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1.
Braz. j. oral sci ; 20: e211701, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1254532

RESUMO

Aim: This study aimed to evaluate how meta-analyses are conducted and reported in dentistry. Methods: We conducted a search to identify dentistry-related Systematic Reviews (SRs) indexed in PubMed in 2017 (from January 01 until December 31) and published in the English language. We included only SRs reporting at least one meta-analysis. The study selection followed the 4-phase flow set forth in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (PRISMA), and it was independently conducted by two researchers. Data extraction was performed by one of three reviewers, and data related to conducting and reporting of the meta-analysis were collected. Descriptive data analysis was performed summarizing frequencies for categorical items or median and interquartile range for continuous data. Results: We included 214 SRs with meta-analyses. Most of the studies reported in the title that a meta-analysis was conducted. We identified three critical flaws in the included studies: Ninety (90) meta-analyses (43.1%) did not specify the primary outcome; most of the meta-analyses reported that a measure of statistical heterogeneity was used to justify the use of a fixed-effect or random-effects meta-analysis model (n=114, 58.5%); and a great part did not assess publication bias (n=106, 49.5%). Conclusion: We identified deficiencies in the reporting and conduct of meta-analysis in dentistry, suggesting that there is room for improvement. Educational approaches are necessary to improve the quality of such analyses and to avoid biased and imprecise results


Assuntos
Saúde Bucal , Relatório de Pesquisa , Revisões Sistemáticas como Assunto
2.
Braz Dent J ; 32(3): 56-64, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34755790

RESUMO

It aims on evaluate the effect of the test environment on static fatigue behavior of lithium disilicate-based (LD), and yttrium oxide-stabilized zirconia (YSZ) ceramics. Specimens of LD (IPS e.max CAD, Ivoclar Vivadent) and YSZ (IPS e.max ZirCAD MO, 3 mol% Y2O3, Ivoclar Vivadent) were randomly allocated into three groups: tested in air, inert (paraffin oil, Sigma Aldrich) or distilled water. The static fatigue test (n=15) was performed using a piston-on-three ball assembly, adapted from ISO 6872, as follows: starting load 100 N for LD and 300 N for YSZ; loading application time set to 1 hour for each loading step; step size of 50 N for LD and 100 N for YSZ, applied successively until fracture. Data from static fatigue strength (MPa) and time to fracture (hours) were recorded. Fractographic analysis was executed. Survival analysis corroborates absence of influence of environment on static fatigue outcomes (fatigue strength, time to fracture and survival rates) for YSZ. For LD, specimens tested in air presented statistically superior survival rate and static fatigue strength (p= 0.025). In regards of time to fracture, LD tested in air were superior than when tested in distilled water (p=0.019) or inert (p=0.017) environments. No statistical differences for Weibull modulus were observed. Failures started on the tensile stress surface. Thus, the test environment did not affect slow crack growth (SCG) mechanisms during static fatigue test of YSZ ceramics, but it plays a significant role for the static fatigue behavior of lithium disilicate-based glass ceramics, indicating a high susceptibility to SCG.


Assuntos
Cerâmica , Porcelana Dentária , Desenho Assistido por Computador , Análise do Estresse Dentário , Vidro , Teste de Materiais , Propriedades de Superfície , Zircônio
3.
J Mech Behav Biomed Mater ; 124: 104833, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34562764

RESUMO

This study evaluated the effect of grinding and polishing the inner surface of monolithic discs made of zirconia polycrystals (ZR) and lithium disilicate glass-ceramic (LD) on the load-bearing capacity under fatigue of the restorations bonded onto a dentin analogue material (epoxy resin). ZR and LD ceramic discs (10 mm in diameter, 1 mm in thickness) were produced and randomly allocated into 10 groups considering the internal adjustment approach: Ctrl - No adjustment; F - Grinding with fine diamond bur (46 µm); F + Pol - Grinding with fine diamond bur followed by polishing with 2 tips (finisher and polisher); FF - Grinding with extrafine diamond bur (30 µm); FF + Pol - Grinding with extrafine diamond bur followed by polishing. In addition, discs (10 mm in diameter, 2.5 mm in thickness) of fiber reinforced epoxy resin were produced. Afterwards, the intaglio surface of the ZR discs were air-abraded with 45 µm alumina particles for 10 s, the LD and resin epoxy discs were etched with hydrofluoric acid (5%/20 s and 10%/60 s, respectively), and the treated discs were primed as recommended. Each ceramic disc was luted onto the epoxy resin disc with resin cement. Then, the samples were tested under a step-stress fatigue test (20 Hz, 10,000 cycles/step, step-size of 100 N starting at 200 N, and proceeding until failure detection). Fractographic, topographic and surface roughness analysis were also performed. The adjustments (grinding with or without polishing) (ZR: 733-880 N; LD: 1040-1106 N) triggered a detrimental effect on the fatigue behavior in both ceramics compared with the absence of treatment (control group; ZR: 973 N; LD: 1406 N). The polishing step had no effect on fatigue findings. Thus, grinding the inner surface of the tested ceramics should be avoided wherever possible to prevent introducing damage and its detrimental effects on the fatigue behavior.


