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Zhu H, Jiang J, Wang Y, Wang S, He Y, He F. Additive manufacturing of dental ceramics in prosthodontics: The status quo and the future. J Prosthodont Res 2024; 68:380-399. [PMID: 38346729 DOI: 10.2186/jpr.jpr_d_23_00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
PURPOSE This review aims to summarize the available technologies, material categories, and prosthodontic applications of additive manufacturing (AM) dental ceramics, evaluate the achievable accuracy and mechanical properties in comparison with current mainstream computer-aided design/computer-aided manufacturing (CAD/CAM) subtractive manufacturing (SM) methods, and discuss future prospects and directions. STUDY SELECTION This paper is based on the latest reviews, state-of-the-art research, and existing ISO standards on AM technologies and prosthodontic applications of dental ceramics. PubMed, Web of Science, and ScienceDirect were amongst the sources searched for narrative reviews. RESULTS Relatively few AM technologies are available and their applications are limited to crowns and fixed partial dentures. Although the accuracy and strength of AM dental ceramics are comparable to those of SM, they have the limitations of relatively inferior curved surface accuracy and low strength reliability. Furthermore, functionally graded additive manufacturing (FGAM), a potential direction for AM, enables the realization of biomimetic structures, such as natural teeth; however, specific studies are currently lacking. CONCLUSIONS AM dental ceramics are not sufficiently developed for large-scale clinical applications. However, with additional research, it may be possible for AM to replace SM as the mainstream manufacturing technology for ceramic restorations.
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Affiliation(s)
- Han Zhu
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Jimin Jiang
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Yujie Wang
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Sijie Wang
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Yong He
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, PR China
| | - Fuming He
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
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Daou EE, Salameh P. Does the choice of the measuring technique affect the comparison of fit between zirconia and cobalt-chromium prostheses? J Indian Prosthodont Soc 2024; 24:201-207. [PMID: 38650346 PMCID: PMC11129817 DOI: 10.4103/jips.jips_429_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/25/2024] Open
Abstract
AIMS The objectives of the study were to compare the adaptation of presintered zirconia and cobalt- chromium prostheses using microcomputed tomography (μCT), scanning electron microscopy (SEM), and stereomicroscope (SM). MATERIALS AND METHODS Twenty-four fixed dental prostheses (FDPs) were fabricated on metal abutments, duplicated from maxillary first premolar and first molar prepared on a typodont model. Teeth were reduced to obtain chamfer of 1.2 mm and reduction occlusaly of 2 mm occlusal. Scanning of the abutments was done with random assignment to two groups receiving the FDPs made from soft-milled Co-Cr (n = 12) and zirconia (n = 12). Marginal and internal gaps were assessed using three evaluation techniques (X-ray microcomputer tomography, SEM, and stereomicroscopy). STATISTICAL ANALYSIS USED Comparison of the results was made using Levene and analysis of variance tests (α =0.05). RESULTS Irrespective of the material tested, statistical differences were found between the measuring techniques (P = 0.001 overall); the obtained mean gaps were for CT scan (92.60 ± 13.31), for SEM (101.92 ± 23.03), and for SM (113.44 ± 14.68): the multiple comparisons between techniques found a significant difference between CT and SM (P < 0.001), and SEM and SM (P = 0.025). When materials were compared within each measuring technique, Co-Cr showed lower values compared to zirconia in SEM (P < 0.001) and Stereo (P = 0.049); similar results were found in CT. CONCLUSIONS Results values differed with the chosen measuring technique. Co-Cr prostheses had a better fit than zirconia prostheses in SEM and Stereo. µCT showed comparable results to SEM, smaller than SM results.
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Affiliation(s)
- Elie E. Daou
- Department of Prosthodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon
- Department of Fixed Prosthodontics, Faculty of Dentistry, Saint Joseph University, Beirut, Lebanon
| | - Pascale Salameh
- Department of Public Health, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
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Daou EE. Effect of lamination layer thickness and abutment preparation on the fit of Co-Cr multi-unit prostheses fabricated by additive manufacturing: An in vitro study. J Prosthet Dent 2024; 131:652-657. [PMID: 35430049 DOI: 10.1016/j.prosdent.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 11/19/2022]
Abstract
STATEMENT OF PROBLEM Selective laser melting has been increasingly used in the fabrication of metal-ceramic prostheses. The lamination layer thickness may influence the fit of the restoration. However, data regarding its impact remain scarce. PURPOSE The purpose of this in vitro study was to evaluate the marginal and internal fit of cobalt-chromium (Co-Cr) 3-unit frameworks fabricated by additive manufacturing with different melting layer thicknesses on different abutments. MATERIAL AND METHODS The first right maxillary premolar and molar from a typodont were prepared with a circumferential 1.2-mm chamfer, 2-mm occlusal reduction, and total taper of 8 degrees to receive 3-unit fixed partial dentures. After framework design, the data were sent to a laser machine, and 30 specimens were fabricated from Co-Cr metal powder (Mediloy S-Co) by selective laser melting. Specimens were assigned to 3 groups (n=10) with different lamination layer thicknesses of 25 (L25), 50 (L50), and 100 (L100) μm. Marginal fit and internal fit were evaluated. Results were compared among layer thickness groups and abutments. Data were compared by using the Levene test, t test, and ANOVA (α=.05). RESULTS A statistical difference was found between different layer thickness groups (P=.016), but not between abutments (P=.429). On the abutment level, significant difference was found in the gap values for the molars (P=.049) between layer thickness groups, but not for the premolars (P=.126). Group L25 reported the smallest mean discrepancy values, and group L100 reported the highest, with statistical difference found between group L100 and groups L25 (P<.001) and L50 (P<.025), but not between groups L25 and L50 (P=.094). CONCLUSIONS The lamination layer thickness affected the adaptation of the metal frameworks. Framework fit did not significantly differ between abutments.
