Effect of wall thickness on shape accuracy of hollow zirconia artificial teeth fabricated by a 3D printer.

PURPOSE: This study aimed to analyze how the wall thickness of 3D-printed hollow zirconia teeth affects shape accuracy. METHODS: Datasets with measurement points were created for different artificial teeth resembling the mandibular right first molar (Geomagic Design X, 3D Systems). Reference distances were 9.8 mm for mesio-distal direction (M-D), 10.9 mm for bucco-lingual direction (B-L), 7.0 mm for MB-BB and DB-BB, and 4.5 mm for ML-LB and DL-LB. The outer geometry was identical for all artificial teeth with wall thicknesses of 0.30, 0.50, 0.75, and 1.00 mm. Twenty zirconia teeth were fabricated using a 3D printer (CeraFab 7500 Dental, Lithoz) for each group and sintered before support removal. After performing analog distance measurements using a micrometer screw, the digital distance measurements and angular deviations between measurement points on 3D scans were analyzed. Possible effects were investigated using nonparametric ANOVA, followed by Tukey's honest significant difference (HSD) test for multiple comparisons. RESULTS: The shape accuracy was acceptable for artificial teeth with wall thicknesses of ≥0.5 mm. The largest distance deviation was observed for a wall thickness of 0.3 mm. In particular, DB-BB showed a median deviation of >56.2 µm, which is significantly larger than that for other test groups, ranging from 7.4-9.5 µm (P < 0.05). In most cases, angular deviations were the largest for teeth with 0.3-mm wall thickness (11.6°) and remained below 5.0° for the other test groups. CONCLUSIONS: Acceptable accuracy was obtained for artificial teeth with wall thicknesses of at least 0.5 mm.

Fit and Retention of Cobalt-Chromium Removable Partial Denture Frameworks Fabricated with Selective Laser Melting.

PURPOSE: To evaluate fit and retention of cobalt-chromium removable partial denture (RPD) frameworks fabricated with selective laser melting (SLM). METHODS: Three types of framework for clasp-retained RPDs were virtually designed and fabricated using SLM (n = 30). For comparison, 30 additional frameworks were produced using conventional lost-wax casting. A biomechanical model was created, incorporating extracted teeth mounted on flexible metal posts. Using this model, horizontal constraint forces resulting from a misfit were measured using strain gauges, while vertical forces were not recorded. The constraint force components and resultant forces were determined for all abutment teeth, and the maximum retention force during RPD removal from the model was also assessed. For statistical evaluation, the two fabrication methods were analyzed by calculating the means and standard deviations. RESULTS: The average horizontal constraint forces showed similar values for both fabrication methods (SLM: 3.5 ± 1.0 N, casting: 3.4 ± 1.6 N). The overall scatter of data for cast RPDs was greater compared to those fabricated using SLM, indicating a better reproducibility of the SLM process. With regard to retention, the intended retention force of 5-10 N per abutment tooth was not attained in one of the cast groups, while it was consistently achieved in all SLM groups. CONCLUSIONS: This in vitro study found that SLM is a promising option for the manufacture of cobalt-chromium RPD frameworks in terms of fit and retention.

Comparison between interocclusal registration using silicone bite registration material and intraoral scanner on clenching strength.

INTRODUCTION: The purpose of this study was to clarify the influence of clenching strength on interocclusal registration using intraoral scanner (IOS). METHODS: Subjects were eight volunteers. Two experimental conditions were light clenching (LC) and 40% maximum voluntary clenching (MVC). The conventional silicone bite registration and IOS were used for comparison. Occlusal contact areas (OCA) for different clenching strengths were compared, along with variation of measured values (VMV) between recording methods. RESULTS: Significant differences were observed between conditions on OCA and between methods on VMV. CONCLUSION: Clenching strength influenced interocclusal registration using IOS. Int J Prosthodont. 10.11607/ijp.8445.

Simultaneous prosthodontic treatment for crowns of natural teeth and dental implants using digital technology: A case report.

The aim of this clinical report was to describe the improvement of masticatory disorders with the use of digital technology to simultaneously perform prosthodontic treatment of natural teeth and edentulous areas. Computer-guided implant surgery was performed, and crown prostheses and implant superstructures were fabricated simultaneously using digital technology.

Effects of hollow structures added by selective laser sintering on the mechanical properties of Co-Cr alloy.