Assuntos
Cerâmica , Zircônio , Porcelana Dentária , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície , Suporte de Carga
4.
Polymers (Basel) ; 13(17)2021 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-34503042

RESUMO

The purpose of this in vitro study was to evaluate the external marginal gap variation with a 3D quantitative method and the residual fracture resistance after cyclic fatigue in endodontically treated molars restored with overlays of different materials, with and without fiber posts-supported buildups. Forty-eight human maxillary molars were selected, endodontically treated, prepared with standardized MOD cavities and randomly allocated into 6 study groups considering the "core strategy" (build-up with composite resin; build-up with composite resin supported by a fiber post); and the "restorative material" of the indirect adhesive overlay (GrandioBlocks, Voco; Cerasmart, GC; CeltraDuo, Dentsply). All procedures were executed according with manufacturers guidelines. Micro-CT analysis prior and after cyclic fatigue were executed, followed by scanning electron microscope analysis and fracture resistance test. The Two-Way ANOVA analysis showed that interfacial gap progression was significantly influenced by the "core strategy" (p < 0.01) but not of "restorative material" (p = 0.59). Concerning fracture resistance, "restorative material" was statistically significant (p < 0.01), while "core strategy" (p = 0.63) and the interaction (p = 0.84) were not. In conclusion, the fiber post presence within the build-up promoted a lower interfacial gap opening after fatigue, evaluated through micro-CT scans. In terms of fracture resistance, teeth restored with Cerasmart and Celtra Duo were statistically similar, but superior to GrandioBlocks.

5.
J Mech Behav Biomed Mater ; 124: 104792, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34488172

RESUMO

This study evaluated the influence of surface treatments of resin composite substrate on the fatigue behavior of adhesively cemented lithium disilicate glass-ceramic simplified restorations. CAD/CAM lithium disilicate ceramic blocks were shaped into discs (N = 60, Ø = 10 mm; thickness = 1.0 mm). Resin composite discs (N = 60, Ø = 10 mm, thickness = 2 mm) were allocated into four groups considering the "surface treatment" factor: Ctrl - no surface treatment; Bur - grinding with coarse diamond bur (#3101G, KG Sorensen); PA - etching with 37% phosphoric acid (15 s); AA - air abrasion with alumina particles (45 µm, 10 mm distance, 2.8 bars, 10 s). The surface topography, the roughness, the fractal dimension (estimated by the box-counting method) and the contact angle analyses were performed after the surface treatments. The lithium disilicate discs were etched (5% hydrofluoric acid, 20 s), silanized and adhesively cemented (Multilink N, Ivoclar Vivadent) on the resin composite discs. The samples (bonded restoration set) were subjected to a step-stress fatigue test at 20 Hz, 10,000 cycles/step with a step-size of 100 N applied on the ceramic surface, having ceramic up and resin composite down. Fractographic analysis was performed. The fatigue data (Fatigue Failure Load - FFL; and Cycles for Failure - CFF) were analyzed by Kaplan Meier with Mantel-Cox log-rank post-hoc tests (α = 0.05). No statistical difference for fatigue performance could be found among the groups (FFL means: 820-867 N; CFF means: 53,195-61,090 cycles). The bur group showed higher surface roughness and contact angle values. The PA group has the highest average fractal dimension. Therefore, the resin composite surface treatment induces topographical changes, however, it has no effect on the fatigue behavior of lithium disilicate restorations.


Assuntos
Cerâmica , Porcelana Dentária , Análise do Estresse Dentário , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície , Suporte de Carga
6.
J Mech Behav Biomed Mater ; 123: 104760, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34418777

