for clinical application. The abutment was fabricated using metal printing (Rainbow Metal Printer, Dentium, Seoul, Korea) (Fig. 1 ). For the crown design, the internal dimensions were set to be slightly larger than the abutment dimensions, The crown's external shape featured a flat occlusal surface with rounded mesio-distal contours, above and below the maximum convexity. The crown design mimics simplified clinical conditions, with the goal of achieving optimal fit and function. The occlusal cement space was set to 0.4mm, while the rest of the crown had a cement space of 0.1mm. The crown's lower margin area had 0mm cement space, and the gap gradually reduced from 1mm above the margin, reflecting typical cement space settings. This design was meant to simulate clinical conditions while maintaining the required typical cement space. 2.1.2. Crown fabrication The control group, which applied SM methods for crown fabrication comprised specimens milled from 4-YTZP zirconia blocks (Prettau; Zirkonzahn SRL, Gais, Italy). For AM group manufacturing, geometric crown data were imported into the pre-processing software provided by each manufacturer. All crowns were placed with the occlusal surface facing the platform's bottom edge without additional supports. The layer thickness (z-axis) was 50 µm. Data were sliced to generate G-code files. Crowns were produced using DLP and SLA technologies with commercial and in-house pastes. Pre-set parameters provided by the manufacturers (scraping, hatching, laser output parameters) were used. Uncured paste was removed according to the manufacturer's instructions, followed by debinding and sintering as recommended. Details of the technologies, paste compositions, and debinding and sintering processes are summarized in Table 2 . Table 2 Details of the group in this study Group SM AM CON DLP spreading DLP spreading gradation DLP vat DLP circular spreading SLA spreading Materials Prettau, (Zirkonzahn SRL, Italy) In-house ININI-CERA (Aon Co., Korea) LithaCon 3Y 210 (Lithoz GmbH, Austria) 3DMix ZrO2 (3D CERAM SINTO, France) Classification by Y2O3 (%) 4Y-TZP 4Y-TZP Unknown 3Y-TZP 3Y-TZP Composition (wt%) ZrO 2 + HfO 2 90–94% 85–93% 75–85% ≥ 99.0 Matrix Y 2 O 3 4–8% 6.5–7.5% 15–25% > 4.5 to ≤ 6.0 Matrix Other oxide ≤ 2% ≤ 4.5% Matrix ≤ 0.5 ≤ 0.36 Sintering Protocol After milling from a solid zirconia block, the restoration was heated at 1500–1600°C for 4–8 hours. After printing, the remaining slurry is removed, washed with ethanol, dried, and sintered at 1450 ° C for 20 h. Unknown Preconditioning was done at 120°C for 134 hours, followed by debinding and sintering at up to 1450°C for 94 hours. Debinding was done by gradually heating to 1000°C and then cooling, followed by sintering at 1450°C for 20 hours. 2.2. Fit Assessment (Replica technique) Fit between the crown and abutment was evaluated using the replica technique. Fit checker (Fit Checker II, GC Corporation, Tokyo, Japan) was applied to the internal surface of the crown and fitted to the abutment to assess marginal and internal gaps. The internal space was filled with light body silicone (Examixfine Injection type, GC Corporation) and a putty-type silicone (Exafine Putty type, GC Corporation) was used to create a base block for reinforcement. Replica specimens were sectioned once mesio-distally and once bucco-lingually to measure gaps at the margin, axial, line angle, and occlusal surfaces. Measurements of 16 points per crown were taken. Images were captured using a stereomicroscope (SMZ-168-TL, Motic Inc., Wetzlar, Germany) at 30x magnification, and measurements were analyzed using image analysis software (ImageJ ver1.47, NIH, USA). 2.3 Microhardness (Vickers hardness) Vickers hardness was tested following the international standard ISO 6507-1 using a diamond pyramid indenter with a 136˚ included angle. Hardness was calculated from the average diagonal length of the indent and the applied load (P = kgf) using the formula: $$\:HV=\frac{1.8544\cdot\:F}{{d}^{2}}$$ F: Load (kgf) d: Average diagonal length(mm) Vickers Micro Hardness Tester (Mitutoyo, Kawasaki, Japan) was used with a 1 kgf load applied for 15 s. Each specimen was measured three times at different locations on the same surface, and the average value was used as the single hardness value. Thus, 30 hardness-tests were performed per group. 2.4 Shear Bond Strength Self-curing resin was poured into a silicone mold (20×20×20 mm) to embed the crown, with the occlusal surface of the crown service as the bonding interface area. After resin curing, the surrounding surface was polished to achieve the flattest possible surface. Al 2 O 3 (Renfert GmbH, Germany) was applied at a pressure of 2 bar, followed by etching with a specialized zirconia and ceramic etching solution (smart etching 2 zirconia & ceramic etching solution, S Bio Gold Co., Korea) and application of a zirconia primer (GC Corporation, Tokyo, Japan) as per manufacturer’s instructions. Resin cement (RelyX™ U200, Deutschland, GmbH) was injected into a bonding mold (Ultradent Products, South Jordan, UT, USA) with a diameter of 2.2 mm and height of 2.5 mm. The cement was then cured by using light-curing (Elipar DeepCure-S, 3M, St. Paul, MN, USA), before the speciens were stored in distilled water at 37°C for 24 h. Shear bond strength was measured using a universal testing machine (TESTONE, Seoul, Korea) equipped with a knife-edge chisel. The test was conducted at a crosshead speed of 0.5 mm/min until failure. Shear bond strength was recorded as the maximum force (N) before failure and divided by the bonding interface's cross-sectional area. The formula for calculating shear bond strength (MPa) was as follows: $$\:MPa=\frac{Load\:at\:failure\left(N\right)}{Bonding\:area\left(3.8{\text{m}\text{m}}^{2}\right)}$$ Fracture patterns were observed using scanning electron microscope (SEM; Apreo2, Thermo Fisher Scientific, Waltham, USA). 2.5 Surface Characteristics (SEM Analysis) Surface characteristics of each group were examined immediately after printing and after sandblasting. Specimens were coated with platinum to enhance conductivity and image resolution, and observed using a SEM (Apreo2, Thermo Fisher Scientific) at magnifications of 5,000x and 50,000x. 2.6 Statistical Analysis Data were analyzed using statistical software (IBM SPSS v26.0; IBM Corp). Normality tests for fit, shear bond strength, and microhardness data were performed. The Shapiro-Wilk test indicated that the data was normally distributed for all groups, and Levene’s test showed that the assumption of homogeneity of variances was met. Therefore, a one-way analysis of variance (ANOVA) was conducted to test for significant differences among the groups, and the Tukey post hoc test was employed to analyze further, allowing pairwise comparisons between groups, with a statistical significance (α) of .05. 3. Results 3.1 Fit Assessment (Replica technique) The mean and standard deviation of the marginal and internal fit measured at each point on replicas obtained from milling and 3DP groups are shown in Table 3 . Larger values indicate a wider gap between the model and the crown. Statistical analysis of marginal fit revealed significant differences between the DLP Vat and DLP Circular Spreading groups compared to the CON group and other additive manufacturing groups (P < 0.001). Additionally, internal fit comparisons (axial, line angle, occlusal) are presented in Table 3 . Table 3 Marginal and internal gap of each group (µm) CON DLP spreading DLP spreading gradation DLP vat DLP circular spreading SLA spreading F df p Margin 48.45 (28.71)Aa 53.57 (29.23)Aa 61.98 (32.56)Aa 67.90 (27.86)Ab 81.95 (34.36)Bb 42.83 (34.36)Aa 9.75 5 < 0.001 Axial 121.88 (34.45)Bb 132.23 (51.22)Bb 156.65 (65.46)Bc 112.80 (32.00)Bb 133.60 (38.65)Db 82.25 (19.62)Ba 12.47 5 < 0.001 Line angle 178.23 (38.52)Cb 193.13 (53.55)Cb 193.05 (66.84)Cb 237 (69.74)Cc 123.85 (30.25)Ca 88.13 (22.10)Ba 46.34 5 < 0.001 Occlusal 198.48 (19.68)Db 224.70 (28.16)Db 189.95 (40.55)Cb 384.43 (96.47)Dc 58.13 (18.19)Aa 87.83 (23.51)Ba 246.77 5 < 0.001 F 186.12 127.38 52.33 202.02 51.52 45.63 df 3 3 3 3 3 3 P < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 df, degrees of freedom; P, p-value. The numbers in parentheses are the standard deviations. The means within the same columns with different uppercase in each parameter are significantly different (p < 0.05), and the means within the same rows with different lowercase in each parameter are significantly different (p < 0.05). 3.2 Microhardness (Vickers hardness) Vickers hardness measurements of zirconia specimens showed the following order of hardness: DLP Spreading, DLP Spreading Gradation, DLP Circular Spreading, CON, DLP Vat, SLA Spreading. Statistically significant differences were observed among the groups (P < 0.001). Table 4 The results of Vickers hardness test (HV) CON DLP spreading DLP spreading gradation DLP vat DLP circular spreading SLA spreading F df p 1473.87 (61.18)ab 1532.53 (35.95)c 1501.83 (57.90)bc 1462.21 (39.65)ab 1510.37 (22.69)bc 1441.94 (27.95)a 6.030 5 < 0.001 df, degrees of freedom; P , p-value. 3.3 Shear Bond Strength The average and standard deviation of shear bond strength for resin cement applied to the zirconia surfaces are shown in Table 5 . The DLP Spreading Gradation group exhibited the highest shear bond strength (8.97 ± 5.73 MPa), while the DLP Spreading group showed the lowest shear bond strength (6.97 ± 5.73 MPa). However, there were no significant differences between groups. Examination of fracture surfaces using SEM revealed adhesive failure patterns across all groups (Fig. 4 ). Table 5 The overall results of the shear bond strength values (MPa) CON DLP spreading DLP spreading gradation DLP vat DLP circular spreading SLA spreading F df p 7.97 (3.24) 6.97 (3.47) 8.97 (5.73) 7.93 (4.55) 7.79 (4.17) 7.59 (4.21) 0.228 5 0.949 df, degrees of freedom; P , p-value. 3.4 Surface Characteristics (SEM Analysis) SEM images of specimens from each group are displayed in Figs. 5 and 6 at various magnifications. At higher magnification (50,000x), zirconia particles were observed clustering together. After sandblasting, the surfaces exhibited deep and wide grooves, and relatively small, diverse particles were scattered across the surfaces. 