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Fan X, Chen L, Chen Q, Wang F, Wu Y, Sun Y. Influence of a mesial cantilever on stress, strain, and axial force in fixed partial dentures with a distally tilted implant in the atrophic posterior maxilla. J Prosthodont Res 2024:JPR_D_23_00218. [PMID: 38616127 DOI: 10.2186/jpr.jpr_d_23_00218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
PURPOSE This study aimed to investigate whether the presence of a mesial cantilever influences the biomechanical behavior and screw loosening in fixed partial dentures (FPDs) with a distally tilted implant in the atrophic posterior maxilla and where to best place the distal implant. METHODS Two configurations of implant-supported four-unit FPDs were modelled using finite element analysis. Five interabutment distances were considered. The stress and strain distributions in the implants, abutments, and prosthetic screws were verified under occlusal loading. The development of the axial force on the abutments and screws was also examined. Two-sample t-tests were used to identify differences (P < 0.05). RESULTS The von Mises stress distributions of the components in the two configurations were similar, as were the maximum plastic strains of the distal prosthetic screws, distal implants, and 30° abutments. The difference in the maximum plastic strains of the straight abutments was statistically significant. The preload of the 30° abutment screws was significantly reduced after the initial loading. In the absence of a mesial cantilever, the axial force on the straight abutments increased. However, when a mesial cantilever was used, the preload of the straight abutments was maintained, and the axial force on the prosthetic screws fluctuated less. The axial force fluctuation of the abutments gradually decreased as the interabutment distance increased. CONCLUSIONS Mesial cantilever usage had minimal effect on stress or strain distribution in FPD implants, abutments, or prostheses. However, it helped resist screw loosening. The distal screw access hole was preferably positioned close to the prosthetic end.
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Affiliation(s)
- Xiaohui Fan
- Shanghai Key Laboratory of Advanced High Temperature Materials and Precision Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Li Chen
- Yangtze Delta Advanced Material Research Institute, Suzhou, China
| | - Qiuren Chen
- Yangtze Delta Advanced Material Research Institute, Suzhou, China
| | - Feng Wang
- Department of Second Dental Center, Shanghai Ninth People's Hospital, School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Yiqun Wu
- Department of Second Dental Center, Shanghai Ninth People's Hospital, School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Yuanyuan Sun
- Department of Second Dental Center, Shanghai Ninth People's Hospital, School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology, Shanghai, China
- Department of Oral Cell Biology, Academic Center for Dentistry Amsterdam (ACTA), Vrije Universiteit Amsterdam and University of Amsterdam, Amsterdam, Netherlands
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Jemaa H, Eisenburger M, Greuling A. Automated Remodelling of Connectors in Fixed Partial Dentures. Dent J (Basel) 2023; 11:252. [PMID: 37999016 PMCID: PMC10669984 DOI: 10.3390/dj11110252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/13/2023] [Accepted: 10/26/2023] [Indexed: 11/25/2023] Open
Abstract
In this study, an approach for automated parametric remodelling of the connector cross-sectional area in a CAD model of a given fixed partial denture (FPD) geometry was developed and then applied to a 4-unit FPD. The remodelling algorithm was implemented using Rhinoceros and the Grasshopper plugin. The generated CAD models were used to perform a finite element analysis with Ansys to analyse the stress distribution in an implant-supported 4-unit FPD for different connector designs. The results showed that the type of connector adjustment matters and that the resulting stress can be significantly different even for connectors with the same cross-sectional area. For tensile stresses, a reduction in the connector cross-sectional area from the gingival side showed the highest influence on each connector type. It can be concluded that the developed algorithm is suitable for automatic connector detection and adjustment.
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Affiliation(s)
| | | | - Andreas Greuling
- Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany; (H.J.); (M.E.)
