| 1. |
- Arneryd, Philip, et al.
(författare)
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Fracture strength of low translucent and high translucent monolithic zirconia crowns with different thicknesses
- 2014
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Ingår i: Swedish Dental Journal. - : Swedish Dental Association. - 0347-9994. ; 38:4, s. 195-195
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Objective. The aim of the study was to examine the fracture strength of fully anatomical monolithic high translucent Y-TZP, yttria-stabilized tetragonal zirconia polycrystal, crowns and to compare them with monolithic low translucent Y-TZP crowns in different thicknesses. Materials and methods. 80 standardized crowns were made out of a master model resembling a first mandibular molar made in composite material; 40 crowns made of Lava Zirconia by 3M ESPE, a monolithic low translucent Y-TZP material, and 40 crowns made of Lava Plus by 3M ESPE, a monolithic high translucent Y-TZP material. In each group ten crowns of the thicknesses 1.0 mm, 0.7 mm, 0.5 mm and 0.3 mm were made. All crowns underwent thermocycling and preload to simulate aging and normal wear. Finally the specimens were placed in a testing jig and underwent load to fracture. Results. No significant difference was found when comparing the two materials. When comparing the materials in each thickness a significant difference was found in the 0.5 mm group where the high translucent YTZ-P had a higher mean fracture strength value. A significant difference was seen between the different thicknesses within both groups. The strength increased with added thicknesses. Conclusions. The low translucent and high translucent monolithic YTZ-P perform equally well. The use of high translucent monolithic Y-TZP could result in more aesthetic results and the minimal invasive preparation could lead to a reduction in biological complications. This could be beneficial for the patient since the results suggest that even a thin restoration sustains reasonable load in an in vitro environment. Clinical studies are needed to confirm this suggestion.
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| 2. |
- Bakitian, Fahad, et al.
(författare)
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Effect of different semimonolithic designs on fracture resistance and fracture mode of translucent and high-translucent zirconia crowns
- 2018
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Ingår i: Clinical, Cosmetic and Investigational Dentistry. - : Nakladatelstvi Lidove noviny. - 1179-1357. ; 10, s. 51-60
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of this study was to describe different designs of semimonolithic crowns made of translucent and high-translucent zirconia materials and to evaluate the effect on fracture resistance and fracture mode. Methods: One hundred crowns with different designs were produced and divided into five groups (n=20): monolithic (M), partially veneered monolithic (semimonolithic) with 0.3 mm buccal veneer (SM0.3), semimonolithic with 0.5 mm buccal veneer (SM0.5), semimonolithic with 0.5 mm buccal veneer supported by wave design (SMW), and semimonolithic with 0.5 mm buccal veneer supported by occlusal cap design (SMC). Each group was divided into two subgroups (n=10) according to the materials used, translucent and high-translucent zirconia. All crowns underwent artificial aging before loading until fracture. Fracture mode analysis was performed. Fracture loads and fracture modes were analyzed using two-way ANOVA and Fisher’s exact probability tests (P≤0.05). Results: SM0.3 design showed highest fracture loads with no significant difference compared to M and SMW designs (P>0.05). SM0.5 design showed lower fracture loads compared to SMW and SWC designs. Crowns made of translucent zirconia showed higher fracture loads compared to those made of high-translucent zirconia. M, SM0.3, and all but one of the SMC crowns showed complete fractures with significant differences in fracture mode compared to SMW and SM0.5 crowns with cohesive veneer fractures (P≤0.05). Conclusion: Translucent and high-translucent zirconia crowns might be used in combination with 0.3 mm microcoating porcelain layer with semimonolithic design to enhance the esthetic properties of restorations without significantly decreasing fracture resistance of the crowns. If 0.5 mm porcelain layer is needed for a semimonolithic crown, wave design or cap design might be used to increase fracture resistance. In both cases, fracture resistance gained is likely to be clinically sufficient as the registered fracture loads were high in relation to expected loads under clinical use.