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Affiliation(s)
- Elie E Daou
- Assistant Professor, Department of Prosthodontics, School of Dentistry, Lebanese University, Beirut, Lebanon; Assistant Professor, Al-Ayen University, Nile Street, Nasiriyah.
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Nakase D, Kubochi K, Kitani J, Honda J, Iwasaki T, Komine F. Influence of an internal firing of feldspathic porcelain before or after sintering on adaptation of high-translucent zirconia laminate veneers. J Mech Behav Biomed Mater 2023; 148:106208. [PMID: 37922759 DOI: 10.1016/j.jmbbm.2023.106208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023]
Abstract
The aim of the present study was to evaluate the influence of two different internal surface treatments, namely, the firing of feldspathic porcelain before or after zirconia sintering, on the marginal and internal adaptation of laminate veneers (LVs) made of high-translucent zirconia. A total of 33 zirconia LVs were fabricated using a CAD/CAM system and divided into three groups based on the internal surface treatment method: the pre-firing (PRE) group involved firing feldspathic porcelain before zirconia sintering, the post-firing (POS) group involved firing feldspathic porcelain after zirconia sintering, and the no treatment (NT) group involved no application of feldspathic porcelain. The adaptation of the LVs was measured using a silicone replica technique. Data were analyzed using the Kruskal-Wallis and Steel-Dwass tests (α = .05). The POS group showed significantly higher marginal discrepancy values than the PRE group across all sites. The internal space values of the PRE groups were significantly lower than those of the NT group at all sites. The internal firing of feldspathic porcelain before zirconia sintering resulted in better marginal adaptation of the high-translucent zirconia LVs than the internal firing of feldspathic porcelain after zirconia sintering. The internal firing of feldspathic porcelain before zirconia sintering can achieve uniform internal adaptation of high-translucent zirconia LVs.
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Affiliation(s)
- Daishi Nakase
- Department of Fixed Prosthodontics, Nihon University School of Dentistry, Japan
| | - Kei Kubochi
- Department of Fixed Prosthodontics, Nihon University School of Dentistry, Japan.
| | - Jin Kitani
- Department of Fixed Prosthodontics, Nihon University School of Dentistry, Japan
| | - Junichi Honda
- Department of Fixed Prosthodontics, Nihon University School of Dentistry, Japan
| | - Taro Iwasaki
- Department of Fixed Prosthodontics, Nihon University School of Dentistry, Japan
| | - Futoshi Komine
- Department of Fixed Prosthodontics, Nihon University School of Dentistry, Japan
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Attia MA, Blunt L, Bills P, Tawfik A, Radawn M. Micro-CT analysis of marginal and internal fit of milled and pressed polyetheretherketone single crowns. J Prosthet Dent 2023:S0022-3913(23)00183-X. [PMID: 37072286 DOI: 10.1016/j.prosdent.2023.03.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/18/2023] [Accepted: 03/20/2023] [Indexed: 04/20/2023]
Abstract
STATEMENT OF PROBLEM Polyetheretherketone (PEEK) has been increasingly used as a framework material in prosthetic dentistry. However, data on the marginal and internal fit of PEEK restorations fabricated by using either the computer-aided design and computer-aided manufacturing (CAD-CAM) or heat-pressing technique are sparse. PURPOSE The aim of this in vitro study was to assess the marginal and internal fit of milled and pressed PEEK single crowns by using microcomputed tomography (μCT). MATERIAL AND METHODS A custom-made, single stainless-steel die was designed to replicate a maxillary first premolar prepared for a ceramic crown. PEEK copings (N=30) were fabricated and allocated to 3 groups (n=10) according to the fabrication technique: milled from a prefabricated PEEK blank, heat pressed from PEEK pellets, and heat pressed from PEEK granules. All copings were veneered with a composite resin material. The marginal fit was recorded at 4 predetermined points and the internal fit at 8 predetermined points on each crown by using μCT. Two-way ANOVA, pair-wise Tukey honestly significant difference (HSD), and simple main effect tests were used for statistical analysis of the data (α=.05). RESULTS Concerning marginal fit, the milled crowns demonstrated the best marginal fit overall (44 ±3 μm), followed by those pressed from pellets (92 ±3 μm), and finally by those pressed from granules (137 ±7 μm) (P<.001). The interaction between the effects of the fabrication technique and the measurement point on the marginal fit was not statistically significant (P=.142). The milled crowns demonstrated the lowest mean gap values overall, followed by those pressed from pellets and those pressed from granules (P<.001). The interaction between the effects of the fabrication technique and the measurement point on the internal fit was statistically significant (P<.001). Except for the distal occlusal gap and mesial occlusal gap, all tested groups showed a statistically significant difference (P<.001). In addition, statistically significant differences were observed among all measurement points in different fabrication techniques (P<.001). CONCLUSIONS The marginal and internal fit of milled PEEK crowns was significantly better than pressed crowns. However, both CAD-CAM and heat-pressing techniques produced PEEK crowns with a clinically acceptable marginal and internal fit. The mean marginal gap of the PEEK crowns pressed from granules was above the range of clinically acceptable value.
