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1.
J Oral Sci ; 63(2): 139-144, 2021 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-33597335

RESUMEN

PURPOSE: This study investigated the flexural properties, shear bond strength (SBS) and interface to dentin of three recently developed self-adhesive bulk-fill materials. METHODS: Bars of Surefil One (SO), Cention N (CN), Activa BioActive Restorative (AB) and EQUIA Forte HT Fil (EQUIA) were tested for flexural strength and flexural modulus in self-curing and light-curing modes. In addition, SBS to dentin was tested in specimens without pretreatment and after application of universal adhesive (Scotchbond Universal). EQUIA was used as the control material. RESULTS: The flexural properties were significantly better in light-curing mode for all materials except CN. CN had the highest SBS values after universal adhesive application (33.8 MPa), and SO had the highest SBS without pretreatment (20.9 MPa). CONCLUSION: The mechanical and adhesive properties of these new materials varied widely.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Resinas Compuestas , Cementos Dentales , Análisis del Estrés Dental , Dentina , Resistencia Flexional , Ensayo de Materiales , Resistencia al Corte , Propiedades de Superficie
2.
Dent Mater J ; 40(2): 487-497, 2021 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-33342921

RESUMEN

To investigate the degree of conversion (DC), Martens hardness (HM), elastic indentation modulus (EIT), and flexural strength (FS) of veneering resin composites (SR Nexco Paste (NP), Ceramage Incisal (CI), Gradia Plus (GP); n=60/group) cured with different polymerization devices (bre.Lux Power Unit, Labolight DUO, Otoflash G171, LC-3DPrint Box, PCU LED; n=12/subgroup) after storage. Otoflash G171 and Labolight DUO showed increased DC/HM/EIT. CI presented the lowest DC and highest HM/EIT. NP showed the highest DC and lowest HM/EIT. Within Otoflash G171, Laboligth DUO and PCU LED, highest FS was observed for CI. Storage did not affect DC/HM/EIT for specimens cured with Otoflash G171 or Labolight DUO. With storage not showing an influence on the tested parameters for polymerization devices that otherwise presented superior results, increased storage time cannot be recommended. For the tested resin composites, this study observed a high/low degree of conversion to coincide with respectively low/high amounts of fillers/mechanical properties.


Asunto(s)
Resinas Compuestas , Resistencia Flexional , Módulo de Elasticidad , Dureza , Ensayo de Materiales , Polimerizacion , Estrés Mecánico , Propiedades de Superficie
3.
Am J Dent ; 33(5): 243-247, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33017526

RESUMEN

PURPOSE: Concurrently with the growing interest in CAD-CAM systems, several new materials of different chemical nature have become available. As an alternative to ceramics, numerous polymer-based materials have recently been proposed for permanent prosthetic restorations. Aim of this study was to test the CAD-CAM polymer-based materials available on the market, comparing mean flexural strength, Weibull characteristic strength and Weibull modulus. METHODS: Seven types of polymer-based blocks were tested: Lava Ultimate, 3M; Brilliant Crios, Coltene; Cerasmart, GC; Block HC, Shofu; Katana Avencia, Noritake; Grandio Blocs, Voco; Tetric CAD, and Ivoclar-Vivadent. Specimens were cut out from blocks, finished, polished, and tested in a three-point bending test apparatus until failure (n=30). Flexural strength, Weibull characteristic strength, and Weibull modulus were calculated. Flexural strength data were statistically analyzed. ANOVA on Ranks was applied, followed by the Dunn's test for post hoc comparisons (P= 0.05). RESULTS: Flexural strength values (MPa) were measured (mean±standard deviation). Different letters in parentheses label statistically significant differences: Grandio Blocs 266±24(a), Brilliant Crios 259±21(ab); Tetric CAD 254±15(ab); Katana Avencia 241±29(bc); Cerasmart 221±24(cd); Lava Ultimate 196±23(de); Block HC 139±10(e). All the tested materials had flexural strengths greater than 100 MPa, thereby satisfying the requirements of ISO standards for polymer-based materials. For all the tested materials the Weibull characteristic strength was greater than 100 MPa. Weibull modulus ranged between 21.20 (Tetric CAD) and 9.09 (Katana Avencia). CLINICAL SIGNIFICANCE: Even though all the CAD-CAM polymer-based materials marketed in blocks tested in the present study satisfy the requirements of ISO standard for polymer-based materials, their flexural resistance differs significantly. The data presented in the study may be helpful to clinicians for selecting the most appropriate materials for each clinical case.