PURPOSE: This study investigates the effects of hollow structures, added by selective laser sintering (SLS), on the mechanical properties of a Co-Cr alloy for providing an optimal structural property to the framework components of removable partial dentures (RPDs). METHODS: The specimens produced using the 3D data of the dumbbell-shaped cylinders were divided into four groups based on the manufacturing method: Cast, Mill, SLS-solid, and SLS-hollow. Tensile tests were performed to measure the mechanical properties of the specimens. The mechanical property values among the four groups were statistically compared using the Kruskal-Wallis test followed by the Steel-Dwass test (α = 0.05). RESULTS: The median elastic modulus was the largest in the Cast, followed by SLS-solid, Mill, and SLS-hollow, with no significant differences observed between all conditions. The median ultimate tensile strength was the largest in the order of SLS-solid, Mill, SLS-hollow, and Cast. The median 0.2% proof stress was the largest in SLS-solid, followed by SLS-hollow, Cast, and Mill. The median elongation was the highest in the order of Mill, SLS-solid, SLS-hollow, and Cast. CONCLUSIONS: With the addition of hollow structures, the elastic modulus decreased while the mechanical strength and proof stress remained high in SLS specimens. In addition, the ISO 22674 standard for dental metals was met, suggesting that SLS may be a possible method to design RPD frameworks with high strength and optimal structural properties.

Digital technology for fabrication of removable dental prosthesis with double crowns combining fiber-reinforced composite and zirconia.

PATIENTS: This clinical report describes the process for fabricating a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia using digital technology. An 83-year-old woman presented with gingival swelling around the maxillary right premolar. The swollen tooth was the abutment tooth of a cross-arch fixed partial denture. An intraoral scanner (IOS) and computer-aided design/manufacturing as digital technology were used to plan treatment with a double-crown-retained removable dental prosthesis. A metal-free prosthesis using zirconia for the primary crown and fiberglass-reinforced composite resin for the secondary crown was planned, and the patient consented to the treatment plan. After autotransplantation of a tooth as one of the abutments, the IOS was used to obtain digital scans of the prepared surface of the abutment teeth, opposing dentition, and occlusal relationships. First, primary crowns were milled using zirconia. Next, the intraoral scanner obtained a pick-up impression of the primary crowns, and secondary crowns were designed and milled from the fiber-reinforced composite. After delivery, the patient expressed satisfaction with the functionality, esthetics, and fit of the double-crown-retained removable dental prosthesis. DISCUSSION: Digital technology offers many advantages such as efficient fabrication of double crowns, reduced material costs, improved biocompatibility, and good aesthetics of metal-free materials. CONCLUSIONS: This clinical report describes the application of digital technology for the fabrication of a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia, resulting in patient satisfaction.

A new proposal for improving the accuracy of intraoral scanning for partially edentulous residual ridge.

Purpose This study investigated the usefulness of a newly proposed intraoral scanning method, using markers that can be used directly in the oral cavity, in order to improve the accuracy of impression taking of the residual ridge for fabrication of removable partial dentures.Methods An intraoral scanner was used to scan a dental model of a partially edentulous mandibular arch (Kennedy Class I). As markers, pieces of dried pasta were used. The scanning operation was performed under three conditions. In Condition 1, scanning was performed on the remaining teeth and the residual ridge without markers. In Condition 2, scanning of the remaining teeth and residual ridge was performed with markers. In Condition 3, the markers were removed from the model used in Condition 2, and the residual ridge was scanned again. The scanning data of each condition was superimposed on the control data, and the shape error was calculated and compared among the conditions.Results There was a significant difference in trueness of the residual ridge before and after marker application. The application of markers improved the trueness, while maintaining precision. Re-scanning after removing the marker did not affect trueness between before and after re-scanning and the re-scanned region showed shape continuity with the surrounding region.Conclusions The present method using markers that can be used in the oral cavity was effective in improving the accuracy of impression taking at the residual ridge.

Retentive force of conical crowns combining zirconia and fiber-reinforced composite.