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Affiliation(s)
- Mazen A Attia
- Associate Professor, Department of Fixed Prosthodontics, Faculty of Dentistry, Beni-Suef University, Beni-Suef, Egypt.
| | - Liam Blunt
- Professor, EPSRC Future Advanced Metrology Hub, University of Huddersfield, Huddersfield, United Kingdom
| | - Paul Bills
- Professor, EPSRC Future Advanced Metrology Hub, University of Huddersfield, Huddersfield, United Kingdom
| | - Ahmed Tawfik
- PhD Researcher, EPSRC Future Advanced Metrology Hub, University of Huddersfield, Huddersfield, United Kingdom
| | - Mohamed Radawn
- Lecturer, Department of Fixed Prosthodontics, Faculty of Dentistry, Beni-Suef University, Beni-Suef, Egypt
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Nagata K, Muromachi K, Kouzai Y, Inaba K, Inoue E, Fuchigami K, Nihei T, Atsumi M, Kimoto K, Kawana H. Fit accuracy of resin crown on a dental model fabricated using fused deposition modeling 3D printing and a polylactic acid filament. J Prosthodont Res 2023; 67:144-149. [PMID: 35466158 DOI: 10.2186/jpr.jpr_d_21_00325] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Purpose We considered the possibility of reducing industrial waste by fabricating and reusing dental models prepared using a fused deposition modeling (FDM) 3D printer and polylactic acid (PLA) filaments. The purpose of this study was to verify the accuracy of models fabricated using FDM and PLA.Methods The same provisional crown was used to check the marginal fit on PLA models prepared using an intraoral scanner (IOS) and FDM, plaster models made with silicone impression material and plaster, and resin models prepared using an IOS and stereolithography apparatus (SLA) 3D printer. The marginal fit was measured using micro-computed tomography at four points on the tooth: the buccal center (B), palatal center (P), mesial center (M), and distal center (D) points.Results At point B, the marginal gaps were 118 ± 21.7, 62 ± 16.4, and 50 ± 26.5 μm for the PLA, resin, and plaster models, respectively, with a significant difference between the PLA model and the other two. However, the marginal gap at all other measurement points was not significantly different between the models (P > 0.05).Conclusions We compared the accuracy of the models fabricated using the FDM, SLA, and conventional methods. The combination of FDM and PLA filaments showed no significant differences from the other models, except at point B, indicating its usefulness. Therefore, FDM and PLA may become necessary materials for dental treatment in the future.
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Affiliation(s)
- Koudai Nagata
- Department of Oral and Maxillofacial Implantology, Kanagawa Dental University, Yokosuka, Japan
| | - Koichiro Muromachi
- Department of Pulp Biology and Endodontics, Kanagawa Dental University, Yokosuka, Japan
| | - Yusuke Kouzai
- Department of Education Planning, Kanagawa Dental University, Yokosuka, Japan
| | - Keitaro Inaba
- Department of Oral Microbiology, Kanagawa Dental University, Yokosuka, Japan
| | - Erika Inoue
- Division of the Dental practice support, Kanagawa Dental University, Yokosuka, Japan
| | - Kei Fuchigami
- Department of Oral and Maxillofacial Implantology, Kanagawa Dental University, Yokosuka, Japan
| | - Tomotaro Nihei
- Department of Clinical Biomaterials, Kanagawa Dental University, Yokosuka, Japan
| | - Mihoko Atsumi
- Department of Fixed Prosthodontics, Kanagawa Dental University, Yokosuka, Japan
| | - Katsuhiko Kimoto
- Department of Fixed Prosthodontics, Kanagawa Dental University, Yokosuka, Japan
| | - Hiromasa Kawana
- Department of Oral and Maxillofacial Implantology, Kanagawa Dental University, Yokosuka, Japan
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Daou EE, Baba NZ. The Effect of Firing Cycles on the Fit of Cobalt-Chromium Multiunit Prostheses Fabricated by Additive Manufacturing. J Prosthodont 2023; 32:71-76. [PMID: 35304798 DOI: 10.1111/jopr.13506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 03/02/2022] [Indexed: 01/25/2023] Open
Abstract
PURPOSE The effect of annealing and firing cycle on the adaptation of cobalt-chromium (CoCr) restorations fabricated by additive manufacturing has been poorly documented. This study compared the marginal and internal fit of CoCr three-unit fixed dental prostheses before and after firing cycles. MATERIAL AND METHODS The first right maxillary premolar (MP) and molar (MM) on a typodont model, were prepared with a circumferential 1.2 mm chamfer, 2 mm occlusal reduction, and total taper of 8 degrees, to receive 3-unit fixed dental prostheses (FDP). After the framework design, 20 framework specimens were fabricated using CoCr metal powder by selective laser melting. The replica technique was used for marginal and internal fit measurements in mesiodistal and buccolingual planes. The specimens were submitted to an annealing process, and to ceramic firing protocol. Measurements were repeated after each firing cycle. The data were compared by using Levene test, t-test, and analysis of variance (ANOVA) (α = 0.05). RESULTS A significant difference was found in the total intaglio surface discrepancy between the 3 treatments. The annealing treatment induced a statistical difference in the discrepancy value compared to the as printed state (p = 0.028). A significant difference was detected between the initial manufacturing phase and the ceramic layering firing cycle (p = 0.003). CONCLUSIONS Firing cycles induced an alteration of the frameworks adaptation.