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Velho HC, da Rosa LS, Dapieve KS, Borges ALS, Pereira GKR, Venturini AB, Valandro LF. How does the occlusal contact region influence the mechanical fatigue performance and fracture region of monolithic lithium disilicate ceramic crowns? J Mech Behav Biomed Mater 2023; 140:105746. [PMID: 36878081 DOI: 10.1016/j.jmbbm.2023.105746] [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: 01/23/2023] [Revised: 02/23/2023] [Accepted: 02/26/2023] [Indexed: 03/05/2023]
Abstract
OBJECTIVE To characterize the effect of the occlusal contact region on the mechanical fatigue performance and on the fracture region of monolithic lithium disilicate ceramic crowns. MATERIALS AND METHODS Monolithic lithium disilicate ceramic crowns were machined in a CAD/CAM system and adhesively luted onto glass-fiber reinforced epoxy resin preparations with resin cement. The crowns were divided into three groups (n = 16) according to load application region (cusp tip: restricted to cusp tips; cusp plane: restricted to cuspal inclined plane; or mixed: associating tip cusp and cuspal inclined plane). The specimens were submitted to a cyclic fatigue test (initial load: 200 N; step-size: 100 N; cycles/step: 20,000; loading frequency: 20 Hz; load applicator: 6 mm or 40 mm diameter stainless steel) until observing cracks (1st outcome) and fracture (2nd outcome). The data were analyzed by the Kaplan-Meier + Mantel-Cox post-hoc tests for both outcomes (cracks and fracture). Finite element analysis (FEA), occlusal contact region, contact radii measurements, and fractographic analyzes were performed. RESULTS The mixed group presented worse fatigue mechanical behavior (550 N / 85.000 cycles) compared to the cuspal inclined plane group (656 N / 111,250 cycles) (p < 0.05) for the first crack outcome, while the cusp tip group was similar to both groups (588 N / 97,500 cycles) (p > 0.05). The mixed group had the worst fatigue behavior (1413 N / 253,029 cycles) in relation to the other groups (Cusp tip: 1644 N / 293,312 cycles; Cuspal inclined plane: 1631 N / 295,174 cycles) considering the crown fracture outcome (p < 0.05). FEA showed higher tensile stress concentration areas just below the load application region. In addition, loading on the cuspal inclined plane induced a higher tensile stress concentration in the groove region. The most prevalent type of crown fracture was the wall fracture. Groove fracture was observed in 50% of the loading specimens exclusively on the cuspal inclined plane. CONCLUSION Load application on distinct occlusal contact regions affects the stress distribution pattern and consequently the mechanical fatigue performance and fracture region of the monolithic lithium disilicate ceramic crowns. A combination of loading at distinct regions is recommended to promote better evaluation of the fatigue behavior of a restored set.
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Affiliation(s)
- Helder Callegaro Velho
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Lucas Saldanha da Rosa
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kiara Serafini Dapieve
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Alexandre Luiz Souto Borges
- Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, São Paulo, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Andressa Borin Venturini
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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Schnitzhofer K, Rauch A, Schmidt M, Rosentritt M. Impact of the occlusal contact pattern and occlusal adjustment on the wear and stability of crowns. J Dent 2023; 128:104364. [PMID: 36403693 DOI: 10.1016/j.jdent.2022.104364] [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: 08/31/2022] [Revised: 10/25/2022] [Accepted: 11/03/2022] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES To investigate the impact of the occlusal contact situation and occlusal adjustment on wear, roughness, and fracture force of molar crowns. MATERIALS AND METHODS CAD/CAM crowns (lower right first molar, n = 64; 4 groups à 8, 3Y-TZP zirconia and resin composite) and corresponding antagonists (upper right first molar; 3Y-TZP zirconia) were manufactured. Crowns were constructed according to two principles of occlusion (group "T": Peter K. Thomas' "point-centric" cusp-to-fossa tripodization concept, with 15 contact points; group "RA" Sigurd P. Ramfjord and Major M. Ash, "freedom in centric" concept with four contacts). On one half of the crowns, occlusal adjustment was performed (groups "T adjusted" and "RA adjusted"). All crowns underwent combined thermal cycling (TC) and mechanical loading (ML) (ML: 1.2 × 106 cycles, 50 N, 