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| 3. |
- Bakitian, Fahad, et al.
(författare)
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Evaluation of Stress Distribution in Tooth-Supported Fixed Dental Prostheses Made of Translucent Zirconia with Variations in Framework Designs : A Three-Dimensional Finite Element Analysis
- 2020
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Ingår i: Journal of Prosthodontics. - : John Wiley & Sons. - 1059-941X .- 1532-849X. ; 29:4, s. 315-322
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To evaluate the influence of the framework designs on the stress distribution within tooth-supported partially veneered fixed dental prostheses (FDPs) made of translucent zirconia under simulated loads using a three-dimensional finite element analysis (3D-FEA). Material and Methods For a linear 3D-FEA, simplified 3D solid models of prepared abutment teeth (first premolar and first molar) with different 3-unit FDPs were created. The models with different FDP designs-monolithic zirconia (control); semi-monolithic zirconia with 0.3 mm veneer thickness (SM0.3); semi-monolithic zirconia with 0.5 mm veneer thickness (SM0.5); semi-monolithic zirconia with 0.5 mm veneer thickness supported with cap design (SMC), and semi-monolithic zirconia with 0.5 mm veneer thickness supported with wave design (SMW)-were analyzed using 3D-FEA. The elastic properties of the components (bone, dentine, cement, translucent zirconia, and veneering porcelain) were obtained from the published data for FEA. Simulated static loading forces (300 N) were applied at 10 degrees oblique direction over six points in the occlusal surfaces of the FDPs. Maximum principal stress, shear stress, and safety factor were calculated and analyzed among the different models. Results Semi-monolithic with cap design showed the smallest maximum principal stress levels in the veneering porcelain compared to all other models (SM0.3, SM0.5, SMW). The SM0.3 had lower maximum principal stress levels in the veneering porcelain compared to SM0.5. Regarding stresses in the zirconia framework, all models had comparable results in maximum principal tensile stresses, except SMW had a lower value. Maximum principal stress levels were located in the veneer component of SM0.3, SM0.5, and SMW, whereas, such levels were observed in the cervical areas of the zirconia frameworks of SMC and control. The SM0.3 had the highest maximum shear stress levels at the zirconia-veneer interface, while SMW had the lowest shear values. The 3D-FEA models with different FDP designs showed different minimum safety factor levels. Conclusions Framework and veneer designs play a significant role in the stress distribution of the partially veneered zirconia FDPs under loading. The FDPs with zirconia frameworks with cap design minimize the maximum principal tensile stress in the veneering porcelain. The FDPs with 0.3-mm-veneering porcelain show low maximum principal tensile stress in the veneering porcelain, but highest maximum shear stress at the zirconia-veneer interface. The FDPs with wave design of zirconia frameworks minimize the maximum shear stress considerably.
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| 4. |
- Bakitian, Fahad, et al.
(författare)
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Fracture strength of veneered translucent zirconium dioxide crowns with different porcelain thicknesses.
- 2017
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Ingår i: Acta Biomaterialia Odontologica Scandinavica. - : Taylor & Francis. - 2333-7931. ; 3:1, s. 74-83
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Objective: To evaluate fracture strength of veneered translucent zirconium dioxide crowns designed with different porcelain layer thicknesses. Materials and Methods: Sixty crowns, divided into six groups of 10, were used in this study. Groups were divided according to different thicknesses of porcelain veneer on translucent zirconium dioxide cores of equal thickness (0.5 mm). Porcelain thicknesses were 2.5, 2.0, 1.0, 0.8, 0.5 and 0.3 mm. Crowns were artificially aged before loaded to fracture. Determination of fracture mode was performed using light microscope. Results: Group 1.0 mm showed significantly (p ≤ .05) highest fracture loads (mean 1540 N) in comparison with groups 2.5, 2.0 and 0.3 mm (mean 851, 910 and 1202 N). There was no significant difference (p>.05) in fracture loads among groups 1.0, 0.8 and 0.5 mm (mean 1540, 1313 and 1286 N). There were significantly (p ≤ .05) more complete fractures in group 0.3 mm compared to all other groups which presented mainly cohesive fractures. Conclusions: Translucent zirconium dioxide crowns can be veneered with minimal thickness layer of 0.5 mm porcelain without showing significantly reduced fracture strength compared to traditionally veneered (1.0–2.0 mm) crowns. Fracture strength of micro-veneered crowns with a layer of porcelain (0.3 mm) is lower than that of traditionally veneered crowns but still within range of what may be considered clinically sufficient. Porcelain layers of 2.0 mm or thicker should be used where expected loads are low only.