4. Discussion This study analyzed the accuracy, mechanical properties, and surface characteristics of zirconia crowns manufactured using subtractive milling and 3D printing techniques. The results revealed differences in fit, surface characteristics, and microhardness among the manufacturing techniques, leading to partial rejection of the first and second hypotheses. To evaluate the fit of zirconia crowns manufactured by two techniques, the replica technique was used to measure the gaps between the crowns and abutments. A larger marginal gap facilitates bacterial invasion and plaque accumulation, potentially leading to secondary caries or periodontal disease. Therefore, marginal fit significantly impacts the clinical lifespan and functionality of prostheses ( 22 , 24 , 25 ). The marginal fits measured in this study ranged from 42.83 to 81.95 µm, which falls within the clinical acceptable range proposed by previous studies. McLean et al. ( 22 ) consider a clinical marginal fit of 120 µm as the benchmark. The marginal fits in this study were lower than those proposed in these studies, suggesting that they are within an acceptable clinical range. Significant differences in marginal fit were observed between the subtractive milling (CON; 48.45 ± 28.71 µm) and 3DP groups (DLP Vat; 67.90 ± 27.86 µm, DLP Circular Spreading; 81.95 ± 34.36 µm). These differences are likely due to variables in the zirconia 3D printing process affecting the marginal fit, such as layer thickness, printing speed, material viscosity, and shrinkage during curing ( 26 , 27 ). Additionally, the DLP Vat and DLP Circular Spreading groups showed significant differences compared to other 3DP groups (DLP Spreading; 53.57 ± 29.23 µm, DLP Spreading Gradation; 61.98 ± 32.56 µm, SLA Spreading; 42.83 ± 34.36 µm), which can be attributed to differences in printing variables and post-processing sintering conditions within the same DLP technique ( 28 ). Hardness indicates the material's resistance to plastic deformation under an applied force ( 29 , 30 ) and is closely related to wear resistance ( 31 ). Lower hardness may compromise the stability of zirconia prostheses in clinical use ( 32 , 33 ). Vickers microhardness testing showed that the milling group had a hardness of 1473.8 HV, while 3D printing groups ranged from 1441.94 to 1532.53 HV, with some groups showing similar or higher hardness than the milling group. The ideal hardness for zirconia prosthetics is known to be above 1,200 HV (ISO 6872:2015), and all groups in this study exceeded this value. This finding aligns with recent studies ( 34 , 35 ), suggesting that 3D printing technology provides comparable or superior hardness performance to traditional milling methods. Shear bond strength was measured between zirconia and resin cement using a method that considered the specimen shape ( 36 , 37 ). Bonding molds were used to ensure uniform application of resin cement. Fracture surface examination revealed adhesive failure across all groups. Despite surface treatments such as sandblasting and priming to enhance mechanical and chemical bonding, the relatively high strength of zirconia likely led to interface separation. Previous studies also observed adhesive failure with zirconia due to its low surface energy and dense surface structure (36–38). The shear bond strengths of resin cement were 7.97 MPa for milling specimens and 6.97–8.97 MPa for 3D printed specimens, with no significant differences between manufacturing techniques. Given that this study is an in vitro study, the use of a simplified design for resin cement application makes it challenging to assess bonding capabilities solely based on shear bond strength. Future clinical studies should measure bonding strength and examine fracture surfaces to obtain more realistic results. SEM images revealed varying sizes of agglomerates in each group. These agglomerations can be attributed to the high surface energy of the zirconia nanoparticles in the slurry, leading to aggregation. Li et al. ( 39 ) reported that the high surface energy of nanoparticles promotes interactions between particles, leading to agglomerate formation. Finer powders have a higher surface area and energy, potentially influencing particle size and distribution ( 40 ). In the subtractive milling group, uniform blocks with minimal height variation were observed, while the printing groups exhibited more contoured shapes. Zirconia blocks used in milling are formed into dense, uniform blocks under strong compression, leading to a consistent surface. The uniformity is maintained during milling, resulting in flat surfaces with minimal height variations. In contrast, during printing, zirconia slurry, in a high-viscosity liquid form, results in uneven particle distribution and aggregation, creating contoured shapes. SEM images of sandblasted specimens showed changes in surface roughness due to the physical reformation of the microstructure. These changes in surface roughness and particle agglomeration can affect the adhesive performance and mechanical properties of prosthetics. Current research on 3D printed zirconia sets the stage for future advancements and improvements in materials or technologies. Testing various 3D printing techniques and comparing results with traditional milling methods is crucial. Future research should test more zirconia printing technologies, include additional variables such as printing orientation and thermal treatment methods, and investigate the impact of physical variables like sandblasting on mechanical properties. 5. Conclusion Both subtractive milling and 3D printing techniques produce zirconia crowns with marginal fits within the clinical acceptance range. Some 3D printing techniques demonstrated zirconia hardness comparable to or better than traditional milling, with all techniques achieving a hardness of over 1,200 VHN. The shear bond strength results are consistent across both subtractive milling and 3D printing methods. SEM images revealed different types of agglomerates among the groups. Milling groups exhibited a uniform surface, while 3D printing groups showed contoured shapes. Abbreviations Y-TZP: Yttria-stabilized tetragonal zirconia polycrystal; FDPs: Fixed dental prostheses; CAD-CAM: Computer-aided design and manufacturing; CAD: Computer-aided design; SM: Subtractive manufacturing; AM: Additive manufacturing; DLP: Digital light processing; SLA: Stereolithography; VAT: Vat-based system; UV: Ultraviolet; HV: Vickers hardness; ISO: International Organization for Standardization. Declarations Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Funding: This work was supported by the Machinery and Equipment Industry Technology Development (RS-2024-00442711) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea). The funder had no role in study design, data collection and analysis, decision to publish, or manuscript preparation. Author Contribution S.M.C. Conceptualization, Methodology, Formal analysis, Investigation, Writing - Original Draft, Visualization, Project administration., H.M.C. Formal analysis, Investigation, Writing - Original Draft., J.M.P. Conceptualization, Methodology, Validation, Resources, Writing - Review & Editing, Supervision, Project administration, Funding acquisition., R.J.K. Conceptualization, Methodology., A.I. Writing - Review & Editing Availability of data and materials: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests : The authors declare that they have no competing interests. References Grech J, Antunes E. Zirconia in dental prosthetics: A literature review. J Mater Res Technol. 2019;8(5):4956–64. https://doi.org/10.1016/j.jmrt.2019.08.008 . Mazza LC, Lemos CAA, Pesqueira AA, Pellizzer EP. Survival and complications of monolithic ceramic for tooth-supported fixed dental prostheses: A systematic review and meta-analysis. J Prosthet Dent. 2022;128(4):566–74. https://doi.org/10.1016/j.prosdent.2021.07.007 . Helvey GA. Zirconia and computer-aided design/computer-aided manufacturing (CAD/CAM) dentistry. Funct Esthet Restor Dent. 2007;1(3):28–39. Kohorst P, Brinkmann H, Li J, Borchers L, Stiesch M. Marginal accuracy of four-unit zirconia fixed dental prostheses fabricated using different computer‐aided design/computer‐aided manufacturing systems. Eur J Oral Sci. 2009;117(3):319–25. https://doi.org/10.1111/j.1600-0722.2009.00624.x . Huang H. Machining characteristics and surface integrity of yttria stabilized tetragonal zirconia in high speed deep grinding. Mater Sci Eng A. 2003;345(1–2):155–63. https://doi.org/10.1016/S0921-5093(02)00439-1 . Methani MM, Revilla-León M, Zandinejad A. The potential of additive manufacturing technologies and their processing parameters for the fabrication of all‐ceramic crowns: A review. J Esthet Restor Dent. 2020;32(2):182–92. https://doi.org/10.1111/jerd.12535 . Revilla-León M, Meyer MJ, Zandinejad A, Özcan M. Additive manufacturing technologies for processing zirconia in dental applications. Int J Comput Dent. 2020;23(1):27–37. Branco AC, Colaço R, Figueiredo-Pina CG, Serro AP. Recent advances on 3D-printed zirconia-based dental materials: A review. Materials. 2023;16(5):1860. https://doi.org/10.3390/ma16051860 . Huang J, Qin Q, Wang J. A review of stereolithography: Processes and systems. Processes. 2020;8(9):1138. https://doi.org/10.3390/pr8091138 . Hussain MI, Xia M, Ren X, Ge C, Jamil M, Gupta MK. Digital light processing 3D printing of ceramic materials: A review on basic concept, challenges, and applications. Int J Adv Manuf Technol. 2024;130(5):2241–67. https://doi.org/10.1007/s00170-024-12345-6 . Zocca A, Colombo P, Gomes CM, Günster J. Additive manufacturing of ceramics: Issues, potentialities, and opportunities. J Am Ceram Soc. 2015;98(7):1983–2001. https://doi.org/10.1111/jace.13700 . Revilla-León M, Husain NA-H, Ceballos L, Özcan M. Flexural strength and Weibull characteristics of stereolithography additive manufactured versus milled zirconia. J Prosthet Dent. 2021;125(4):685–90. https://doi.org/10.1016/j.prosdent.2020.05.022 . Suominen JM, Frankberg EJ, Vallittu PK, Levänen E, Vihinen J, Vastamäki T, et al. Three-dimensional printing of zirconia: Characterization of early-stage material properties. Biomater Investig Dent. 2019;6(1):23–31. https://doi.org/10.1080/26415275.2019.1642331 . Osman RB, van der Veen AJ, Huiberts D, Wismeijer D, Alharbi N. 3D-printing zirconia implants; A dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs. J Mech Behav Biomed Mater. 2017;75:521–8. https://doi.org/10.1016/j.jmbbm.2017.08.018 . Baysal N, Kalyoncuoğlu UT, Ayyıldız S. Mechanical properties and bond strength of additively manufactured and milled dental zirconia: A pilot study. J Prosthodont. 2022;31(7):629–34. https://doi.org/10.1111/jopr.13472 . Abualsaud R, Abussaud M, Assudmi Y, Aljoaib G, Khaled A, Alalawi H, et al. Physiomechanical and surface characteristics of 3D-printed zirconia: An in vitro study. Materials. 2022;15(19):6988. https://doi.org/10.3390/ma15196988 . Bergler M, Korostoff J, Torrecillas-Martinez L, Mante FK. Ceramic printing—Comparative study of the flexural strength of 3D-printed and milled zirconia. Int J Prosthodont. 2022;35(6). https://doi.org/10.11607/ijp.7534 . Revilla-León M, Al‐Haj Husain N, Barmak AB, Pérez‐López J, Raigrodski AJ, Özcan M. Chemical composition and flexural strength discrepancies between milled and lithography‐based additively manufactured zirconia. J Prosthodont. 2022;31(9):778–83. https://doi.org/10.1111/jopr.13482 . Lakhdar Y, Tuck C, Binner J, Terry A, Goodridge R. Additive manufacturing of advanced ceramic materials. Prog Mater Sci. 2021;116:100736. https://doi.org/10.1016/j.pmatsci.2021.100736 . Cho S-M, Kim RJY, Park J-M, Chung H-M, Kim D-Y. Trueness, physical properties, and surface characteristics of additive-manufactured zirconia crown. J Mech Behav Biomed Mater. 