RESUMO

The fatigue behavior and FEA analysis of different ceramic materials cemented over distinct substrates for implant-supported crowns were evaluated in this study. Discs of 10 mm in diameter of both restorative and substrate materials were made and randomly allocated into pairs (n = 15) considering the two study factors: 'restorative ceramic material' (1 mm thickness) - polymer-infiltrated ceramic network (PICN), lithium disilicate (LD), zirconia-reinforced lithium silicate (ZLS), or translucent zirconia (TZ); and 'foundation substrate' (2 mm thickness) - polyetheretherketone (Peek) or yttrium-stabilized zirconia (YZ). Adhesive cementation was made with a dual cure resin cement. Fatigue testing was run using the step-stress methodology: initial load of 200 N for 5000 cycles, followed by steps of 10,000 cycles starting at 400 N up to 2800 N or until failure, step size of 200 N, frequency of 20 Hz. Data were analyzed by the Kaplan Meier and log-rank post-hoc tests. Fractography analysis (stereomicroscope and SEM) and FEA were also performed. Both factors under study and their interaction statistically influenced the fatigue failure load (FFL), cycles for failure (CFF) and survival rates (p < 0.001). The restorative materials bonded to YZ had higher FFL and CFF than when adhering to Peek, while restorative materials with more crystalline content (TZ and ZLS) showed higher FFL and CFF than LD and PICN. The fractography analysis showed that all materials bonded to YZ resulted in failures starting at the occlusal surface (Hertzian cone cracks), while materials bonded to Peek had radial cracks from the ceramic-cement intaglio surface. FEA analysis showed that tensile stress concentration decreased in the intaglio surface when testing the restorative material over a stiffer (YZ) foundation substrate. In addition, the higher the restorative material's crystalline content, the more the stress is concentrated within the material (TZ > ZLS ≥ LD > PICN) when bonded to the same foundation substrate. Thus, it concluded that a stiffer foundation substrate (YZ) enhances the load-bearing capacity under fatigue of the restorative set; that restorative materials with higher crystalline content results in higher fatigue performance of the set, regardless of the foundation used; and that the foundation material influences the failure pattern of the restorative set.


Assuntos
Cerâmica , Zircônio , Desenho Assistido por Computador , Porcelana Dentária , Falha de Restauração Dentária , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície , Suporte de Carga
7.
J Prosthet Dent ; 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34238537

RESUMO

STATEMENT OF PROBLEM: Various strategies have been proposed to reduce the cement space of foundation restorations for endodontically treated teeth. However, they may add more operative steps, or the dentist must keep different sizes of drills and posts in stock. A 2-piece universal adjustable post system has been developed to overcome this problem, but whether the system has acceptable fatigue survival performance is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the fatigue survival and stress distribution of endodontically treated teeth without a ferrule and restored with different glass fiber post strategies versus a recently introduced universal 2-piece fiber post system. MATERIAL AND METHODS: Bovine incisor roots were randomly assigned to 3 groups as per the post used (n=13): adapted glass fiber post with post space preparation of the same size, composite resin-custom glass fiber post (CTM), and universal 2-piece glass fiber-reinforced composite resin post (UNI). The posts were adhesively luted, the composite resin core was added, and a composite resin crown was produced with computer-aided design and computer-aided manufacturing (CAD-CAM), and then adhesively luted to each core. A fatigue test was performed with the stepwise stress method (10 000 cycles/step; 20 Hz; load=100 N to 750 N; step=50 N) until fracture, and the failure mode analyzed. The stress distribution was evaluated by finite element analysis with the maximum principal stress criteria by following the parameters of the in vitro test. The solids were considered homogeneous, linear, and isotropic, except for the glass fiber post (orthotropic), and a load of 450 N at 30 degrees was applied. The fatigue failure load and the number of cycles for failure were analyzed with Kaplan-Meier and Mantel-Cox (log rank test) (α=.05). The finite element analysis results were analyzed with colorimetric graphs. RESULTS: The highest fatigue failure load and the number of cycles for failure were found in the UNI system, whereas the lowest results were found in the CTM group. All groups exhibited repairable failures. The finite element analysis showed the lowest stress in root dentin in the UNI system. The CTM system had the largest stress regions at the dentin and dentin-core interface. CONCLUSIONS: The use of a 2-piece universal glass fiber post system resulted in more fatigue behavior compared with composite resin-custom glass fiber posts.

8.
J Esthet Restor Dent ; 33(7): 1017-1028, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34105868

RESUMO

OBJECTIVE: To evaluate the effect of surface treatments on optical, colorimetric, and surface characteristics of lithium disilicate glass-ceramic. MATERIALS AND METHODS: Specimens (n = 5, IPS e.max CAD) were randomly allocated to the following treatments: mirror-polished: SiC papers; as-cut: mimicking CAD-CAM milling; ground: 90-120 µm-grit diamond bur; ground polished: ground, finished (46-30 µm-grit diamond bur), polished (diamond cups, brush and diamond paste); ground glazed: ground, glazed; ground polished glazed: association of methods. CIELAB color coordinates were obtained by a spectrophotometer. CIEDE2000 color differences (ΔE00 ) and the translucency parameter (TP00 ) were calculated. Light transmittance was assessed with a colorimeter. Surface characteristics (topography and roughness) were analyzed. Statistical differences for each condition and outcome were detected using one-way ANOVA with Tukey's post-hoc test (α = 0.05). RESULTS: TP00 data show statistical reduction after grinding (p < 0.05), which was only restored with polishing (solely or with glazing). ΔE00 shows that grinding results in perceptible variations in color (above 0.81), which were restored after all post-processing protocols (exception to only glaze application in contact with a black background). Light transmittance data corroborated such performance. Polishing and glazing reduced roughness and improved surface topography. CONCLUSION: Grinding statistically increased roughness, reduced translucency, light transmittance through the ceramic, and resulted on color differences. On contrary, polishing (followed or not by glazing) reduced roughness and enhanced ceramic translucency and light transmittance. Glaze also reduced roughness, but it still presented reduced translucency. The positioning (facing up or down) of the ceramic treated surface influenced the considered outcomes. CLINICAL SIGNIFICANCE: Grinding with diamond burs results in a deleterious impact to the optical, colorimetric and surface characteristics of lithium disilicate ceramic. Thus, polishing (followed or not by glazing) is recommended for optical and topographical enhancements when lithium disilicate monolithic restorations require occlusal adjustments.


