Comparative Evaluation of Surface Adaptation and Mechanical Properties of Maxillary Complete Denture Bases Fabricated by Conventional and Three-Dimensional Printing Methods: A comparative in vitro study

Comparative Evaluation of Surface Adaptation and Mechanical Properties of Maxillary Complete Denture Bases Fabricated by Conventional and Three-Dimensional Printing Methods: A comparative in vitro study | 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 Evaluation of Surface Adaptation and Mechanical Properties of Maxillary Complete Denture Bases Fabricated by Conventional and Three-Dimensional Printing Methods: A comparative in vitro study Afra Banu, Murat ALKURT This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8642763/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 15 You are reading this latest preprint version Abstract Background Proper conformity of the denture base to the underlying mucosal tissues plays a fundamental role in ensuring the retention and stability of complete dentures. Although three-dimensional (3D) printing offers a more standardized manufacturing process than conventional compression molding, differences in surface adaptation and mechanical strength among fabrication techniques remain. The objective of this investigation was to evaluate and contrast the tissue surface adaptation and mechanical performance of maxillary complete denture bases produced through various fabrication techniques. Methods A gypsum cast derived from a prefabricated edentulous maxillary silicone mold was digitally scanned using an extraoral scanner, after which a denture base with a uniform thickness of 2 mm was designed in Exocad and saved in STL format. Denture bases were fabricated using digital light processing (DLP; Phrozen Lumi), liquid crystal display (LCD; Elegoo Saturn 4 Ultra 16K), and conventional compression molding (CM). For adaptation analysis, specimens were sectioned along transverse (maxillary second molar level) and sagittal (midline) planes, and the denture base–model gap was measured at six predefined ridge and palatal reference points using a stereomicroscope (20× magnification, 1 µm resolution). For mechanical evaluation, bar-shaped specimens (64 × 10 × 3.3 mm; n = 10 per group) were prepared according to ISO 20795-1:2013 and tested using a three-point flexural strength test on a universal testing machine (Instron). Results Regarding denture base adaptation, the compression molding (CM) group showed significantly better adaptation in the midpalatal region (B) than the LCD group. At the left ridge crest (C), the DLP group demonstrated superior adaptation compared with both the LCD and CM groups, while at the anterior ridge crest (D), the CM and DLP groups outperformed the LCD group. At the most posterior sagittal point (F), the CM group exhibited significantly better adaptation than both additively manufactured groups. Flexural strength differed significantly among groups, with the highest values observed in the CM group (153.88 ± 35.38 MPa). Among the additively manufactured groups, the LCD group (73.09 ± 2.23 MPa) showed higher flexural strength than the DLP group (66.93 ± 2.29 MPa). Conclusions The manufacturing technique significantly affects maxillary denture base adaptation in a region-dependent manner. Compression molding provided more favorable adaptation in the posterior palatal region, whereas DLP showed better adaptation than LCD. Conventionally heat-polymerized PMMA exhibited the highest flexural strength, while both 3D-printed groups met the ISO 20795-1:2013 minimum requirements. Therefore, fabrication technique selection should consider both the target adaptation region and mechanical performance requirements. Complete denture denture base tissue surface adaptation DLP LCD 3D conventional compression molding flexural strength Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION Complete dentures remain a widely used and effective treatment option for restoring oral function, esthetics, and quality of life in edentulous patients.[ 1 ] The ability of complete dentures to achieve sufficient retention and stability is largely determined by the accuracy of the fit between the denture’s intaglio surface and the underlying supporting mucosa.[ 2 ] Reducing dimensional distortion throughout the fabrication process enhances the conformity of the denture base to the mucosal tissues.[ 3 ] In compression molding procedures, polymerization of PMMA-based resins has been shown to induce volumetric shrinkage of approximately 7% and linear shrinkage ranging from 0.45% to 0.9%, potentially compromising the adaptation between the denture base and the supporting mucosa.[ 4 ] Advances in CAD/CAM systems have led to the widespread adoption of both additive and subtractive digital workflows in complete denture production. Nevertheless, subtractive techniques are associated with considerable material wastage, and the final morphology of the restoration may be limited by the size and geometry of the milling tools. In particular, when the bur diameter exceeds the size of certain anatomical regions, internal fit accuracy and marginal quality may be adversely affected.[ 5 ] In addition, the high cost associated with subtractive manufacturing systems limits their widespread clinical application.[ 6 ] In contrast, additive manufacturing enables the fabrication of more complex geometries and offers advantages over milling techniques, including reduced material waste and lower equipment costs.[ 7 ] In additive manufacturing processes, unpolymerized resin is deposited in a three-dimensional manner and subsequently polymerized using ultraviolet (UV) or visible light sources.[ 8 ] Complete denture bases produced by additive manufacturing are most commonly fabricated using light-curable acrylic-based resins via liquid crystal display (LCD) and digital light processing (DLP) techniques. Following fabrication, residual unpolymerized resin is removed using ultrasonic cleaning and isopropyl alcohol, after which post-curing is performed to achieve final polymerization of the material.² Polymerization-related deformations may occur during this process.[ 9 ] In the DLP technique, each layer is polymerized simultaneously using a projection system located beneath the resin vat. This approach provides high accuracy while rendering the manufacturing time largely independent of layer geometry or the number of printed objects.[ 10 ] The distinction between LCD and DLP technologies is mainly associated with the type of imaging system used and the output characteristics of the light source.[ 11 ] During photopolymerization, the intensity of the light source plays a decisive role in determining printing efficiency and the extent of material polymerization. In LCD-based systems, reliance on an LCD panel as the imaging mechanism may lead to reduced manufacturing accuracy when compared with DLP technology.[ 10 ] With the increasing adoption of three-dimensional manufacturing systems in dentistry, research in this field has expanded considerably. In the literature, DLP-type printers are frequently preferred in studies evaluating surface adaptation,[ 12 – 15 ] whereas investigations focusing on LCD-type printers remain limited.[ 16 ] Accurate fabrication of dentures to ensure appropriate fit and function within the patient’s oral cavity is a fundamental requirement.[ 17 ] As defined in ISO 5725-1, trueness denotes how closely a measured result approximates the true value, while precision refers to the reproducibility of repeated measurements performed under the same conditions.[ 18 ] In this context, trueness represents the deviation between the intaglio surface of complete dentures fabricated based on a gypsum model and the reference value, while precision reflects the extent to which the same intaglio surface is reproducibly manufactured within each fabrication technique.[ 19 ] In addition, the mechanical and physical properties of denture bases—particularly their resistance to masticatory forces—are of critical importance for clinical performance, as the mechanical behavior of a material reflects its fundamental physical and chemical characteristics.[ 20 ] Denture bases must exhibit sufficient mechanical properties to withstand functional loads and maintain dimensional stability over time.[ 21 ] In accordance with ADA Specification No. 139 and ISO 20795-1 for denture base polymers, flexural strength of denture base resins is commonly assessed using the three-point bending test, which provides information on material stiffness and resistance to deformation.[ 22 – 24 ] Flexural strength describes the highest level of bending stress a material can tolerate before fracture and is regarded as a key indicator of the clinical performance of complete dentures.[ 25 ] This in-vitro investigation sought to evaluate and compare the tissue surface adaptation and mechanical performance of maxillary complete denture bases manufactured by compression molding (CM), liquid crystal display (LCD), and digital light processing (DLP) methods. The first null hypothesis proposed that tissue surface adaptation would not differ significantly among the fabrication techniques, while the second null hypothesis stated that no significant differences in mechanical strength would be observed between the groups. MATERIALS AND METHODS In the present study, a prefabricated edentulous maxillary silicone mold served as the master reference. Type IV dental stone (Elite Master; Zhermack) was poured into the mold following the manufacturer’s recommendations, resulting in 30 gypsum casts (n = 10 per group). For digital reference generation, the gypsum cast was digitized using a calibrated extraoral scanner (7 Series DentalWings; DentalWings/Straumann). The scanned data were subsequently imported into Exocad software, where a removable maxillary complete denture base with a standardized thickness of 2 mm was designed and exported in STL format. Fabrication of Complete Denture Bases Using DLP and LCD Technologies For denture base fabrication, a DLP-type 3D printer (Phrozen Lumi; Phrozen) and an LCD-type 3D printer (Elegoo Saturn 4 Ultra 16K; Elegoo) were used. In both systems, support structures were positioned on the buccal surface of the denture bases at a 90° build orientation to ensure fabrication stability. A 405-nm LED light source and a layer thickness of 100 µm were employed, and 10 denture bases were produced for each group. A photopolymerizable resin compatible with both printing systems (Alias Dental Denture Resin; Dokuz Kimya) was used. Following the printing process, the denture bases were separated from the build platform, and support structures were carefully removed by hand to avoid surface damage. Subsequent cleaning and post-curing procedures were carried out in accordance with the manufacturer’s guidelines using an Elegoo Mercury Plus unit. Specimens were washed in isopropyl alcohol for 5 minutes, followed by post-curing under a light source for an additional 5 minutes. Fabrication of Complete Denture Bases Using the Compression Molding (CM) Technique For the conventional compression molding technique, a heat-polymerized PMMA-based acrylic resin (Imicryl IQ 15; Imicryl) was used. The material was manipulated according to the manufacturer’s guidelines using a powder-to-liquid ratio of 23.4 g to 10 mL and was mixed for approximately 1 minute until a uniform consistency was obtained. To ensure consistent denture base thickness among all specimens, denture base designs produced by the 3D printing systems were utilized as reference templates during the compression molding process. The denture base forms were transferred to negative molds created using a condensation silicone impression material (Oxasil; Zhermack). The acrylic resin in the dough stage was manually packed into the molds, and polymerization was completed according to the manufacturer’s protocol by maintaining the flasks in a boiling water bath for 15 minutes, followed by an additional 20 minutes of heating. Fabrication of Specimens for Flexural Strength Testing For flexural strength testing, rectangular specimens with dimensions compliant with ISO 20795-1:2013 (64 × 10 × 3.3 mm) were designed and fabricated using DLP and LCD 3D printing systems. For the conventional compression molding group, wax patterns of identical dimensions were prepared, invested in a metal mold, and stabilized with dental plaster, followed by a standard compression molding procedure. Wax elimination was performed in a hot water bath, after which the resulting mold spaces were packed with PMMA acrylic resin in the dough stage. Polymerization was completed in a boiling water bath in accordance with the manufacturer’s protocol. Specimens obtained from all fabrication methods were lightly polished to ensure surface smoothness and thickness standardization, and their dimensions were verified using a digital caliper. Specimens that did not meet the ISO 20795-1:2013 criteria were excluded from the study. Ultimately, a total of 30 specimens, equally distributed among the CM, DLP, and LCD groups, were prepared for mechanical testing, with each group representing a different fabrication technique. Sectioning of Denture Bases and Measurement Procedure To assess the adaptation of the denture bases to the supporting models, each specimen was sectioned along two predefined planes (Fig. 1 ). 1) Transverse (Horizontal) section : at the level of the maxillary second molars. 