2024;154:106536. https://doi.org/10.1016/j.jmbbm.2023.106536 . Lee J-W, Park J-M. Evaluation of marginal and internal gap under model-free monolithic zirconia restoration fabricated by digital intraoral scanner. J Korean Acad Prosthodont. 2016;54(3):210–7. https://doi.org/10.4047/jkap.2016.54.3.210 . McLean J. The estimation of cement film thickness by an in vivo technique. Br Dent J. 1971;131(3):107–11. https://doi.org/10.1038/sj.bdj.4802708 . Bindl A, Mörmann W. Marginal and internal fit of all-ceramic CAD/CAM crown‐copings on chamfer preparations. J Oral Rehabil. 2005;32(6):441–7. https://doi.org/10.1111/j.1365-2842.2005.01446.x . Beschnidt S, Strub J. Evaluation of the marginal accuracy of different all-ceramic crown systems after simulation in the artificial mouth. J Oral Rehabil. 1999;26(7):582–93. https://doi.org/10.1046/j.1365-2842.1999.00434.x . Felton D, Kanoy B, Bayne SA, Wirthman G. Effect of in vivo crown margin discrepancies on periodontal health. J Prosthet Dent. 1991;65(3):357–64. https://doi.org/10.1016/0022-3913(91)90234-8 . Zhang Z-C, Li P-L, Chu F-T, Shen G. Influence of the three-dimensional printing technique and printing layer thickness on model accuracy. J Orofac Orthop. 2019;80(4):221–32. https://doi.org/10.1007/s00056-019-00182-1 . Tan X, Lu Y, Gao J, Wang Z, Xie C, Yu H. Effect of high-speed sintering on the microstructure, mechanical properties and ageing resistance of stereolithographic additive-manufactured zirconia. Ceram Int. 2022;48(7):9797–804. https://doi.org/10.1016/j.ceramint.2022.01.107 . Cao J, Liu X, Cameron A, Aarts J, Choi JJE. Influence of different post-processing methods on the dimensional accuracy of 3D-printed photopolymers for dental crown applications—A systematic review. J Mech Behav Biomed Mater. 2024;150:106314. https://doi.org/10.1016/j.jmbbm.2023.106314 . Gilman JJ. Chemistry and physics of mechanical hardness. Hoboken, NJ: Wiley; 2009. Pintaude G. Hardness as an indicator of material strength: A critical review. Crit Rev Solid State Mater Sci. 2023;48(5):623–41. https://doi.org/10.1080/10408436.2023.2174463 . D’arcangelo C, Vanini L, Rondoni GD, De Angelis F. Wear properties of dental ceramics and porcelains compared with human enamel. J Prosthet Dent. 2016;115(3):350–5. https://doi.org/10.1016/j.prosdent.2015.09.013 . Li K, Rao J, Ning C. Optimized sintering and mechanical properties of Y-TZP ceramics for dental restorations by adding lithium disilicate glass ceramics. J Adv Ceram. 2021;10:1326–37. https://doi.org/10.1007/s40145-021-0482-6 . Turon-Vinas M, Anglada M. Strength and fracture toughness of zirconia dental ceramics. Dent Mater. 2018;34(3):365–75. https://doi.org/10.1016/j.dental.2017.12.003 . Fayazfar H, Liravi F, Ali U, Toyserkani E. Additive manufacturing of high loading concentration zirconia using high-speed drop-on-demand material jetting. Int J Adv Manuf Technol. 2020;109(9):2733–46. https://doi.org/10.1007/s00170-020-05744-4 . Su G, Zhang Y, Jin C, Zhang Q, Lu J, Liu Z, et al. 3D printed zirconia used as dental materials: A critical review. J Biol Eng. 2023;17(1):78. https://doi.org/10.1186/s13036-023-00378-6 . Qeblawi DM, Muñoz CA, Brewer JD, Monaco EA Jr. The effect of zirconia surface treatment on flexural strength and shear bond strength to a resin cement. J Prosthet Dent. 2010;103(4):210–20. https://doi.org/10.1016/S0022-3913(10)60032-9 . Akın H, Ozkurt Z, Kırmalı O, Kazazoglu E, Ozdemir AK. Shear bond strength of resin cement to zirconia ceramic after aluminum oxide sandblasting and various laser treatments. Photomed Laser Surg. 2011;29(12):797–802. https://doi.org/10.1089/pho.2011.3072 . Altan B, Cinar S, Tuncelli B. Evaluation of shear bond strength of zirconia-based monolithic CAD-CAM materials to resin cement after different surface treatments. Niger J Clin Pract. 2019;22(11):1475–82. https://doi.org/10.4103/njcp.njcp_51_19 . Li H, Song L, Sun J, Ma J, Shen Z. Dental ceramic prostheses by stereolithography-based additive manufacturing: Potentials and challenges. Adv Appl Ceram. 2019;118(1–2):30–6. https://doi.org/10.1080/17436753.2019.1709687 . Balakrishnan A, Pizette P, Martin C, Joshi S, Saha B. Effect of particle size in aggregated and agglomerated ceramic powders. Acta Mater. 2010;58(3):802–12. https://doi.org/10.1016/j.actamat.2009.10.034 . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 01 Aug, 2025 Read the published version in BMC Oral Health → Version 1 posted Editorial decision: Revision requested 15 Apr, 2025 Reviews received at journal 11 Apr, 2025 Reviews received at journal 08 Apr, 2025 Reviews received at journal 02 Apr, 2025 Reviewers agreed at journal 31 Mar, 2025 Reviewers agreed at journal 30 Mar, 2025 Reviewers agreed at journal 30 Mar, 2025 Reviewers agreed at journal 28 Mar, 2025 Reviewers invited by journal 27 Mar, 2025 Editor assigned by journal 27 Mar, 2025 Submission checks completed at journal 27 Mar, 2025 First submitted to journal 21 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6273991","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":441883822,"identity":"253eea96-eedb-47db-9b7d-bd3a90a6a392","order_by":0,"name":"Su-Min Cho","email":"","orcid":"","institution":"Seoul National University School of Dentistry","correspondingAuthor":false,"prefix":"","firstName":"Su-Min","middleName":"","lastName":"Cho","suffix":""},{"id":441883823,"identity":"10dd848e-1b98-4ddf-8d74-4420a3aeb5d6","order_by":1,"name":"Hye-Min Chung","email":"","orcid":"","institution":"Seoul National University School of Dentistry","correspondingAuthor":false,"prefix":"","firstName":"Hye-Min","middleName":"","lastName":"Chung","suffix":""},{"id":441883824,"identity":"b633fe99-97e7-4a20-9ae5-f658eb0ad3ff","order_by":2,"name":"Ji-Man Park","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAsUlEQVRIiWNgGAWjYBACxmYwZQPjJxCtJY0ELVBwmAQtzO3ciZ8rd5y3N5dIYPzwgyEtnwiH8W6WPHvmduLOGQnMkj0MOZYNRGjZINnYdjvB4EYCgzQDQ4UBUbb8bGw7Zw/UwvybWC3bgLYcYNxwI4ENaEsOcVosG9uSEzecedhm2WOQRliLYf/ZzTcb2+zsDY4nH77xoyKZCC0NCAuBTMIaGBjkiVAzCkbBKBgFIx0AAF6+OJWQqPOwAAAAAElFTkSuQmCC","orcid":"","institution":"Seoul National University School of Dentistry","correspondingAuthor":true,"prefix":"","firstName":"Ji-Man","middleName":"","lastName":"Park","suffix":""},{"id":441883827,"identity":"1e1e286a-59d9-4444-b758-a6c84d3c85d1","order_by":3,"name":"Ryan Jin Young Kim","email":"","orcid":"","institution":"Seoul National University School of Dentistry","correspondingAuthor":false,"prefix":"","firstName":"Ryan","middleName":"Jin Young","lastName":"Kim","suffix":""},{"id":441883828,"identity":"370a8b40-76da-4d09-a308-6871ca398adc","order_by":4,"name":"Alexis Ioannidis","email":"","orcid":"","institution":"University of Zurich","correspondingAuthor":false,"prefix":"","firstName":"Alexis","middleName":"","lastName":"Ioannidis","suffix":""}],"badges":[],"createdAt":"2025-03-21 04:38:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6273991/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6273991/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12903-025-06561-7","type":"published","date":"2025-08-01T16:21:04+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":80663484,"identity":"2ba68c64-acbc-44d8-a2e9-ad2d53490d72","added_by":"auto","created_at":"2025-04-15 17:00:57","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":34777,"visible":true,"origin":"","legend":"\u003cp\u003eDesign dimension (A) Abutment, (B) External contour of the crown\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/1c3f67b5dbbcb5c1bad6ad6c.jpg"},{"id":80662552,"identity":"2f772dbf-286f-453b-ace1-2292053890be","added_by":"auto","created_at":"2025-04-15 16:52:56","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":53817,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement locations for zirconia crown fit. (A) Sectioning area of the replica specimen, (B) Measurement points on the replica specimen\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/7c63bde8aee24441aaa9b6d6.jpg"},{"id":80662553,"identity":"e1441608-7731-4239-8343-6f148ec038d0","added_by":"auto","created_at":"2025-04-15 16:52:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":63334,"visible":true,"origin":"","legend":"\u003cp\u003eA schematic diagram of the shear bond strength test\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/726c83235a747cc285102495.jpg"},{"id":80662558,"identity":"dea0f118-c428-4c0f-a5c3-bb6cb10a512b","added_by":"auto","created_at":"2025-04-15 16:52:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":854047,"visible":true,"origin":"","legend":"\u003cp\u003eField-emission scanning microscope images of the fractured zirconia. The white arrows represent the cements on the zirconia surface and those means that they showed cohesive failure. (magnification: 138×). (A) CON, (B) DLP spreading, (C) DLP spreading gradation, (D) DLP vat, (E) DLP circular spreading, (F) SLA spreading\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/c34cdd76ac2cb6d535e360e2.png"},{"id":80663493,"identity":"1e13af2b-f896-4980-87c4-b3730c3886ff","added_by":"auto","created_at":"2025-04-15 17:00:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1932525,"visible":true,"origin":"","legend":"\u003cp\u003eScanning Electron Microscope Observation and Surface Analysis (at 5,000X). (A) CON, (B) DLP spreading, (C) DLP spreading gradation, (D) DLP vat, (E) DLP circular spreading, (F) SLA spreading\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/639fe247efc0cc9c6e5c3371.png"},{"id":80662554,"identity":"7a978c46-3fdf-4ef5-b404-5e04659b4af0","added_by":"auto","created_at":"2025-04-15 16:52:57","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1882131,"visible":true,"origin":"","legend":"\u003cp\u003eScanning Electron Microscope Observation and Surface Analysis (at 50,000X). (A) CON, (B) DLP spreading, (C) DLP spreading gradation, (D) DLP vat, (E) DLP circular spreading, (F) SLA spreading\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/5f9d34f91166d2a5aaf579c1.png"},{"id":88268248,"identity":"0f769d5a-7379-43de-a169-dfb74261d348","added_by":"auto","created_at":"2025-08-04 16:50:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6225951,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6273991/v1/4a88f2ef-db35-42b8-9e50-d7d134d19b9e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparative Analysis of Fit, Mechanical Properties, and Surface Characteristics in Subtractive and Additive Manufactured Zirconia Crowns","fulltext":[{"header":"1. Background","content":"\u003cp\u003eYttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is a widely used dental restorative material for fixed dental prostheses (FDPs), valued for its mechanical strength, biocompatibility, and aesthetic qualities (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). They are typically fabricated using computer-aided design and manufacturing (CAD-CAM) technology, in which the prosthesis is digitally designed (CAD) and then produced via subtractive manufacturing (SM) methods within the CAM process, followed by sintering to achieve full density (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)The subtractive nature of the SM process has inherent drawbacks, including challenges in creating thin internal structures due to toolpath constraints, excessive material waste, and frequent maintenance requirements resulting from tool wear(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo address these limitations, additive manufacturing (AM), commonly known as 3D printing, has emerged as an alternative. AM enables for the precise fabrication of complex internal structures by building material layer by layer. This approach reduces material consumption and provides greater design flexibility than SM (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The main AM-technologies for zirconia fabrication are digital light processing (DLP) and stereolithography (SLA) (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Both methods use a light-curable resin within a vat (VAT) for fabrication. DLP controls ultraviolet (UV) light exposure patterns through a digital micromirror device, curing resin layer by layer (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Since it uses a projector to cure an entire layer at once, DLP offers relatively fast printing speeds. In contrast, SLA selectively cures cross-sections of the object using a laser beam, allowing for the production of highly intricate patterns in an automated manner (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePrevious studies on the mechanical properties of zirconia ceramics reported that AM zirconia exhibits lower mechanical strength compared to SM zirconia (\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). However, recent advancements in materials and printing technologies have enhanced the mechanical properties of AM zirconia (\u003cspan additionalcitationids=\"CR15 CR16 CR17\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Zirconia 3D printing technology however still faces challenges due to the high viscosity of the slurry, a mix of curable liquid and ceramic particles. To facilitate material delivery and deposition, techniques such as blade spreading and tank polymerization have been introduced (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). Consequently, differing technologies and material compositions 3D-printed zirconia could result in varied hardness, bonding strength, and surface characteristics (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Additionally, for definitive FDPs, the fit between the restoration and the abutment tooth is crucial, as poor marginal fit can lead to periodontal disease, making it a clinically significant factor (\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis study therefore aims to introduce the various materials and technologies currently employed and to evaluate the fit, microhardness, shear bond strength, and surface properties of zirconia FDPs fabricated using AM compared to those produced through conventional SM processes. These properties are all critical indicators for assessing the clinical accuracy, mechanical performance, and physical characteristics of zirconia FDPs. The study hypotheses are: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) there will be no significant differences between additively and subtractively manufactured zirconia crowns in these characteristics, and (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) no significant differences will be observed among zirconia crowns produced using different AM methods.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Group Classification\u003c/h2\u003e \u003cp\u003eFor ths study, six groups of zirconia crowns were formed, each containing 10 specimens (n\u0026thinsp;=\u0026thinsp;10), resulting in a total of 60 crowns fabricated using both SM (1 control group) and AM (5 test groups). The test groups, applying AM technologies for crown fabrication included four digital light processing (DLP) groups and one stereolithography (SLA) group. The DLP groups differed in slurry delivery techniques, shading approaches, and platform movements (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe DLP Circular Spreading method employed an downward approach with the platform moving from above to bellow, whereas all other groups used a upward approach.\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\u003eProcessing methods and characteristics in this study\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\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eManufacturing Method\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMachines\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNumber of Specimens\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eSM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCON\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFabricated using a 5-axis milling machine with SM techniques.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM1\u003c/p\u003e \u003cp\u003e(Zirkonzahn SRL, Italy)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eAM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eDLP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP spreading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUsed a rectangular table and blade for slurry delivery in a uniform color shade.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eVeltz-Cera90\u003c/p\u003e \u003cp\u003e(Hephzibah Co., Korea)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP spreading gradation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUsed a rectangular table and blade for slurry delivery with different shades applied layer by layer to create a shade-gradation effect.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eVeltz-Cera90\u003c/p\u003e \u003cp\u003e(Hephzibah Co., Korea)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP vat\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEmployed a vat-based slurry supply.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZIPRO Dental\u003c/p\u003e \u003cp\u003e(Aon Co., Korea)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP circular spreading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUsed a circular table and blade for slurry delivery.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCeraFab System S65 Medical\u003c/p\u003e \u003cp\u003e(Lithoz GmbH, Austria)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSLA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSLA spreading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eused a rectangular table and blade for slurry delivery.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCERAMAKER C900 Flex\u003c/p\u003e \u003cp\u003e(3D CERAM SINTO, France)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e60\u003c/b\u003e\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=\"Sec4\" class=\"Section3\"\u003e \u003ch2\u003e2.1.1. Design of geometric abutment and crown\u003c/h2\u003e \u003cp\u003eAbutments and crowns were designed using a CAD software (Rhino 7, Robert McNeel \u0026amp; Associates, USA). The dimensions of the abutment were set at 8mm length, 8mm width, and 6mm height, with a 5.5-degree taper starting 1mm above the margin\u0026mdash;defined as the internal boundary of the crown-abutment interface. The abutment was specifically designed for the purpose of evaluating the fit using the replica technique, as the slight gap at the margin and the tapering shape were intended to provide a reliable fit for clinical application. The abutment was fabricated using metal printing (Rainbow Metal Printer, Dentium, Seoul, Korea) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFor the crown design, the internal dimensions were set to be slightly larger than the abutment dimensions, The crown's external shape featured a flat occlusal surface with rounded mesio-distal contours, above and below the maximum convexity. The crown design mimics simplified clinical conditions, with the goal of achieving optimal fit and function.\u003c/p\u003e \u003cp\u003eThe occlusal cement space was set to 0.4mm, while the rest of the crown had a cement space of 0.1mm. The crown's lower margin area had 0mm cement space, and the gap gradually reduced from 1mm above the margin, reflecting typical cement space settings. This design was meant to simulate clinical conditions while maintaining the required typical cement space.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.1.2. Crown fabrication\u003c/h2\u003e \u003cp\u003eThe control group, which applied SM methods for crown fabrication comprised specimens milled from 4-YTZP zirconia blocks (Prettau; Zirkonzahn SRL, Gais, Italy).\u003c/p\u003e \u003cp\u003eFor AM group manufacturing, geometric crown data were imported into the pre-processing software provided by each manufacturer. All crowns were placed with the occlusal surface facing the platform's bottom edge without additional supports. The layer thickness (z-axis) was 50 \u0026micro;m. Data were sliced to generate G-code files. Crowns were produced using DLP and SLA technologies with commercial and in-house pastes. Pre-set parameters provided by the manufacturers (scraping, hatching, laser output parameters) were used. Uncured paste was removed according to the manufacturer's instructions, followed by debinding and sintering as recommended. Details of the technologies, paste compositions, and debinding and sintering processes are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\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\u003eDetails of the group in this study\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eSM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c9\" namest=\"c5\"\u003e \u003cp\u003eAM\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eCON\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDLP spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDLP spreading gradation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eDLP vat\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eDLP circular spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eSLA spreading\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eMaterials\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003ePrettau, (Zirkonzahn SRL, Italy)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eIn-house\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eININI-CERA (Aon Co., Korea)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLithaCon 3Y 210 (Lithoz GmbH, Austria)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e3DMix ZrO2 (3D CERAM SINTO, France)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eClassification\u003c/p\u003e \u003cp\u003eby Y2O3 (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e4Y-TZP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e4Y-TZP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e3Y-TZP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e3Y-TZP\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eComposition (wt%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eZrO\u003csub\u003e2\u003c/sub\u003e \u003cb\u003e+\u003c/b\u003e\u003c/p\u003e \u003cp\u003eHfO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e90\u0026ndash;94%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e85\u0026ndash;93%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e75\u0026ndash;85%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;99.