RESUMO

STATEMENT OF PROBLEM: The mechanical strength of 3-dimensionally (3D) printed interim resins is unclear but influenced by printing parameters. Evidence regarding standardization of the postpolymerization type and time for 3D printed interim resins is sparse. PURPOSE: The purpose of this in vitro study was to evaluate the influence of postpolymerization type and time on flexural strength and dimensional stability of 3D printed resins for interim restorations. MATERIAL AND METHODS: A total of 288 bars were 3D printed (Form 2; Formlabs, stereolithography-SLA, 50 µm, 30 degrees), (25×2×2 mm; International Organization for Standardization-ISO 4049:2019) abraded and randomly divided into 9 groups (n=30) according to postpolymerization (Ultraviolet device-UV; Microwave with water-MWA; Microwave without water-MW) and time (15, 20, and 30 minutes for UV; and 5, 8, and 10 minutes for MW and MWA). Each bar was then measured with digital calipers at 11 points for length, thickness, and width before and after postpolymerization to analyze dimensional stability. The flexural strength was then measured (σ; 980.6 N, 1 mm/minute) and the fractured surfaces were analyzed with scanning electron microscopy. The σ (MPa) data were evaluated by using a 2-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) pairwise comparisons test (α=.05). Dimensional stability data (mm) were analyzed by using the Kruskal-Wallis test and Dwass-Steel-Critchlow-Fligner multiple comparisons. The Weibull analysis was performed with σ data. RESULTS: The 2-way ANOVA revealed that all factors and their interaction were significant for σ (P<.001). The UV groups presented the highest σ values, being statistically higher than all MW and MWA groups. The Weibull analysis revealed that postpolymerization UV groups found the highest values regarding the characteristic strength, although the MW 8-minute group (13.71) found the highest value for the Weibull modulus. Furthermore, the Kruskal-Wallis test revealed that only the postpolymerization factor was significant for dimensional stability (P<.001). The postpolymerization microwave groups found greater expansion variations at all times, with the MW 8-minute group (0.78 ±0.54) presenting the greatest variation in dimensional stability. CONCLUSIONS: UV was determined to be the most suitable type of postpolymerization for interim printed resin among the postpolymerization methods, regardless of the application time. The postpolymerization MW groups found greater variations in dimensional stability.

Assuntos

Resistência à Flexão , Estereolitografia , Teste de Materiais , Análise de Variância , Água , Impressão Tridimensional , Propriedades de Superfície

RESUMO

Bonding to different dental restorative materials is challenging. This study aimed to evaluate the effect of a 10-MDP-based dentin adhesive on the shear bond strength (SBS) of self-adhesive resin cement (RC) to implant abutment materials. One hundred and twenty specimens were obtained from zirconia (ZO), cobalt-chromium alloy (CoCr), and commercially pure titanium (Ti), which were treated as follows (n = 10): control group-non-treated (CG), 10-MDP-based dentin adhesive (SB), light-cured SB (SB-LC), and zirconia primer (ZP). Blocks of RC were buildup and, after 24 h, were tested for bond strength. Data of SBS (MPa) were submitted to two-way ANOVA and Tukey test (α = 0.05). There was no difference in SBS among materials for CG and ZP, higher SBS were recorded for Ti SB and Ti SB-LC compared to ZO upon the same surface treatments. For the comparisons among treatments, SB-LC showed the highest SBS for CoCr. For ZO and Ti, higher SBS were recorded with SB and SB-LC. No cohesive failures were observed. It was concluded that the surface treatment with 10-MDP-based materials increased the bond strength of the resin cement to abutment materials, which showed to be material dependent.