Asunto(s)
Resistencia Flexional , Polímeros , Diseño Asistido por Computadora , Materiales Dentales , Ensayo de Materiales
4.
Int J Prosthodont ; 33(5): 523-526, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32956433

RESUMEN

PURPOSE: To investigate the three-point flexural strength of a novel CAD/CAM fiber-reinforced composite (FRC) material following different aging conditions. MATERIALS AND METHODS: The specimens were randomly assigned to one of five groups based on aging condition: (1) control (no treatment); (2) short-term water storage; (3) thermal degradation with autoclaving; (4) chemical degradation with hydrochloric acid; and (5) chemical degradation with citric acid (n = 10 per group). The specimens in the control group received no treatment. Following each treatment protocol, the three-point bending test was used to calculate the flexural strength. Data were statistically analyzed (α = .05), and scanning electron microscopy (SEM) analysis of the specimens was conducted. RESULTS: No significant differences in flexural strength were observed among the groups (P = .199). In addition, no distinct morphologic differences were detected in the SEM images of the specimens. CONCLUSION: The flexural strength of this novel CAD/CAM FRC material was unaffected by different aging methods.


Asunto(s)
Resinas Compuestas , Resistencia Flexional , Diseño Asistido por Computadora , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Proyectos Piloto , Docilidad , Estrés Mecánico , Propiedades de Superficie
5.
Braz Dent J ; 31(4): 431-439, 2020 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-32901721

RESUMEN

The aim of this study was to evaluate the Streptococcus mutans biofilm influence on the roughness (Ra), gloss (GU), surface hardness (KHN) and flexural strength (FS) of high viscosity bulk fill composites. Filtek Bulk Fill (FBF), Tetric N Ceram Bulk Fill (TNC), X-tra fil Bulk Fill (XF) and Filtek Z350 (FZ) were used. Ten discs of each composite were prepared for Ra, KHN and GU and 20 bars for the FS. After 24 h, specimens were polished and initial analyzes performed. Samples were sterilized and subjected to biodegradation for 7 days and final analyzes performed. Representative samples of each group were evaluated in Scanning Electron Microscope. Data were submitted to ANOVA two factors and Tukey test. XF presented the highest values (p<0.05) of Ra before and after biodegradation (0.1251; 0.3100), and FZ (0.1443) the lowest after biodegradation (p<0.05). The highest GU values (p<0.05) were observed for FZ (71.7; 62) and FBF (69.0; 64.6), and the lowest (p<0.05) for TNC (61.4; 53.3) and XF (58.5; 53.5), both before and after biodegradation. For KHN the highest values were obtained by XF (151.7; 106), and the (p< 0.05) lowest values for TNC (62.2; 51.8), both before and after biodegradation. The highest values (p<0.05) of FS were observed for FZ (127.6) and the lowest (p<0.05) for TNC (86.9); after biodegradation, XF (117.7) presented the highest (p<0.05) values compared to TNC and FZ." In conclusion, biodegradation increased Ra and decreased GU and KHN for all. Concerning FS, degradation provided a significant decreased value only for FZ.


Asunto(s)
Resistencia Flexional , Streptococcus mutans , Dureza , Ensayo de Materiales , Propiedades de Superficie
6.
Braz Oral Res ; 34: e095, 2020 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-32901725

RESUMEN

The purpose of this study was to synthesize dicalcium phosphate dihydrate (DCPD) particles functionalized with triethylene glycol dimethacrylate (TEGDMA) through different routes by varying the receptor solution: ammonium phosphate (AP groups) or calcium nitrate (CN groups) and the moment in which TEGDMA was incorporated: ab initio (ab) or at the end of dripping the solution (ap). Two syntheses were performed without adding TEGDMA (nf). The particles were characterized by X-ray diffractometry, true density (using a helium pycnometer), surface area, and scanning electron microscopy. A 20 vol% of DCPD particles from the D, E, and F groups was added to the resin matrix to determine the degree of conversion (DC), biaxial flexural strength (BFS), the flexural modulus (FM), and surface roughness after an abrasive challenge (RA). A group with silanized barium glass particles was tested as a control. The data were submitted to ANOVA/Tukey's test (DC, BFS, and RA), and the Kruskal-Wallis test (FM) (alpha = 0.05). BFS values varied between 83 and 142 MPa, and the CN_ab group presented a similar value (123 MPa) to the control group. FM values varied between 3.6 and 8.7 GPa (CN_ab and CN_nf groups, respectively), with a significant difference found only between these groups. RA did not result in significant differences. The use of calcium nitrate solution as a receptor, together with ab initio functionalization formed particles with larger surface areas. Higher BFS values were observed for the material containing DCPD particles with a higher surface area. In general, the DC, FM, and RA values were not affected by the variables studied.