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| 5. |
- Bakitian, Fahad, et al.
(författare)
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Load-Bearing Capacity of Monolithic Zirconia Fixed Dental Prostheses Fabricated with Different Connector Designs and Embrasure Shaping Methods
- 2019
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Ingår i: Journal of Prosthodontics. - : John Wiley & Sons. - 1059-941X .- 1532-849X. ; 28:1, s. 64-70
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Tidskriftsartikel (refereegranskat)abstract
- Aim> To investigate the load-bearing capacity and failure mode of monolithic zirconia fixed dental prostheses (FDPs) fabricated with different connector designs and embrasure shaping methods. Materials and methods> Seventy 4-unit zirconia FDPs (with 2 premolar pontics) were fabricated and divided into 7 groups (n = 10) according to the different connector designs gained by using different embrasure shaping methods. The groups were as follows: monolithic FDPs fabricated with sharp embrasures, monolithic FDPs fabricated with blunt embrasures, monolithic FDPs fabricated with blunt embrasures and no occlusal embrasures, 2 groups of monolithic FDPs fabricated with blunt embrasures and interproximal separations made with diamond discs at the soft stage and at the fully sintered stage, and monolithic FDPs fabricated with blunt embrasures and interproximal separation accentuated by localized porcelain build-up. A final group of fully veneered traditional zirconia FDPs to be used as a control group were fabricated with default milling settings. The FDPs were artificially aged and loaded to fracture. Load to fracture and failure modes were analyzed by 1-way ANOVA, Tukey post-hoc test, and Fisher exact test (α = 0.05). Results> The FDPs fabricated with interproximal porcelain separation showed significantly the highest load to fracture (1038 N ± 82) of all groups (p < 0.001), with no significant difference compared to the FDPs with no occlusal embrasures (934 N ± 175) (p ˃ 0.29). The FDPs fabricated with blunt embrasures showed significantly higher load to fracture (873 N ± 115) compared to the FDPs in control group (689 N ± 75) and the FDPs with sharp embrasures (417 N ± 87) (p < 0.001). There were no significant differences between the FDPs with sharp embrasures (417 N ± 87) and the FDPs with interproximal discs separations (467 N ± 94; p ˃ 0.23). Failure mode of the FDPs fabricated with sharp embrasures and interproximal discs separations differed significantly compared to the FDPs in the other groups (p < 0.001). Conclusions> Sharp embrasures and interproximal separations made with diamond discs significantly decrease the load-bearing capacity of monolithic zirconia FDPs compared to FDPs made with blunt embrasures. Blunt embrasures in combination with localized porcelain build-up produce FDPs with high load-bearing capacity in relation to loads that might be expected under clinical use. This article is protected by copyright. All rights reserved.
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| 6. |
- Bergvall, Hanna, et al.
(författare)
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Gender differences in self-assessment among dental students at an ”Objective Structured Clinical Examination (OSCE).