RESUMO

OBJECTIVES: This study evaluated the influence of two aging procedures on the biaxial flexural strength of yttria-stabilized tetragonal zirconia ceramics. MATERIAL AND METHODS: Disc-shaped zirconia specimens and (ZE: E.max ZirCAD, Ivoclar; ZT: Zirkon Translucent, Zirkonzahn) (N = 80) (∅:12 mm; thickness:1.2 mm, ISO 6872) were prepared and randomly divided into four groups (n = 10 per group) according to the aging procedures: C: Control, no aging; M: mechanical cycling (2 × 106 cycles/3.8 Hz/200 N); AUT: Aging in autoclave at 134°C, 2 bar for 24 h; AUT + M: Autoclave aging followed by mechanical cycling. After aging, the transformed monoclinic zirconia (%) were evaluated using X-ray diffraction and surface roughness was measured using atomic force microscopy. The average grain size was measured by scanning electron microscopy and the specimens were submitted to biaxial flexural strength testing (1 mm/min, 1000 kgf in water). Data (MPa) were statistically analyzed using 2-way analysis of variance and Tukey's test (α = 0.05). RESULTS: Aging procedures significantly affected (p = 0.000) the flexural strength data but the effect of zirconia type was not significant (p = 0.657). AUTZT (936.4 ± 120.9b ) and AUT + MZE (867.2 ± 49.3b ) groups presented significantly higher values (p < 0.05) of flexural strength than those of the control groups (CZT : 716.5 ± 185.7a ; CZE : 779.9 ± 114a ) (Tukey's test). The monoclinic phase percentage (%) was higher for AUTZE (71), AUTZT (66), AUT + MZE (71), and AUT + MZM (66) compared to the C groups (ZE:0; ZT:0). Surface roughness (µm) was higher for AUTZE (0.09), AUTZT (0.08), AUT + MZE (0.09 µm), and AUT + MZT (0.09 µm) than those of other groups. CONCLUSIONS: Regardless of the zirconia type, autoclave aging alone or with mechanical aging increased the flexure strength but also induced higher transformation from tetragonal to monoclinic phase in both zirconia materials tested. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1972-1977, 2017.

Assuntos

Cerâmica/química , Estresse Mecânico , Zircônio/química , Temperatura Alta , Pressão

RESUMO

OBJECTIVE: To determine the effects of different aging methods on the degradation and flexural strength of yttria-stabilized tetragonal zirconia (Y-TZP) METHODS: Sixty disc-shaped specimens (∅, 12mm; thickness, 1.6mm) of zirconia (Vita InCeram 2000 YZ Cubes, VITA Zahnfabrik) were prepared (ISO 6872) and randomly divided into five groups, according to the aging procedures (n=10): (C) control; (M) mechanical cycling (15,000,000 cycles/3.8Hz/200N); (T) thermal cycling (6,000 cycles/5-55°C/30s); (TM) thermomechanical cycling (1,200,000 cycles/3.8Hz/200N with temperature range from 5°C to 55°C for 60s each); (AUT) 12h in autoclave at 134°C/2bars; and (STO) storage in distilled water (37°C/400 days). After the aging procedures, the monoclinic phase percentages were evaluated by X-ray diffraction (XRD), and topographic surface analysis was performed by 3D profilometry. The specimens were then subjected to biaxial flexure testing (1mm/min, load 100kgf, in water). The biaxial flexural strength data (MPa) were analyzed by 1-way ANOVA and Tukey's test (α=0.05). The data for monoclinic phase percentage and profilometry (Ra) were analyzed by Kruskal-Wallis and Dunn's tests. RESULTS: ANOVA revealed that flexural strength was affected by the aging procedures (p=0.002). The M (781.6MPa) and TM (771.3MPa) groups presented lower values of flexural strength than did C (955MPa), AUT (955.8MPa), T (960.8MPa) and STO (910.4MPa). The monoclinic phase percentage was significantly higher only for STO (12.22%) and AUT (29.97%) when compared with that of the control group (Kruskal-Wallis test, p=0.004). In addition, the surface roughnesses were similar among the groups (p=0.165). SIGNIFICANCE: Water storage for 400 days and autoclave aging procedures induced higher phase transformation from tetragonal to monoclinic; however, they did not affect the flexural strength of Y-TZP ceramic, which decreased only after mechanical and thermomechanical cycling.