Asunto(s)
Polímeros/química , Resinas Compuestas , Resistencia Flexional
7.
Med. oral patol. oral cir. bucal (Internet) ; 25(5): e691-e699, sept. 2020. tab, graf, ilus
Artículo en Inglés | IBECS | ID: ibc-196526

RESUMEN

BACKGROUND: To assess the effect of implantoplasty and implant-abutment design on the fracture resistance and macroscopic morphology of narrow-diameter (3.5 mm) dental implants. MATERIAL AND METHODS: SCREW-shaped titanium dental implants (n = 48) were studied in vitro. Three groups (n = 16) were established, based on implant-abutment connection type: external hexagon, internal hexagon and conical. Eight implants from each group were subjected to an implantoplasty procedure; the remaining 8 implants served as controls. Implant wall thickness was recorded. All samples were subjected to a static strength test. RESULTS: The mean wall thickness reductions varied between 106.46 and 153.75 μm. The mean fracture strengths for the control and test groups were, respectively, 1211.90 ± 89.95 N and 873.11 ± 92.37 N in the external hexagon implants; 918.41 ± 97.19 N and 661.29 ± 58.03 N in the internal hexagon implants; and 1058.67 ± 114.05 N and 747.32 ± 90.05 N in the conical connection implants. Implant wall thickness and fracture resistance (P < 0.001) showed a positive correlation. Fracture strength was influenced by both implantoplasty (P < 0.001) and connection type (P < 0.001). CONCLUSIONS: Implantoplasty in diameter-reduced implants decreases implant wall thickness and fracture resistance, and varies depending on the implant-abutment connection. Internal hexagon and conical connection implants seem to be more prone to fracture after implantoplasty


No disponible


Asunto(s)
Resistencia Flexional , Diseño de Implante Dental-Pilar , Implantación Dental/métodos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Valores de Referencia , Análisis de Varianza , Factores de Tiempo , Propiedades de Superficie , Reproducibilidad de los Resultados
8.
Rehabilitación (Madr., Ed. impr.) ; 54(3): 162-172, jul.-sept. 2020. tab, graf
Artículo en Español | IBECS | ID: ibc-196732

RESUMEN

OBJETIVO: Definir el papel del fenómeno de flexión-relajación (FR), valorado mediante ratios (FRR), como test diagnóstico para definir una situación de déficit (impairment) en pacientes con dolor lumbar crónico (DLC). MATERIAL Y MÉTODO: La muestra del estudio consta de 180 sujetos, 16 voluntarios sanos y 164 pacientes en situación de incapacidad laboral por DLC, que fueron remitidos consecutivamente desde enero de 2012 a diciembre de 2017 para su valoración al laboratorio de biomecánica de una mutua de accidentes de trabajo. Las evaluaciones consistieron en un test de dinamometría isométrica, una prueba cinemática y una valoración del fenómeno FR. Se establecieron unos criterios mínimos en la ejecución de los test para ser aceptados como pruebas válidas para el estudio. El estado de déficit lumbar o de recuperación clínica en un paciente se definió a partir de los test de dinamometría y de cinemática. La respuesta FR se valoró con los FRR. Se tomaron un total de 4 ratios diferentes para el análisis con curvas ROC. RESULTADOS: Se obtuvieron 86 pruebas válidas (16 clasificadas como déficit lumbar y 71 como casos recuperados). La mejor ratio obtiene un área bajo la curva ROC de 0,87, una S: 0,84 y una E: 0,87 para identificarlos y un valor predictivo positivo del 97%. CONCLUSIONES: El test FR guarda con las evaluaciones de dinamometría y de cinemática una alta coherencia para objetivar una situación de déficit, siendo este una prueba de fácil ejecución por parte de los pacientes con DLC