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objective: The objective of this study was to compare dental student’s real/practical results at an Objective Structured Clinical Examination (OSCE) with their self-assessed results. These results were compared depending on gender. Introduction: There are several studies published comparing differences in self-assessment between women and men in theoretical exams. However, knowledge is lacking in regards to clinical examinations. At theoretical examinations, it has been found that men tend to over-estimate their performance more frequently than women do. Whether these differences in self-assessment exist because men tend to over-estimate themselves, women tend to under-estimate themselves, a combination of both or that self-assessments actually are consistent with the results at the examination, vary between different studies. Materials and methods: All students (35 women and 16 men) at the sixth semester at Malmö Dental School were examined with an OSCE with 13 stations. The student’s real results at OSCE were compared with their self-assessment at each station. The assessments were compared regarding gender. Results: At most of the 13 stations there were no significant differences in over- and under-estimation regarding women and men. It was more difficult for men to assess their performance regarding impression with alginate. These misjudgments were mainly caused by over-estimation. There were no results indicating that women under-estimate their performance at greater extent than men. Conclusion: Contrary to studies where gender differences concerning self-assessment in theoretical examinations are observed, the present study found no significant differences in over- and under-estimation between women and men.
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| 7. |
- Borg, Marcus, et al.
(författare)
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Titanium- and zirconia-based implant-supported fixed dental prostheses : A randomized, prospective clinical pilot trial
- 2014
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Ingår i: Swedish Dental Journal. - : Swedish dental association. - 0347-9994. ; 38:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- Målsättningen med studien var att jämföra implantat-stödda partiella broar av titan-porslin respektive yttria-stabiliserad zirkoniumdioxid med ytporslin. Sexton patienter fick sammanlagt 18 broar; 8 av titan-porslin och 10 av yttria-stabiliserad zirkoniumdioxid-porslin. Broarna fördelades randomiserat till respektive material-grupp. Patienterna följdes upp och kontrollerades en första gång efter 3 månader och därefter en gång per år. Ett bedömningsprotokoll baserat på California Dental Association (CDA) kriterier användes. Alla patienter genomförde kontrollbesöken. Genomsnittlig uppföljningstid var 15,2 månader (12-24 månader). Alla konstruktioner var i funktion vid uppföljning och alla patienter var nöjda med behandlingen. Inga tekniska komplikationer noterades i någon av grupperna. Biologiska komplikationer av ringa betydelse, plack och/eller mucosit, som inte påverkade konstruktionernas överlevnad noterades vid 6 av titan-keramik broarna och 2 av zirkonia-porslins broarna. Skillnaden var inte statistiskt signifikant. Sammanfattningsvis kan vi i denna studie konstatera att båda materialen fungerade jämförbart. Data från denna studie antyder att implantat-stödda partiella broar av titan-porslin respektive zirkoniumdioxid med ytporslin uppvisar goda resultat över kort sikt. Studier med fler patienter och längre uppföljningstid rekommenderas emellertid innan definitiva slutsatser kan dras.
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| 8. |
- Chrcanovic, Bruno Ramos, et al.
(författare)
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Analysis of technical complications and risk factors for failure of combined tooth-implant-supported fixed dental prostheses
- 2020
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Ingår i: Clinical Implant Dentistry and Related Research. - : John Wiley & Sons. - 1523-0899 .- 1708-8208. ; 22:4, s. 523-532
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The oral rehabilitation with fixed restorations supported by the combination of teeth and dental implants has been advocated in some cases.PURPOSE: To assess the clinical outcomes of these prostheses. Fixed restorations supported by the combination of teeth and dental implants.MATERIALS AND METHODS: This retrospective study included all patients treated with combined tooth-implant-supported fixed dental prostheses (FDPs) at one specialist clinic. Abutment/prosthesis failure and technical complications were the outcomes analyzed.RESULTS: A total of 85 patients with 96 prostheses were included, with a mean follow-up of 10.5 years. Twenty prostheses failed. The estimated cumulative survival rate was 90.7%, 84.8%, 69.9%, and 66.2% at 5, 10, 15, and 20 years, respectively. The failure of tooth and/or implant abutments in key positions affected the survival of the prostheses. There were seven reasons for prostheses failure, with the loss of abutments exerting a significant influence. Bruxism was possibly associated with failures. Prostheses with cantilevers did not show a statistically significant higher failure rate. No group had a general higher prevalence of technical complications in comparison to the other groups.CONCLUSIONS: Although combined tooth-implant-supported FDPs are an alternative treatment option, this study has found that across 20 years of service nearly 35% the prostheses may fail.