Assuntos
Colorimetria , Polimento Dentário , Cerâmica , Porcelana Dentária , Teste de Materiais , Propriedades de Superfície
9.
J Mech Behav Biomed Mater ; 121: 104604, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34087550

RESUMO

The aim of this study was to evaluate the effect of in-lab simulation procedures performed on a lithium disilicate ceramic luted to a dentin-analogue material regarding the fatigue performance and topographic changes. Lithium disilicate ceramic (IPS e.max CAD) discs (Ø = 13.5 mm and 1.5 mm of thickness) were produced in different ways: milled in a CAD/CAM system (CAD/CAM - control group); mirror-polished (POL group); produced in-lab and ground with #60 silicon carbide paper (SiC group); with #60 wood sandpaper (WS group); with a fine diamond bur (DB group); or with a CAD/CAM bur adapted in a handpiece with a custom mandrel (MANDREL group). The ceramic discs were adhesively luted (Multilink N) onto dentin analogue discs (Ø = 12 mm and 2 mm of thickness) and fatigue testing (n = 19 discs) was performed by step-stress methodology (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). Surface roughness and contact angle analysis were also performed. According to Kaplan-Meier and post-hoc Mantel-Cox (log-rank), distinct fabrication methods affected the fatigue performance of bonded glass-ceramic discs (p< 0.001). The CAD/CAM group presented the lowest fatigue failure loads (1250 N) and number of cycles for failure (185,000), while the POL groups obtained the highest results (1752 N; 284,444 cycles). The in-lab groups had intermediate values (1355 - 1526 N; 206,052 - 238,684 cycles). Polished specimens presented the lowest roughness values (Ra = 0.041 µm), while the SiC (1.604 µm), WS (1.701 µm), and MANDREL (1.867 µm) groups showed statistically similar roughness values to the CAD/CAM group (1.738 µm). Despite differences before etching, the contact angle was similar among the milled and simulated groups after etching, except for the polished group. Even with some topographic similarities, the tested in-lab simulation methods were not able to mimic the milled specimens in terms of fatigue findings, leading to distinct magnitude of overestimations of the results.


Assuntos
Cerâmica , Desenho Assistido por Computador , Porcelana Dentária , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície
10.
J Mech Behav Biomed Mater ; 121: 104592, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34144359

RESUMO

The aim of this study was to characterize the flexural strength and elastic modulus of CAD/CAM resin composite material and to evaluate the influence of different surface treatments and storage conditions on the fatigue behavior of bonded composite crowns. Bars (flexural strength, n= 30; elastic modulus, n= 5) (1.2 × 4 × 12 mm) were produced for three-point bending test and CAD/CAM milled crowns (n= 5) (thickness= 1 mm) adhesively cemented to an epoxy resin substrate for fatigue tests. Bars and crowns were randomly allocated into two "surface treatments": no surface treatment (CTRL) and air-abrasion with 110 µm Al2O3 particles (AlOx); while the crowns were also subdivided into "aging condition" (baseline - storage for 24 h to 7 days, and aging - storage for 150 days + 25,000 thermal cycles). The three-point bending test was performed according to ISO 6872 and the luted crowns were subjected to step-stress fatigue test (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). Complementary analysis by Stereomicroscopy and Field Emission Scanning Electron Microscopy (FE-SEM) were performed. The flexural strength and fatigue data were submitted to statistical tests (α= 0.05). The results showed that air-abrasion reduces the flexural strength and the characteristic strength of the resin composite, without modifying its elastic modulus or its structural reliability (Weibull Modulus). Air-abrasion did not influence the fatigue behavior of the cemented crowns. Notwithstanding, a decrease in the survival rate was observed after 445,000 cycles (2,400 N) when subjected to aging at both the CTRL or AlOx conditions. FE-SEM micrographs of the crowns showed that alumina particle air-abrasion treatment can modify the topography of its treated inner surface. Therefore, air-abrasion with alumina powder introduces defects onto the surface of the CAD/CAM resin composite material, decreasing the flexural strength, but without changing its elastic modulus and reliability. Adhesive cementation onto an epoxy resin substrate prevented an influence of the introduced defects on the fatigue performance of the resin composite restoration. Nevertheless, the fatigue behavior may be damaged by aging regimen.