OBJECTIVE: To define the role of the flexion-relaxation phenomenon (FRP), assessed through ratios (FRR), as a diagnostic test to define impairment in patients with chronic low back pain (CLBP). MATERIAL AND METHOD: The study sample consisted of 180 participants (16 healthy volunteers and 164 patients on work disability due to CLBP), who were consecutively referred for evaluation at the Biomechanics Laboratory of a workplace accident insurance company from January 2012 to December 2017. The evaluations consisted of an isometric dynamometry test, a kinematic test and assessment of the FRP phenomenon. Minimum criteria were established in the performance of the tests for their acceptance as valid for the study. Lumbar impairment or clinical recovery was defined on the basis of the results of the dynamometry and kinematic tests. The FRP response was assessed with FRRs. A total of 4 different ratios were taken for analysis with ROC curves. RESULTS: A total of 86 valid tests were obtained (16 classified as lumbar impairment and 71 as recovered cases). The best ratio obtained an area under the ROC curve of 0.87, with a sensitivity of 0.84, a specificity of 0.87, and a positive predictive value of 97%. CONCLUSION: The FRP test, along with dynamometry and kinematic evaluations, is effective in identifying lumbar impairment and is the easiest test for patients with CLBP to perform


Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Resistencia Flexional/fisiología , Relajación/fisiología , Dolor de la Región Lumbar/diagnóstico , Dolor de la Región Lumbar/rehabilitación , Dinamómetro de Fuerza Muscular , Fenómenos Biomecánicos/fisiología , Curva ROC , Sensibilidad y Especificidad , Estudios de Casos y Controles
10.
Braz Oral Res ; 34: e053, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32578763

RESUMEN

The objective was to evaluate the compressive strength (CS), diametral tensile strength (DTS), flexural strength (FS), and Knoop microhardness (KH) of different conventional restorative glass-ionomer cements (GICs) and to correlate these mechanical properties (MP) with the stabilization time (ST) of their chemical bonds. Eighteen GICs were tested: Bioglass [B], Chemfil Rock [CR], Equia Forte [EF], Gold Label 2 [GL2], Gold Label 9 [GL9], Glass Ionomer Cement II [GI], Ionglass [IG], Ion Z[ IZ], Ionomaster [IM], Ionofil Plus [IP], Ionostar Plus [IS], Ketac Molar Easymix [KM], Magic Glass [MG], Maxxion R [Ma], Riva Self Cure [R], Vidrion R [V], Vitro Fil [VF] and Vitro Molar [VM]. The mechanical strength tests were performed in a universal testing machine. KH readings were done with a diamond indenter. STs were examined by Fourier Transform Infrared spectroscopy (FTIR). Data were analyzed with ANOVA and Tukey test (p<0.05). The Spearman rank test was used to evaluate the dependence between the MPs and ST results. The highest MP values were EF, GL2, GL9, GI and KM and the lowest for MG, MA, B, VF and IM. The longest ST was for GL2 and the shortest was for B. ST correlated positively with MP. GICs with longer chemical bonds ST are generally stronger and the ST value obtained from FTIR was useful in predicting the strength of GICs tested.


Asunto(s)
Cementos de Ionómero Vitreo/química , Auto-Curación de Resinas Dentales/métodos , Análisis de Varianza , Fuerza Compresiva , Resistencia Flexional , Pruebas de Dureza , Ensayo de Materiales , Valores de Referencia , Reproducibilidad de los Resultados , Espectroscopía Infrarroja por Transformada de Fourier , Resistencia a la Tracción , Factores de Tiempo
11.
Braz Dent J ; 31(2): 127-134, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32556011

RESUMEN

The aim of this study was to assess the internal and vertical marginal fit of metallic copings to abutments and the fracture strength of different narrow diameter dental implant/abutments, either submitted to thermomechanical cycling or not. Sixty-four implant/abutments (n=16) were divided into 4 groups according to diameter and abutment type: G3.5-UAC (morse taper implant Ø3.5mm + universal abutment with beveled chamfer finish); G2.9-UAS (morse taper implant Ø2.9mm + universal abutment with shoulder finish); G2.8-AA (morse taper friction implant Ø2.8mm + anatomical abutment) and G2.5-HP (one-piece implant Ø2.5mm with indexed hexagonal platform). Each group was divided into two subgroups (n=8): submitted and not submitted to thermomechanical cycling (TMC). To assess internal and vertical marginal fit of metallic copings, the assemblies were scanned using microtomography (micro-CT) (n=5). The samples were subjected to the compressive strength test on a universal test machine. Group G3.5-UAC showed the highest marginal misfit regardless of TMC (p<0.05). All other groups were similar after TMC. Group G2.8-AA showed the lowest internal misfit both with and without TMC (p<0.05). Group G2.8-AA showed the highest fracture strength, similar only to G2.5-HP without TMC and G3.5-UAC with TMC. The type of abutment affects the internal and marginal fit of metallic copings and the anatomical abutment led to the best internal and marginal coping fit. The narrow diameter dental implant/abutments differ in terms of fracture strength, the strongest assembly was that composed by implant of type V grade titanium without internal threads (friction implant).