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eMatrix\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eY\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u0026ndash;8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e6.5\u0026ndash;7.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e15\u0026ndash;25%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;4.5 to \u0026le;\u0026thinsp;6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eMatrix\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eOther\u003c/p\u003e \u003cp\u003eoxide\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;4.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMatrix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eSintering Protocol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eAfter milling from a solid zirconia block, the restoration was heated at 1500\u0026ndash;1600\u0026deg;C for 4\u0026ndash;8 hours.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eAfter printing, the remaining slurry is removed, washed with ethanol, dried, and sintered at 1450 \u0026deg; C for 20 h.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePreconditioning was done at 120\u0026deg;C for 134 hours, followed by debinding and sintering at up to 1450\u0026deg;C for 94 hours.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eDebinding was done by gradually heating to 1000\u0026deg;C and then cooling, followed by sintering at 1450\u0026deg;C for 20 hours.\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 \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Fit Assessment (Replica technique)\u003c/h2\u003e \u003cp\u003eFit between the crown and abutment was evaluated using the replica technique. Fit checker (Fit Checker II, GC Corporation, Tokyo, Japan) was applied to the internal surface of the crown and fitted to the abutment to assess marginal and internal gaps. The internal space was filled with light body silicone (Examixfine Injection type, GC Corporation) and a putty-type silicone (Exafine Putty type, GC Corporation) was used to create a base block for reinforcement.\u003c/p\u003e \u003cp\u003eReplica specimens were sectioned once mesio-distally and once bucco-lingually to measure gaps at the margin, axial, line angle, and occlusal surfaces. Measurements of 16 points per crown were taken. Images were captured using a stereomicroscope (SMZ-168-TL, Motic Inc., Wetzlar, Germany) at 30x magnification, and measurements were analyzed using image analysis software (ImageJ ver1.47, NIH, USA).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Microhardness (Vickers hardness)\u003c/h2\u003e \u003cp\u003eVickers hardness was tested following the international standard ISO 6507-1 using a diamond pyramid indenter with a 136˚ included angle. Hardness was calculated from the average diagonal length of the indent and the applied load (P\u0026thinsp;=\u0026thinsp;kgf) using the formula:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:HV=\\frac{1.8544\\cdot\\:F}{{d}^{2}}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eF: Load (kgf)\u003c/p\u003e \u003cp\u003ed: Average diagonal length(mm)\u003c/p\u003e \u003cp\u003eVickers Micro Hardness Tester (Mitutoyo, Kawasaki, Japan) was used with a 1 kgf load applied for 15 s. Each specimen was measured three times at different locations on the same surface, and the average value was used as the single hardness value. Thus, 30 hardness-tests were performed per group.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Shear Bond Strength\u003c/h2\u003e \u003cp\u003eSelf-curing resin was poured into a silicone mold (20\u0026times;20\u0026times;20 mm) to embed the crown, with the occlusal surface of the crown service as the bonding interface area. After resin curing, the surrounding surface was polished to achieve the flattest possible surface. Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (Renfert GmbH, Germany) was applied at a pressure of 2 bar, followed by etching with a specialized zirconia and ceramic etching solution (smart etching 2 zirconia \u0026amp; ceramic etching solution, S Bio Gold Co., Korea) and application of a zirconia primer (GC Corporation, Tokyo, Japan) as per manufacturer\u0026rsquo;s instructions.\u003c/p\u003e \u003cp\u003eResin cement (RelyX\u0026trade; U200, Deutschland, GmbH) was injected into a bonding mold (Ultradent Products, South Jordan, UT, USA) with a diameter of 2.2 mm and height of 2.5 mm. The cement was then cured by using light-curing (Elipar DeepCure-S, 3M, St. Paul, MN, USA), before the speciens were stored in distilled water at 37\u0026deg;C for 24 h.\u003c/p\u003e \u003cp\u003eShear bond strength was measured using a universal testing machine (TESTONE, Seoul, Korea) equipped with a knife-edge chisel. The test was conducted at a crosshead speed of 0.5 mm/min until failure. Shear bond strength was recorded as the maximum force (N) before failure and divided by the bonding interface's cross-sectional area. The formula for calculating shear bond strength (MPa) was as follows:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:MPa=\\frac{Load\\:at\\:failure\\left(N\\right)}{Bonding\\:area\\left(3.8{\\text{m}\\text{m}}^{2}\\right)}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eFracture patterns were observed using scanning electron microscope (SEM; Apreo2, Thermo Fisher Scientific, Waltham, USA).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Surface Characteristics (SEM Analysis)\u003c/h2\u003e \u003cp\u003eSurface characteristics of each group were examined immediately after printing and after sandblasting. Specimens were coated with platinum to enhance conductivity and image resolution, and observed using a SEM (Apreo2, Thermo Fisher Scientific) at magnifications of 5,000x and 50,000x.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Statistical Analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using statistical software (IBM SPSS v26.0; IBM Corp). Normality tests for fit, shear bond strength, and microhardness data were performed. The Shapiro-Wilk test indicated that the data was normally distributed for all groups, and Levene\u0026rsquo;s test showed that the assumption of homogeneity of variances was met. Therefore, a one-way analysis of variance (ANOVA) was conducted to test for significant differences among the groups, and the Tukey post hoc test was employed to analyze further, allowing pairwise comparisons between groups, with a statistical significance (α) of .05.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Fit Assessment (Replica technique)\u003c/h2\u003e \u003cp\u003eThe mean and standard deviation of the marginal and internal fit measured at each point on replicas obtained from milling and 3DP groups are shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Larger values indicate a wider gap between the model and the crown. Statistical analysis of marginal fit revealed significant differences between the DLP Vat and DLP Circular Spreading groups compared to the CON group and other additive manufacturing groups (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Additionally, internal fit comparisons (axial, line angle, occlusal) are presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\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\u003eMarginal and internal gap of each group (\u0026micro;m)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCON\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDLP spreading gradation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDLP vat\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDLP circular spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSLA spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMargin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48.45\u003c/p\u003e \u003cp\u003e(28.71)Aa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.57\u003c/p\u003e \u003cp\u003e(29.23)Aa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e61.98\u003c/p\u003e \u003cp\u003e(32.56)Aa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e67.90\u003c/p\u003e \u003cp\u003e(27.86)Ab\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e81.95\u003c/p\u003e \u003cp\u003e(34.36)Bb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e42.83\u003c/p\u003e \u003cp\u003e(34.36)Aa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\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\u003eAxial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e121.88\u003c/p\u003e \u003cp\u003e(34.45)Bb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e132.23\u003c/p\u003e \u003cp\u003e(51.22)Bb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e156.65\u003c/p\u003e \u003cp\u003e(65.46)Bc\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e112.80\u003c/p\u003e \u003cp\u003e(32.00)Bb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e133.60\u003c/p\u003e \u003cp\u003e(38.65)Db\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e82.25\u003c/p\u003e \u003cp\u003e(19.62)Ba\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e12.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\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\u003eLine angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e178.23\u003c/p\u003e \u003cp\u003e(38.52)Cb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e193.13\u003c/p\u003e \u003cp\u003e(53.55)Cb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e193.05\u003c/p\u003e \u003cp\u003e(66.84)Cb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e237\u003c/p\u003e \u003cp\u003e(69.74)Cc\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e123.85\u003c/p\u003e \u003cp\u003e(30.25)Ca\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e88.13\u003c/p\u003e \u003cp\u003e(22.10)Ba\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e46.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\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\u003eOcclusal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e198.48\u003c/p\u003e \u003cp\u003e(19.68)Db\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e224.70\u003c/p\u003e \u003cp\u003e(28.16)Db\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e189.95\u003c/p\u003e \u003cp\u003e(40.55)Cb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e384.43\u003c/p\u003e \u003cp\u003e(96.47)Dc\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e58.13\u003c/p\u003e \u003cp\u003e(18.19)Aa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e87.83\u003c/p\u003e \u003cp\u003e(23.51)Ba\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e246.