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Affiliation(s)
- Elie E Daou
- Department of Prosthodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon.,Al-Ayen University, Nile Street, Nasiriyah
| | - Nadim Z Baba
- Advanced Specialty Education Program in Implant Dentistry, Loma Linda University, School of Dentistry, California, USA
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Daou EE, Özcan M. Evaluation of ceramic adherence to cobalt-chromium alloys fabricated by different manufacturing techniques. J Prosthet Dent 2022; 128:1364.e1-1364.e8. [DOI: 10.1016/j.prosdent.2022.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 10/17/2022] [Accepted: 10/17/2022] [Indexed: 12/15/2022]
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Ryniewicz W, Bojko Ł, Ryniewicz AM. The Impact of Sintering Technology and Milling Technology on Fitting Titanium Crowns to Abutment Teeth-In Vitro Studies. MATERIALS (BASEL, SWITZERLAND) 2022; 15:5835. [PMID: 36079217 PMCID: PMC9457018 DOI: 10.3390/ma15175835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/14/2022] [Accepted: 08/19/2022] [Indexed: 06/15/2023]
Abstract
INTRODUCTION The aim of the study is to evaluate the marginal and internal fit of titanium alloy (Ti6Al4V) crowns using the Selective Laser Melting (SLM) method and CAD/CAM milling. MATERIALS AND METHODS The research materials are abutment teeth and prosthetic crowns. The method is based on scanning the abutments and the interior of the substructures, creating their 3D models, using the program for comparison, and determining error maps of fitting crowns to the reference models, in the form of positive and negative deviations. Adding the deviations gives information about the tightness of the crowns. The Shapiro-Wilk test and the one-way ANOVA analysis were performed. The level of significance was p = 0.05. RESULTS The crowns made in SLM, a slightly better internal fit was found than for milled crowns, as well as a comparable marginal fit. The mean deviations for the sintering were the values [mm]: -0.039 and +0.107 for tooth 15 and -0.033 and +0.091 for tooth 36, and for the milling -0.048 and +0.110 for tooth 15 and -0.038 and +0.096 and for tooth 36. CONCLUSION Based on the research conducted and the experience in therapeutic procedures, it can be indicated that the fitting of titanium alloy crowns in SLM and milling meets the clinical requirements. To evaluate the technology, a method was developed that determines the accuracy of mapping the shape of the tooth abutments in the crown substructures for the individual conditions of the patient.
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Affiliation(s)
- Wojciech Ryniewicz
- Department of Dental Prosthodontics and Orthodontics, Dental Institute, Faculty of Medicine, Jagiellonian University Medical College, 4 Montelupich Street, 31-155 Krakow, Poland
| | - Łukasz Bojko
- Faculty of Mechanical Engineering and Robotics, AGH University of Science and Technology, 30 Mickiewicza Ave., 30-059 Krakow, Poland
| | - Anna M. Ryniewicz
- Faculty of Mechanical Engineering and Robotics, AGH University of Science and Technology, 30 Mickiewicza Ave., 30-059 Krakow, Poland
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Lüchtenborg J, Willems E, Zhang F, Wesemann C, Weiss F, Nold J, Sun J, Sandra F, Bai J, Reveron H, Chevalier J, Spies BC. Accuracy of additively manufactured zirconia four-unit fixed dental prostheses fabricated by stereolithography, digital light processing and material jetting compared with subtractive manufacturing. Dent Mater 2022; 38:1459-1469. [DOI: 10.1016/j.dental.2022.06.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 06/08/2022] [Accepted: 06/22/2022] [Indexed: 11/27/2022]
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New generation CAD-CAM materials for implant-supported definitive frameworks fabricated by using subtractive technologies. BIOMED RESEARCH INTERNATIONAL 2022; 2022:3074182. [PMID: 35281596 PMCID: PMC8906986 DOI: 10.1155/2022/3074182] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 01/05/2022] [Accepted: 02/02/2022] [Indexed: 12/31/2022]
Abstract
Innovations in digital manufacturing enabled the fabrication of implant-supported fixed dental prostheses (ISFDPs) in a wide variety of recently introduced materials. Computer-aided design and computer-aided manufacturing (CAD-CAM) milling allows the fabrication of ISFDPs with high accuracy by reducing the fabrication steps of large-span frameworks. The longevity of ISFDPs depends on the overall mechanical properties of the framework material including its fit, and the physical properties of the veneering material and its bond with the framework. This comprehensive review summarizes the recent information on millable CAD-CAM framework materials such as pre-sintered soft alloys, fiber-reinforced composite resins, PEEK, and PEKK in high-performance polymer family, and 4Y-TZP. Even though promising results have been obtained with the use of new generation millable CAD-CAM materials for ISFDPs, clinical studies are lacking and future research should focus on the overall performance of these millable materials in both static and dynamic conditions.