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| 9. |
- Chrcanovic, Bruno Ramos, et al.
(författare)
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Retrospective clinical evaluation of 2- to 6-unit implant-supported fixed partial dentures : Mean follow-up of 9 years.
- 2020
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Ingår i: Clinical Implant Dentistry and Related Research. - : John Wiley & Sons. - 1523-0899 .- 1708-8208. ; 22:2, s. 201-212
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Implant-supported fixed partial dentures (ISFPDs) are one of the most common options to rehabilitate partially edentulous patients.PURPOSE: To assess the clinical outcomes of ISFPDs.METHODS: This retrospective study included all patients treated with ISFPDs with 2 to 6 prosthetic units at one specialist clinic. Implant/prosthesis failure and technical complications were the outcomes analyzed.RESULTS: Six hundred and forty-two patients with 876 ISFPDs (2241 implants) were included, followed up for 108.0 ± 76.2 months. Eighty-eight prostheses and 112 implants (26 before, 86 after prosthesis installation) failed. The estimated CSR of ISFPDs at 30 years was 72.7%. Smokers presented lower implant survival than nonsmokers. Two hundred and ninety-nine ISFPDs (33.2%) presented technical complications. Bruxism was a factor to exert a higher risk of screw and implant fracture, and ceramic chipping. ISFPDs with cantilever presented higher risk of failure, and screw loosening/fracture. Prostheses supported by implants with internal abutment connection or with two pontics had higher risk of presenting ceramic chipping. Extension of the prosthesis did not seem to exert influence on prosthesis failure/complications.CONCLUSIONS: ISFPDs presented good long-term prognosis. Implant failure was the main reason for ISFPD failure. The results suggest that bruxism and the presence of cantilever may contribute to the increased rate of mechanical complications and prosthesis failure.
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| 10. |
- Chrcanovic, Bruno Ramos, et al.
(författare)
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Retrospective clinical evaluation of implant‐supported single crowns : mean follow‐up of 15 years
- 2019
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Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 30:7
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To retrospectively assess the clinical outcomes of implant‐supported single crowns and the supporting implants. Material and Methods: This retrospective study included all patients treated with implant‐supported single crowns at one specialist clinic. Implant and prosthesis failure, and mechanical/technical complications (ceramic fracture/chipping; crown loss of retention/mobility; crown failure/fracture; loosening/loss/fracture of prosthetic screw; implant failure/fracture) were the outcomes analyzed. Any condition/situation that led to the removal/replacement of crowns was considered prosthesis failure. Results: 438 patients with 567 crowns were included. Mean±SD follow‐up of 183.4±69.3 months. 37 implants (6.5%) and 54 crowns (9.5%) failed. If only technical problems were considered, the crown failure rate decreased to 4.1% (23/567). Most common reasons for crown failure: esthetic issue (n=12), crown constantly mobile (n=9), change to another type of prosthesis together with other implants (n=8), crown fracture (n=7), crown in infraposition in comparison to adjacent teeth (n=7). The odds of crown failure were shown to be statistically significantly higher for the following factors: younger patients, maxillary crowns, and screw‐retained crowns. Loose prosthetic screw was much more prevalent in screw‐retained than in cemented crowns. Ceramic fracture/chipping was more prevalent in screw‐retained crowns, maxillae, females. Crown fracture was more prevalent in ceramic crowns, screw‐retained crowns, maxillae, posterior region, females. However, these differences were statistically significant only for crown fractures in females. Conclusions: The odds of crown failure were significant for some factors, but one must keep in mind that non‐technical complications are as common as technical ones as reasons for the replacement of implant‐supported single crowns.
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