Assuntos
Óxido de Alumínio , Resistência à Flexão , Cerâmica , Resinas Compostas , Desenho Assistido por Computador , Análise do Estresse Dentário , Teste de Materiais , Reprodutibilidade dos Testes , Cimentos de Resina , Propriedades de Superfície
11.
J Mech Behav Biomed Mater ; 120: 104543, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33957570

RESUMO

This study evaluated the effect of distinct surface treatments on the fatigue behavior (biaxial flexural fatigue testing) and surface characteristics (topography and roughness) of a 5% mol yttria partially stabilized zirconia ceramic (5Y-PSZ). Disc-shaped specimens of 5Y-PSZ (IPS e.max ZirCAD MT Multi) were manufactured (ISO 6872-2015) and allocated into six groups (n = 15) considering the following surface treatments: Ctrl - no-treatment; GLZ - low-fusing porcelain glaze application; SNF - 5 nm SiO2 nanofilm; AlOx - aluminum oxide particle air-abrasion; SiC - silica-coated aluminum oxide particles (silica-coating); and 7%Si - 7% silica-coated aluminum oxide particles (silica-coating). The biaxial flexural fatigue tests were performed by the step-stress method (20Hz for 10,000 cycles) with a step increment of 50N starting at 100N and proceeding until failure detection. The samples were tested with the treated surface facing down (tensile stress side). Topography, fractography, roughness, and phase content assessments of treated specimens were performed. GLZ group presented the highest fatigue behavior, while AlOx presented the lowest performance, and was only similar to SiC and 7%Si. Ctrl and SNF presented intermediary fatigue behavior, and were also similar to SiC and 7%Si. GLZ promoted a rougher surface, Ctrl and SNF had the lowest roughness, while the air-abrasion groups presented intermediary roughness. No m-phase content was detected (only t and c phases were detected). In conclusion, the application of a thin-layer of low-fusing porcelain glaze, the deposition of silica nanofilms and the air-abrasion with silica-coated alumina particles had no detrimental effect on the fatigue behavior of the 5Y-PSZ, while the air-abrasion with alumina particles damaged the fatigue outcomes.


Assuntos
Dióxido de Silício , Ítrio , Óxido de Alumínio , Cerâmica , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície , Zircônio
12.
Clin Oral Investig ; 25(10): 5967-5975, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33860368

RESUMO

OBJECTIVES: To evaluate different direct restoration techniques on various cavity designs in anterior endodontically treated teeth (ETT). MATERIALS AND METHODS: Ninety upper central incisors (n = 90) were selected, endodontically treated, and divided into three groups (n = 30) accordingly to the cavity design: minimal endodontic cavity access (group A), endodontic access + mesial class III cavity (group B), and endodontic access + two class III cavities (group C). Three subgroups (n = 10) were then created accordingly to the restoration technique: nano hybrid composite restoration (subgroup a), glass fiber post + dual-cure luting cement (subgroup b), and bundled glass fiber + dual-cure luting cement (subgroup c). Samples underwent micro-CT scan, chewing simulation, and a second micro-CT scan. 3D quantification (mm3) of interfacial gap progression was performed; then, samples underwent fracture resistance test. Data were statistically analyzed setting significance at p < 0.05. RESULTS: Groups A and B showed significantly lower interfacial gap progression compared with group C. Subgroup b performed significantly better compared with subgroups a and c. Improved fracture strength was reported for group C compared with group A, while both subgroups b and c performed better than subgroup a. CONCLUSIONS: Cavity design significantly influenced interfacial gap progression and fracture resistance. Fiber posts significantly lowered gap progression and improved fracture resistance while bundled fibers only increased fracture resistance. A significant reduction of non-repairable fractures was recorded when fibers were applied. CLINICAL RELEVANCE: A minimally invasive approach, conserving marginal crests, should be applied whenever possible. Inserting a fiber post is indicated when restoring anterior ETT, in order to reduce gap progression, improve fracture resistance, and avoid catastrophic failures.