PURPOSE: This study investigated the retentive force of conical crowns combining zirconia primary and fiber-reinforced composite (FRC) secondary crowns and their changes due to aging. METHODS: Zirconia primary crowns were produced with a convergence angle of 3°. Thirty-two secondary crowns were milled from FRC and divided into two groups (n = 16/group) based on the polishing method of the secondary crown inner surfaces: diamond paste (Group 1) and silicone points (Group 2). After fitting the secondary crowns with different fitting forces (F), loosening forces (L) were determined. Tests were repeated after an occlusal stop (OS) was added to the secondary crown and artificial aging (10,000 insertion/removal cycles). Data were compared using the Wilcoxon and Mann-Whitney U tests. RESULTS: Crowns without an OS showed L/F ratios of 0.4586 (Group 1) and 0.4104 (Group 2). With an OS, maximum retention was not significantly affected by the polishing method and could be limited to Lmax = 19.31±7.77 N (Group 1) and Lmax = 16.12±5.92 N (Group 2). CONCLUSIONS: These findings suggest that the combination of conical zirconia primary and FRC secondary crowns can obtain acceptable retentive forces that are not affected by aging if the inner surfaces are polished with diamond paste. OS generation could limit maximum retention, but should be adjusted if the target value of 10 N is not to be exceeded. With a change of the convergence angle to 4°, L/F values for crowns without an OS would be close to 1/3, which is considered ideal for conical crowns. CLINICAL SIGNIFICANCE: The combination of zirconia primary crowns and FRC secondary crowns was found feasible to ensure the required retention for clinical use over a long time span. Furthermore, it offers an alternative to metal-based restorations while ensuring high levels of biocompatibility and esthetics.

Influence of molding angle on the trueness and defects of removable partial denture frameworks fabricated by selective laser melting.

PURPOSE: To examine the effect of molding angle on the trueness and defects associated with removable partial denture (RPD) frameworks fabricated by selective laser melting (SLM). METHODS: A plaster model of a partially edentulous mandibular arch classified as Kennedy class II modification 1 was used. After obtaining the 3D data of the model (design data), a framework was designed using CAD software. Based on the design data, three different molding angle conditions (0°, 45°, and -45°) were set in the CAM software. The frameworks were fabricated by SLM under each condition, and 3D data were captured (fabrication data). The design and fabrication data were superimposed using 3D inspection software to verify the shape errors. The number of support structures was then measured. To examine the internal defects, micro-computed tomography (µCT) was performed for void analysis. Surface roughness was measured using a laser microscope. RESULTS: The overall shape errors of the RPD framework were smaller under the 0° condition compared with the others, and the largest number of support structures was observed at 0°. Many internal defects were observed in the large components of the framework at 45° and -45°. The surface roughness was the smallest at -45°. CONCLUSION: The trueness and defects associated with the RPD frameworks were affected by the difference in the SLM molding angle.

Intraoral scanner and computer-aided design/manufacturing technology for the fabrication of double-crown-retained removable dental prosthesis: A clinical report.

PATIENT: This clinical report describes treatment with a double-crown-retained removable dental prosthesis fabricated using an intraoral scanner (IOS) and computer-aided design/manufacturing technology (CAD/CAM). A 68-year-old female patient presented with complaints of missing maxillary right first and left second premolars. CAD/CAM technology was applied to plan treatment with a double-crown-retained removable dental prosthesis. The patient consented to this treatment option but did not want orthodontic treatment for the anterior crossbite of the right side. After the definitive preparation of the abutment teeth, the shape of the provisional restoration was adjusted to match the definitive prosthesis. An IOS was used to obtain digital scans of the provisional restoration, occlusion, antagonist arch, and prepared surface of the abutment teeth. First, the primary crowns were milled from cobalt-chromium alloy. Next, using an intraoral scanner, a pick-up impression of the primary crowns was performed, and the secondary crowns were designed, milled, and veneered. After delivery, the patient expressed satisfaction with the functionality, esthetics, and fit of the double-crown-retained removable dental prosthesis. DISCUSSION: The surface of the primary crowns was coated with scan spray when the pick-up impression was made using the IOS. Practice is needed to achieve a thin and homogeneous coating with scan spray to improve reproducibility. CONCLUSION: Double-crown-retained removable dental prostheses can be successfully fabricated using an IOS and CAD/CAM technology, resulting in patient satisfaction.

Retentive force of telescopic crowns combining fiber-reinforced composite and zirconia.