2 Hz, mouth opening 1 mm; TC: 2 × 3000 cycles, 5/55°C). Wear area and depth of each contact point on the occlusal surfaces of crowns and antagonists were determined using a digital microscope. Surface roughness (Ra, Rz) was measured in and besides (reference) the worn area (3D laser-scanning microscope). Fracture force of the crowns was determined (statistics: Levene-test, one-way-ANOVA; Bonferroni-post-hoc-test; between-subjects effects, Pearson correlation, α=0.05). RESULTS The resin composite crowns yielded significantly higher mean values for wear area and depth (p < 0.001) and lower fracture forces (p < 0.001). Resin composite surfaces showed increased roughness after TCML while zirconia exhibited smoothened surfaces. The occlusal design significantly impacted wear depth (p = 0.012) and fracture force (p < 0.001). Resin composite crowns with fewer contact points (group RA) showed more wear and lower fracture force. Adjusted resin composite crowns showed increased wear areas and depths (p = 0.009-0.013). For zirconia crowns, the adjustment impacted wear area (p = 0.013), wear depth (p = 0.008), and fracture force (p = 0.006), with adjusted zirconia crowns exhibiting more wear and lower maximum forces until fracture. Zirconia wear depth was also impacted by the occlusal design (p = 0.012). Antagonistic wear was influenced by the restorative material, the occlusal contact pattern, and the adjustment. CONCLUSIONS The investigated materials show strongly varying performances with zirconia being significantly influenced by the adjustment, while for resin composites, contact design and adjustment had a major impact. CLINICAL RELEVANCE The results show the necessity of adapting occlusal design and adjustment in order to improve roughness, wear, and stability of zirconia and resin composite crowns.
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Affiliation(s)
- Karin Schnitzhofer
- Department of Prosthetic Dentistry, UKR University Hospital Regensburg, Regensburg 93042, Germany
| | - Angelika Rauch
- Department of Prosthetic Dentistry, UKR University Hospital Regensburg, Regensburg 93042, Germany
| | - Michael Schmidt
- Department of Prosthetic Dentistry, UKR University Hospital Regensburg, Regensburg 93042, Germany
| | - Martin Rosentritt
- Department of Prosthetic Dentistry, UKR University Hospital Regensburg, Regensburg 93042, Germany.
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Bataineh K, Al Janaideh M, Abu-Naba'a LA. Fatigue Resistance of 3-Unit CAD-CAM Ceramic Fixed Partial Dentures: An FEA Study. J Prosthodont 2022; 31:806-814. [PMID: 35118758 DOI: 10.1111/jopr.13487] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/25/2022] [Indexed: 01/04/2023] Open
Abstract
PURPOSE To estimate the fatigue life of 3-unit molar fixed partial dentures (FPDs) made from two different monolithic ceramic systems, zirconia cercon (ZC) and lithium disilicate (LD). The effect of the connector size on the fatigue resistance of the monolithic FPD was also investigated. METHODS Two models for the FPDs were built, a 3-unit all-ceramic and a porcelain-fused-to-metal. The porcelain-fused-to-metal FPD model was used as the control. Actual 3-unit FPDs (replacing the second lower premolar) were constructed using a computer aided design and computer-aided manufacturing (CAD-CAM) system. Finite element analysis (FEA) was executed. A hemispherical indenter was used to simulate occlusal load. The occlusal load phase of the chewing cycle was applied at the premolar pontic. RESULTS The failure location for the monolithic FPD was always located at the distal connector. Connector size played a key role in determining the long-term survival of the prosthesis. The fatigue resistance was predicted to be 670 N for the ZC with a connector size 4 × 3 mm, while it was only 226 N for LD. As for porcelain-fused-to-metal (PFM), FEA predicts that fatigue resistance can reach up to 770 N. Under the cyclic load of 670 N, the fatigue life for the zirconia FPD with connector size 4 × 3 mm was 2.23 × 106 cycles while it survived only 3.1 × 105 cycles when the connector was reduced to 3.5 × 2.5 mm. The angle of the oblique load has a significant effect on the stress distribution. CONCLUSION 3-unit monolithic FPDs made of ZC have superior fatigue performance compared to those made of LD. The fatigue life of the zirconia FPD was about three times longer than that made of LD with a connector size of 4 mm × 3 mm. The survival rates of ZC FPDs are comparable to porcelain-fused-to-metal. A significant reduction in fatigue strength is predicted for reduced connector size. Therefore, it is necessary to establish general guidelines for the minimum connector size.