Assuntos

Cerâmica/química , Materiais Dentários/química , Ítrio/química , Zircônio/química , Algoritmos , Cristalografia , Imageamento Tridimensional/métodos , Teste de Materiais , Maleabilidade , Distribuição Aleatória , Estresse Mecânico , Propriedades de Superfície , Temperatura , Fatores de Tempo , Água/química , Difração de Raios X

RESUMO

OBJECTIVES: This study evaluated the influence of air-particle abrasion protocols on the surface roughness (SR) of zirconia and the shear bond strength (SBS) of dual-polymerized resin cement to this ceramic. MATERIALS AND METHODS: Sintered zirconia blocks (n = 115) (Lava, 3M ESPE) were embedded in acrylic resin and polished. The specimens were divided according to the 'particle type' (Al: 110 µm Al2O3; Si: 110 µm SiO2) and 'pressure' factors (2.5 or 3.5 bar) (n = 3 per group): (a) Control (no air-abrasion); (b) Al2.5; (c) Si2.5; (d) Al3.5; (e) Si3.5. SR (Ra) was measured 3-times from each specimen after 20 s of air-abrasion (distance: 10 mm) using a digital optical profilometer. Surface topography was evaluated under SEM analyses. For the SBS test, 'particle type', 'pressure' and 'thermocycling' (TC) factors were considered (n = 10; n = 10 per group): Control (no air-abrasion); Al2.5; Si2.5; Al3.5; Si3.5; ControlTC; Al2.5TC; Si2.5TC; Al3.5TC; Si3.5TC. After silane application, resin cement (Panavia F2.0) was bonded and polymerized. Specimens were thermocycled (6.000 cycles, 5-55°C) and subjected to SBS (1 mm/min). Data were analyzed using ANOVA, Tukey's and Dunnett tests (5%). RESULTS: 'Particle' (p = 0.0001) and 'pressure' (p = 0.0001) factors significantly affected the SR. All protocols significantly increased the SR (Al2.5: 0.45 ± 0.02; Si2.5: 0.39 ± 0.01; Al3.5: 0.80 ± 0.01; Si3.5: 0.64 ± 0.01 µm) compared to the control group (0.16 ± 0.01 µm). For SBS, only 'particle' factor significantly affected the results (p = 0.015). The SiO2 groups presented significantly higher SBS results than Al2O3 (Al2.5: 4.78 ± 1.86; Si2.5: 7.17 ± 2.62; Al3.5: 4.97 ± 3.74; Si3.5: 9.14 ± 4.09 MPa) and the control group (3.67 ± 3.0 MPa). All TC specimens presented spontaneous debondings. SEM analysis showed that Al2O3 created damage in zirconia in the form of grooves, different from those observed with SiO2 groups. CONCLUSIONS: Air-abrasion with 110 µm Al2O3 resulted in higher roughness, but air-abrasion protocols with SiO2 promoted better adhesion.

Assuntos

Abrasão Dental por Ar , Cimentos de Resina , Zircônio/química , Teste de Materiais , Microscopia Eletrônica de Varredura , Propriedades de Superfície

RESUMO

The purpose of this study was to evaluate the influence of zirconia surface treatments on low-temperature degradation (LTD). Disc-shaped specimens were subjected to one of four surface treatments, denoted as C (control-no surface treatment), Si (air abrasion with 30 µm silica-modified alumina particles), Al (air abrasion with 30 µm alumina particles), and Gr (grinding with 120 grit diamond discs). Half of the samples were submitted to autoclave treatment for 12 h (127°C, 1.5 bar). Samples were characterized by x-ray diffraction and profilometer analysis and were subjected to biaxial flexural strength test. All of the groups exhibited an increase in the amount of monoclinic phase (m-phase) after LTD. The t→m transformation was remarkable for the specimens from the C group, which also exhibited a significant increase in strength. The Gr group also exhibited an increase in strength but lower initial roughness, which probably suppressed LTD on the zirconia surface. The specimens subjected to air abrasion exhibited higher initial amounts of m-phase and a small increase in m-phase after LTD; the strength was not affected in these groups. The effects of LTD were different with each surface treatment applied. Apparently, LTD may be suppressed by smoother surfaces or the presence of an initial amount of m-phase on zirconia surface.