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Ashtiani AH, Mardasi N, Fathi A. Effect of multiple firings on the shear bond strength of presintered cobalt-chromium alloy and veneering ceramic. J Prosthet Dent 2021; 126:803.e1-803.e6. [PMID: 34716011 DOI: 10.1016/j.prosdent.2021.09.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 09/22/2021] [Accepted: 09/22/2021] [Indexed: 11/29/2022]
Abstract
STATEMENT OF PROBLEM How multiple firing cycles may affect the oxide layer and, consequently, the shear bond strength of metal-ceramic restorations is unclear. PURPOSE The purpose of this in vitro study was to determine the effect of multiple firings on the shear bond strength of porcelain to cobalt-chromium (Co-Cr) alloy. MATERIAL AND METHODS Forty cylinders (Ø6.8×9 mm) of a representative presintered Co-Cr alloy (Ceramill Sintron) were prepared with computer-aided design and computer-aided manufacturing (CAD-CAM) technology. After airborne-particle abrasion and polishing, the specimens were ultrasonically cleaned of surface contaminants. A circular surface (Ø4×2 mm) was veneered on each specimen with porcelain (VM13) after 3 firings (wash opaque, opaque, and dentin). The specimens were then randomly divided into 4 groups (n=10). The normal group underwent 3 firings. The other groups underwent an additional porcelain firing: the one-plus firing group underwent 4 firings, the two-plus firing group underwent 5 firings, and the three-plus firing group underwent 6 firings. Next, the specimens were mounted in autopolymerized acrylic resin and tested in a universal testing machine and loaded at a crosshead speed of 0.5 mm/min at the metal-ceramic interface until fracture occurred. The average shear bond strength (MPa) was calculated by dividing the maximum fracture force (N) by the bonded surface of the specimens (mm2). The fracture patterns were observed microscopically and classified as adhesive, cohesive, or mixed. One-way ANOVA was used to determine differences between groups (α=.05). RESULTS No significant differences were found among the shear bond strengths of specimens after 3, 4, 5, and 6 porcelain firings (P>.05). The mean bond strength of all groups ranged from 30 to 34 MPa. The fracture pattern of all specimens was mixed, indicating that multiple firings had no significant effect on the failure pattern. CONCLUSIONS Multiple porcelain firings under controlled conditions had no significant effect on the fracture pattern or shear bond strength of porcelain to a presintered Co-Cr alloy.
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Affiliation(s)
- Alireza Hashemi Ashtiani
- Assistant Professor, Prosthodontic Department, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Nahal Mardasi
- Assistant Professor, Prosthodontic Department, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
| | - Amirhossein Fathi
- Assistant Professor, Dental Material Research Center, Department of Prosthodontics, Isfahan University of Medical Sciences, Isfahan, Iran
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Kayikci O, Ates SM. Comparison of marginal and internal fit of three-unit implant-supported fixed prosthetic substructures fabricated using CAD/CAM systems. Clin Oral Investig 2021; 26:1283-1291. [PMID: 34331593 DOI: 10.1007/s00784-021-04102-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/23/2021] [Indexed: 11/25/2022]
Abstract
OBJECTIVE This study compared the marginal and internal fit of implant-supported fixed dentures fabricated using CAD/CAM systems. MATERIALS AND METHODS A lower jaw model representing partial edentulism was produced. Two dental implants were inserted in the area of teeth 35 and 37, onto which cemented abutments were screwed. The model was scanned using a laboratory scanner and transferred to a design software program for substructure fabrication. Sixty substructures were fabricated out of each group for six substructure types (n = 10), cast Co-Cr (control), milling Co-Cr, laser sintering Co-Cr, titanium (Ti), zirconium, and polyetheretherketone (PEEK) substructures. The marginal and internal fit was evaluated using a silicone replica viewed under a stereomicroscope. The data were analyzed using the statistical package program for social sciences (SPSS, Chicago, IL, USA, v. 17) at a significance level of 0.05. Marginal and internal gaps were compared using the one-way ANOVA test and Tukey's post hoc test. The differences between abutment teeth were determined using the independent sample t-test. RESULTS There was a significant difference in the marginal gap between PEEK and Ti groups (p < 0.05) but no difference between other groups (p > 0.05). There was a significant difference in the internal gap between PEEK, laser sintering Co-Cr, and milling Co-Cr groups (p < 0.05) but no difference between other groups (p > 0.05). The PEEK group had a higher marginal gap than the Ti group and a higher internal gap than the DMLS Co-Cr group (p < 0.05). CONCLUSION All substructures have a marginal and internal fit within acceptable clinical limits. CLINICAL RELEVANCE This in vitro study suggests that materials and techniques used in CAD/CAM systems improve the fitting accuracy of implant-supported fixed restorations.
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Affiliation(s)
- Ozlem Kayikci
- Department of Prosthodontics, Faculty of Dentistry, Recep Tayyip Erdogan University, Rize, Turkey
| | - Sabit Melih Ates
- Department of Prosthodontics, Faculty of Dentistry, Recep Tayyip Erdogan University, Rize, Turkey.