2) Sagittal (Vertical) section : along the maxillary midline. Sectioning was carried out using a precision cutting machine (Isomet 1000; Buehler, USA) under continuous water irrigation, with standardized speed and load parameters. To ensure standardization, all models were positioned in custom-made guiding jigs during sectioning. Two sectional planes were obtained from each specimen, and specific anatomical reference points were defined on each section to ensure consistency in adaptation measurements. Based on previously published studies, the following measurement points were selected [ 26 , 27 ]. Transverse Section (Fig. 2 ) Sagittal Section (Fig. 3 ) A) Right alveolar ridge crest D) Anterior ridge crest B) Midline palatal point E) Midpoint of the sagittal section C) Left alveolar ridge crest F) Most posterior point of the sagittal section A total of six measurement points were evaluated for each specimen. To ensure that reference points were obtained at identical locations across all specimens, a silicone-based positioning guide was used. In the sectioned denture bases, the gap between the intaglio surface and the model surface was measured using a stereomicroscope (Stemi 305; Carl Zeiss) at 20× magnification with a resolution of 1 µm; the device was calibrated with a standard reference scale prior to each measurement session. Measurements were performed using microscope-integrated analysis software (ZEN Blue; Carl Zeiss). Before measurement, all specimens were stored at room temperature in a light-proof, closed environment to ensure dimensional stabilization. Application of the Flexural Strength Test Flexural strength testing was conducted in compliance with ISO 20795-1:2013 using a universal testing machine (Instron 3344; Instron). Rectangular specimens measuring 64 × 10 × 3.3 mm were subjected to a three-point bending protocol, with a support span of 50 mm and a crosshead speed of 5 mm/min until fracture occurred. The peak fracture load (N) was automatically recorded by the testing software, and flexural strength values were calculated in megapascals (MPa) according to the equation specified in ISO 1567:1999. RESULTS Statistical evaluations were conducted using SPSS software (version 27; SPSS Inc.), with descriptive outcomes reported as means and standard deviations. The assumption of normal data distribution was examined using the Shapiro–Wilk test, while variance homogeneity was verified through Levene’s test. Intergroup comparisons were performed using one-way ANOVA for datasets demonstrating normal distribution, whereas the Kruskal–Wallis test was applied when normality assumptions were not met. In cases of statistically significant findings, Bonferroni-adjusted post-hoc tests were used to determine pairwise differences. Statistical significance was defined at an alpha level of 0.05 for all analyses (Table 1 ). Table 1 Kruskal-Wallis and ANOVA analysis results of denture base adaptation measurements (µm) at measurement points A-F for the LCD, DLP, and compression molding (CM) groups. LCD DLP CM Test statistic p Bonferroni Point Mean ± SD Mean ± SD Mean ± SD A 464.3 ± 115.14 448.04 ± 142 508.44 ± 191.48 KW = 0.591 0.744 - B 1722.8 ± 439.31 1589.01 ± 350.89 1323.53 ± 300.44 KW = 8.101 0.017* CM < LCD C 678.02 ± 178.43 461.89 ± 147.58 774.74 ± 141.53 KW = 12.707 0.002* DLP < LCD; DLP < CM D 582.65 ± 135.95 368.42 ± 88.19 343.03 ± 163.79 KW = 13.680 0.001* CM < LCD; DLP < LCD E 1005.22 ± 213.46 847.7 ± 209.93 754.38 ± 304.34 KW = 4.895 0.086 - F 1721.19 ± 139.19 1505.49 ± 267.8 1129.91 ± 152.83 KW = 17.799 < 0.001* CM < DLP; CM < LCD Test statistic F = 107.660 F = 51.499 F = 31.790 p < 0.001* < 0.001* < 0.001* Bonferroni A < B; A < E; A < F; C < B; C < E; C < F; D < B; D < E; D < F; E < B; E < F A < B; A < E; A < F; C < B; D < B; E < B; C < E; C < F; D < E; D < F; E < F A < B; A < C; A < F; C < B; D < B; E < B; D < C; C < F; D < E; D < F p < 0.05; F: ANOVA test statistic (analysis of variance); KW: Kruskal-Wallis test statistic; Mean; SD: standard deviation. For comparisons among the DLP, LCD, and compression molding (CM) groups across measurement points A–F, the Kruskal–Wallis test was applied due to non-normal data distribution. No significant intergroup differences were identified at point A (right ridge crest) or point E (midpoint of the sagittal section) (p > 0.05). However, a statistically significant difference was observed at point B (midpalatal region) (KW = 8.101; p = 0.017), where Bonferroni-adjusted post-hoc analysis demonstrated significantly lower values in the CM group compared with the LCD group (Fig. 4 ) At point C (left alveolar ridge crest), the DLP group demonstrated significantly lower values compared with both the LCD and CM groups (KW = 12.707; p = 0.002). At point D (anterior ridge crest), the LCD group showed significantly higher values than the DLP and CM groups (KW = 13.680; p = 0.001). At point F (the most posterior point of the sagittal section), the CM group exhibited significantly lower values than both 3D printing groups (KW = 17.799; p < 0.001). These findings indicate that denture base adaptation should be evaluated in a region-specific manner and that fabrication techniques do not demonstrate uniform performance across all anatomical regions (Fig. 5 ). Within the LCD group, differences among measurement points A-F were evaluated using one-way ANOVA, which revealed statistically significant differences among the points (F = 107.660; p < 0.001). According to Bonferroni post-hoc analysis, points A, C, and D exhibited significantly lower values compared with points B (midpalatal), E (midpoint of the sagittal section), and F (posterior point of the sagittal section) (p < 0.05). In addition, point E demonstrated significantly lower values than points B and F. The highest measurement value was observed at point B (midpalatal region). Within the DLP group, differences among measurement points A-F were analyzed using one-way ANOVA, revealing statistically significant differences among the points (F = 51.499; p < 0.001). Bonferroni post-hoc analysis indicated that points A, C, and D exhibited significantly lower values compared with points B (midpalatal), E (midpoint of the sagittal section), and F (posterior point of the sagittal section). In addition, point E showed significantly lower values than points B and F (p < 0.05). The highest measurement value was observed at point B (midpalatal region). Within the compression molding (CM) group, variations among measurement points A–F were analyzed using one-way ANOVA, revealing statistically significant differences across the points (F = 31.790; p < 0.001). Bonferroni-adjusted post-hoc comparisons indicated that values at point A were significantly lower than those at points B, C, and F. Furthermore, point C demonstrated significantly lower values compared with points B and F, while point D showed significantly lower values than points B, C, E, and F. Additionally, point E exhibited significantly lower values than point B (p < 0.05). The highest measurement value within the CM group was recorded at point B, corresponding to the midpalatal region. Evaluation of Flexural Strength Flexural strength outcomes among the DLP, LCD, and compression molding (CM) groups were analyzed using the Kruskal–Wallis test, revealing a statistically significant intergroup difference (KW = 25.806; p < 0.001). Bonferroni-adjusted post-hoc comparisons indicated that the DLP group demonstrated significantly lower flexural strength values compared with both the LCD and CM groups (Fig. 6 ). In addition, the LCD group demonstrated significantly lower flexural strength values compared with the CM group (p < 0.05). The highest flexural strength was recorded in the CM group (Table 2 ). Table 2 Evaluation of Flexural Strength (MPa) n M. (Min.-Max.) Mean ± SD Test statistic p Bonferroni DLP 1 10 66.91 (0-63.46) 66.93 ± 2.29 KW = 25.806 < 0.001* 1 < 2 1 < 3 2 < 3 LCD 2 10 72.97 (0-69.59) 73.09 ± 2.23 CM 3 10 147.29 (0-116.12) 153.88 ± 35.38 p < 0.05; KW: Kruskal–Wallis test statistic; n: number of specimens; Min: minimum; Max: maximum; Mean; SD: standard deviation. DISCUSSION In this in vitro study, the surface adaptation of 2-mm-thick complete denture bases fabricated using conventional compression molding, as well as DLP and LCD additive manufacturing techniques, and the mechanical strength of specimens prepared in accordance with ISO 20795 were compared. The aim was to identify the advantages and limitations of different fabrication techniques and to provide clinicians with a scientific basis for method selection. The findings demonstrated statistically significant differences among the fabrication methods in terms of both adaptation and mechanical strength; therefore, the null hypotheses were rejected. Previous studies have reported that in three-dimensionally printed complete dentures, a reduction in denture base thickness below 2 mm results in a marked decrease in flexural strength, and consequently, a minimum denture base thickness of 2 mm has been recommended for maxillary complete dentures.[ 28 ] DLP and LCD systems have emerged as alternatives to stereolithography (SLA) because of their high resolution and rapid production capabilities. DLP printers can fabricate objects with layer thicknesses of up to approximately 50 µm using a 405-nm LED light source, whereas LCD printers, although more cost-effective, operate with lower light intensity compared with DLP systems.[ 29 ] Chih-Yuan et al.[ 30 ] fabricated 2-mm-thick denture base plates using different manufacturing techniques and reported that CAD/CAM milling achieved the best adaptation based on analyses performed at 60 measurement points. In a related investigation, Oğuz et al. [ 31 ] analyzed the adaptation of denture base plates manufactured from digitized edentulous models across six anatomical regions using micro–computed tomography. Their findings indicated that the smallest interfacial gaps were recorded in the milling (PMMA milling) group, whereas progressively larger gap values were observed in the conventional compression molding (CM), injection molding (IM), and three-dimensional (3D) printing groups. Notably, in the maxilla, a pronounced increase in the palatal gap was reported in the compression molding group. Kanyakorn et al. [ 15 ] evaluated the tissue surface adaptation of denture base plates produced by milling and three-dimensional printing, demonstrating that the milled specimens achieved superior adaptation across the overall intaglio surface and primary stress-bearing regions, whereas additively manufactured specimens showed improved adaptation in the peripheral and posterior palatal seal areas. This difference was attributed to the presence of anatomical undercuts in these regions and the inherent structural limitations of the milling technique in reproducing such complex geometries. Although the superior performance of milled dentures has been reported, this technique is associated with several disadvantages, including high initial investment costs, substantial material waste, and prolonged fabrication time. While the production time for milled dentures is approximately 5 hours, this duration is reduced to an average of about 1.5 hours with three-dimensional printing techniques, and the cost of milling blocks is generally higher than that of printing resins. Nevertheless, both manufacturing methods have been reported to provide clinically acceptable outcomes. These findings indicate that, in addition to accuracy and mechanical durability, factors such as cost, time efficiency, and specific clinical requirements should be considered when selecting a fabrication technique.[ 32 – 34 ] Hwang et al. [ 2 ] demonstrated that denture bases produced using the DLP technique achieved superior accuracy and more favorable tissue surface adaptation than those fabricated by milling or conventional compression molding, with reported adaptation values remaining below the 100-µm threshold. This superiority was attributed to the ability of the DLP technique to more effectively reproduce the morphological irregularities of the residual ridge. Kaya and Yanıkoğlu [ 35 ] compared denture bases fabricated with different palatal depths and reported that, in shallow palatal morphologies, the DLP technique yielded significantly lower deviation values in the palatal region. These findings highlight region-dependent variability in adaptation and suggest an advantage of DLP under specific morphological conditions. The literature does not present a definitive consensus on the comparative performance of fabrication techniques with respect to surface adaptation and accuracy, a variability that has been attributed to differences in printer systems, resin formulations, and processing parameters. While some studies have reported superior adaptation with SLA or subtractive milling compared with DLP[ 12 , 15 , 30 ] others have demonstrated that DLP provides more favorable outcomes than milling, conventional compression molding, and LCD techniques.