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Affiliation(s)
- Khaled Bataineh
- Department of Mechanical Engineering, Jordan University of Science and Technology, Irbid, Jordan
| | - Mohammad Al Janaideh
- Department of Mechanical Engineering, Jordan University of Science and Technology, Irbid, Jordan
| | - Layla A Abu-Naba'a
- Department of Prosthodontics, Jordan University of Science and Technology, Irbid, Jordan
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Fardin VP, Bonfante G, Coelho PG, Bergamo ETP, Bordin D, Janal MN, Tovar N, Witek L, Bonfante EA. Residual stress estimated by nanoindentation in pontics and abutments of veneered zirconia fixed dental prostheses. J Appl Oral Sci 2022; 30:e20210475. [PMID: 35476114 PMCID: PMC9041093 DOI: 10.1590/1678-7757-2021-0475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 01/19/2022] [Indexed: 11/22/2022] Open
Abstract
Glass ceramics’ fractures in zirconia fixed dental prosthesis (FDP) remains a clinical challenge since it has higher fracture rates than the gold standard, metal ceramic FDP. Nanoindentation has been shown a reliable tool to determine residual stress of ceramic systems, which can ultimately correlate to failure-proneness.
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Affiliation(s)
| | | | - Paulo G. Coelho
- New York University College of Dentistry, United States; New York University Tandon, United States; New York University Grossman School of Medicine, United States
| | | | | | | | - Nick Tovar
- New York University College of Dentistry, United States
| | - Lukasz Witek
- New York University College of Dentistry, United States; New York University, United States
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7
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Fardin VP, Bonfante EA, Coelho PG, Janal MN, Tovar N, Witek L, Bordin D, Bonfante G. Residual stress of porcelain-fused to zirconia 3-unit fixed dental prostheses measured by nanoindentation. Dent Mater 2017; 34:260-271. [PMID: 29258696 DOI: 10.1016/j.dental.2017.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 08/12/2017] [Accepted: 11/09/2017] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To evaluate the residual stress (nanoindentation based on hardness) of fatigued porcelain-fused to zirconia 3-unit fixed dental prostheses (FDP) with different framework designs. METHODS Twenty maxillary 3-unit FDP replacing second-premolar (pontic) were fabricated with conventional framework-design (even-thickness of 0.5mm and 9mm2 connector area) and modified framework-design (thickness of 0.5mm presenting lingual collar connected to proximal struts and 12mm2 connector area). Connector marginal ridges were loaded and the fractured and suspended FDPs were divided (n=3/each) into: (1) Fractured zirconia even-thickness (ZrEvenF); (2) Suspended zirconia even-thickness (ZrEvenS); (3) Fractured zirconia with modified framework (ZrModF); (4) Suspended zirconia with modified framework (ZrModS); (5) Non-fatigued FDP with conventional framework design (Control). The FDPs were nanoindented at 0.03mm (Region of Interest (ROI) 1), 0.35mm (ROI 2) and 1.05mm (ROI 3) distances from porcelain veneer outer surface with peak load 4000μN. The Linear Mixed Analysis of Variance (ANOVA) Model on ranks and Least Significant Difference Test on ranks (95%) were used. RESULTS Highest rank hardness values were found for Control group and ZrModS, whereas the lowest values were found in ZrModF. Statistical differences (p=0.000) were found among all groups except for comparison between ZrModS and Control group (p=0.371). Hardness between ROIs were statistically significant different (p<0.001) where ROI 1 presented the lowest values. SIGNIFICANCE Framework-design modification did not influence the residual stress of porcelain-fused to zirconia fatigued 3-unit FDP. Whereas fractured FDPs showed the highest residual stress compared to suspended and control FDPs. Residual stress increased as nanoindented away from framework.