Assuntos

Materiais Biocompatíveis/química , Ítrio/química , Zircônio/química , Absorção , Ar , Porcelana Dentária/química , Diamante , Teste de Materiais , Distribuição de Poisson , Pressão , Reprodutibilidade dos Testes , Silício/química , Propriedades de Superfície , Temperatura , Difração de Raios X

RESUMO

OBJECTIVE: To determine whether the thickness, processing technique, and cooling protocol of veneer ceramic influence the flexural strength of a bilayer ceramic system. MATERIALS AND METHODS: Sixty-four bar-shaped specimens (20mm×4mm×1mm) of yttria-stabilized tetragonal zirconia (Vita In-Ceram YZ, Vita) were fabricated (ISO 6872) and randomly divided into 8 groups (n=8) according to the factors "processing technique" (P - PM9 and V - VM9), "thickness" (1mm and 3mm), and "cooling protocol" (S - slow and F - fast). The veneer ceramics were applied only over one side of the bar-shaped specimens. All specimens were mechanically cycled (2×10(6) cycles, 84N, 3.4Hz, in water), with the veneer ceramic under tension. Then, the specimens were tested in 4-point bending (1mm/min, load 100kgf, in water), also with the veneer ceramic under tension, and the maximum load was recorded at first sign of fracture. The flexural strength (σ) was calculated, and the mode of failure was determined by stereomicroscopy (30×). The data (MPa) were analyzed statistically by 3-way ANOVA and Tukey's test (α=0.05). RESULTS: ANOVA revealed that the factor "thickness" (p=0.0001) was statistically significant, unlike the factors "processing technique" (p=0.6025) and "cooling protocol" (p=0.4199). The predominant mode of failure was cracking. SIGNIFICANCE: The thickness of the veneer ceramic has an influence on the mechanical strength of the bilayer ceramic system, regardless of processing technique and cooling protocol of the veneer ceramic.

Assuntos

Cerâmica , Temperatura Baixa , Teste de Materiais

RESUMO

This study evaluated the effect of different air-particle abrasion protocols on the biaxial flexural strength and structural stability of zirconia ceramics. Zirconia ceramic specimens (ISO 6872) (Lava, 3M ESPE) were obtained (N=336). The specimens (N=118, n=20 per group) were randomly assigned to one of the air-abrasion protocols: Gr1: Control (as-sintered); Gr2: 50 µm Al2O3 (2.5 bar); Gr3: 50 µm Al2O3 (3.5 bar); Gr4: 110 µm Al2O3(2.5 bar); Gr5: 110 µm Al2O3 (3.5 bar); Gr6: 30 µm SiO2 (2.5 bar) (CoJet); Gr7: 30 µm SiO2(3.5 bar); Gr8: 110 µm SiO2 (2.5 bar) (Rocatec Plus); and Gr9: 110 µm SiO2 (3.5 bar) (duration: 20 s, distance: 10 mm). While half of the specimens were tested immediately, the other half was subjected to cyclic loading in water (100,000 cycles; 50 N, 4 Hz, 37 °°C) prior to biaxial flexural strength test (ISO 6872). Phase transformation (t→m), relative amount of transformed monoclinic zirconia (FM), transformed zone depth (TZD) and surface roughness were measured. Particle type (p=0.2746), pressure (p=0.5084) and cyclic loading (p=0.1610) did not influence the flexural strength. Except for the air-abraded group with 110 µm Al2O3 at 3.5 bar, all air-abrasion protocols increased the biaxial flexural strength (MPa) (Controlnon-aged: 1,030 ± 153, Controlaged: 1,138 ± 138; Experimentalnon-aged: 1,307 ± 184-1,554 ± 124; Experimentalaged: 1,308 ± 118-1,451 ± 135) in both non-aged and aged conditions, respectively. Surface roughness (Ra) was the highest with 110 µm Al2O3(0.84 µm. FM values ranged from 0% to 27.21%, higher value for the Rocatec Plus (110 µm SiO2) and 110 µm Al2O3 groups at 3.5 bar pressure. TZD ranged between 0 and 1.43 µm, with the highest values for Rocatec Plus and 110 µm Al2O3 groups at 3.5 bar pressure.