[ 2 , 16 , 36 ] Oh et al. [ 37 ] reported that polymerization shrinkage associated with palatal concavity tends to occur toward the residual ridge, resulting in a more pronounced lifting effect in the midpalatal region. Consani et al. [ 38 ] indicated that linear shrinkage renders the palatal region—particularly the molar area—the most critical site for gap formation. Tan et al. [ 39 ] further reported that manual finger pressure is insufficient to ensure adequate denture base adaptation. This phenomenon may be explained by the broad, concave anatomy of the palatal region, which provides relatively limited structural support and is therefore unable to adequately counteract polymerization shrinkage forces. In addition, the three-dimensional and directional nature of polymerization shrinkage causes the denture base to be drawn toward the more rigid, residual ridge–supported areas, thereby amplifying the lifting effect observed in the palatal region. In the literature, surface adaptation of complete dentures has commonly been evaluated by dividing the intaglio surface into anatomical regions such as the palatal vault, alveolar ridges, and peripheral borders,[ 16 , 38 , 40 ] while some studies have also included areas distant from the denture border in their analyses.[ 3 , 15 ] This region-based approach highlights performance differences of fabrication techniques according to specific anatomical areas. In the present study, measurement points were defined as three alveolar ridge crest regions and three palatal midline regions. In one study, maxillary models were sectioned transversely at the canine, molar, and posterior midpalatal regions to assess anterior–posterior adaptation, and gaps at the right and left ridge crests and the midpalatal region in each section were measured using a stereomicroscope at 20× magnification.[ 26 ] Similarly, in the present study, both transverse and sagittal sections were obtained, and measurements at the right and left ridge crests and the midpalatal region in the transverse section were performed using a stereomicroscope at 20× magnification. In another study, adaptation of maxillary complete dentures was evaluated at seven predefined measurement points on coronal and sagittal sections using a stereomicroscope, and the highest degree of misfit was reported to occur in the midpalatal region.[ 27 ] Consistent with these findings, the greatest misfit in the present study was also observed in the palatal region. Sinha et al. [ 41 ] assessed the marginal adaptation of complete denture bases produced by conventional and three-dimensional printing techniques at the midpalatal region as well as the right and left maxillary tuberosities using stereomicroscopic evaluation. Their results indicated lower misfit values for the conventional fabrication method, while the greatest marginal discrepancy for both techniques was detected at the left maxillary tuberosity. In contrast, in the present study, the greatest misfit in denture bases fabricated using both conventional and additive techniques was identified in the midpalatal region. This discrepancy may be attributed to the broader surface area and concave morphology of the palatal region, which render it more susceptible to polymerization shrinkage–induced stresses. Furthermore, compared with the residual ridge areas, the midpalatal region lacks structural support, allowing polymerization-related deformation to manifest more prominently. Consequently, regardless of the fabrication technique, the midpalatal region appears to represent a critical area where adaptation inaccuracies tend to concentrate. In a systematic review, it was reported that printing orientation significantly influences the accuracy and adaptation of 3D-printed denture bases, with 90° (vertical) orientation providing the highest adaptation, particularly in the posterior and peripheral palatal regions. This superiority was associated with more uniform light penetration, improved layer alignment, reduced support-induced distortion, and enhanced manufacturing efficiency.[ 42 ] Charoenphol et al.[ 43 ] reported that overall intaglio surface adaptation of DLP-fabricated complete denture bases was not affected by printing angle; however, a 90° printing orientation resulted in significantly better adaptation in the posterior palatal seal region. This improvement was attributed to a reduction in the staircase effect associated with layer deposition and decreased support-related deformation. Accordingly, in the present study, a 90° build orientation was selected to optimize adaptation in critical anatomical regions. Flexural strength constitutes a key determinant of denture base performance, and ISO 20795-1:2013 defines a minimum required value of 65 MPa for denture base materials [ 44 ]. For the assessment of flexural strength in polymer-based dental materials, the three-point bending test is commonly employed and has been shown to yield more consistent and reproducible outcomes than the four-point bending method [ 45 ]. Accordingly, the three-point bending test was chosen in the present study to evaluate the flexural strength of the denture base materials. Several studies in the literature have reported that PMMA-based denture bases fabricated using three-dimensional printing exhibit relatively low flexural strength values and may fall below the international standard threshold of 65 MPa. Çakmak et al.[ 46 ] reported that only the CAD/CAM milling group met the international standard of 65 MPa, whereas the 3D-printed specimens remained below this limit. Similarly, Prpić et al.[ 47 ] demonstrated that denture base materials produced by 3D printing showed significantly lower flexural strength compared with conventionally heat-polymerized acrylic resins. Gad et al.[ 48 ] further revealed that microscopic voids observed at the fracture sites of 3D-printed specimens constitute one of the primary causes of mechanical weakness, which was associated with insufficient interlayer bonding and irregular polymerization. In contrast, some studies have reported that denture base materials fabricated using three-dimensional printing technologies are capable of meeting the minimum flexural strength requirement of 65 MPa specified in ISO 20795-1:2013, thereby demonstrating mechanically acceptable performance for clinical use. Fouda et al.[ 49 ] reported flexural strength values of approximately 67–71 MPa for the SLA group and about 69 MPa for the DLP group in three-point bending tests, attributing the differences between SLA and DLP to variations in interlayer bonding and light-curing mechanisms; importantly, all reported values exceeded the clinical acceptance threshold of 65 MPa. Dai et al.[ 50 ] reported flexural strength values of approximately 80.92 MPa for DLP-printed specimens. Chhabra et al.[ 51 ] reported flexural strength values of 92.01 ± 12.14 MPa for heat-polymerized PMMA and 69.78 ± 7.54 MPa for 3D-printed denture base resin using the three-point bending test. The lower values observed for additively manufactured specimens were attributed to interfacial bonding weaknesses associated with layer-by-layer fabrication and to printing and post-curing parameters, whereas the more homogeneous structure and predictable mechanical behavior of heat-polymerized acrylic resins account for their higher strength. Al-Dwairi et al.[ 52 ] similarly reported that conventionally heat-polymerized denture base resin exhibited significantly superior flexural strength and hardness compared with 3D-printed materials. In the present study, denture bases fabricated using the conventional method demonstrated higher flexural strength than those produced by additive manufacturing techniques, and specimens fabricated using LCD printers exhibited superior flexural strength compared with those produced by DLP. Notably, both additive manufacturing groups demonstrated flexural strength values exceeding the minimum requirements specified by international standards. Appropriate post-polymerization protocols have been reported to enhance interlayer bonding by increasing polymerization time and light energy delivery, thereby significantly improving flexural strength. In this regard, Temizci et al.[ 53 ] demonstrated that 3D-printed specimens subjected to a two-stage post-polymerization protocol (30 + 30 minutes) exhibited statistically higher flexural strength compared with other fabrication methods. These findings indicate that the mechanical behavior of 3D-printed denture bases is influenced not only by the manufacturing technology itself but also by multiple parameters, including resin composition, printing orientation and layer thickness, printer type, as well as post-curing duration and light intensity. The main limitations of this study include the absence of subtractive manufacturing methods, reliance on stereomicroscopic two-dimensional measurements for adaptation analysis, and the in vitro study design. These factors may have limited the direct generalizability of the findings to all digital fabrication techniques and to clinical conditions. CONCLUSION 1. In this in vitro study, the tissue surface adaptation and flexural strength of maxillary complete denture bases fabricated using three different manufacturing techniques—DLP, LCD, and conventional compression molding—were compared. The findings demonstrated that the fabrication method had a significant influence on both adaptation and mechanical properties. When evaluated according to measurement points, the compression molding group exhibited more favorable adaptation in the posterior palatal regions, whereas the DLP group showed better adaptation at the ridge crest compared with the LCD group. These results suggest that no single fabrication technique provides superior performance across all anatomical regions of maxillary denture bases. 2. With respect to flexural strength, the conventional compression molding group demonstrated the highest values. Between the additive manufacturing techniques, the LCD group exhibited higher flexural strength than the DLP group. Nevertheless, both three-dimensional printing groups met the minimum requirements specified in ISO 20795-1:2013. These findings indicate that, from a mechanical standpoint, digital fabrication methods are clinically acceptable, although the conventional technique maintains a mechanical advantage. 3. Based on the results of this study, the selection of a fabrication technique in clinical practice should not be based solely on a distinction between digital and conventional approaches, but rather on a combined consideration of the targeted anatomical region requiring optimal adaptation and the expected mechanical demands. When digital methods are preferred, the influence of printer technology, resin type, and post-processing protocols on clinical outcomes should be carefully taken into account. Abbreviations Three-dimensional 3D Megapascal MPa Computer-aided design CAD Computer-aided manufacturing CAM Digital Light Processing DLP Liquid Crystal Display LCD Stereolithography SLA Compression Molding CM Standard Triangle Language STL International Organization for Standardization ISO Light Emitting Diode LED Declarations Ethics approval and consent to participate: As the study was conducted exclusively under laboratory conditions and did not involve patient data, ethics committee approval was not required. Consent for publication: Not applicable Availability of data and materials: All data generated or analysed during this study are included in this published article. Competing interests: The authors declare that they have no competing interests. Funding: This study has been supported by Recep Tayyip Erdogan University Development Foundation Authors' contributions: AE and MA contributed to the conceptualization of the study, writing, and preparation of the original draft. MA contributed to data curation, interpretation of the results, formal analysis, and critical revision of the manuscript. AE contributed to methodology design, data collection, literature review, and figure preparation. Both authors contributed to the review, editing, and final approval of the manuscript. All authors have read and approved the published version of the manuscript. Acknowledgements: Not applicable Clinical trial number: Not applicable References Lee DJ, Saponaro PC. Management of edentulous patients. Dent Clin. 2019;63:249–61. Hwang H-J, Lee SJ, Park E-J, Yoon H-I. Assessment of the trueness and tissue surface adaptation of CAD/CAM maxillary denture bases manufactured using digital light processing. J Prosthet Dent. 2019;121:110–7. Goodacre BJ, Goodacre CJ, Baba NZ, Kattadiyil MT. Comparison of denture base adaptation between CAD/CAM and conventional fabrication techniques. J Prosthet Dent. 2016;116:249–56. Parvizi A, Lindquist T, Schneider R, Williamson D, Boyer D, Dawson DV. Comparison of the dimensional accuracy of injection-molded denture base materials to that of conventional pressure‐pack acrylic resin. J Prosthodontics: Implant Esthetic Reconstr Dentistry. 2004;13:83–9. Steinmassl P-A, Klaunzer F, Steinmassl O, Dumfahrt H, Grunert I. Evaluation of currently available CAD/CAM denture systems. Int J Prosthodont. 2017, 30. Anadioti E, Musharbash L, Blatz MB, Papavasiliou G, Kamposiora P. 3D printed complete removable dental prostheses: a narrative review. BMC Oral Health. 2020;20:343. Javaid M, Haleem A. Current status and applications of additive manufacturing in dentistry: A literature-based review. J oral biology Craniofac Res. 2019;9:179–85. Lee S, Hong S-J, Paek J, Pae A, Kwon K-R, Noh K. 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Grande F, Tesini F, Pozzan MC, Zamperoli EM, Carossa M, Catapano S. Comparison of the accuracy between denture bases produced by subtractive and additive manufacturing methods: a pilot study. Prosthesis. 2022;4:151–9. Zattera ACA, Morganti FA, de Souza Balbinot G, Della Bona A, Collares FM. The influence of filler load in 3D printing resin-based composites. Dent Mater. 