PURPOSE: This study investigated changes in the retentive force of telescopic crowns fabricated by combining a zirconia primary crown and a fiber-reinforced composite (FRC) secondary crown. METHODS: Primary zirconia crowns were produced with a nominal convergence angle of 0°. Forty-eight secondary crowns were milled from FRC and divided into three study groups (n=16/group) based on milling parameters and post-milling adjustment. The offset parameter used for the final milling step of the inner crown surface was adjusted for a tight initial fit in Group 1 (milling offset: +10 µm, i.e., 2 × 10 µm = 20 µm lower inner diameter compared with the CAD file of the crown) and for improved initial fit (milling offset: -10 µm, i.e., an enlargement of the inner crown diameter by 2 × 20 µm = 40 µm in relation to Group 1) in Groups 2 and 3. The inner surfaces of the secondary crowns were polished with diamond paste in Groups 1 and 2, and silicon points were used for Group 3. The retentive force was measured using a universal testing device. The secondary crown was placed on the primary crown, with the final fitting force set to a load of 100 N. This test was conducted before and after aging (10,000 insertion/removal cycles) under dry and wet conditions. A generalized linear model was used to estimate the differences in the retentive force to elucidate the effects of the milling parameters and polishing methods. RESULTS: We realized an initial retentive force of approximately 10 N. In Groups 2 and 3, the difference was statistically significant between the dry and wet conditions before aging (P < 0.05). There was no significant difference between the dry and wet conditions after aging in any of the groups (P > 0.05). CONCLUSION: An adequate initial retentive force can be achieved with telescopic crowns combining zirconia and FRC.

Measuring peri-implant bone lesions using low-dose cone-beam computed tomography.

PURPOSE: High-definition cone-beam computed tomography (HD-CBCT) offers superior image quality at the cost of higher radiation dose compared to low-dose CBCT (LD-CBCT). The aim of this study was to investigate whether peri-implant bone lesions can be accurately quantified using LD-CBCT, even when including the influence of surrounding tissues. METHODS: Twelve titanium implants restored with all-ceramic crowns were placed in bovine bone, and peri-implant lesions were prepared. Radiographic imaging was performed using IR (intraoral radiography), HD-CBCT and LD-CBCT. To simulate the in-vivo situation, the samples were placed inside a dry human mandible, and a second LD-CBCT imaging was performed (LD-CBCT*). The datasets were presented to four observers in random order. Maximum lesion depth and width were measured in a standardized mesiodistal slice in IR, HD-CBCT, LD-CBCT, and LD-CBCT*. Mean lesion depth and width measurements for each sample in HD-CBCT served as reference. RESULTS: Interrater agreement was slight for depth and excellent for width in HD-CBCT and both LD modes. For all observers, measurement deviations from HD-CBCT were below 0.3 mm in the LD protocols (LD-CBCT depth: 0.22 ± 0.17 mm, width: 0.22 ± 0.13 mm; LD-CBCT* depth: 0.24 ± 0.23 mm, width: 0.25 ± 0.21 mm) and at 0.4 mm in IR. CONCLUSION: Absolute differences between LD-CBCT and HD-CBCT are small, although surrounding tissues decrease LD-CBCT image quality. Within the limitations of an in-vitro trial, LD-CBCT may become an adequate imaging modality for monitoring peri-implant lesions at a substantially decreased radiation dose.

Fabrication of Zirconia Abutment Crown and Clasp Under Existing Removable Partial Denture Using CAD/CAM Technology.

This clinical report describes a technique for fabricating a retrofit zirconia crown and clasp for an existing removable partial denture (RPD) using computer-aided design and computer-aided manufacturing (CAD/CAM). A 58-year-old patient developed acute pulpitis of a tooth, and the RPD clasp was broken on the tooth. A pre-preparation scan was captured using an intraoral scanner. The existing RPD was placed in the mouth, and scans of the post-preparation, antagonist arch, and interocclusal record were made. A zirconia crown was designed by superimposing the pre-preparation scan and the post-preparation scan of the abutment tooth. The design data were transferred to a 5-axis milling machine, and the crown was milled from zirconia. The crown was luted using resin cement. An intraoral scan of the crown with RPD was taken, and the RPD was removed to re-scan the proximal guide plane of the crown. The I-bar clasp was designed, and the casting pattern was built using a 3D printer. The pattern was used to cast the clasp. The clasp was set using autopolymerizing acrylic resin to the RPD. The main advantages of this efficient process are that patients can use their RPDs during fabrication of the crown of the abutment tooth. The limitations of using this technique include the cost of the intraoral scanner and the education for the dental clinicians and technicians. In this clinical report, CAD/CAM technology prevented human error, required no adjustment, and uninterrupted use of the RPD for fabricating a retrofit zirconia crown and clasp for an existing RPD.