Assuntos

Ar , Cerâmica/química , Fenômenos Mecânicos , Transição de Fase , Zircônio/química , Temperatura Alta , Pressão , Propriedades de Superfície

RESUMO

The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (µTBS) between a feldspathic ceramic and two composites. Forty blocks (6.0 x 6.0 x 5.0 mm³) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm² ± 0.2 mm) were stored in distilled water at 37 degrees C for 30 days and submitted to thermocycling (7,000 cycles; 5 degrees C/55 degrees C ± 1 degree C). The µTBS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (a = 0.05). The surface treatments significantly affected the results (P < 0.05); no difference was observed between the composites (P > 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength.

Assuntos

Condicionamento Ácido do Dente/métodos , Cerâmica/química , Materiais Dentários/química , Silicatos de Alumínio/química , Resinas Compostas/química , Colagem Dentária , Polimento Dentário/métodos , Porcelana Dentária/química , Reparação em Prótese Dentária , Análise do Estresse Dentário/instrumentação , Humanos , Ácido Fluorídrico/química , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Compostos de Potássio/química , Cimentos de Resina/química , Silanos/química , Estresse Mecânico , Propriedades de Superfície , Temperatura , Resistência à Tração , Tionas/química , Fatores de Tempo , Triazinas/química , Água/química

RESUMO

Polymerization of indirect resin composites (IRC) is carried out in the 'laboratories using special photo-polymerization devices to achieve a higher degree of conversion (DC). Such devices present variation in chambers and light output which may have consequences on the chemical and physical properties of IRCs. This study evaluated the effect of different polymerization devices on the flexural strength, Vickers microhardness and DC of an IRC. Specimens were prepared from an IRC material, Sinfony (3M ESPE), using special molds for flexural strength test (N=30) (25 x 2 x 2 mm, ISO 4049), Vickers microhardness test (N=30) (5 x 4 mm) and for DC (N=30) utilizing Micro-raman Spectroscopy. All specimens were submitted to initial polymerization with a Visio Alpha unit (3M ESPE) and then randomly divided into three groups (n=10/ group). Specimens in Group 1 (control) received additional polymerizations using a Visio Beta Vario device (3M ESPE), and those in Group 2 and Group 3 using Powerlux (EDG) and Strobolux (EDG) devices, respectively. DC and mechanical tests were then conducted. For the mechanical tests, the data were analyzed using ANOVA and Tukey's tests (p < 0.05) and for DC, one-way ANOVA was used. Polymerization in Strobolux (Group 3) resulted in significantly lower flexural strength (MPa) values (134 +/- 27) compared to Visio Beta Vario (165 +/- 20) (Group 1) (p < 0.05). The lowest microhardness values (Kg/mm2) were obtained in Group 3 (30 +/- 1) (p < 0.05). DC was similar in all groups (75 +/- 1, 91 +/- 5, 85 +/- 7% for Visio Beta Vario, Powerlux and Strobolux, respectively) (p = 0.1205). The type of polymerization device may affect the flexural strength and Vickers hardness of the IRC tested. DC also seems to be affected by the type of polymerization device but the results were not significant.

Assuntos

Resinas Compostas , Polimerização , Desenho de Equipamento , Testes de Dureza , Teste de Materiais