2024;40:1041–6. de Oliveira Limírio JPJ, de Luna Gomes JM, Rezende MCRA, Lemos CAA, Rosa CDDRD, Pellizzer EP. Mechanical properties of polymethyl methacrylate as a denture base: Conventional versus CAD/CAM resin–A systematic review and meta-analysis of in vitro studies. J Prosthet Dent. 2022;128:1221–9. No ANSIA. AS. 139 (ISO 20795-1), Denture base polymers. American Dental Association; 2013. Gharechahi J, Asadzadeh N, Shahabian F, Gharechahi M. Flexural strength of acrylic resin denture bases processed by two different methods. J Dent Res Dent Clin Dent Prospects. 2014;8:148. Abdulwahhab SS. High-impact strength acrylic denture base material processed by autoclave. J Prosthodontic Res. 2013;57:288–93. Zappini G, Kammann A, Wachter W. Comparison of fracture tests of denture base materials. J Prosthet Dent. 2003;90:578–85. Aneesha PN, Babu MS, Vineela G, Devarapalli S, Chowdary NK, Shaik H. Comparative Evaluation of the Adaptation Accuracy of Two Commercially-Available Denture Base Resins: An In Vitro Study. Cureus. 2025, 17. Sayed ME, Porwal A, Ehrenberg D, Weiner S. Effect of cast modification on denture base adaptation following maxillary complete denture processing. J Prosthodont. 2019;28:e6–12. Choi M, Acharya V, Berg RW, Marotta J, Green CC, Barbizam JV, White SN. Resinous denture base fracture resistance: effects of thickness and teeth. Int J Prosthodont. 2012, 25. Li P, Fernandez PK, Spintzyk S, Schmidt F, Yassine J, Beuer F, Unkovskiy A. Effects of layer thickness and build angle on the microbial adhesion of denture base polymers manufactured by digital light processing. J Prosthodontic Res. 2023;67:562–7. Hsu C-Y, Yang T-C, Wang T-M, Lin L-D. Effects of fabrication techniques on denture base adaptation: An in vitro study. J Prosthet Dent. 2020;124:740–7. Oğuz Eİ, Kılıçarslan MA, Özcan M, Ocak M, Bilecenoğlu B, Orhan K. Evaluation of denture base adaptation fabricated using conventional, subtractive, and additive technologies: a volumetric micro-computed tomography analysis. J Prosthodont. 2021;30:257–63. Kattadiyil MT, Jekki R, Goodacre CJ, Baba NZ. Comparison of treatment outcomes in digital and conventional complete removable dental prosthesis fabrications in a predoctoral setting. J Prosthet Dent. 2015;114:818–25. Cristache CM, Totu EE, Iorgulescu G, Pantazi A, Dorobantu D, Nechifor AC, Isildak I, Burlibasa M, Nechifor G, Enachescu M. Eighteen months follow-up with patient-centered outcomes assessment of complete dentures manufactured using a hybrid nanocomposite and additive CAD/CAM protocol. J Clin Med. 2020;9:324. Pereyra NM, Marano J, Subramanian G, Quek S, Leff D. Comparison of patient satisfaction in the fabrication of conventional dentures vs. DENTCA (CAD/CAM) dentures: a case report. J N J Dent Assoc. 2015;86:26–33. Kaya N, Yanıkoğlu N. Investigation of the effect of different palatal vault depths on tissue surface adaptation of 3D-printed maxillary denture bases. J Prosthodont. 2025. Tasaka A, Matsunaga S, Odaka K, Ishizaki K, Ueda T, Abe S, Yoshinari M, Yamashita S, Sakurai K. Accuracy and retention of denture base fabricated by heat curing and additive manufacturing. J Prosthodontic Res. 2019;63:85–9. Oh W-s, May KB. Two-stage technique for optimum fit and stability of light-polymerized record bases. J Prosthet Dent. 2008;99:410–1. Consani RLX, Domitti SS, Barbosa CR, Consani S. Effect of commercial acrylic resins on dimensional accuracy of the maxillary denture base. Braz Dent J. 2002;13:57–60. Tan H-K, Brudvik JS, Nicholls JI, Smith DE. Adaptation of a visible light-cured denture base material. J Prosthet Dent. 1989;61:326–31. Wemken G, Spies BC, Pieralli S, Adali U, Beuer F, Wesemann C. Do hydrothermal aging and microwave sterilization affect the trueness of milled, additive manufactured and injection molded denture bases? J Mech Behav Biomed Mater. 2020;111:103975. Sinha D, Lakkoji KS, Faiz N. Comparative Analysis of Adaptation of Conventional and Printable Complete Denture Bases to the Underlying Casts-An In Vitro Stereomicroscopic Study. Indian J Dent Res. 2024;35:315–9. Alqutaibi AY, Aljohani R, Almuzaini S, Alghauli MA. Physical–mechanical properties and accuracy of additively manufactured resin denture bases: impact of printing orientation. J Prosthodontic Res. 2025:JPRD2400263. Charoenphol K, Peampring C. An in vitro study of intaglio surface, periphery/palatal seal area, and primary bearing area adaptation of 3D-printed denture base manufactured in various build angles. Int J Dent. 2022;2022:3824894. Polymers—Part DB. 1: Denture base polymers. International Organization for Standardization. 2013:20795 – 20791. Chitchumnong P, Brooks S, Stafford G. Comparison of three-and four-point flexural strength testing of denture-base polymers. Dent Mater. 1989;5:2–5. Çakmak G, Donmez MB, Akay C, Abou-Ayash S, Schimmel M, Yilmaz B. Effect of thermal cycling on the flexural strength and hardness of new‐generation denture base materials. J Prosthodont. 2023;32:81–6. Prpić V, Schauperl Z, Ćatić A, Dulčić N, Čimić S. Comparison of mechanical properties of 3D-printed, CAD/CAM, and conventional denture base materials. J Prosthodont. 2020;29:524–8. Abualsaud R, Gad MM. Flexural Strength of CAD/CAM Denture Base Materials: Systematic Review and Meta-Analysis of: In-Vitro: Studies. J Int Soc Prev Community Dentistry. 2022;12:160–70. Gad MM, Fouda SM. Factors affecting flexural strength of 3D-printed resins: A systematic review. J Prosthodont. 2023;32:96–110. Dai J, Luo K, Liu Q, Unkovskiy A, Spintzyk S, Xu S, Li P. Post-processing of a 3D-printed denture base polymer: Impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity. J Dent. 2024;147:105102. Chhabra M, Kumar MN, RaghavendraSwamy K, Thippeswamy H. Flexural strength and impact strength of heat-cured acrylic and 3D printed denture base resins-A comparative in vitro study. J oral biology Craniofac Res. 2022;12:1–3. Al-Dwairi ZN, Tahboub KY, Baba NZ, Goodacre CJ. A comparison of the flexural and impact strengths and flexural modulus of CAD/CAM and conventional heat‐cured polymethyl methacrylate (PMMA). J Prosthodont. 2020;29:341–9. Temizci T, Bozoğulları HN. Effect of thermal cycling on the flexural strength of 3-D printed, CAD/CAM milled and heat-polymerized denture base materials. BMC Oral Health. 2024;24:357. Additional Declarations No competing interests reported. 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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-8642763","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":592596597,"identity":"4b17973e-a624-40ad-838e-33375b4a3a9b","order_by":0,"name":"Afra Banu","email":"data:image/png;base64,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","orcid":"","institution":"Recep Tayyip Erdogan University","correspondingAuthor":true,"prefix":"","firstName":"Afra","middleName":"","lastName":"Banu","suffix":""},{"id":592596598,"identity":"4c8e44e6-2673-4fe1-8fa4-627383fb239d","order_by":1,"name":"Murat ALKURT","email":"","orcid":"","institution":"Recep Tayyip Erdogan University","correspondingAuthor":false,"prefix":"","firstName":"Murat","middleName":"","lastName":"ALKURT","suffix":""}],"badges":[],"createdAt":"2026-01-19 20:08:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8642763/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8642763/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103049722,"identity":"792f1883-5ad5-403d-9ec1-3adab9167e70","added_by":"auto","created_at":"2026-02-20 07:45:11","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":510132,"visible":true,"origin":"","legend":"\u003cp\u003eComplete denture base model illustrating the transverse (horizontal) and sagittal (vertical) sections\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/7f056d16330aa6b19b8fcab4.png"},{"id":103049462,"identity":"18a55a2c-695b-4832-9548-f7108a9dec7e","added_by":"auto","created_at":"2026-02-20 07:41:28","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":380085,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement points defined on the transverse section\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/01104fe0b254157c8b20dd73.png"},{"id":103049788,"identity":"8719c71f-0759-4115-b8f8-bf94f1af2c7c","added_by":"auto","created_at":"2026-02-20 07:46:17","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":337320,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement points defined on the sagittal section\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/8b6bc2c08767790930dab468.png"},{"id":102986606,"identity":"5556493a-8d23-4a01-8375-93df5de3e444","added_by":"auto","created_at":"2026-02-19 10:26:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":65141,"visible":true,"origin":"","legend":"\u003cp\u003eBar chart comparison of denture base adaptation values (µm) of the LCD, DLP, and compression molding (CM) groups according to measurement points A-F (Mean ± Standard Deviation).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/76b0f43bea354ca2c7587177.png"},{"id":103049917,"identity":"e70dee24-7bb0-444f-9fef-580821cd1109","added_by":"auto","created_at":"2026-02-20 07:47:13","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":558589,"visible":true,"origin":"","legend":"\u003cp\u003eStereomicroscopic images of measurement points A-F (µm)\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/aa3505104cb48318a0c17234.png"},{"id":103049915,"identity":"62d1f6b4-2f93-48c6-9c93-7ab9b382b9f2","added_by":"auto","created_at":"2026-02-20 07:47:13","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":46295,"visible":true,"origin":"","legend":"\u003cp\u003eBar chart illustrating the flexural strength (MPa) of denture base materials fabricated using digital light processing (DLP), liquid crystal display (LCD), and compression molding (CM). Data are presented as mean ± standard deviation. All values were obtained according to ISO 20795-1.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/00454ea8152c1a87af05dbcf.png"},{"id":103050964,"identity":"3fd91129-7012-438d-a50e-d2f4d442f1d0","added_by":"auto","created_at":"2026-02-20 07:57:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3296228,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8642763/v1/2de3187a-b511-45fb-b037-14805b1fbdf7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparative Evaluation of Surface Adaptation and Mechanical Properties of Maxillary Complete Denture Bases Fabricated by Conventional and Three-Dimensional Printing Methods: A comparative in vitro study","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eComplete dentures remain a widely used and effective treatment option for restoring oral function, esthetics, and quality of life in edentulous patients.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] The ability of complete dentures to achieve sufficient retention and stability is largely determined by the accuracy of the fit between the denture\u0026rsquo;s intaglio surface and the underlying supporting mucosa.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Reducing dimensional distortion throughout the fabrication process enhances the conformity of the denture base to the mucosal tissues.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] In compression molding procedures, polymerization of PMMA-based resins has been shown to induce volumetric shrinkage of approximately 7% and linear shrinkage ranging from 0.45% to 0.9%, potentially compromising the adaptation between the denture base and the supporting mucosa.[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eAdvances in CAD/CAM systems have led to the widespread adoption of both additive and subtractive digital workflows in complete denture production. Nevertheless, subtractive techniques are associated with considerable material wastage, and the final morphology of the restoration may be limited by the size and geometry of the milling tools. In particular, when the bur diameter exceeds the size of certain anatomical regions, internal fit accuracy and marginal quality may be adversely affected.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] In addition, the high cost associated with subtractive manufacturing systems limits their widespread clinical application.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn contrast, additive manufacturing enables the fabrication of more complex geometries and offers advantages over milling techniques, including reduced material waste and lower equipment costs.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] In additive manufacturing processes, unpolymerized resin is deposited in a three-dimensional manner and subsequently polymerized using ultraviolet (UV) or visible light sources.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] Complete denture bases produced by additive manufacturing are most commonly fabricated using light-curable acrylic-based resins via liquid crystal display (LCD) and digital light processing (DLP) techniques. Following fabrication, residual unpolymerized resin is removed using ultrasonic cleaning and isopropyl alcohol, after which post-curing is performed to achieve final polymerization of the material.\u0026sup2; Polymerization-related deformations may occur during this process.[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn the DLP technique, each layer is polymerized simultaneously using a projection system located beneath the resin vat. This approach provides high accuracy while rendering the manufacturing time largely independent of layer geometry or the number of printed objects.