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Affiliation(s)
- Vinicius P Fardin
- Department of Prosthodontics, University of Vila Velha, Vila Velha, ES, Brazil; Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil.
| | - Estevam A Bonfante
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil
| | - Paulo G Coelho
- Department of Biomaterials and Biomimetics, New York University, New York, NY, USA; Hansjörg Wyss Department of Plastic Surgery, NYU Langone Medical Center, New York, NY, USA
| | - Malvin N Janal
- Department of Epidemiology and Health Promotion, New York University College of Dentistry, New York, NY, USA
| | - Nick Tovar
- Department of Biomaterials and Biomimetics, New York University, New York, NY, USA
| | - Lukasz Witek
- Department of Biomaterials and Biomimetics, New York University, New York, NY, USA
| | - Dimorvan Bordin
- Department of Operative Dentistry, Guarulhos University, Guarulhos, SP, Brazil
| | - Gerson Bonfante
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil
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Calha N, Messias A, Guerra F, Martinho B, Neto MA, Nicolau P. Effect of geometry on deformation of anterior implant-supported zirconia frameworks: An in vitro study using digital image correlation. J Prosthodont Res 2016; 61:139-148. [PMID: 27667555 DOI: 10.1016/j.jpor.2016.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 07/20/2016] [Accepted: 08/27/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE To evaluate the effect of geometry on the displacement and the strain distribution of anterior implant-supported zirconia frameworks under static load using the 3D digital image correlation method. METHODS Two groups (n=5) of 4-unit zirconia frameworks were produced by CAD/CAM for the implant-abutment assembly. Group 1 comprised five straight configuration frameworks and group 2 consisted of five curved configuration frameworks. Specimens were cemented and submitted to static load up to 200N. Displacements were captured with two high-speed photographic cameras and analyzed with video correlation system in three spacial axes U, V, W. Statistical analysis was made using the nonparametric Mann-Whitney test. RESULTS Up to 150N loads, the vertical displacements (V axis) were statistically higher for curved frameworks (-267.83±23.76μm), when compared to the straight frameworks (-120.73±36.17μm) (p=0.008), as well as anterior displacements in the W transformed axis (589.55±64.51μm vs 224.29±50.38μm for the curved and straight frameworks), respectively (p=0.008). The mean von Mises strains over the surface frameworks were statistically higher for the curved frameworks under any load. CONCLUSION Within the limitations of this in vitro study, it is possible to conclude that the geometric configuration influences the deformation of 4-unit anterior frameworks under static load. The higher strain distribution and micro-movements of the curved frameworks reflect less rigidity and increased risk of fractures associated to FPDs.
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Affiliation(s)
- Nuno Calha
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal
| | - Ana Messias
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal; Centre for Mechanical Engineering, University of Coimbra, Portugal.
| | - Fernando Guerra
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal; Centre for Mechanical Engineering, University of Coimbra, Portugal
| | - Beatriz Martinho
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal
| | | | - Pedro Nicolau
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal; Centre for Mechanical Engineering, University of Coimbra, Portugal
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Stress Distribution in All-Ceramic Posterior 4-Unit Fixed Dental Prostheses Supported in Different Ways. IMPLANT DENT 2016; 25:485-91. [DOI: 10.1097/id.0000000000000429] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Wang G, Zhang S, Bian C, Kong H. Verification of finite element analysis of fixed partial denture with in vitro electronic strain measurement. J Prosthodont Res 2016; 60:29-35. [DOI: 10.1016/j.jpor.2015.08.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 08/07/2015] [Accepted: 08/31/2015] [Indexed: 11/24/2022]
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Effect of different dental articulating papers on SEMG activity during maximum clenching. J Electromyogr Kinesiol 2015; 25:612-8. [DOI: 10.1016/j.jelekin.2015.04.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 04/12/2015] [Accepted: 04/14/2015] [Indexed: 11/18/2022] Open
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12
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Lifetime comparison of Y-TZP/porcelain crowns under different loading conditions. J Dent 2015; 43:450-7. [DOI: 10.1016/j.jdent.2015.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 01/13/2015] [Accepted: 01/20/2015] [Indexed: 11/21/2022] Open
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Takahashi JMFK, Dayrell AC, Consani RLX, de Arruda Nóbilo MA, Henriques GEP, Mesquita MF. Stress Evaluation of Implant-Abutment Connections Under Different Loading Conditions: A 3D Finite Element Study. J ORAL IMPLANTOL 2015; 41:133-7. [DOI: 10.1563/aaid-joi-d-11-00205] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study evaluated the effects of axial and oblique occlusal loading on implant-supported partial dentures with different connection systems (external hexagon, internal hexagon, and Morse taper). Upon axial loading, all systems presented similar stress values. Stress values increased under oblique loading. Stress distribution changed for some of the internal connection structures. It can be concluded that oblique load increases stress on bone structures and prosthetic components. Internal connection system implants present more favorable stress distribution patterns than do external connection system implants.