Accuracy of 3D printing compared with milling - A multi-center analysis of try-in dentures.

OBJECTIVES: In recent years, computer-aided design/computer-aided manufacturing (CAD/CAM) has been used to produce removable complete dentures. Most workflows include fabrication of milled or 3D-printed try-in prostheses. 3D-printing accuracy is affected by laboratory-specific and operator-dependent factors. This international five-center study sought to compare the accuracy of 3D-printed and milled try-in dentures. METHODS: The construction file of a maxillary removable complete denture was selected as a reference. Eight try-in dentures were 3D printed at each of the five centers. Each center used their own printer (Objet260 Connex, Stratasys; MAX, Asiga; Anycubic Photon, Anycubic 3D; PRO2, Asiga and cara Print 4.0, Kulzer) along with their own material, printing settings, post-processing and light-curing parameters. At center 2, eight try-in dentures were milled to serve as a benchmark (PrograMill PM7, Ivoclar Vivadent). Dentures were scanned and aligned to the reference file using best-fit algorithms. Geometric accuracy was analyzed using the root mean square value (trueness) and standard deviation (precision) of the distributed absolute mesh deviations. Mean values of the five sets of printed dentures and the single set of milled dentures were compared. RESULTS: Milled dentures showed a mean trueness of 65 ±â€¯6 µm and a mean precision of 48 ±â€¯5 µm. Thus, they were significantly more accurate than the 3D-printed dentures in four out of five centers. In mean absolute numbers, 3D printing was less true than milling by 17-89 µm and less precise by 8-66 µm. CONCLUSIONS: Although milling remains the benchmark technique for accuracy, differences between milled and 3D-printed dentures were non-significant for one printing center. Furthermore, the overall performance of 3D printing at all centers was within a clinically acceptable range for try-in prostheses. CLINICAL SIGNIFICANCE: The accuracy of 3D printing varies widely between and within laboratories but nonetheless lies within the range of accuracy of conventional manufacturing methods.

Effects of repetitive insertion/removal cycles and simulated occlusal loads on retention of denture retainers.

The purpose of this study was to investigate the effects of repetitive insertion/removal cycle tests on denture retainers with simulated occlusal loads on the retentive force and deformation of clasp. Abutment teeth in the form of mandibular secondary premolars and clasp in the form of Akers clasps were prepared. The retentive force of the clasp on the abutment teeth were evaluated before and after undergoing repetitive insertion/removal cycle tests with or without cyclic loading. Changes in the clasp shape were monitored using a 3D scanner and scanning electron microscope. The initial retentive force was approximately 10 N and this value later decreased due to deformation of the clasp tips. In contrast to the non-load group, the load group exhibited a reduction in retentive force during earlier stages. Therefore, cyclic loading was related to a decrease in retentive forces, specifically in the early stages of repetitive insertion/removal cycles.

Influence of reinforcement bar on accuracy of removable partial denture framework fabricated by casting with a 3D-printed pattern and selective laser sintering.

PURPOSE: The purpose of this study was to investigate the accuracy of removable partial denture frameworks fabricated by 3D-printed pattern casting (AM-Cast) and selective laser sintering (SLS) under different co nditions with a reinforcement bar. METHODS: A partially edentulous model was scanned with a dental laboratory scanner, and CAD software was used to design the framework. Reinforcement bars (n=0-2) were set on the lingual side of the framework. 3D scanning of the fabricated frameworks by AM-Cast and SLS was performed, and the obtained data were overlapped with the design data. The differences in shape among setting conditions of the bar were statistically compared using the Bonferroni method after the Kruskal-Wallis test. RESULTS: The ranges in differences of the AM-Cast-0, AM-Cast-1, and AM-Cast-2 were -0.167 to 0.128 mm, -0.101 to 0.105 mm, and -0.185 to 0.015 mm, respectively. The ranges of SLS-0, SLS-1, and SLS-2 were -0.166 to 0.035 mm, -0.182 to 0.049 mm, and -0.138 to 0.038 mm, respectively. Large discrepancies were observed at the joining area of the lingual bar on the right side of the AM-Cast. A significant difference was found between the AM-Cast-0 and AM-Cast-1, and between the AM-Cast-0 and AM-Cast-2. CONCLUSIONS: The setting conditions of the reinforcement bar affected the accuracy of the lingual bar in the AM-Cast; however, no effect was observed on the displacement of the central area of the lingual bar in SLS. Setting a single reinforcing bar on the retentive latticework contributed to improving the accuracy of the lingual bar in the AM-Cast but not the displacement of the central area of the lingual bar in SLS.