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] The distinction between LCD and DLP technologies is mainly associated with the type of imaging system used and the output characteristics of the light source.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] During photopolymerization, the intensity of the light source plays a decisive role in determining printing efficiency and the extent of material polymerization. In LCD-based systems, reliance on an LCD panel as the imaging mechanism may lead to reduced manufacturing accuracy when compared with DLP technology.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] With the increasing adoption of three-dimensional manufacturing systems in dentistry, research in this field has expanded considerably. In the literature, DLP-type printers are frequently preferred in studies evaluating surface adaptation,[\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] whereas investigations focusing on LCD-type printers remain limited.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eAccurate fabrication of dentures to ensure appropriate fit and function within the patient\u0026rsquo;s oral cavity is a fundamental requirement.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] As defined in ISO 5725-1, trueness denotes how closely a measured result approximates the true value, while precision refers to the reproducibility of repeated measurements performed under the same conditions.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] In this context, trueness represents the deviation between the intaglio surface of complete dentures fabricated based on a gypsum model and the reference value, while precision reflects the extent to which the same intaglio surface is reproducibly manufactured within each fabrication technique.[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn addition, the mechanical and physical properties of denture bases\u0026mdash;particularly their resistance to masticatory forces\u0026mdash;are of critical importance for clinical performance, as the mechanical behavior of a material reflects its fundamental physical and chemical characteristics.[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Denture bases must exhibit sufficient mechanical properties to withstand functional loads and maintain dimensional stability over time.[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] In accordance with ADA Specification No. 139 and ISO 20795-1 for denture base polymers, flexural strength of denture base resins is commonly assessed using the three-point bending test, which provides information on material stiffness and resistance to deformation.[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] Flexural strength describes the highest level of bending stress a material can tolerate before fracture and is regarded as a key indicator of the clinical performance of complete dentures.[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThis \u003cem\u003ein-vitro\u003c/em\u003e investigation sought to evaluate and compare the tissue surface adaptation and mechanical performance of maxillary complete denture bases manufactured by compression molding (CM), liquid crystal display (LCD), and digital light processing (DLP) methods. The first null hypothesis proposed that tissue surface adaptation would not differ significantly among the fabrication techniques, while the second null hypothesis stated that no significant differences in mechanical strength would be observed between the groups.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eIn the present study, a prefabricated edentulous maxillary silicone mold served as the master reference. Type IV dental stone (Elite Master; Zhermack) was poured into the mold following the manufacturer\u0026rsquo;s recommendations, resulting in 30 gypsum casts (n\u0026thinsp;=\u0026thinsp;10 per group). For digital reference generation, the gypsum cast was digitized using a calibrated extraoral scanner (7 Series DentalWings; DentalWings/Straumann). The scanned data were subsequently imported into Exocad software, where a removable maxillary complete denture base with a standardized thickness of 2 mm was designed and exported in STL format.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eFabrication of Complete Denture Bases Using DLP and LCD Technologies\u003c/h2\u003e \u003cp\u003eFor denture base fabrication, a DLP-type 3D printer (Phrozen Lumi; Phrozen) and an LCD-type 3D printer (Elegoo Saturn 4 Ultra 16K; Elegoo) were used. In both systems, support structures were positioned on the buccal surface of the denture bases at a 90\u0026deg; build orientation to ensure fabrication stability. A 405-nm LED light source and a layer thickness of 100 \u0026micro;m were employed, and 10 denture bases were produced for each group.\u003c/p\u003e \u003cp\u003eA photopolymerizable resin compatible with both printing systems (Alias Dental Denture Resin; Dokuz Kimya) was used. Following the printing process, the denture bases were separated from the build platform, and support structures were carefully removed by hand to avoid surface damage. Subsequent cleaning and post-curing procedures were carried out in accordance with the manufacturer\u0026rsquo;s guidelines using an Elegoo Mercury Plus unit. Specimens were washed in isopropyl alcohol for 5 minutes, followed by post-curing under a light source for an additional 5 minutes.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eFabrication of Complete Denture Bases Using the Compression Molding (CM) Technique\u003c/h3\u003e\n\u003cp\u003eFor the conventional compression molding technique, a heat-polymerized PMMA-based acrylic resin (Imicryl IQ 15; Imicryl) was used. The material was manipulated according to the manufacturer\u0026rsquo;s guidelines using a powder-to-liquid ratio of 23.4 g to 10 mL and was mixed for approximately 1 minute until a uniform consistency was obtained. To ensure consistent denture base thickness among all specimens, denture base designs produced by the 3D printing systems were utilized as reference templates during the compression molding process. The denture base forms were transferred to negative molds created using a condensation silicone impression material (Oxasil; Zhermack). The acrylic resin in the dough stage was manually packed into the molds, and polymerization was completed according to the manufacturer\u0026rsquo;s protocol by maintaining the flasks in a boiling water bath for 15 minutes, followed by an additional 20 minutes of heating.\u003c/p\u003e\n\u003ch3\u003eFabrication of Specimens for Flexural Strength Testing\u003c/h3\u003e\n\u003cp\u003eFor flexural strength testing, rectangular specimens with dimensions compliant with ISO 20795-1:2013 (64 \u0026times; 10 \u0026times; 3.3 mm) were designed and fabricated using DLP and LCD 3D printing systems. For the conventional compression molding group, wax patterns of identical dimensions were prepared, invested in a metal mold, and stabilized with dental plaster, followed by a standard compression molding procedure. Wax elimination was performed in a hot water bath, after which the resulting mold spaces were packed with PMMA acrylic resin in the dough stage. Polymerization was completed in a boiling water bath in accordance with the manufacturer\u0026rsquo;s protocol.\u003c/p\u003e \u003cp\u003eSpecimens obtained from all fabrication methods were lightly polished to ensure surface smoothness and thickness standardization, and their dimensions were verified using a digital caliper. Specimens that did not meet the ISO 20795-1:2013 criteria were excluded from the study. Ultimately, a total of 30 specimens, equally distributed among the CM, DLP, and LCD groups, were prepared for mechanical testing, with each group representing a different fabrication technique.\u003c/p\u003e\n\u003ch3\u003eSectioning of Denture Bases and Measurement Procedure\u003c/h3\u003e\n\u003cp\u003eTo assess the adaptation of the denture bases to the supporting models, each specimen was sectioned along two predefined planes (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e1) \u003cb\u003eTransverse (Horizontal) section\u003c/b\u003e: at the level of the maxillary second molars.\u003c/p\u003e \u003cp\u003e2) \u003cb\u003eSagittal (Vertical) section\u003c/b\u003e: along the maxillary midline.\u003c/p\u003e \u003cp\u003eSectioning was carried out using a precision cutting machine (Isomet 1000; Buehler, USA) under continuous water irrigation, with standardized speed and load parameters. To ensure standardization, all models were positioned in custom-made guiding jigs during sectioning. Two sectional planes were obtained from each specimen, and specific anatomical reference points were defined on each section to ensure consistency in adaptation measurements. Based on previously published studies, the following measurement points were selected [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eTransverse Section\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003e) \u003cb\u003eSagittal Section\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eA) Right alveolar ridge crest D) Anterior ridge crest\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eB) Midline palatal point E) Midpoint of the sagittal section\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eC) Left alveolar ridge crest F) Most posterior point of the sagittal section\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eA total of six measurement points were evaluated for each specimen. To ensure that reference points were obtained at identical locations across all specimens, a silicone-based positioning guide was used. In the sectioned denture bases, the gap between the intaglio surface and the model surface was measured using a stereomicroscope (Stemi 305; Carl Zeiss) at 20\u0026times; magnification with a resolution of 1 \u0026micro;m; the device was calibrated with a standard reference scale prior to each measurement session. Measurements were performed using microscope-integrated analysis software (ZEN Blue; Carl Zeiss).\u003c/p\u003e \u003cp\u003eBefore measurement, all specimens were stored at room temperature in a light-proof, closed environment to ensure dimensional stabilization.\u003c/p\u003e\n\u003ch3\u003eApplication of the Flexural Strength Test\u003c/h3\u003e\n\u003cp\u003eFlexural strength testing was conducted in compliance with ISO 20795-1:2013 using a universal testing machine (Instron 3344; Instron). Rectangular specimens measuring 64 \u0026times; 10 \u0026times; 3.3 mm were subjected to a three-point bending protocol, with a support span of 50 mm and a crosshead speed of 5 mm/min until fracture occurred. The peak fracture load (N) was automatically recorded by the testing software, and flexural strength values were calculated in megapascals (MPa) according to the equation specified in ISO 1567:1999.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eStatistical evaluations were conducted using SPSS software (version 27; SPSS Inc.), with descriptive outcomes reported as means and standard deviations. The assumption of normal data distribution was examined using the Shapiro\u0026ndash;Wilk test, while variance homogeneity was verified through Levene\u0026rsquo;s test.\u003c/p\u003e \u003cp\u003eIntergroup comparisons were performed using one-way ANOVA for datasets demonstrating normal distribution, whereas the Kruskal\u0026ndash;Wallis test was applied when normality assumptions were not met. In cases of statistically significant findings, Bonferroni-adjusted post-hoc tests were used to determine pairwise differences. Statistical significance was defined at an alpha level of 0.05 for all analyses (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eKruskal-Wallis and ANOVA analysis results of denture base adaptation measurements (\u0026micro;m) at measurement points A-F for the LCD, DLP, and compression molding (CM) groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\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\u003eLCD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDLP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTest statistic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBonferroni\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePoint\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e464.3\u0026thinsp;\u0026plusmn;\u0026thinsp;115.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e448.04\u0026thinsp;\u0026plusmn;\u0026thinsp;142\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e508.44\u0026thinsp;\u0026plusmn;\u0026thinsp;191.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;0.591\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.744\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1722.8\u0026thinsp;\u0026plusmn;\u0026thinsp;439.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1589.01\u0026thinsp;\u0026plusmn;\u0026thinsp;350.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1323.53\u0026thinsp;\u0026plusmn;\u0026thinsp;300.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;8.101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.017*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCM\u0026thinsp;\u0026lt;\u0026thinsp;LCD\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e678.02\u0026thinsp;\u0026plusmn;\u0026thinsp;178.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e461.89\u0026thinsp;\u0026plusmn;\u0026thinsp;147.