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\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\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e186.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e127.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e202.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e51.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e45.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003edf\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP\u003c/b\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 \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003edf, degrees of freedom; P, p-value.\u003c/p\u003e \u003cp\u003eThe numbers in parentheses are the standard deviations.\u003c/p\u003e \u003cp\u003eThe means within the same columns with different uppercase in each parameter are significantly different (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), and the means within the same rows with different lowercase in each parameter are significantly different (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Microhardness (Vickers hardness)\u003c/h2\u003e \u003cp\u003eVickers hardness measurements of zirconia specimens showed the following order of hardness: DLP Spreading, DLP Spreading Gradation, DLP Circular Spreading, CON, DLP Vat, SLA Spreading. Statistically significant differences were observed among the groups (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\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\u003eThe results of Vickers hardness test (HV)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCON\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDLP spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP spreading gradation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDLP vat\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDLP circular spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSLA spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1473.87\u003c/p\u003e \u003cp\u003e(61.18)ab\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1532.53\u003c/p\u003e \u003cp\u003e(35.95)c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1501.83\u003c/p\u003e \u003cp\u003e(57.90)bc\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1462.21\u003c/p\u003e \u003cp\u003e(39.65)ab\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1510.37\u003c/p\u003e \u003cp\u003e(22.69)bc\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1441.94\u003c/p\u003e \u003cp\u003e(27.95)a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6.030\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003edf, degrees of freedom; \u003cem\u003eP\u003c/em\u003e, p-value.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Shear Bond Strength\u003c/h2\u003e \u003cp\u003eThe average and standard deviation of shear bond strength for resin cement applied to the zirconia surfaces are shown in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The DLP Spreading Gradation group exhibited the highest shear bond strength (8.97\u0026thinsp;\u0026plusmn;\u0026thinsp;5.73 MPa), while the DLP Spreading group showed the lowest shear bond strength (6.97\u0026thinsp;\u0026plusmn;\u0026thinsp;5.73 MPa). However, there were no significant differences between groups. Examination of fracture surfaces using SEM revealed adhesive failure patterns across all groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe overall results of the shear bond strength values (MPa)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCON\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDLP spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP spreading gradation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDLP vat\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDLP circular spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSLA spreading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7.97\u003c/p\u003e \u003cp\u003e(3.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.97\u003c/p\u003e \u003cp\u003e(3.47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.97\u003c/p\u003e \u003cp\u003e(5.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.93\u003c/p\u003e \u003cp\u003e(4.55)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.79\u003c/p\u003e \u003cp\u003e(4.17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e7.59\u003c/p\u003e \u003cp\u003e(4.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.949\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003edf, degrees of freedom; \u003cem\u003eP\u003c/em\u003e, p-value.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Surface Characteristics (SEM Analysis)\u003c/h2\u003e \u003cp\u003eSEM images of specimens from each group are displayed in Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e at various magnifications. At higher magnification (50,000x), zirconia particles were observed clustering together. After sandblasting, the surfaces exhibited deep and wide grooves, and relatively small, diverse particles were scattered across the surfaces.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThis study analyzed the accuracy, mechanical properties, and surface characteristics of zirconia crowns manufactured using subtractive milling and 3D printing techniques. The results revealed differences in fit, surface characteristics, and microhardness among the manufacturing techniques, leading to partial rejection of the first and second hypotheses.\u003c/p\u003e \u003cp\u003eTo evaluate the fit of zirconia crowns manufactured by two techniques, the replica technique was used to measure the gaps between the crowns and abutments. A larger marginal gap facilitates bacterial invasion and plaque accumulation, potentially leading to secondary caries or periodontal disease. Therefore, marginal fit significantly impacts the clinical lifespan and functionality of prostheses (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). The marginal fits measured in this study ranged from 42.83 to 81.95 \u0026micro;m, which falls within the clinical acceptable range proposed by previous studies. McLean et al. (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e) consider a clinical marginal fit of 120 \u0026micro;m as the benchmark. The marginal fits in this study were lower than those proposed in these studies, suggesting that they are within an acceptable clinical range. Significant differences in marginal fit were observed between the subtractive milling (CON; 48.45\u0026thinsp;\u0026plusmn;\u0026thinsp;28.71 \u0026micro;m) and 3DP groups (DLP Vat; 67.90\u0026thinsp;\u0026plusmn;\u0026thinsp;27.86 \u0026micro;m, DLP Circular Spreading; 81.95\u0026thinsp;\u0026plusmn;\u0026thinsp;34.36 \u0026micro;m). These differences are likely due to variables in the zirconia 3D printing process affecting the marginal fit, such as layer thickness, printing speed, material viscosity, and shrinkage during curing (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Additionally, the DLP Vat and DLP Circular Spreading groups showed significant differences compared to other 3DP groups (DLP Spreading; 53.57\u0026thinsp;\u0026plusmn;\u0026thinsp;29.23 \u0026micro;m, DLP Spreading Gradation; 61.98\u0026thinsp;\u0026plusmn;\u0026thinsp;32.56 \u0026micro;m, SLA Spreading; 42.83\u0026thinsp;\u0026plusmn;\u0026thinsp;34.36 \u0026micro;m), which can be attributed to differences in printing variables and post-processing sintering conditions within the same DLP technique (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHardness indicates the material's resistance to plastic deformation under an applied force (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e) and is closely related to wear resistance (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Lower hardness may compromise the stability of zirconia prostheses in clinical use (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). Vickers microhardness testing showed that the milling group had a hardness of 1473.8 HV, while 3D printing groups ranged from 1441.94 to 1532.53 HV, with some groups showing similar or higher hardness than the milling group. The ideal hardness for zirconia prosthetics is known to be above 1,200 HV (ISO 6872:2015), and all groups in this study exceeded this value. This finding aligns with recent studies (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e), suggesting that 3D printing technology provides comparable or superior hardness performance to traditional milling methods.\u003c/p\u003e \u003cp\u003eShear bond strength was measured between zirconia and resin cement using a method that considered the specimen shape (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). Bonding molds were used to ensure uniform application of resin cement. Fracture surface examination revealed adhesive failure across all groups. Despite surface treatments such as sandblasting and priming to enhance mechanical and chemical bonding, the relatively high strength of zirconia likely led to interface separation. Previous studies also observed adhesive failure with zirconia due to its low surface energy and dense surface structure (36\u0026ndash;38). The shear bond strengths of resin cement were 7.97 MPa for milling specimens and 6.97\u0026ndash;8.97 MPa for 3D printed specimens, with no significant differences between manufacturing techniques. Given that this study is an in vitro study, the use of a simplified design for resin cement application makes it challenging to assess bonding capabilities solely based on shear bond strength. Future clinical studies should measure bonding strength and examine fracture surfaces to obtain more realistic results.\u003c/p\u003e \u003cp\u003eSEM images revealed varying sizes of agglomerates in each group. These agglomerations can be attributed to the high surface energy of the zirconia nanoparticles in the slurry, leading to aggregation. Li et al. (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e) reported that the high surface energy of nanoparticles promotes interactions between particles, leading to agglomerate formation. Finer powders have a higher surface area and energy, potentially influencing particle size and distribution (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). In the subtractive milling group, uniform blocks with minimal height variation were observed, while the printing groups exhibited more contoured shapes. Zirconia blocks used in milling are formed into dense, uniform blocks under strong compression, leading to a consistent surface. The uniformity is maintained during milling, resulting in flat surfaces with minimal height variations. In contrast, during printing, zirconia slurry, in a high-viscosity liquid form, results in uneven particle distribution and aggregation, creating contoured shapes. SEM images of sandblasted specimens showed changes in surface roughness due to the physical reformation of the microstructure. These changes in surface roughness and particle agglomeration can affect the adhesive performance and mechanical properties of prosthetics.