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Effect of ceramic layering on the fit of cobalt-chromium alloy 3-unit fixed dental prostheses fabricated by additive, soft milling, and casting technologies. J Prosthet Dent 2021; 126:130.e1-130.e7. [PMID: 34034899 DOI: 10.1016/j.prosdent.2021.03.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 11/22/2022]
Abstract
STATEMENT OF PROBLEM The change in fit after ceramic layering of additively manufactured cobalt-chromium alloy frameworks has not been evaluated extensively. PURPOSE The purpose of this in vitro study was to compare the fit of cobalt-chromium alloy fixed dental prostheses fabricated by different techniques before and after ceramic layering. MATERIAL AND METHODS A cobalt-chromium alloy master model was prepared to receive a 3-unit fixed dental prosthesis. Sixty cobalt-chromium alloy frameworks (N=60) were manufactured by using 3 manufacturing techniques (n=20): selective laser melting (Mediloy S-Co), soft milling (Ceramill Sintron), and conventional casting as the control group (Girobond NB). The replica technique was used to measure the marginal and internal discrepancies. The frameworks were then layered with ceramic, and the same fit measuring procedure was repeated. The results were compared before and after ceramic layering within each group. The data were analyzed using the Levene, ANOVA, and paired-samples t tests (α=.05). RESULTS A significant difference was found within groups before and after ceramic layering for selective laser melting (P=.006) and soft milling (P=.009) but not for conventional casting (P>.05). No statistical difference was reported in the marginal region for conventional casting group (P=.155) in contrast with the soft milling and selective laser melting groups (P=.003). Soft milling showed increased gap values in the marginal (P=.006) and occlusal regions (P=.004). CONCLUSIONS Ceramic layering increased the discrepancy of the laser-sintered and milled frameworks, increasing the marginal discrepancy.
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Levartovsky S, Arieli A, Fridenberg N, Matalon S, Pilo R. Survival and success rates of soft-milled cobalt-chromium-ceramic full-arch screw-retained implant-supported prostheses: a 2- to 7-year follow-up retrospective study. Clin Oral Investig 2021; 25:5341-5350. [PMID: 33616806 DOI: 10.1007/s00784-021-03842-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 02/16/2021] [Indexed: 12/15/2022]
Abstract
OBJECTIVES To retrospectively assess implant and prosthesis survival and success and patient satisfaction in edentulous patients treated with soft-milled cobalt-chromium-ceramic full-arch screw-retained implant-supported prostheses (SCCSIPs) over a mean clinical follow-up period of 4 years. MATERIALS AND METHODS Twenty-one edentulous patients, aged 47-80 years, underwent restoration with 27 SCCSIPs (210 implants, 349 crown units). After definitive prosthesis insertion, patients participated in a yearly dental check-up recall program, including clinical and radiographic examinations. All supporting implants were examined for biological and technical complications, and the restorations were evaluated using modified California Dental Association (CDA) criteria. Life table and Kaplan-Meier survival analyses were performed. Patient satisfaction regarding chewing, esthetics, comfort, and phonetics was evaluated using a visual analog scale (VAS). RESULTS After a mean of 4 years, two implants (3.8%) failed, with no effect on prosthesis survival. The cumulative survival rate was 98.6% and 100% for implants and prostheses, respectively. The most frequent minor biological complication was soft tissue recession (11%). Porcelain fracture was the only major technical complication (0.6% of crown units), while the only minor technical complication was porcelain chipping (4% of crown units), which required only polishing. Overall, 66.7% of the prostheses were free of technical complications. Patient satisfaction was high to very high. Less satisfaction was noted with comfort due to soft tissue recession and food impaction. CONCLUSIONS Within the limitations of this study, we conclude that the survival and success rates of SCCSIPs in edentulous patients were excellent. CLINICAL RELEVANCE SCCSIPs should be considered when planning metal-ceramic implant-supported restorations.
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Affiliation(s)
- S Levartovsky
- Department of Oral Rehabilitation, the Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
| | - A Arieli
- Department of Oral Rehabilitation, the Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - N Fridenberg
- Department of Oral Rehabilitation, the Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - S Matalon
- Department of Oral Rehabilitation, the Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - R Pilo
- Department of Oral Biology, the Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
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Rizonaki M, Jacquet W, Bottenberg P, Depla L, Boone M, De Coster PJ. Evaluation of marginal and internal fit of lithium disilicate CAD-CAM crowns with different finish lines by using a micro-CT technique. J Prosthet Dent 2021; 127:890-898. [PMID: 33541816 DOI: 10.1016/j.prosdent.2020.11.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 01/08/2023]
Abstract
STATEMENT OF PROBLEM Whether the precision of fit of computer-aided design and computer-aided manufacturing (CAD-CAM) complete crowns is affected by the finish line configuration is unclear. PURPOSE The purpose of this in vitro study was to evaluate the marginal and internal fit of CAD-CAM ceramic crowns made from lithium disilicate based on 3 different finish lines (rounded shoulder, chamfer, feather-edge). MATERIALS AND METHODS Thirty anterior lithium disilicate complete crowns (n=10 per finish line group) were fabricated by following a completely digital workflow based on digital scans made with the TRIOS scanner. The crowns were adhesively cemented on duplicate dies of the respective prepared Typodont teeth, and the marginal gap, absolute marginal discrepancy, and internal gap were evaluated by using microcomputed tomography (μCT). A total of 66 values were obtained for each specimen from sagittal and transaxial sections, and a rendering software program was used to calculate the volume of the cement gap for each specimen by means of 3D region growing. Two-way ANOVA, Tukey post hoc tests with Bonferroni correction, and the Kruskal-Wallis test were used to compare the values between the experimental groups (α=.05). RESULTS Marginal gap and absolute marginal discrepancy values were statistically significantly different between groups. In ascending order, marginal gap values were 23 ±14 μm for rounded shoulder, 54 ±28 μm for chamfer, and 96 ±36 μm for feather-edge finish lines. Absolute marginal discrepancy values were 96 ±34 μm for rounded shoulder, 124 ±37 μm for chamfer, and 157 ±34 μm for feather-edge finish lines. Internal gap values were 111 ±14 μm for feather-edge, 136 ±22 μm for chamfer, and 168 ±25 μm for rounded shoulder finish lines. The differences in cement volume between groups were not statistically significant (P=.200). CONCLUSIONS All 3 finish lines produced marginal gaps within the range of clinically accep table values. Lithium disilicate CAD crowns with a rounded shoulder finish line had the best marginal fit but the poorest internal fit, and lithium disilicate CAD crowns with a feather-edge finish line had the best internal fit but the poorest marginal fit.