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e774.74\u0026thinsp;\u0026plusmn;\u0026thinsp;141.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;12.707\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.002*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eDLP\u0026thinsp;\u0026lt;\u0026thinsp;LCD;\u003c/p\u003e \u003cp\u003eDLP\u0026thinsp;\u0026lt;\u0026thinsp;CM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e582.65\u0026thinsp;\u0026plusmn;\u0026thinsp;135.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e368.42\u0026thinsp;\u0026plusmn;\u0026thinsp;88.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e343.03\u0026thinsp;\u0026plusmn;\u0026thinsp;163.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;13.680\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCM \u0026lt; LCD;\u003c/p\u003e \u003cp\u003eDLP\u0026thinsp;\u0026lt;\u0026thinsp;LCD\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1005.22\u0026thinsp;\u0026plusmn;\u0026thinsp;213.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e847.7\u0026thinsp;\u0026plusmn;\u0026thinsp;209.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e754.38\u0026thinsp;\u0026plusmn;\u0026thinsp;304.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;4.895\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.086\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1721.19\u0026thinsp;\u0026plusmn;\u0026thinsp;139.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1505.49\u0026thinsp;\u0026plusmn;\u0026thinsp;267.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1129.91\u0026thinsp;\u0026plusmn;\u0026thinsp;152.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;17.799\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCM\u0026thinsp;\u0026lt;\u0026thinsp;DLP;\u003c/p\u003e \u003cp\u003eCM\u0026thinsp;\u0026lt;\u0026thinsp;LCD\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTest statistic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;107.660\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;51.499\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;31.790\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBonferroni\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u0026thinsp;\u0026lt;\u0026thinsp;B; A\u0026thinsp;\u0026lt;\u0026thinsp;E; A\u0026thinsp;\u0026lt;\u0026thinsp;F;\u003c/p\u003e \u003cp\u003eC\u0026thinsp;\u0026lt;\u0026thinsp;B; C\u0026thinsp;\u0026lt;\u0026thinsp;E; C\u0026thinsp;\u0026lt;\u0026thinsp;F;\u003c/p\u003e \u003cp\u003eD\u0026thinsp;\u0026lt;\u0026thinsp;B; D\u0026thinsp;\u0026lt;\u0026thinsp;E; D\u0026thinsp;\u0026lt;\u0026thinsp;F;\u003c/p\u003e \u003cp\u003eE\u0026thinsp;\u0026lt;\u0026thinsp;B; E\u0026thinsp;\u0026lt;\u0026thinsp;F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eA\u0026thinsp;\u0026lt;\u0026thinsp;B; A\u0026thinsp;\u0026lt;\u0026thinsp;E; A\u0026thinsp;\u0026lt;\u0026thinsp;F; C\u0026thinsp;\u0026lt;\u0026thinsp;B; D\u0026thinsp;\u0026lt;\u0026thinsp;B; E\u0026thinsp;\u0026lt;\u0026thinsp;B; C\u0026thinsp;\u0026lt;\u0026thinsp;E; C\u0026thinsp;\u0026lt;\u0026thinsp;F; D\u0026thinsp;\u0026lt;\u0026thinsp;E; D\u0026thinsp;\u0026lt;\u0026thinsp;F; E\u0026thinsp;\u0026lt;\u0026thinsp;F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA\u0026thinsp;\u0026lt;\u0026thinsp;B; A\u0026thinsp;\u0026lt;\u0026thinsp;C; A\u0026thinsp;\u0026lt;\u0026thinsp;F; C\u0026thinsp;\u0026lt;\u0026thinsp;B; D\u0026thinsp;\u0026lt;\u0026thinsp;B; E\u0026thinsp;\u0026lt;\u0026thinsp;B; D\u0026thinsp;\u0026lt;\u0026thinsp;C; C\u0026thinsp;\u0026lt;\u0026thinsp;F; D\u0026thinsp;\u0026lt;\u0026thinsp;E; D\u0026thinsp;\u0026lt;\u0026thinsp;F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05; F: ANOVA test statistic (analysis of variance); KW: Kruskal-Wallis test statistic; Mean; SD: standard deviation.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFor comparisons among the DLP, LCD, and compression molding (CM) groups across measurement points A\u0026ndash;F, the Kruskal\u0026ndash;Wallis test was applied due to non-normal data distribution. No significant intergroup differences were identified at point A (right ridge crest) or point E (midpoint of the sagittal section) (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, a statistically significant difference was observed at point B (midpalatal region) (KW\u0026thinsp;=\u0026thinsp;8.101; p\u0026thinsp;=\u0026thinsp;0.017), where Bonferroni-adjusted post-hoc analysis demonstrated significantly lower values in the CM group compared with the LCD group (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eAt point C (left alveolar ridge crest), the DLP group demonstrated significantly lower values compared with both the LCD and CM groups (KW\u0026thinsp;=\u0026thinsp;12.707; p\u0026thinsp;=\u0026thinsp;0.002). At point D (anterior ridge crest), the LCD group showed significantly higher values than the DLP and CM groups (KW\u0026thinsp;=\u0026thinsp;13.680; p\u0026thinsp;=\u0026thinsp;0.001). At point F (the most posterior point of the sagittal section), the CM group exhibited significantly lower values than both 3D printing groups (KW\u0026thinsp;=\u0026thinsp;17.799; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eThese findings indicate that denture base adaptation should be evaluated in a region-specific manner and that fabrication techniques do not demonstrate uniform performance across all anatomical regions (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWithin the LCD group, differences among measurement points A-F were evaluated using one-way ANOVA, which revealed statistically significant differences among the points (F\u0026thinsp;=\u0026thinsp;107.660; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). According to Bonferroni \u003cem\u003epost-hoc\u003c/em\u003e analysis, points A, C, and D exhibited significantly lower values compared with points B (midpalatal), E (midpoint of the sagittal section), and F (posterior point of the sagittal section) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In addition, point E demonstrated significantly lower values than points B and F. The highest measurement value was observed at point B (midpalatal region).\u003c/p\u003e \u003cp\u003eWithin the DLP group, differences among measurement points A-F were analyzed using one-way ANOVA, revealing statistically significant differences among the points (F\u0026thinsp;=\u0026thinsp;51.499; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Bonferroni \u003cem\u003epost-hoc\u003c/em\u003e analysis indicated that points A, C, and D exhibited significantly lower values compared with points B (midpalatal), E (midpoint of the sagittal section), and F (posterior point of the sagittal section). In addition, point E showed significantly lower values than points B and F (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The highest measurement value was observed at point B (midpalatal region).\u003c/p\u003e \u003cp\u003eWithin the compression molding (CM) group, variations among measurement points A\u0026ndash;F were analyzed using one-way ANOVA, revealing statistically significant differences across the points (F\u0026thinsp;=\u0026thinsp;31.790; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Bonferroni-adjusted post-hoc comparisons indicated that values at point A were significantly lower than those at points B, C, and F. Furthermore, point C demonstrated significantly lower values compared with points B and F, while point D showed significantly lower values than points B, C, E, and F. Additionally, point E exhibited significantly lower values than point B (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The highest measurement value within the CM group was recorded at point B, corresponding to the midpalatal region.\u003c/p\u003e\n\u003ch3\u003eEvaluation of Flexural Strength\u003c/h3\u003e\n\u003cp\u003eFlexural strength outcomes among the DLP, LCD, and compression molding (CM) groups were analyzed using the Kruskal\u0026ndash;Wallis test, revealing a statistically significant intergroup difference (KW\u0026thinsp;=\u0026thinsp;25.806; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Bonferroni-adjusted post-hoc comparisons indicated that the DLP group demonstrated significantly lower flexural strength values compared with both the LCD and CM groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn addition, the LCD group demonstrated significantly lower flexural strength values compared with the CM group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The highest flexural strength was recorded in the CM group (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\u003eEvaluation of Flexural Strength (MPa)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026minus;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" 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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM. (Min.-Max.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTest statistic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBonferroni\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDLP\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c3\"\u003e \u003cp\u003e66.91 (0-63.46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e66.93\u0026thinsp;\u0026plusmn;\u0026thinsp;2.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eKW\u0026thinsp;=\u0026thinsp;25.806\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e1\u0026thinsp;\u0026lt;\u0026thinsp;2\u003c/p\u003e \u003cp\u003e1\u0026thinsp;\u0026lt;\u0026thinsp;3\u003c/p\u003e \u003cp\u003e2\u0026thinsp;\u0026lt;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLCD\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c3\"\u003e \u003cp\u003e72.97 (0-69.59)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e73.09\u0026thinsp;\u0026plusmn;\u0026thinsp;2.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCM\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c3\"\u003e \u003cp\u003e147.29 (0-116.12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e153.88\u0026thinsp;\u0026plusmn;\u0026thinsp;35.38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.05; KW: Kruskal\u0026ndash;Wallis test statistic; n: number of specimens; Min: minimum; Max: maximum; Mean; SD: standard deviation.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eIn this \u003cem\u003ein vitro\u003c/em\u003e study, the surface adaptation of 2-mm-thick complete denture bases fabricated using conventional compression molding, as well as DLP and LCD additive manufacturing techniques, and the mechanical strength of specimens prepared in accordance with ISO 20795 were compared. The aim was to identify the advantages and limitations of different fabrication techniques and to provide clinicians with a scientific basis for method selection. The findings demonstrated statistically significant differences among the fabrication methods in terms of both adaptation and mechanical strength; therefore, the null hypotheses were rejected.\u003c/p\u003e \u003cp\u003ePrevious studies have reported that in three-dimensionally printed complete dentures, a reduction in denture base thickness below 2 mm results in a marked decrease in flexural strength, and consequently, a minimum denture base thickness of 2 mm has been recommended for maxillary complete dentures.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eDLP and LCD systems have emerged as alternatives to stereolithography (SLA) because of their high resolution and rapid production capabilities. DLP printers can fabricate objects with layer thicknesses of up to approximately 50 \u0026micro;m using a 405-nm LED light source, whereas LCD printers, although more cost-effective, operate with lower light intensity compared with DLP systems.[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eChih-Yuan et al.[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] fabricated 2-mm-thick denture base plates using different manufacturing techniques and reported that CAD/CAM milling achieved the best adaptation based on analyses performed at 60 measurement points. In a related investigation, Oğuz et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] analyzed the adaptation of denture base plates manufactured from digitized edentulous models across six anatomical regions using micro\u0026ndash;computed tomography. Their findings indicated that the smallest interfacial gaps were recorded in the milling (PMMA milling) group, whereas progressively larger gap values were observed in the conventional compression molding (CM), injection molding (IM), and three-dimensional (3D) printing groups. Notably, in the maxilla, a pronounced increase in the palatal gap was reported in the compression molding group.\u003c/p\u003e \u003cp\u003eKanyakorn et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] evaluated the tissue surface adaptation of denture base plates produced by milling and three-dimensional printing, demonstrating that the milled specimens achieved superior adaptation across the overall intaglio surface and primary stress-bearing regions, whereas additively manufactured specimens showed improved adaptation in the peripheral and posterior palatal seal areas. This difference was attributed to the presence of anatomical undercuts in these regions and the inherent structural limitations of the milling technique in reproducing such complex geometries.