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Affiliation(s)
| | - Andreza Costa Dayrell
- Diamantina Dental School, University of Jequitinhonha and Mucuri Valleys, Diamantina, Minas Gerais, Brazil
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14
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Näpänkangas R, Pihlaja J, Raustia A. Outcome of zirconia single crowns made by predoctoral dental students: a clinical retrospective study after 2 to 6 years of clinical service. J Prosthet Dent 2015; 113:289-94. [PMID: 25702968 DOI: 10.1016/j.prosdent.2014.09.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 09/30/2014] [Accepted: 09/30/2014] [Indexed: 10/24/2022]
Abstract
STATEMENT OF PROBLEM Zirconia has established its role as a reliable ceramic material for fixed prostheses. PURPOSE The purpose of this retrospective study was to evaluate the outcome of zirconia single crowns made by predoctoral students after 2 to 6 years of clinical service. MATERIAL AND METHODS A cohort of 88 patients treated with zirconia single crowns (mean 3 crowns per patient, range 1 to 12 crowns) from 2007 to 2010 by predoctoral dental students was identified. The patients were invited to attend a clinical examination. RESULTS Sixty-six participants (75%) took part in the clinical follow-up (30 women and 36 men; mean age 60.4 years, range 19 to 81 years). Altogether, 190 teeth with single crowns were examined, and the mean follow-up time was 3.88 years (1.85 to 6.04 years). The most common complications were chipping of veneering porcelain (4%) and loss of cementation (4%). The success rate of the zirconia single crowns after 2 to 6 years was 80% and the survival rate 89%. CONCLUSIONS Zirconia crowns can be successfully used in predoctoral dental education. The success rate of zirconia single crowns after 2 to 6 years was 80% and the survival rate was 89%, in accordance with previous studies.
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Affiliation(s)
- Ritva Näpänkangas
- Senior Lecturer, Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Oulu; and Medical Research Center, Oulu, Oulu University Hospital and University of Oulu, Finland.
| | - Juha Pihlaja
- Research Assistant, Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Oulu; and Medical Research Center, Oulu, Oulu University Hospital and University of Oulu, Finland
| | - Aune Raustia
- Professor, Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Oulu; and Medical Research Center, Oulu, Oulu University Hospital and University of Oulu, Finland
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Anami LC, Lima JMDC, Corazza PH, Yamamoto ETC, Bottino MA, Borges ALS. Finite element analysis of the influence of geometry and design of zirconia crowns on stress distribution. J Prosthodont 2014; 24:146-51. [PMID: 24975118 DOI: 10.1111/jopr.12175] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2013] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To evaluate the influence of the geometry and design of prosthetic crown preparations on stress distribution in compression tests, using finite element analysis (FEA). MATERIALS AND METHODS Six combinations of 3D drawings of all-ceramic crowns (yttria-stabilized zirconia framework and porcelain veneer) were evaluated: F, flat preparation and simplified crown; FC, flat preparation and crown with contact point; FCM, flat preparation and modified crown; A, anatomical preparation and simplified anatomical crown framework; AC, anatomical preparation and crown with contact point; and ACM, anatomical preparation and modified crown. Bonded contact types at all interfaces with the mesh were assigned, and the material properties used were according to the literature. A 200 N vertical load was applied at the center of each model. The maximum principal stresses were quantitatively and qualitatively analyzed. RESULTS The highest values of tensile stress were observed at the interface between the ceramics in the region under the load application for the simplified models (F and A). Reductions in stress values were observed for the model with the anatomical preparation and modified infrastructure (ACM). The stress distribution in the flat models was similar to that of their respective anatomical models. CONCLUSIONS The modified design of the zirconia coping reduces the stress concentration at the interface with the veneer ceramic, and the simplified preparation can exert a stress distribution similar to that of the anatomical preparation at and near the load point, when load is applied to the center of the crown.