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Affiliation(s)
- Maria Rizonaki
- Postgraduate student, Postgraduate Reconstructive Dentistry, Department of Reconstructive Dentistry, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Wolfgang Jacquet
- Professor, Oral Health Research Group ORHE, Faculty of Medicine and Pharmacy, VUB Vrije Universiteit Brussel, Brussels, Belgium; Professor, Department of Special Needs in Oral Health, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Peter Bottenberg
- Professor, Department of Oral Health Sciences, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium; Professor, Department of Educational Sciences EDWE-LOCI, Faculty of Psychology and Educational Sciences, VUB Vrije Universiteit Brussel, Brussels, Belgium
| | - Lennert Depla
- Undergraduate student, Master of Science in Dentistry, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Matthieu Boone
- Professor, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Peter J De Coster
- Professor, Department of Reconstructive Dentistry, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
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Daou EE, Baba NZ. Fit Alteration of Presintered Co-Cr and Zirconia Multiple-Unit Prostheses After Ceramic Layering. J Prosthodont 2021; 30:789-794. [PMID: 33486845 DOI: 10.1111/jopr.13336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2021] [Indexed: 11/30/2022] Open
Abstract
PURPOSE The fit alteration after ceramic layering of soft Cobalt-Chromium (Co-Cr) and zirconia is poorly documented. This study compared the marginal and internal fit of presintered Co-Cr and zirconia three-unit fixed dental prostheses before and after ceramic veneering. MATERIALS AND METHODS Co-Cr master model was prepared and duplicated 60 times to receive three-unit fixed dental prostheses (FDPs). Sixty dies were prepared, scanned and assigned to 3 groups (n = 20/group), to receive the FDPs made of presintered Co-Cr (CS), presintered zirconia (CZ) and cast Ni-Cr (Wi). Each framework was seated on its specific cast. A replica technique was used for marginal and internal discrepancy measurements in mesiodistal and buccolingual planes. Frameworks were ceramic veneered. Results were compared before and after ceramic layering within each group. Data were analyzed using the Levene, t test, and ANOVA (α = 0.05). RESULTS Significant difference was found when gaps were compared within groups for CS and CZ but not for Wi. At the abutments level, significant difference was found for both premolars and molars in the buccolingual planes (p < 0.001). A multiple comparison between materials tested showed significant differences between presintered and cast Ni-Cr. No significant difference was detected between CS and CZ (p = 1.000). CONCLUSIONS Although ceramic layering increased the discrepancy for presintered Co-Cr and zirconia, the marginal adaptation remained clinically acceptable.
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Affiliation(s)
- Elie E Daou
- Department of Prosthodontics Faculty of Dentistry, Faculty of Dental Medicine, Beirut, Lebanon
| | - Nadim Z Baba
- Advanced Specialty Education Program in Implant Dentistry, School of Dentistry, Loma Linda University, Loma Linda, CA
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Daou EE. X-ray microtomographic evaluation of the absolute marginal fit of fixed prostheses made from soft Co-Cr and zirconia. J Prosthet Dent 2020; 127:289-294. [PMID: 33279157 DOI: 10.1016/j.prosdent.2020.07.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 07/23/2020] [Accepted: 07/23/2020] [Indexed: 11/30/2022]
Abstract
STATEMENT OF PROBLEM The absolute marginal fit of CAD-CAM presintered fixed partial dentures has been poorly documented. PURPOSE The purpose of this in vitro study was to evaluate the marginal fit of presintered cobalt-chromium (Co-Cr) and zirconia 3-unit fixed partial dentures by using X-ray microcomputed tomography (μCT). MATERIAL AND METHODS A metal model was prepared from a typodont to receive fixed partial dentures (N=12). The maxillary first premolar and first molar were prepared with a circumferential 1.2-mm chamfer and 2-mm occlusal reduction. The dies were scanned and assigned to 1 of 2 groups to receive the prostheses made of presintered Co-Cr or presintered zirconia (n=6). Each framework was seated on its model without load application. The abutments were scanned by using μCT. A circle with 10 diameters, with a step of 18 degrees, was projected at the center of the obtained image. Absolute marginal discrepancy and marginal gap mean values were measured, and overextended and underextended margins determined. The data were analyzed by using the Levene t test and ANOVA (α=.05). RESULTS No statistically significant difference was found in the marginal fit between the materials tested (P=.939). The mean values were 66 ±14 μm for Co-Cr and 61 ±12 μm for zirconia. The absolute marginal discrepancy mean value for the premolar was 69 ±12 μm and 41 ±9 μm for the molar (P<.001). Overextension was predominant for both materials tested, with a higher percentage reported for the zirconia group. CONCLUSIONS Presintered alloys presented clinically acceptable adaptation with a predominance of marginal overextensions.