\u003c/p\u003e \u003cp\u003eAlthough the superior performance of milled dentures has been reported, this technique is associated with several disadvantages, including high initial investment costs, substantial material waste, and prolonged fabrication time. While the production time for milled dentures is approximately 5 hours, this duration is reduced to an average of about 1.5 hours with three-dimensional printing techniques, and the cost of milling blocks is generally higher than that of printing resins. Nevertheless, both manufacturing methods have been reported to provide clinically acceptable outcomes. These findings indicate that, in addition to accuracy and mechanical durability, factors such as cost, time efficiency, and specific clinical requirements should be considered when selecting a fabrication technique.[\u003cspan additionalcitationids=\"CR33\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eHwang et al. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] demonstrated that denture bases produced using the DLP technique achieved superior accuracy and more favorable tissue surface adaptation than those fabricated by milling or conventional compression molding, with reported adaptation values remaining below the 100-\u0026micro;m threshold. This superiority was attributed to the ability of the DLP technique to more effectively reproduce the morphological irregularities of the residual ridge.\u003c/p\u003e \u003cp\u003eKaya and Yanıkoğlu [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] compared denture bases fabricated with different palatal depths and reported that, in shallow palatal morphologies, the DLP technique yielded significantly lower deviation values in the palatal region. These findings highlight region-dependent variability in adaptation and suggest an advantage of DLP under specific morphological conditions.\u003c/p\u003e \u003cp\u003eThe literature does not present a definitive consensus on the comparative performance of fabrication techniques with respect to surface adaptation and accuracy, a variability that has been attributed to differences in printer systems, resin formulations, and processing parameters. While some studies have reported superior adaptation with SLA or subtractive milling compared with DLP[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] others have demonstrated that DLP provides more favorable outcomes than milling, conventional compression molding, and LCD techniques.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eOh et al. [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e] reported that polymerization shrinkage associated with palatal concavity tends to occur toward the residual ridge, resulting in a more pronounced lifting effect in the midpalatal region. Consani et al. [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e] indicated that linear shrinkage renders the palatal region\u0026mdash;particularly the molar area\u0026mdash;the most critical site for gap formation. Tan et al. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] further reported that manual finger pressure is insufficient to ensure adequate denture base adaptation. This phenomenon may be explained by the broad, concave anatomy of the palatal region, which provides relatively limited structural support and is therefore unable to adequately counteract polymerization shrinkage forces. In addition, the three-dimensional and directional nature of polymerization shrinkage causes the denture base to be drawn toward the more rigid, residual ridge\u0026ndash;supported areas, thereby amplifying the lifting effect observed in the palatal region.\u003c/p\u003e \u003cp\u003eIn the literature, surface adaptation of complete dentures has commonly been evaluated by dividing the intaglio surface into anatomical regions such as the palatal vault, alveolar ridges, and peripheral borders,[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e] while some studies have also included areas distant from the denture border in their analyses.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] This region-based approach highlights performance differences of fabrication techniques according to specific anatomical areas. In the present study, measurement points were defined as three alveolar ridge crest regions and three palatal midline regions.\u003c/p\u003e \u003cp\u003eIn one study, maxillary models were sectioned transversely at the canine, molar, and posterior midpalatal regions to assess anterior\u0026ndash;posterior adaptation, and gaps at the right and left ridge crests and the midpalatal region in each section were measured using a stereomicroscope at 20\u0026times; magnification.[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] Similarly, in the present study, both transverse and sagittal sections were obtained, and measurements at the right and left ridge crests and the midpalatal region in the transverse section were performed using a stereomicroscope at 20\u0026times; magnification.\u003c/p\u003e \u003cp\u003eIn another study, adaptation of maxillary complete dentures was evaluated at seven predefined measurement points on coronal and sagittal sections using a stereomicroscope, and the highest degree of misfit was reported to occur in the midpalatal region.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] Consistent with these findings, the greatest misfit in the present study was also observed in the palatal region.\u003c/p\u003e \u003cp\u003eSinha et al. [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e] assessed the marginal adaptation of complete denture bases produced by conventional and three-dimensional printing techniques at the midpalatal region as well as the right and left maxillary tuberosities using stereomicroscopic evaluation. Their results indicated lower misfit values for the conventional fabrication method, while the greatest marginal discrepancy for both techniques was detected at the left maxillary tuberosity. In contrast, in the present study, the greatest misfit in denture bases fabricated using both conventional and additive techniques was identified in the midpalatal region. This discrepancy may be attributed to the broader surface area and concave morphology of the palatal region, which render it more susceptible to polymerization shrinkage\u0026ndash;induced stresses. Furthermore, compared with the residual ridge areas, the midpalatal region lacks structural support, allowing polymerization-related deformation to manifest more prominently. Consequently, regardless of the fabrication technique, the midpalatal region appears to represent a critical area where adaptation inaccuracies tend to concentrate.\u003c/p\u003e \u003cp\u003eIn a systematic review, it was reported that printing orientation significantly influences the accuracy and adaptation of 3D-printed denture bases, with 90\u0026deg; (vertical) orientation providing the highest adaptation, particularly in the posterior and peripheral palatal regions. This superiority was associated with more uniform light penetration, improved layer alignment, reduced support-induced distortion, and enhanced manufacturing efficiency.[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eCharoenphol et al.[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e] reported that overall intaglio surface adaptation of DLP-fabricated complete denture bases was not affected by printing angle; however, a 90\u0026deg; printing orientation resulted in significantly better adaptation in the posterior palatal seal region. This improvement was attributed to a reduction in the staircase effect associated with layer deposition and decreased support-related deformation. Accordingly, in the present study, a 90\u0026deg; build orientation was selected to optimize adaptation in critical anatomical regions.\u003c/p\u003e \u003cp\u003eFlexural strength constitutes a key determinant of denture base performance, and ISO 20795-1:2013 defines a minimum required value of 65 MPa for denture base materials [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. For the assessment of flexural strength in polymer-based dental materials, the three-point bending test is commonly employed and has been shown to yield more consistent and reproducible outcomes than the four-point bending method [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Accordingly, the three-point bending test was chosen in the present study to evaluate the flexural strength of the denture base materials.\u003c/p\u003e \u003cp\u003eSeveral studies in the literature have reported that PMMA-based denture bases fabricated using three-dimensional printing exhibit relatively low flexural strength values and may fall below the international standard threshold of 65 MPa. \u0026Ccedil;akmak et al.[\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e] reported that only the CAD/CAM milling group met the international standard of 65 MPa, whereas the 3D-printed specimens remained below this limit. Similarly, Prpić et al.[\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e] demonstrated that denture base materials produced by 3D printing showed significantly lower flexural strength compared with conventionally heat-polymerized acrylic resins. Gad et al.[\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e] further revealed that microscopic voids observed at the fracture sites of 3D-printed specimens constitute one of the primary causes of mechanical weakness, which was associated with insufficient interlayer bonding and irregular polymerization.\u003c/p\u003e \u003cp\u003eIn contrast, some studies have reported that denture base materials fabricated using three-dimensional printing technologies are capable of meeting the minimum flexural strength requirement of 65 MPa specified in ISO 20795-1:2013, thereby demonstrating mechanically acceptable performance for clinical use.\u003c/p\u003e \u003cp\u003eFouda et al.[\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e] reported flexural strength values of approximately 67\u0026ndash;71 MPa for the SLA group and about 69 MPa for the DLP group in three-point bending tests, attributing the differences between SLA and DLP to variations in interlayer bonding and light-curing mechanisms; importantly, all reported values exceeded the clinical acceptance threshold of 65 MPa. Dai et al.[\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e] reported flexural strength values of approximately 80.92 MPa for DLP-printed specimens.\u003c/p\u003e \u003cp\u003eChhabra et al.[\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e] reported flexural strength values of 92.01\u0026thinsp;\u0026plusmn;\u0026thinsp;12.14 MPa for heat-polymerized PMMA and 69.78\u0026thinsp;\u0026plusmn;\u0026thinsp;7.54 MPa for 3D-printed denture base resin using the three-point bending test. The lower values observed for additively manufactured specimens were attributed to interfacial bonding weaknesses associated with layer-by-layer fabrication and to printing and post-curing parameters, whereas the more homogeneous structure and predictable mechanical behavior of heat-polymerized acrylic resins account for their higher strength. Al-Dwairi et al.[\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e] similarly reported that conventionally heat-polymerized denture base resin exhibited significantly superior flexural strength and hardness compared with 3D-printed materials.\u003c/p\u003e \u003cp\u003eIn the present study, denture bases fabricated using the conventional method demonstrated higher flexural strength than those produced by additive manufacturing techniques, and specimens fabricated using LCD printers exhibited superior flexural strength compared with those produced by DLP. Notably, both additive manufacturing groups demonstrated flexural strength values exceeding the minimum requirements specified by international standards.\u003c/p\u003e \u003cp\u003eAppropriate post-polymerization protocols have been reported to enhance interlayer bonding by increasing polymerization time and light energy delivery, thereby significantly improving flexural strength. In this regard, Temizci et al.[\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e] demonstrated that 3D-printed specimens subjected to a two-stage post-polymerization protocol (30\u0026thinsp;+\u0026thinsp;30 minutes) exhibited statistically higher flexural strength compared with other fabrication methods. These findings indicate that the mechanical behavior of 3D-printed denture bases is influenced not only by the manufacturing technology itself but also by multiple parameters, including resin composition, printing orientation and layer thickness, printer type, as well as post-curing duration and light intensity.\u003c/p\u003e \u003cp\u003eThe main limitations of this study include the absence of subtractive manufacturing methods, reliance on stereomicroscopic two-dimensional measurements for adaptation analysis, and the \u003cem\u003ein vitro\u003c/em\u003e study design. These factors may have limited the direct generalizability of the findings to all digital fabrication techniques and to clinical conditions.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003e1. In this \u003cem\u003ein vitro\u003c/em\u003e study, the tissue surface adaptation and flexural strength of maxillary complete denture bases fabricated using three different manufacturing techniques\u0026mdash;DLP, LCD, and conventional compression molding\u0026mdash;were compared. The findings demonstrated that the fabrication method had a significant influence on both adaptation and mechanical properties. When evaluated according to measurement points, the compression molding group exhibited more favorable adaptation in the posterior palatal regions, whereas the DLP group showed better adaptation at the ridge crest compared with the LCD group. These results suggest that no single fabrication technique provides superior performance across all anatomical regions of maxillary denture bases.