\u003c/p\u003e \u003cp\u003eCurrent research on 3D printed zirconia sets the stage for future advancements and improvements in materials or technologies. Testing various 3D printing techniques and comparing results with traditional milling methods is crucial. Future research should test more zirconia printing technologies, include additional variables such as printing orientation and thermal treatment methods, and investigate the impact of physical variables like sandblasting on mechanical properties.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eBoth subtractive milling and 3D printing techniques produce zirconia crowns with marginal fits within the clinical acceptance range. Some 3D printing techniques demonstrated zirconia hardness comparable to or better than traditional milling, with all techniques achieving a hardness of over 1,200 VHN. The shear bond strength results are consistent across both subtractive milling and 3D printing methods. SEM images revealed different types of agglomerates among the groups. Milling groups exhibited a uniform surface, while 3D printing groups showed contoured shapes.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eY-TZP: Yttria-stabilized tetragonal zirconia polycrystal; FDPs: Fixed dental prostheses; CAD-CAM: Computer-aided design and manufacturing; CAD: Computer-aided design; SM: Subtractive manufacturing; AM: Additive manufacturing; DLP: Digital light processing; SLA: Stereolithography; VAT: Vat-based system; UV: Ultraviolet; HV: Vickers hardness; ISO: International Organization for Standardization.\u003c/p\u003e\n"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Machinery and Equipment Industry Technology Development (RS-2024-00442711) funded By the Ministry of Trade, Industry \u0026amp; Energy (MOTIE, Korea). The funder had no role in study design, data collection and analysis, decision to publish, or manuscript preparation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eS.M.C. Conceptualization, Methodology, Formal analysis, Investigation, Writing - Original Draft, Visualization, Project administration., H.M.C. Formal analysis, Investigation, Writing - Original Draft., J.M.P. Conceptualization, Methodology, Validation, Resources, Writing - Review \u0026amp; Editing, Supervision, Project administration, Funding acquisition., R.J.K. Conceptualization, Methodology., A.I. Writing - Review \u0026amp; Editing\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e: The authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGrech J, Antunes E. Zirconia in dental prosthetics: A literature review. J Mater Res Technol. 2019;8(5):4956\u0026ndash;64. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmrt.2019.08.008\u003c/span\u003e\u003cspan address=\"10.1016/j.jmrt.2019.08.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMazza LC, Lemos CAA, Pesqueira AA, Pellizzer EP. Survival and complications of monolithic ceramic for tooth-supported fixed dental prostheses: A systematic review and meta-analysis. J Prosthet Dent. 2022;128(4):566\u0026ndash;74. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.prosdent.2021.07.007\u003c/span\u003e\u003cspan address=\"10.1016/j.prosdent.2021.07.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHelvey GA. Zirconia and computer-aided design/computer-aided manufacturing (CAD/CAM) dentistry. Funct Esthet Restor Dent. 2007;1(3):28\u0026ndash;39.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKohorst P, Brinkmann H, Li J, Borchers L, Stiesch M. Marginal accuracy of four-unit zirconia fixed dental prostheses fabricated using different computer‐aided design/computer‐aided manufacturing systems. Eur J Oral Sci. 2009;117(3):319\u0026ndash;25. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1600-0722.2009.00624.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1600-0722.2009.00624.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang H. Machining characteristics and surface integrity of yttria stabilized tetragonal zirconia in high speed deep grinding. Mater Sci Eng A. 2003;345(1\u0026ndash;2):155\u0026ndash;63. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0921-5093(02)00439-1\u003c/span\u003e\u003cspan address=\"10.1016/S0921-5093(02)00439-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMethani MM, Revilla-Le\u0026oacute;n M, Zandinejad A. The potential of additive manufacturing technologies and their processing parameters for the fabrication of all‐ceramic crowns: A review. J Esthet Restor Dent. 2020;32(2):182\u0026ndash;92. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jerd.12535\u003c/span\u003e\u003cspan address=\"10.1111/jerd.12535\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRevilla-Le\u0026oacute;n M, Meyer MJ, Zandinejad A, \u0026Ouml;zcan M. Additive manufacturing technologies for processing zirconia in dental applications. Int J Comput Dent. 2020;23(1):27\u0026ndash;37.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBranco AC, Cola\u0026ccedil;o R, Figueiredo-Pina CG, Serro AP. Recent advances on 3D-printed zirconia-based dental materials: A review. Materials. 2023;16(5):1860. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/ma16051860\u003c/span\u003e\u003cspan address=\"10.3390/ma16051860\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang J, Qin Q, Wang J. A review of stereolithography: Processes and systems. Processes. 2020;8(9):1138. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/pr8091138\u003c/span\u003e\u003cspan address=\"10.3390/pr8091138\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHussain MI, Xia M, Ren X, Ge C, Jamil M, Gupta MK. Digital light processing 3D printing of ceramic materials: A review on basic concept, challenges, and applications. Int J Adv Manuf Technol. 2024;130(5):2241\u0026ndash;67. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00170-024-12345-6\u003c/span\u003e\u003cspan address=\"10.1007/s00170-024-12345-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZocca A, Colombo P, Gomes CM, G\u0026uuml;nster J. Additive manufacturing of ceramics: Issues, potentialities, and opportunities. J Am Ceram Soc. 2015;98(7):1983\u0026ndash;2001. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jace.13700\u003c/span\u003e\u003cspan address=\"10.1111/jace.13700\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRevilla-Le\u0026oacute;n M, Husain NA-H, Ceballos L, \u0026Ouml;zcan M. Flexural strength and Weibull characteristics of stereolithography additive manufactured versus milled zirconia. J Prosthet Dent. 2021;125(4):685\u0026ndash;90. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.prosdent.2020.05.022\u003c/span\u003e\u003cspan address=\"10.1016/j.prosdent.2020.05.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuominen JM, Frankberg EJ, Vallittu PK, Lev\u0026auml;nen E, Vihinen J, Vastam\u0026auml;ki T, et al. Three-dimensional printing of zirconia: Characterization of early-stage material properties. Biomater Investig Dent. 2019;6(1):23\u0026ndash;31. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/26415275.2019.1642331\u003c/span\u003e\u003cspan address=\"10.1080/26415275.2019.1642331\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOsman RB, van der Veen AJ, Huiberts D, Wismeijer D, Alharbi N. 3D-printing zirconia implants; A dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs. J Mech Behav Biomed Mater. 2017;75:521\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmbbm.2017.08.018\u003c/span\u003e\u003cspan address=\"10.1016/j.jmbbm.2017.08.018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaysal N, Kalyoncuoğlu UT, Ayyıldız S. Mechanical properties and bond strength of additively manufactured and milled dental zirconia: A pilot study. J Prosthodont. 2022;31(7):629\u0026ndash;34. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jopr.13472\u003c/span\u003e\u003cspan address=\"10.1111/jopr.13472\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbualsaud R, Abussaud M, Assudmi Y, Aljoaib G, Khaled A, Alalawi H, et al. Physiomechanical and surface characteristics of 3D-printed zirconia: An in vitro study. Materials. 2022;15(19):6988. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/ma15196988\u003c/span\u003e\u003cspan address=\"10.3390/ma15196988\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBergler M, Korostoff J, Torrecillas-Martinez L, Mante FK. Ceramic printing\u0026mdash;Comparative study of the flexural strength of 3D-printed and milled zirconia. Int J Prosthodont. 2022;35(6). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11607/ijp.7534\u003c/span\u003e\u003cspan address=\"10.11607/ijp.7534\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRevilla-Le\u0026oacute;n M, Al‐Haj Husain N, Barmak AB, P\u0026eacute;rez‐L\u0026oacute;pez J, Raigrodski AJ, \u0026Ouml;zcan M. Chemical composition and flexural strength discrepancies between milled and lithography‐based additively manufactured zirconia. J Prosthodont. 2022;31(9):778\u0026ndash;83. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jopr.13482\u003c/span\u003e\u003cspan address=\"10.1111/jopr.13482\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLakhdar Y, Tuck C, Binner J, Terry A, Goodridge R. Additive manufacturing of advanced ceramic materials. Prog Mater Sci. 2021;116:100736. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.pmatsci.2021.100736\u003c/span\u003e\u003cspan address=\"10.1016/j.pmatsci.2021.100736\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCho S-M, Kim RJY, Park J-M, Chung H-M, Kim D-Y. Trueness, physical properties, and surface characteristics of additive-manufactured zirconia crown. J Mech Behav Biomed Mater. 2024;154:106536. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmbbm.2023.106536\u003c/span\u003e\u003cspan address=\"10.1016/j.jmbbm.2023.106536\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee J-W, Park J-M. Evaluation of marginal and internal gap under model-free monolithic zirconia restoration fabricated by digital intraoral scanner. J Korean Acad Prosthodont. 2016;54(3):210\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4047/jkap.2016.54.3.210\u003c/span\u003e\u003cspan address=\"10.4047/jkap.2016.54.3.210\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcLean J. The estimation of cement film thickness by an in vivo technique. Br Dent J. 1971;131(3):107\u0026ndash;11. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/sj.bdj.4802708\u003c/span\u003e\u003cspan address=\"10.1038/sj.bdj.4802708\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBindl A, M\u0026ouml;rmann W. Marginal and internal fit of all-ceramic CAD/CAM crown‐copings on chamfer preparations. J Oral Rehabil. 