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Affiliation(s)
- Elie E Daou
- Lecturer, Department of Prosthodontics Faculty of Dentistry, Faculty of Dental Medicine, Beirut, Lebanon.
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Daou EE, Baba NZ. Evaluation of Marginal and Internal Fit of Presintered Co-Cr and Zirconia Three-Unit Fixed Dental Prosthesis Compared to Cast Co-Cr. J Prosthodont 2020; 29:792-799. [PMID: 32334442 DOI: 10.1111/jopr.13183] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 11/30/2022] Open
Abstract
PURPOSE The precision of soft metal processing technologies is poorly documented. This study compared marginal and internal fit of presintered cobalt-chromium (Co-Cr) and zirconia three-unit fixed dental prostheses (FDPs) to cast Co-Cr. MATERIALS AND METHODS Three-unit FDPs were prepared on metal dies (N = 60) from typodont preparations of the maxillary right first premolar and molar. A standardized preparation of a metal-ceramic restoration was done on abutment teeth. The dies (N = 60) were scanned and divided into three groups (n = 20/group) to receive the FDP made of presintered Co-Cr (Ceramill Si), presintered zirconia (Ceramill Zi), and cast Co-Cr (Girobond NB). Each framework was seated on its specific cast. A replica technique was used for marginal and internal discrepancies measurements in mesiodistal and buccolingual planes. Data were analyzed using the Levene test, t-test, and analysis of variance (α = 0.05). RESULTS When the overall mean discrepancy values were compared in the mesiodistal plane, a significant difference was found between Ceramill Sintron and Ceramill Zi groups (p = 0.026). No significant difference was detected between Girobond NB and Ceramill Sintron groups and between Girobond NB and Ceramill Zi groups (p = 0.537 and p = 0.569, respectively). In the buccolingual plane, there was no significant difference in the overall mean discrepancy between the three groups: CS/CZ (p = 1.000), GI/CS (p = 0.51), and GI/CZ (p = 0.87). Significant differences at several measurement points were found at the inter or intramaterial level. The increase in discrepancy values between marginal and occlusal measurements was evident for the three groups. CONCLUSIONS Presintered three-unit FDPs fabricated from zirconia and Co-Cr exhibited internal and marginal discrepancy values similar to cast Co-Cr. A significant difference was reported between CS and CZ in mesiodistal planes. The axial and marginal differences in values for the three tested groups were below or around the 120 µm clinically acceptable threshold except for the occlusal area. When comparing first premolar to first molar, the internal and marginal discrepancies were similar with no apparent distortion of the framework after the sintering process.
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Affiliation(s)
- Elie E Daou
- Lecturer, Department of Prosthodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon
| | - Nadim Z Baba
- Professor, Advanced Specialty Education Program in Implant Dentistry, School of Dentistry, Loma Linda University, Loma Linda, CA
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Bousnaki M, Chatziparaskeva M, Bakopoulou A, Pissiotis A, Koidis P. Variables affecting the fit of zirconia fixed partial dentures: A systematic review. J Prosthet Dent 2019; 123:686-692.e8. [PMID: 31703922 DOI: 10.1016/j.prosdent.2019.06.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 06/02/2019] [Accepted: 06/03/2019] [Indexed: 10/25/2022]
Abstract
STATEMENT OF PROBLEM Different parameters affect the marginal and internal fit of zirconia fixed partial dentures (FPDs) on natural teeth. Determining a way to optimize these restorations is essential. PURPOSE The purpose of this systematic review was to determine the variables affecting the marginal fit and internal accuracy of zirconia FPDs on natural teeth. MATERIAL AND METHODS An electronic search was conducted by 2 independent reviewers by using the MEDLINE, Cochrane, Web of Science, and Scopus databases, as well as Google Scholar, for studies published up to July 2018, and a manual search was conducted from the reference lists of related articles. Eligibility criteria included articles in English published in peer-reviewed journals that assessed the marginal and/or internal adaptation of zirconia FPDs on teeth with 3 or more units, with at least 1 of the experimental groups being frameworks or FPDs fabricated from zirconia. Risk of bias was assessed with the aid of the Cochrane Handbook for Systematic Reviews of Interventions. RESULTS The search provided 418 records, with 41 fulfilling the inclusion criteria. The selected studies showed considerable heterogeneity regarding materials, state of sintering, manufacturer and computer-aided design and computer-aided manufacturing (CAD-CAM) system, experimental methodology, sample size, and span length. Of the included articles, 36 were in vitro studies and 5 were clinical studies, most of which exhibited high-performance and detection biases. CAD-CAM systems provided more precise marginal and internal fit than CAM systems. An increase of framework span length to 6 or more units decreased both marginal and internal fit. The reported marginal gap tended to increase after the veneering process. The introduction of a conventional impression into an otherwise digital workflow seems to have a negative effect on the marginal fit. CONCLUSIONS The accuracy of zirconia FPDs or frameworks is considerably influenced by the processing procedure used and the choice of CAD-CAM system.
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Affiliation(s)
- Maria Bousnaki
- Doctoral student, Department of Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | - Maria Chatziparaskeva
- Postgraduate student, Department of Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Athina Bakopoulou
- Assistant Professor, Department of Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Argiris Pissiotis
- Professor, Department of Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Petros Koidis
- Professor and Chairman, Department of Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
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