Assuntos
Técnica para Retentor Intrarradicular , Fraturas dos Dentes , Dente não Vital , Resinas Compostas , Análise do Estresse Dentário , Humanos
13.
J Adhes Dent ; 23(2): 133-143, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33825427

RESUMO

PURPOSE: To evaluate the effect of different etching times of a self-etching ceramic primer on the microshear bond strength (µSBS) and topographic surface pattern of a lithium-disilicate glass-ceramic. MATERIALS AND METHODS: Ceramic slices were subjected to an in-lab simulation of CAD/CAM milling and randomly allocated to 10 groups (n = 35) considering two factors: "surface treatment" in 5 levels - one control group (5% hydrofluoric acid + silane application [HF5+SIL]), and 4 experimental groups using ceramic etching/primer (Monobond Etch & Prime, E&P) with different passive application times (40 s, 2 min, 5 min, or 10 min); and "aging" factor in 2 levels - short-term (after 24 h), or long-term (storage for 180 days + 12,000 thermal cycles). Composite cement cylinders were built and µSBS tests were run in a universal testing machine. The failure patterns were categorized, and complementary analyses with SEM and Atomic Force Microscopy (AFM) were performed. RESULTS: The groups showed statistically similar bond strengths in the short term (range 22.4 to 25.1 MPa). However, only the E&P 20s+40s (19.3 MPa) and E&P 20s+5min (21.5 MPa) groups maintained stable bond strength in the long term, and HF5+SIL (17.1 MPa) presented statistically significantly lower values than did E&P 20s+5min. The failure pattern was predominantly adhesive. The increased application time of the ceramic primer promoted greater dissolution of the glass matrix; thus, the E&P 20s+10min group presented the most complex surface characteristics in the fractal dimension analysis. CONCLUSION: The self-etching ceramic primer can be used as an alternative to classical conditioning with HF plus silane, promoting stable bond strength for etching times of 40 s or 5 min of passive application.


Assuntos
Colagem Dentária , Lítio , Cerâmica , Porcelana Dentária , Ácido Fluorídrico , Teste de Materiais , Cimentos de Resina , Silanos , Propriedades de Superfície
14.
J Evid Based Med ; 14(1): 56-64, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33595200

RESUMO

OBJECTIVE: This study aimed to assess the characteristics of different designs of systematic reviews (SRs) registered in the International Prospective Register of Systematic Reviews (PROSPERO) about COVID-19. METHODS: The search was performed in the PROSPERO database using the strategy proposed by the database and considered only human studies. The last date of the search was April 27, 2020. Full text of all records was accessed, and data were extracted by a single researcher, which was further double-checked by another researcher. A descriptive analysis was performed considering record characteristics using tables. RESULTS: We included 564 records from which the vast majority were registered as SRs (n = 513, 91%). In general, we found poor reporting and missing or confusing information, since 84% of the records (n = 474) did not report the full search that would be adopted, 16% (n = 90) did not report clearly the databases that would be used, and 49.1% (n = 277) did not report the number of primary outcomes. The main focus of most of the records involved clinical, epidemiological, complication, and laboratory characteristics (n = 173, 30.7%) or the treatment of COVID-19 (n = 138, 24.5%). CONCLUSION: A large number of SRs about COVID-19 have been conducted, and many of the assessed records were poorly reported and would be difficult to replicate. Besides, collected data points to an epidemic of redundant reviews on COVID-19.


Assuntos
COVID-19 , Projetos de Pesquisa , Revisões Sistemáticas como Assunto , Bibliometria , Humanos , Pandemias , Pneumonia Viral/virologia , SARS-CoV-2
15.
J Mech Behav Biomed Mater ; 117: 104391, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33618242

RESUMO

This study evaluated the influence of distinct substrates on the mechanical fatigue behavior of adhesively cemented simplified restorations made of glass, polycrystalline or polymer infiltrated-ceramics. CAD/CAM ceramic blocks (feldspathic - FEL; lithium disilicate - LD; yttria-stabilized zirconia - YZ; and polymer-infiltrated ceramic network - PICN) were shaped into discs (n = 15, Ø = 10 mm; thickness = 1.0 mm), mimicking a simplified monolithic restoration. After, they were adhesively cemented onto different foundation substrates (epoxy resin - ER; or Ni-Cr metal alloy - MA) of the same shape (Ø = 10 mm; thickness = 2.0 mm). The assemblies were subjected to fatigue testing using a step-stress approach (200N-2800 N; step-size of 200 N; 10,000 cycles per step; 20 Hz) upon the occurrence of a radial crack or fracture. The data was submitted to two-way ANOVA (α = 0.05) to analyze differences considering 'ceramic material' and 'type of substrate' as factors. In addition, a survival analysis (Kaplan Meier with Mantel-Cox log-rank post-hoc tests; α = 0.05) was conducted to obtain the survival probability during the steps in the fatigue test. Fractographic and finite element (FEA) analyzes were also conducted. The factors 'ceramic material', 'type of substrate' and the interaction between both were verified to be statistically significant (p < .001). All evaluated ceramics presented higher fatigue failure load (FFL), cycles for failure (CFF) and survival probabilities when cemented to the metallic alloy substrate. Among the restorative materials, YZ and LD restorations presented the best fatigue behavior when adhesively cemented onto the metallic alloy substrate, while FEL obtained the lowest FFL and CFF for both substrates. The LD, PICN and YZ restorations showed similar fatigue performance considering the epoxy resin substrate. A more rigid foundation substrate improves the fatigue performance of adhesively cemented glass, polycrystalline and polymer infiltrated-ceramic simplified restorations.