Comparison of retentive forces between telescopic crowns made of poly(ether ether ketone) and type 4 gold alloy.

In this study, retentive forces were compared between telescopic crowns (TSC) made with poly(ether ether ketone) (PEEK) using computer-aided design and manufacturing and type 4 gold alloy using the conventional method. The retentive forces of TSCs were evaluated by performing a pull-out test with primary and secondary crowns. Initial retentive force was approximately 12 N for both PEEK and gold alloy TSCs. The retentive force of PEEK TSC was approximately 6.5 N after 10,000 cycles of insertion and removal. The reduction rate in retentive force was smaller for gold alloy TSC. PEEK TSC displayed greater surface roughness on the primary crown compared to the gold alloy TSC. Surface roughness slightly increased at the cervical margin after repetitive insertion and removal. The retentive force of PEEK TSC was smaller than gold alloy TSC, however the retentive force of PEEK TSC was adequate for stabilizing dental prostheses even after 10,000 cycles.

Three-dimensional-guided removal and preparation of dental root posts-concept and feasibility.

PATIENTS: This case report presents a novel method to remove glass fiber-reinforced composite root posts in a minimally invasive way while simultaneously shaping the canal for a new post-endodontic restoration. A multi-morbid, handicapped 62-year-old patient was referred with a horizontally fractured maxillary incisor presenting approximately 1 mm residual coronal tooth height. Endodontic revision was necessary, which required removal of a glass fiber-reinforced composite post. A cone-beam computed tomography (CBCT) scan was imported into conventional implant-planning software and matched to a stone cast of the intraoral situation. Position, length, and axis of the future post were planned virtually. Based on this planning, a tooth-supported splint was three-dimensionally (3D) printed. This splint allowed use of a 2.2-mm spiral drill for removal of the fractured post and shaping of the root canal for a new cast post-and-core. This metal post-and-core was adhesively cemented and prepared for a zirconia single crown veneered in the labial aspect. DISCUSSION: This method currently requires use of CBCT-based, ionizing 3D imaging. Additional refinements to this approach can be made regarding spiral drill design and coating as well as regarding the post-and-core workflow. CONCLUSIONS: 3D-guided post-endodontic management is feasible. More research is needed to balance higher radiation doses against therapeutic success.

Accuracy of removable partial denture framework fabricated by casting with a 3D printed pattern and selective laser sintering.

PURPOSE: The present study aimed to compare the accuracy of removable partial denture (RPD) frameworks fabricated by 3D-printed pattern casting and those fabricated by selective laser sintering (SLS). METHODS: A partially edentulous mandibular model was used for the simulation model. Scanning of the model was performed using a dental scanner. The framework was designed by using CAD software. The 3D-printed resin pattern was formed using a 3D printer and casting was performed (AM-Cast framework), and a direct metal laser sintering machine was used for the framework of SLS (SLS framework). 3D scanning of fabricated two types of framework were performed, and these data were overlapped with design data. Fabrication accuracy was verified using the Mann-Whitney U test to compare the discrepancy between the AM-Cast and SLS frameworks. RESULTS: The range of differences for the AM-Cast and SLS framework were -0.185±0.138 to 0.352±0.143mm and -0.166±0.009 to 0.123±0.009mm, respectively. Statistically significant differences were observed at the rests, proximal plates, connectors, and clasp arms. Regarding the rests, both lateral and medial displacement in the two types framework was observed in relation to the design data. Large lateral discrepancies of the connectors were observed at the joining area on the tooth-supported side of the lingual bar for the AM-Cast framework. Localized discrepancies were observed at the center of the lingual bar for the SLS framework. CONCLUSION: The accuracies of RPD frameworks fabricated by AM-Cast and SLS differ depending on the specific structural component of the RPD.