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Affiliation(s)
- Lilian Costa Anami
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, UNESP - Univ Estadual Paulista, São José dos Campos, Brazil
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Wimmer T, Erdelt KJ, Raith S, Schneider JM, Stawarczyk B, Beuer F. Effects of differing thickness and mechanical properties of cement on the stress levels and distributions in a three-unit zirconia fixed prosthesis by FEA. J Prosthodont 2014; 23:358-66. [PMID: 24417273 DOI: 10.1111/jopr.12125] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2013] [Indexed: 11/26/2022] Open
Abstract
PURPOSE This study analyzed the impact of cement layer thickness (CLT) and Young's modulus of the cement on the stress distribution in a three-unit zirconia fixed dental prosthesis (FDP) and in the bonding interfaces by means of finite element method. MATERIALS AND METHODS A 3D finite element model was created from a stylized three-unit FDP-cement-tooth/socket system. The pulp and the periodontal ligament were not modeled. Two CLTs (50 and 150 μm) and two values of Young's modulus of the cement (4.9 for simulation of resin cement, 20.1 GPa for glass ionomer cement) were evaluated. A 500 N static vertical load was applied at the central fossa of the pontic to calculate maximum displacement in the framework and maximum principal stresses in both framework and bonding interfaces. RESULTS The simulated results showed that the Young's modulus affected stress occurrence only in the cement interface. Lower moduli were associated with less stress. The thickness of the cement layer influenced the maximum principal stress in both the FDP and in the cement layer itself. Thicker cement layers led to higher stresses in the framework but lower stresses in the cement layer. Maximum displacement was less dependent of the investigated variables. During all trials, the location of the maximum principal stress did not change. Maximum stress concentrations were observed at the lower embrasures of the connector areas and in the bonding layer at the cervical margin of the preparation. CONCLUSIONS Choosing cements with a preferably low Young's modulus in combination with a CLT as small as possible might increase the clinical survival rate.
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Affiliation(s)
- Timea Wimmer
- Department of Prosthodontics, Ludwig-Maximilians University, Munich Dental School, Munich, Germany
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Ohlmann B, Dittmar A, Rues S, Rammelsberg P. Comparison of fracture-load values of cantilevered FDPs. Acta Odontol Scand 2013; 71:584-9. [PMID: 22834726 DOI: 10.3109/00016357.2012.700061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Evaluation of the effect of different framework designs and of fatigue on the fracture-load values of cantilevered fixed dental prostheses (FDPs). The load values were compared with those for lithium disilicate ceramic and metal-ceramic FDPs. MATERIALS AND METHODS Fifty cantilevered FDPs were manufactured using a zirconia framework veneered with a feldspathic ceramic. Ten FDPs were made from a lithium disilicate ceramic and 10 were designed as metal-ceramic FDPs. All FDPs were anchored by two premolar crowns to replace a missing premolar. Twenty of the 50 zirconia FDPs were regarded as the control groups; these were divided into two groups-with and without fatigue. The other 30 zirconia FDPs were divided into three test groups with different framework designs. The load to fracture was measured and fracture sites were identified. The Kruskal-Wallis test and the Mann-Whitney U-test were used for statistical analysis. RESULTS Most of the all-ceramic FDPs fractured within the distal wall of the terminal crown abutment. The mean fracture-load ranged between 346-493 N for the FDPs with the 0.7 mm framework. Mean values for the three zirconia test groups ranged from 529-590 N. Reinforcement of the framework resulted in significantly higher fracture-loads than for the control group. Values for lithium disilicate restorations were significantly lower than those for the test groups and the values for the metal-ceramic group were significantly higher than those for the test groups. CONCLUSION Although reinforcement of the distal crown core might enhance the fracture resistance of all-ceramic cantilever FPDs, they cannot yet be unreservedly recommended for clinical use.
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Affiliation(s)
- Brigitte Ohlmann
- Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
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Sarafidou K, Stiesch M, Dittmer MP, Jörn D, Borchers L, Kohorst P. Load-bearing capacity of artificially aged zirconia fixed dental prostheses with heterogeneous abutment supports. Clin Oral Investig 2011; 16:961-8. [DOI: 10.1007/s00784-011-0569-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 05/13/2011] [Indexed: 12/01/2022]
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