Assuntos
Cerâmica , Polímeros , Desenho Assistido por Computador , Porcelana Dentária , Falha de Restauração Dentária , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície , Zircônio
16.
Eur J Dent ; 15(3): 448-453, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33511603

RESUMO

OBJECTIVES: To evaluate the effect of different artificial aging methods on the bond strength of a resin composite associated with a universal adhesive (Scotchbond Universal) used under two etching approaches (self-etch [SE] or etch-and-rinse [ER]) to enamel and dentin substrates. MATERIALS AND METHODS: A total of 96 noncarious human third molars were prepared and randomly divided according to three factors (n = 6): substrate (enamel and dentin), adhesive approach (SE and ER), and aging method (water storage for 24 hours, 6 months, or 1 year; subjected to 10,000, 20,000, or 30,000 thermal cycles; and sodium hypochlorite [NaOCl] storage for 1 or 5 hours). STATISTICAL ANALYSIS: Microshear bond strength tests were conducted, and the collected data (MPa) were subjected to three-way analysis of variance (ANOVA) with post hoc Bonferroni tests (p < 0.05) and Weibull analysis. The failure pattern was also evaluated. RESULTS: Three-way ANOVA revealed that the factors "substrate" (p = 0.00) and "aging method" (p = 0.00) had a significant effect on the bond strength, but the factor "adhesive approach" did not (p = 0.84). The bond strength in the enamel group for the SE approach was negatively affected under 20,000 and 30,000 thermal cycles. Weibull presented the highest m in the NaOCl storage for the 5 hours group to enamel using the SE and to dentin using ER approaches. Adhesive/mixed failures were predominant for all groups. CONCLUSION: Thermocycling aging (20,000 and 30,000 cycles) significantly reduced the bond strength to enamel using the SE approach. On the contrary, storage with the NaOCl method proved to increase bond strength under the evaluated conditions.

17.
J Prosthodont Res ; 65(2): 202-207, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33028795

RESUMO

PURPOSE: To evaluate the influence of quantity and positioning of veneered zirconia specimens during firing of porcelain on their fatigue performance and colorimetric differences. METHODS: Bilayer discs (Ø=15 mm) were made, following ISO 6872 guidelines, using a Y-TZP core (yttria-stabilized tetragonal zirconia polycrystal ceramic; VITA In-Ceram YZ) and a feldspathic veneering material (VITA VM9), being both layers with 0.7 mm thickness. Y-TZP discs were sintered, the veneering material was applied over it, and the bilayer specimens were fired according to two factors (n=20): 'quantity' (1 or 5 samples per firing cycle; G1 and G5 groups respectively) and 'positioning' of the specimens inside the furnace (center or periphery of the refractory tray; G5C and G5P groups, respectively). The CIEL*a*b* parameters were recorded with a spectrophotometer and the color difference (ΔE 00 ) and translucency (TP 00 ) were calculated using CIEDE2000 equations. The step-stress fatigue test was performed with the veneer facing down (region of tensile stress concentration), 10 Hz frequency, initial tension of 20 MPa for 5,000 cycles, followed by steps of 10,000 cycles using a step size of 10 MPa, up to 100 MPa; data from strength and number of cycles for failure were recorded for statistical analysis. RESULTS: Unacceptable color differences (ΔE 00 >1.8) were observed comparing G5C vs. G1 (quantity) and G5C vs. G5P (positioning), meanwhile translucency parameters were not affected. Besides, only the 'quantity' factor influenced the fatigue performance (G1>G5C). None of the tested specimens survived beyond 90N and/or 75000 cycles. CONCLUSIONS: The quantity and position of the specimens during firing influence the final color of porcelain-veneered zirconia, and firing one specimen per cycle improved the fatigue performance of the bilayer system.


Assuntos
Porcelana Dentária , Facetas Dentárias , Cerâmica , Colorimetria , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície , Ítrio , Zircônio
18.
J Prosthodont Res ; 65(2): 162-170, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33028796