\u003c/p\u003e\n\u003cp\u003e2. With respect to flexural strength, the conventional compression molding group demonstrated the highest values. Between the additive manufacturing techniques, the LCD group exhibited higher flexural strength than the DLP group. Nevertheless, both three-dimensional printing groups met the minimum requirements specified in ISO 20795-1:2013. These findings indicate that, from a mechanical standpoint, digital fabrication methods are clinically acceptable, although the conventional technique maintains a mechanical advantage.\u003c/p\u003e\n\u003cp\u003e3. Based on the results of this study, the selection of a fabrication technique in clinical practice should not be based solely on a distinction between digital and conventional approaches, but rather on a combined consideration of the targeted anatomical region requiring optimal adaptation and the expected mechanical demands. When digital methods are preferred, the influence of printer technology, resin type, and post-processing protocols on clinical outcomes should be carefully taken into account.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eThree-dimensional\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003e3D\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMegapascal\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMPa\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eComputer-aided design\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCAD\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eComputer-aided manufacturing\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCAM\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDigital Light Processing\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDLP\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLiquid Crystal Display\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLCD\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eStereolithography\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSLA\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCompression Molding\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCM\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eStandard Triangle Language\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSTL\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eInternational Organization for Standardization\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eISO\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLight Emitting Diode\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLED\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eAs the study was conducted exclusively under laboratory conditions and did not involve patient data, ethics committee approval was not required.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eAll data generated or analysed during this study are included in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This study has been supported by Recep Tayyip Erdogan University Development Foundation\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions:\u0026nbsp;\u003c/strong\u003eAE and MA contributed to the conceptualization of the study, writing, and preparation of the original draft. MA contributed to data curation, interpretation of the results, formal analysis, and critical revision of the manuscript. AE contributed to methodology design, data collection, literature review, and figure preparation. Both authors contributed to the review, editing, and final approval of the manuscript. All authors have read and approved the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLee DJ, Saponaro PC. Management of edentulous patients. Dent Clin. 2019;63:249\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHwang H-J, Lee SJ, Park E-J, Yoon H-I. 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Braz Dent J. 2002;13:57\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTan H-K, Brudvik JS, Nicholls JI, Smith DE. Adaptation of a visible light-cured denture base material. J Prosthet Dent. 1989;61:326\u0026ndash;31.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWemken G, Spies BC, Pieralli S, Adali U, Beuer F, Wesemann C. Do hydrothermal aging and microwave sterilization affect the trueness of milled, additive manufactured and injection molded denture bases? J Mech Behav Biomed Mater. 2020;111:103975.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSinha D, Lakkoji KS, Faiz N. Comparative Analysis of Adaptation of Conventional and Printable Complete Denture Bases to the Underlying Casts-An In Vitro Stereomicroscopic Study. Indian J Dent Res. 2024;35:315\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlqutaibi AY, Aljohani R, Almuzaini S, Alghauli MA. Physical\u0026ndash;mechanical properties and accuracy of additively manufactured resin denture bases: impact of printing orientation. J Prosthodontic Res. 2025:JPRD2400263.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCharoenphol K, Peampring C. An in vitro study of intaglio surface, periphery/palatal seal area, and primary bearing area adaptation of 3D-printed denture base manufactured in various build angles. Int J Dent. 2022;2022:3824894.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePolymers\u0026mdash;Part DB. 1: Denture base polymers. International Organization for Standardization. 2013:20795\u0026thinsp;\u0026ndash;\u0026thinsp;20791.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChitchumnong P, Brooks S, Stafford G. Comparison of three-and four-point flexural strength testing of denture-base polymers. Dent Mater. 1989;5:2\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e\u0026Ccedil;akmak G, Donmez MB, Akay C, Abou-Ayash S, Schimmel M, Yilmaz B. Effect of thermal cycling on the flexural strength and hardness of new‐generation denture base materials. J Prosthodont. 2023;32:81\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrpić V, Schauperl Z, Ćatić A, Dulčić N, Čimić S. Comparison of mechanical properties of 3D-printed, CAD/CAM, and conventional denture base materials. J Prosthodont. 2020;29:524\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbualsaud R, Gad MM. Flexural Strength of CAD/CAM Denture Base Materials: Systematic Review and Meta-Analysis of: In-Vitro: Studies. J Int Soc Prev Community Dentistry. 2022;12:160\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGad MM, Fouda SM. Factors affecting flexural strength of 3D-printed resins: A systematic review. J Prosthodont. 2023;32:96\u0026ndash;110.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDai J, Luo K, Liu Q, Unkovskiy A, Spintzyk S, Xu S, Li P. Post-processing of a 3D-printed denture base polymer: Impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity. J Dent. 2024;147:105102.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChhabra M, Kumar MN, RaghavendraSwamy K, Thippeswamy H. Flexural strength and impact strength of heat-cured acrylic and 3D printed denture base resins-A comparative in vitro study. J oral biology Craniofac Res. 2022;12:1\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl-Dwairi ZN, Tahboub KY, Baba NZ, Goodacre CJ. A comparison of the flexural and impact strengths and flexural modulus of CAD/CAM and conventional heat‐cured polymethyl methacrylate (PMMA). J Prosthodont. 2020;29:341\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTemizci T, Bozoğulları HN. Effect of thermal cycling on the flexural strength of 3-D printed, CAD/CAM milled and heat-polymerized denture base materials. BMC Oral Health. 2024;24:357.\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":false,"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":"Complete denture, denture base, tissue surface adaptation, DLP, LCD, 3D, conventional compression molding, flexural strength","lastPublishedDoi":"10.21203/rs.3.rs-8642763/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8642763/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eProper conformity of the denture base to the underlying mucosal tissues plays a fundamental role in ensuring the retention and stability of complete dentures. Although three-dimensional (3D) printing offers a more standardized manufacturing process than conventional compression molding, differences in surface adaptation and mechanical strength among fabrication techniques remain. The objective of this investigation was to evaluate and contrast the tissue surface adaptation and mechanical performance of maxillary complete denture bases produced through various fabrication techniques.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA gypsum cast derived from a prefabricated edentulous maxillary silicone mold was digitally scanned using an extraoral scanner, after which a denture base with a uniform thickness of 2 mm was designed in Exocad and saved in STL format. Denture bases were fabricated using digital light processing (DLP; Phrozen Lumi), liquid crystal display (LCD; Elegoo Saturn 4 Ultra 16K), and conventional compression molding (CM). For adaptation analysis, specimens were sectioned along transverse (maxillary second molar level) and sagittal (midline) planes, and the denture base\u0026ndash;model gap was measured at six predefined ridge and palatal reference points using a stereomicroscope (20\u0026times; magnification, 1 \u0026micro;m resolution). For mechanical evaluation, bar-shaped specimens (64 \u0026times; 10 \u0026times; 3.3 mm; n\u0026thinsp;=\u0026thinsp;10 per group) were prepared according to ISO 20795-1:2013 and tested using a three-point flexural strength test on a universal testing machine (Instron).\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eRegarding denture base adaptation, the compression molding (CM) group showed significantly better adaptation in the midpalatal region (B) than the LCD group. At the left ridge crest (C), the DLP group demonstrated superior adaptation compared with both the LCD and CM groups, while at the anterior ridge crest (D), the CM and DLP groups outperformed the LCD group. At the most posterior sagittal point (F), the CM group exhibited significantly better adaptation than both additively manufactured groups. Flexural strength differed significantly among groups, with the highest values observed in the CM group (153.88\u0026thinsp;\u0026plusmn;\u0026thinsp;35.38 MPa). Among the additively manufactured groups, the LCD group (73.09\u0026thinsp;\u0026plusmn;\u0026thinsp;2.23 MPa) showed higher flexural strength than the DLP group (66.93\u0026thinsp;\u0026plusmn;\u0026thinsp;2.29 MPa).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe manufacturing technique significantly affects maxillary denture base adaptation in a region-dependent manner. Compression molding provided more favorable adaptation in the posterior palatal region, whereas DLP showed better adaptation than LCD. Conventionally heat-polymerized PMMA exhibited the highest flexural strength, while both 3D-printed groups met the ISO 20795-1:2013 minimum requirements. Therefore, fabrication technique selection should consider both the target adaptation region and mechanical performance requirements.\u003c/p\u003e","manuscriptTitle":"Comparative Evaluation of Surface Adaptation and Mechanical Properties of Maxillary Complete Denture Bases Fabricated by Conventional and Three-Dimensional Printing Methods: A comparative in vitro study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-19 10:26:27","doi":"10.21203/rs.3.rs-8642763/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-03-05T21:33:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-04T14:50:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"40591996672146135298578479184815444374","date":"2026-03-03T19:04:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-28T03:15:42+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-24T16:34:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"97187333818567134053865798175804437465","date":"2026-02-24T13:55:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"222768305073414922190670396288507831879","date":"2026-02-24T03:35:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-19T15:45:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"171525784888217854769021040978619723746","date":"2026-02-19T15:26:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"336149997248477670594278935174616339799","date":"2026-02-19T02:41:50+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-17T08:34:46+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-27T06:54:57+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-23T10:45:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-23T10:40:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2026-01-19T19:58:01+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":"adbcf614-3c7f-4d40-a2ab-e010409eab39","owner":[],"postedDate":"February 19th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-19T10:26:27+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-19 10:26:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8642763","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8642763","identity":"rs-8642763","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}