Asunto(s)
Implantes Dentales , Pilares Dentales , Diseño de Implante Dental-Pilar , Análisis del Estrés Dental , Resistencia Flexional , Ensayo de Materiales , Titanio , Circonio
12.
J Esthet Restor Dent ; 32(5): 505-511, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32564471

RESUMEN

OBJECTIVE: To assess the influence of time period on strength for different conventional Y-TZP porcelains. MATERIALS AND METHODS: Four types of porcelain were used. Porcelain powders were pressed in a steel die and fired in a furnace as recommended by the manufacturer. The blocks were sectioned into 2 mm-thick discs. Seventy specimens were fabricated from each type of porcelain. Of six jars, three contained 40 mL of dH2 O and three were dry. Ten specimens were placed in each jar and stored in an incubator at 37°C. A biaxial flexural strength test was performed for all specimens at the baseline and each succeeding year for all groups, for 3 years, using an Instron with a crosshead speed of 0.5 mm/min. RESULTS: The data were analyzed by ANOVA and Tukey at α = .05. At the baseline, the biaxial flexural strength of VitaVM9 was significantly higher than that of NobelRondo; however, there were no significant differences among Vita VM9 and Noritake CZR or NobelRondo, Lava Ceram, and Noritake CZR. There were significant reductions in the biaxial flexural strengths of all porcelains. CONCLUSIONS: After 3 years, all porcelain groups showed a significant decrease in biaxial flexural strength. The medium used is found to have no significant effects on the mean biaxial flexural strength. CLINICAL SIGNIFICANCE: Certain commercially available Y-TZP porcelains are susceptible to decrease in strength over time, which might impact the integrity of veneered zirconia restorations. This reduction in strength is among the most common reasons for the failure of veneered zirconia as reported in several studies.


Asunto(s)
Porcelana Dental , Coronas con Frente Estético , Análisis del Estrés Dental , Resistencia Flexional , Ensayo de Materiales , Propiedades de Superficie , Circonio
13.
Rev. Eugenio Espejo ; 14(1): 95-104, 20200615.
Artículo en Español | LILACS | ID: biblio-1117195

RESUMEN

Las restauraciones dentales con técnica indirecta fueron concebidas con el propósito de optimizar las propiedades mecánicas, físicas y químicas de los materiales polimerizados. En tal sentido, se realizó una investigación cuyo objetivo fue comparar restauraciones mediante la técnica indirecta utilizando resina híbrida (P60/3M) y un cerómero (Ceramage-Shofu), a través de la resistencia flexural y la estabilidad del color. Se realizó un estudio observacional comparativo en 30 muestras estructuradas en forma de bloques, distribuidas en 2 grupos, ambos con 15 piezas, en el primero (G1) se utilizó resina Filtek P60/3M; mientras que, en el segundo (G2) se empleó cerómero marca Ceramage-Shofu. el 80,00% de las piezas del grupo 1 evolucionó de A1 a B1; sin embargo, en el grupo 2 (piezas de resina), la transformación resultó desfavorable, más del 50% alcanzó una categoría imprecisa entre los valores B3 y B4. A través de la prueba U Mann Whitney se determinó la existencia de una diferencia significativa entre ambos grupos, así como entre los estados inicial y final del color de las piezas en ambos grupos (p<0,001). La prueba t de Student permitió comparar los valores medios, obteniéndose diferencias significativas (p<0,001), en cuanto a la resistencia observada en ambos materiales odontológicos. Los resultados relativos a la resistencia flexural y la estabilidad del color entre los dos biomateriales odontológicos analizados, permitió establecer una diferencia estadísticamente significativa entre estos.