RESUMO

PURPOSE: This study evaluated the influence of different surface treatments of zirconia used to enhance bonding with veneering porcelain, and thermocycling on the resistance to porcelain cracking and delamination during fatigue test. METHODS: Bilayer ceramic discs were made from zirconia blocks (IPS e.max Zircad MO, Ivoclar Vivadent - 0.7 mm thickness) and randomized into 8 groups (n= 15) according to two factors: 'zirconia surface treatment' (Control; Grinding - diamond bur; Air-abrasion - aluminum oxide particles; and Liner - application of a ceramic liner [IPS e.max Zirliner, Ivoclar Vivadent]); and 'thermocycling' (presence - 12,000 thermal cycles; 5-55ºC; or absence). The discs were veneered with porcelain (IPS e.max Ceram, Ivoclar Vivadent - 0.7 mm; totaling 1.4 mm thickness) according to ISO 6872:2015 for biaxial flexure strength testing. Fatigue tests (step-stress approach; 20 to 100 MPa; step of 10 MPa; 10,000 cycles per step; 10 Hz frequency) were run, followed by the data analysis (Kaplan-Meier and Mantel-Cox post-hoc tests). Analysis of roughness, topography, crystallographic phase arranges and fractography were also executed. RESULTS: The surface treatment and thermocycling did not influence the porcelain crack nor delamination resistance. When only comparing the surface treatments for crack resistance outcome, the liner application depicted the worst fatigue performance in comparison to grinding and air-abrasion, while all groups were similar for delamination. CONCLUSIONS: Neither the surface treatment of the zirconia nor the thermocycling influences the porcelain crack resistance or the resistance to delamination of the bilayer porcelain-veneered zirconia specimens.


Assuntos
Porcelana Dentária , Zircônio , Cerâmica , Análise do Estresse Dentário , Facetas Dentárias , Fadiga , Humanos , Teste de Materiais , Propriedades de Superfície
19.
J Biomed Mater Res B Appl Biomater ; 109(6): 890-901, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33155731

RESUMO

This scoping review study aimed to map the evidence about solvents' use for gutta-percha dissolution and removal during endodontic retreatments. The study protocol followed the Joanna Briggs Institute guidelines, available online (https://osf.io/5vy8n/). Reporting was based on PRISMA Extension for Scoping Reviews. We selected dentistry studies that considered the effectiveness of solvents in gutta-percha dissolution in endodontic retreatments and compared their performance to the use of instrumentation techniques without solvents. The search and study screening were performed in PubMed and Scopus databases by two independent researchers. A descriptive analysis considered the study design, method/technique used for obturation, method/technique used for instrumentation during retreatment, solvent solutions tested, exposure time, and main findings. A total of 41 studies were included. Despite that, most studies suggested that solvents' use may complicate root canal cleanliness, regardless of the type of instrumentation used, and facilitate the presence of gutta-percha remnants in the root surface. Thus, the use of solvents should be avoided and its use should only be considered if the previous working length was not possible to access without it. Despite that, high heterogeneity was observed, further studies are still encouraged comparing the performance and effects of different solvents in different clinical scenarios.

20.
Int J Oral Maxillofac Implants ; 35(6): 1209-1217, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33270062

RESUMO

PURPOSE: The aim of this study was to inspect the mechanical fatigue behavior of an implant-supported restorative system using polyether ether ketone (PEEK) and yttria partially stabilized zirconia polycrystals (YZ) as materials for customized definitive implant-supported hybrid abutments, supporting two types of all-ceramic restorations: translucent zirconia (TZ) and lithium disilicate (LD) monolithic crowns. MATERIALS AND METHODS: Forty Morse taper implants were included in epoxy resin. Titanium intermediary abutments were placed, and the specimens were randomly allocated into four groups (n = 10) according to the customized hybrid abutment material (PEEK or YZ) and the monolithic crowns (TZ or LD) representing a maxillary central incisor crown. The specimens were subjected to a mechanical fatigue test (step-stress analysis) by means of an initial 200-N load for 5,000 cycles and subsequent increase of 50 N (step-size) at each 10,000 cycles, until failure occurred. The load at failure and number of cycles until failure were recorded; survival probabilities and specimen displacement were calculated for each step. The failure pattern was evaluated, and the Weibull modulus was obtained for each condition. RESULTS: Fatigue of both types of crowns was not influenced by the abutment material (LD-PEEK = LD-YZ; TZ-PEEK = TZ-YZ). In the PEEK abutment, the values obtained in the LD and TZ crowns showed no statistical difference; however, in the YZ abutment, the TZ crown presented a load at failure value that was statistically higher than that for LD. Failure pattern analysis revealed a higher prevalence of crown fracture for LD groups, while screw/implant platform fractures were shown for TZ groups. CONCLUSION: YZ and PEEK hybrid abutments promoted similar fatigue levels regardless of the crown materials, TZ crowns promoted a higher fatigue level than LD ones when associated with YZ abutments, and LD crowns promoted a similar fatigue level to TZ ones when associated with PEEK custom abutments. Higher prevalence of crown fractures was shown for LD and screw/implant platform fractures for TZ groups.


Assuntos
Projeto do Implante Dentário-Pivô , Zircônio , Cerâmica , Coroas , Dente Suporte , Porcelana Dentária , Falha de Restauração Dentária , Análise do Estresse Dentário , Cetonas , Teste de Materiais , Polietilenoglicóis
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