2005;32(6):441\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1365-2842.2005.01446.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1365-2842.2005.01446.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeschnidt S, Strub J. Evaluation of the marginal accuracy of different all-ceramic crown systems after simulation in the artificial mouth. J Oral Rehabil. 1999;26(7):582\u0026ndash;93. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1046/j.1365-2842.1999.00434.x\u003c/span\u003e\u003cspan address=\"10.1046/j.1365-2842.1999.00434.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFelton D, Kanoy B, Bayne SA, Wirthman G. Effect of in vivo crown margin discrepancies on periodontal health. J Prosthet Dent. 1991;65(3):357\u0026ndash;64. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0022-3913(91)90234-8\u003c/span\u003e\u003cspan address=\"10.1016/0022-3913(91)90234-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Z-C, Li P-L, Chu F-T, Shen G. Influence of the three-dimensional printing technique and printing layer thickness on model accuracy. J Orofac Orthop. 2019;80(4):221\u0026ndash;32. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00056-019-00182-1\u003c/span\u003e\u003cspan address=\"10.1007/s00056-019-00182-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTan X, Lu Y, Gao J, Wang Z, Xie C, Yu H. Effect of high-speed sintering on the microstructure, mechanical properties and ageing resistance of stereolithographic additive-manufactured zirconia. Ceram Int. 2022;48(7):9797\u0026ndash;804. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ceramint.2022.01.107\u003c/span\u003e\u003cspan address=\"10.1016/j.ceramint.2022.01.107\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCao J, Liu X, Cameron A, Aarts J, Choi JJE. Influence of different post-processing methods on the dimensional accuracy of 3D-printed photopolymers for dental crown applications\u0026mdash;A systematic review. J Mech Behav Biomed Mater. 2024;150:106314. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmbbm.2023.106314\u003c/span\u003e\u003cspan address=\"10.1016/j.jmbbm.2023.106314\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGilman JJ. Chemistry and physics of mechanical hardness. Hoboken, NJ: Wiley; 2009.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePintaude G. Hardness as an indicator of material strength: A critical review. Crit Rev Solid State Mater Sci. 2023;48(5):623\u0026ndash;41. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/10408436.2023.2174463\u003c/span\u003e\u003cspan address=\"10.1080/10408436.2023.2174463\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eD\u0026rsquo;arcangelo C, Vanini L, Rondoni GD, De Angelis F. Wear properties of dental ceramics and porcelains compared with human enamel. J Prosthet Dent. 2016;115(3):350\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.prosdent.2015.09.013\u003c/span\u003e\u003cspan address=\"10.1016/j.prosdent.2015.09.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi K, Rao J, Ning C. Optimized sintering and mechanical properties of Y-TZP ceramics for dental restorations by adding lithium disilicate glass ceramics. J Adv Ceram. 2021;10:1326\u0026ndash;37. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s40145-021-0482-6\u003c/span\u003e\u003cspan address=\"10.1007/s40145-021-0482-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTuron-Vinas M, Anglada M. Strength and fracture toughness of zirconia dental ceramics. Dent Mater. 2018;34(3):365\u0026ndash;75. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.dental.2017.12.003\u003c/span\u003e\u003cspan address=\"10.1016/j.dental.2017.12.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFayazfar H, Liravi F, Ali U, Toyserkani E. Additive manufacturing of high loading concentration zirconia using high-speed drop-on-demand material jetting. Int J Adv Manuf Technol. 2020;109(9):2733\u0026ndash;46. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00170-020-05744-4\u003c/span\u003e\u003cspan address=\"10.1007/s00170-020-05744-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSu G, Zhang Y, Jin C, Zhang Q, Lu J, Liu Z, et al. 3D printed zirconia used as dental materials: A critical review. J Biol Eng. 2023;17(1):78. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/s13036-023-00378-6\u003c/span\u003e\u003cspan address=\"10.1186/s13036-023-00378-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQeblawi DM, Mu\u0026ntilde;oz CA, Brewer JD, Monaco EA Jr. The effect of zirconia surface treatment on flexural strength and shear bond strength to a resin cement. J Prosthet Dent. 2010;103(4):210\u0026ndash;20. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0022-3913(10)60032-9\u003c/span\u003e\u003cspan address=\"10.1016/S0022-3913(10)60032-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkın H, Ozkurt Z, Kırmalı O, Kazazoglu E, Ozdemir AK. Shear bond strength of resin cement to zirconia ceramic after aluminum oxide sandblasting and various laser treatments. Photomed Laser Surg. 2011;29(12):797\u0026ndash;802. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1089/pho.2011.3072\u003c/span\u003e\u003cspan address=\"10.1089/pho.2011.3072\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAltan B, Cinar S, Tuncelli B. Evaluation of shear bond strength of zirconia-based monolithic CAD-CAM materials to resin cement after different surface treatments. Niger J Clin Pract. 2019;22(11):1475\u0026ndash;82. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4103/njcp.njcp_51_19\u003c/span\u003e\u003cspan address=\"10.4103/njcp.njcp_51_19\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi H, Song L, Sun J, Ma J, Shen Z. Dental ceramic prostheses by stereolithography-based additive manufacturing: Potentials and challenges. Adv Appl Ceram. 2019;118(1\u0026ndash;2):30\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/17436753.2019.1709687\u003c/span\u003e\u003cspan address=\"10.1080/17436753.2019.1709687\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBalakrishnan A, Pizette P, Martin C, Joshi S, Saha B. Effect of particle size in aggregated and agglomerated ceramic powders. Acta Mater. 2010;58(3):802\u0026ndash;12. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.actamat.2009.10.034\u003c/span\u003e\u003cspan address=\"10.1016/j.actamat.2009.10.034\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\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":"Zirconia, 3D-printed crown, Dental prosthesis fit, Physical properties, Mechanical properties","lastPublishedDoi":"10.21203/rs.3.rs-6273991/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6273991/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e This study aims to present different zirconia 3D printing materials and technologies, and to evaluate the fit, hardness and shear bond strength of crowns produced by additive (AM) and subtractive (SM) manufacturing methods, along with an assessment of surface characteristics.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e Zirconia crowns fabricated using one 5-axis SM and five AM approaches, including four different digital light processing (DLP) principles and one stereolithography (SLA) technique, each with varying slurry delivery and light-curing mechanisms. The marginal and internal gaps (axial, line angle, occlusal) between crowns and abutments were measured using the replica technique. Vickers hardness and shear bond strength between the crowns and resin cement was evaluated. Surface characteristics were analyzed with scanning electron microscopy (SEM) after printing and sandblasting.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Marginal fit analysis revealed that the marginal fit was 48.45 µm for the milling group and ranged from 42.83 to 81.95 µm for the additive manufacturing groups, with significant differences between groups (\u0026lt;0.001), but all within the clinical acceptance range (120 µm). Vickers hardness measurements showed the milling group had a hardness of 1473.87 HV, while the additive manufacturing groups ranged from 1441.94 to 1532.53 HV, with statistically significant differences (P\u0026lt;0.001). Shear bond strength measurements showed 7.97 MPa for the milling group and 6.97 to 8.97 MPa for the additive manufacturing groups, with no significant differences between groups. SEM analysis of crown surfaces revealed agglomerated zirconia particles, with various grooves observed after sandblasting.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eZirconia crowns produced by both AM and SM methods demonstrated clinically acceptable marginal fit and ideal hardness above 1200 HV. Some additive manufacturing groups exhibited higher hardness and shear bond strength compared to the milling group. The diverse physical and mechanical properties of various zirconia 3D printing technologies suggest their selective use based on specific clinical situations.\u003c/p\u003e","manuscriptTitle":"Comparative Analysis of Fit, Mechanical Properties, and Surface Characteristics in Subtractive and Additive Manufactured Zirconia Crowns","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-15 16:52:52","doi":"10.21203/rs.3.rs-6273991/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-15T12:24:51+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-11T17:27:48+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-08T07:39:23+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-03T01:08:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"337483528783039773410821705687885141083","date":"2025-03-31T19:12:00+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"220101211099877095018437443723627947959","date":"2025-03-31T03:30:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"126278736495447667754106168317842128831","date":"2025-03-30T23:24:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"272781339890292920625104832037941218311","date":"2025-03-28T08:33:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-28T03:39:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-27T11:45:18+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-27T11:44:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-03-21T04:31:03+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":"ee58ead7-8885-493a-ad53-b088909db6e7","owner":[],"postedDate":"April 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-08-04T16:40:59+00:00","versionOfRecord":{"articleIdentity":"rs-6273991","link":"https://doi.org/10.1186/s12903-025-06561-7","journal":{"identity":"bmc-oral-health","isVorOnly":false,"title":"BMC Oral Health"},"publishedOn":"2025-08-01 16:21:04","publishedOnDateReadable":"August 1st, 2025"},"versionCreatedAt":"2025-04-15 16:52:52","video":"","vorDoi":"10.1186/s12903-025-06561-7","vorDoiUrl":"https://doi.org/10.1186/s12903-025-06561-7","workflowStages":[]},"version":"v1","identity":"rs-6273991","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6273991","identity":"rs-6273991","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}