Dental restorations using indirect technique were developed to optimize the mechanical, physical and chemical properties of the polymerized materials. In this sense, this research was carried out in order to compare restorations by the indirect technique using hybrid resin (P60 / 3M) and a ceromer (Ceramage-Shofu) through flexural resistance and color stability. A comparative and observational study was carried out in 30 samples structured in the form of blocks, distributed in 2 groups, 15 pieces each one; in the first (G1) Filtek P60 / 3M resin were analyzed; while, in the second (G2), Ceramage-Shofu brand ceromer was used. 80.00% of the pieces in group 1 evolved from A1 to B1; however, in group 2 (resin pieces), the transformation was unfavorable, more than 50% selecting an imprecise category between the B3 and B4 values. The U Mann Whitney test determined the existence of a significant difference between both groups, as well as between the initial and final states of the color of the pieces in both groups (p <0.001). The Student's t-test compares the mean values, obtaining different differences (p <0.001), regarding the resistance observed in both dental materials. The results related to flexural resistance and color stability between the two dental biomaterials analyzed establish a statistically significant difference between them.


Asunto(s)
Humanos , Masculino , Femenino , Materiales Biocompatibles , Color , Materiales Dentales , Propiedades Químicas , Materiales , Resistencia Flexional
14.
J Contemp Dent Pract ; 21(2): 114-118, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32381812

RESUMEN

AIM: Newer zirconia materials may have greater strength degradation under cyclic fatigue with increased yttria and cubic content. The purpose of this study was to evaluate the flexural strength (FS) degradation of newer zirconia materials compared to more traditional tetragonal zirconia materials. MATERIALS AND METHODS: The following materials were tested: two 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) materials (Lava Plus, 3M ESPE; Katana ML, Kuraray), one 4 mol% partially stabilized zirconia (4Y-PSZ) material (Katana STML, Kuraray), two 5 mol% partially stabilized zirconia (5Y-PSZ) materials (Katana STML, Kuraray; Lava Esthetic, 3M ESPE), and one lithium disilicate material (IPS e.max CAD LT, Ivoclar Vivadent). Thirty beams were milled for each ceramic material with final dimensions of 4.0 × 1.3 × 18.0 mm after sintering or crystallization. Each specimen was placed on a 3-point bend test device on a universal testing machine (Instron, Norwood, MA). Flexural strength was determined on 10 beam specimens per group with a central load applied until fracture. Flexural fatigue strength was then measured on the remaining 20 beam specimens per group using the staircase method for 6,000 cycles at 2 Hz. Data were analyzed with one-way ANOVAs/Tukey post hoc tests (α = 0.05). RESULTS: A significant difference was found between groups (p < 0.001) per property. The 3Y-TZP zirconia materials had the greatest flexural and flexural fatigue strength. The cubic containing zirconia materials performed more moderately. The lithium disilicate material had the lowest strength values. The percent degradation in flexural fatigue strength of the 3Y-TZP zirconia materials was less than the 5Y-PSZ, Katana UTML, and the 4Y-PSZ, Katana STML, cubic containing materials, but similar to the 5Y-PSZ cubic containing material, Lava Esthetic. CONCLUSION: The amount of strength degradation was material dependent, with the 4Y-PSZ or 5Y-PSZ cubic containing zirconia materials demonstrating greater or similar strength degradation compared to the primarily tetragonal 3Y-TZP zirconia materials. CLINICAL SIGNIFICANCE: The differences in FS degradation between cubic containing materials and traditional zirconia materials could significantly impact the long-term success of these newer materials. Clinicians should be aware that these cubic containing materials may perform differently long-term than the very strong traditional 3Y-TZP materials and to follow manufacturer instructions on required material thickness and indications for use to prevent premature failure of the restoration.


Asunto(s)
Materiales Dentales , Resistencia Flexional , Estética Dental , Ensayo de Materiales , Circonio
15.
Dent Mater J ; 39(5): 742-751, 2020 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-32418950

RESUMEN

The objective of this study was to examine the effects of storage conditions on the flexural strengths of resin composite materials for CAD/CAM restorations. Seven commercially available resin composite CAD/CAM blanks were examined. Rectangular specimens (4.0×1.2×4.0 mm) of each material were trimmed from the blanks and subjected to thermal cycling between 5°C and 55°C in deionized water at 10,000 cycles or stored in 37°C deionized water for one week or air for one day (n=10 for each condition). The difference in storage condition between water immersion and thermal cycling did not affect the flexural strengths of resin composite materials for CAD/CAM examined in this study. The resin composite block CS300 made from Bis-MEPP and UDMA showed the greatest flexural strength under all storage conditions and less deterioration of strength by thermal cycling and water immersion among the resin composite blocks tested.


Asunto(s)
Resinas Compuestas , Coronas , Diseño Asistido por Computadora , Resistencia Flexional , Ensayo de Materiales , Propiedades de Superficie
16.
J Esthet Restor Dent ; 32(5): 472-479, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32369271

RESUMEN

OBJECTIVES: The purpose of this in vitro study was to compare the effect of simulated endodontic access preparation on the failure loads of lithium disilicate crowns and resin-matrix ceramic (RMC) crowns. MATERIALS AND METHODS: Eighty maxillary first premolar crowns were manufactured by using four different CAD/CAM blocks (n = 20): lithium disilicate (LD; IPS e.max CAD), resin nanoceramic (RNC; Lava Ultimate), flexible nanaoceramic (FNC; GC Cerasmart), and polymer-infiltrated ceramic (PIC; VITA Enamic). Half of each group was accessed and repaired to simulate endodontic treatment. After cyclic loading, all specimens were loaded to failure. Data were analyzed with two-way ANOVA followed by Tukey-HSD test (α = .05). RESULTS: The load to failure results showed significant differences for material types (P < .001), but not for endodontic access simulation (P = .09). The highest and lowest mean failure loads were obtained for LD (1546 N) and PIC (843 N), respectively. CONCLUSION: The endodontic access preparation was not found to affect the fracture strength of LD and RMC crowns. The LD showed higher fracture strength than RMC crowns. Even though significant differences were noted for failure loads regarding different crown materials, all could reasonably withstand masticatory forces. CLINICAL SIGNIFICANCE: The endodontic access preparation through a restoration is known to be a common challenge in clinical practice. Maintaining a repaired LD or RMC crown is feasible and replacement may not be necessary.


Asunto(s)
Resistencia Flexional , Litio , Cerámica , Resinas Compuestas , Diseño Asistido por Computadora , Coronas , Porcelana Dental , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Ensayo de Materiales
17.
Dent Mater ; 36(7): 838-845, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32370908

RESUMEN

OBJECTIVE: This investigation tested pre-shaded 3Y-TZP materials on optical, mechanical and structural properties and calculated correlations between these properties. METHODS: Seven A2-shaded 3Y-TZP zirconia materials were investigated on translucency (T) via UV-vis-spectrophotometer, fracture load of 3-unit FDPs (FL), biaxial flexural strength (FS), Chevron-Notch Beam (CNB), fracture toughness (KIC) and Martens parameter (hardness: HM and indentation modulus: EIT). FL, FS and KIC were measured in a universal testing machine. The grain size was evaluated by scanning electron microscopy (SEM). Data was analyzed using one-way ANOVA followed by post hoc Scheffé, Kruskal-Wallis-, Mann-Whitney-U- and Pearson-test (p<0.05). RESULTS: For translucency, negative correlations were found with results of facture load (R=-0.444, p<0.001) and KIC (R=-0.503, p<0.001). While a positive correlation was found between translucency and flexural strength (R=0.238, p=0.019), between fracture load and EIT (R=0.227, p<0.029), between fracture load and KIC (R=0.362, p<0.001) as well as between fracture load and the grain size (R=0.598, p=0.007). While the grain size positively correlated with EIT (R=0.534, p=0.017) as well as EIT with HM (R=0.720, p<0.001). SIGNIFICANCE: Despite of being based on the same raw material, tested zirconia materials significantly differed regarding optical, mechanical (except biaxial flexural strength and Martens hardness) and structural properties. Materials with highest optical properties were those with lowest mechanical properties (CER, COP).


Asunto(s)
Resistencia Flexional , Mustelidae , Animales , Materiales Dentales , Dureza , Ensayo de Materiales , Propiedades de Superficie , Circonio
18.
Ned Tijdschr Tandheelkd ; 127(4): 245-253, 2020 Apr.
Artículo en Holandés | MEDLINE | ID: mdl-32459220

RESUMEN

The fracture strength of endodontically treated molars restored by means of various types of direct and indirect materials was studied in vitro. 105 sound molars were endodontically treated and randomly assigned to 1 control group (endodontic access cavity only) and 6 experimental groups (n = 15) with restorations of the following materials: glass fibre reinforced composite (GFRC); microhybrid composite (C); microhybrid composite restoration with glass fiber post (CP); full-contour lithium disilicate crown (LDS); full-contour lithium disilicate crown with glass fiber post (P-LDS); and an endocrown (EC). Specimens were thermo-mechanically aged and axially loaded until failure. Data were analysed using ANOVA and Tukey's post hoc test (α = 0.05). Fracture strength was significantly affected by the type of restoration (p = 0.000). LDS had significantly higher fracture strength than the control group and GFRC, C and CP groups. Groups EC, LDS and P-LDS were not statistically different from each other in fracture strength. This was also the case with EC, P-LDS and all composite groups. The glass fibre strength of composite restoration resulted in significantly fewer fatal fractures.


Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes , Diente no Vital , Resinas Compuestas , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Resistencia Flexional , Humanos , Ensayo de Materiales , Diente Molar
19.
Niger J Clin Pract ; 23(5): 720-728, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32367882

RESUMEN

Objective: To evaluate the effects of surface coating and 1-year water aging on flexural strength, compressive strength (CS) and surface roughness of fluoride-releasing restorative materials. Materials and Methods: The specimens were prepared from seven materials: GCP Glass Fill (GCP), Amalgomer CR (AHL), Zirconomer (Shofu), Fuji IX GP Capsule (GC), Beautifil II (Shofu), Estelite Σ Quick (Tokuyama), and reliaFIL LC (AHL). The specimens were randomly divided into two groups for each test: surface coated with G-Coat Plus (GC) and uncoated. Each group was subdivided into two groups stored in distilled water at 37°C for 24 h and 1 year before testing (n = 10). The flexural and CS were evaluated according to ISO standards on a universal testing machine. The surface roughness was assessed with AFM. After flexural strength test, a cross-section of the coated specimens was evaluated with SEM. Data were analyzed with one-way analysis of variance, Duncan and independent t-tests (P = 0.05). Results: After 24 h, a significant increase was observed on the flexural and CS of Amalgomer CR, Zirconomer, and Fuji IX GP by coating (P < 0.05). After 1 year, the coating increased the flexural strength of Amalgomer CR and Zirconomer, and CS of GCP Glass Fill (P < 0.05). The coating decreased the surface roughness of GCP Glass Fill, Amalgomer CR, and Zirconomer after 1 year (P < 0.05). The water aging decreased the mechanical properties of glass ionomer-based materials and increased their surface roughness (P < 0.05). Conclusion: The mechanical properties and surface roughness of glass ionomer-based materials were affected by coating and water aging.


Asunto(s)
Materiales Dentales/química , Fluoruros/química , Fuerza Compresiva , Resistencia Flexional , Ensayo de Materiales , Propiedades de Superficie , Factores de Tiempo , Agua
20.
Dent Mater ; 36(5): 592-602, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32317110

RESUMEN

OBJECTIVES: To optimize the nucleation mechanism in leucite glass-ceramics to allow more efficacious glass-ceramic manufacture and improvements in microstructure and mechanical reliability. MATERIALS AND METHODS: An alumino-silicate glass was designed and synthesized using melt quench methods. The glass was crushed and milled using various milling times (48-93h) and spray drying. Nucleation and growth heat treatment schedules were applied to synthesize glass-ceramics. Glass/glass-ceramic powders and frit specimens were characterized using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) and X-ray diffraction analyses (XRD). Glass-ceramic specimens were tested using the biaxial flexural strength test (BFS). RESULTS: Application of defined nucleation heat treatments resulted in the synthesis of Na/Ca titanates. NMR indicated changes to the 23Na glass spectra in the nucleated glass and TEM/EDX the presence of Na/Ca/Ti domains (<200nm) within the leucite crystals and associated with the nucleation of the leucite phase. XRD confirmed the presence of a bulk leucite phase in the glass-ceramics. SEM/TEM confirmed the crystallization of the leucite phase (65.5-69.3%) in a thermally matched glass, in conjunction with the nano Na/Ca titanate phase. The leucite glass-ceramics resulted in a high BFS (255-268MPa), with reduction in powder milling time prior to heat treatments having no significant effect on flexural strength and reliability (p>0.05). SIGNIFICANCE: Na/Ca titanates were synthesized in leucite glass-ceramics for the first time and associated with its nucleation and efficacious growth. This nucleation optimization provides opportunities for more efficient manufacturing and microstructural/mechanical reliability improvements. Improved synthesis of high strength/reliable leucite glass-ceramics is useful for construction of esthetic minimally invasive restorations.


Asunto(s)
Porcelana Dental , Resistencia Flexional , Silicatos de Aluminio , Cerámica , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Reproducibilidad de los Resultados , Propiedades de Superficie
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