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1.
Acta Odontol Latinoam ; 33(2): 98, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32920611

RESUMEN

The aim of the current study was to compare the effect of two lithium disilicate ceramic processing techniques (pressing and CAD/CAM) on the degree of conversion of resin cement when it is photoactivated and the microshear bond strength of resin cement to ceramics. Two ceramic discs were manufactured: one by the Press technique and another by CAD/CAM technique. Five Variolink Veneer resin cement samples were photoactivated through each ceramic disc and subjected to attenuated total reflectance Fourier transform infrared spectroscopy to evaluate their degree of conversion. To evaluate microshear bond strength, 20 ceramic bars were prepared: 10 using the Press technique and 10 using the CAD/CAM technique. The bars were air abraded with 50-µm Al2O3 particles, treated with 10% hydrofluoric acid for 20 s and subjected to RelyX Ceramic Primer application. Adper Scotchbond Multi-Purpose Adhesive was applied to the bars and cured for 10 s. Two 1-mm-height plastic tubes were placed on each bar and filled with Variolink Veneer resin cement. Each cylinder was cured for 20 s. Then the plastic tubes were removed and the microshear bond strength of each cylinder was tested. Data for degree of conversion (%) and microshear bond strength (MPa) were subjected to Student's t-test (α = 0.05). Both degree of conversion of resin cement photoactivated through ceramic and microshear bond strength of resin cement to ceramic were statistically higher in the group in which ceramic was prepared by CAD/CAM technique (44.74% and 22.18 MPa) than in the group in which the ceramic was prepared by the Press technique (25.71% and 19.83 MPa). The lithium disilicate ceramic processing techniques affected the degree of conversion of resin cement when it is photoactivated through the ceramics and the microshear bond strength of resin cement to ceramics.


Asunto(s)
Cerámica/química , Recubrimiento Dental Adhesivo , Porcelana Dental/química , Cementos de Resina/química , Humanos , Ensayo de Materiales , Propiedades de Superficie
2.
Braz Oral Res ; 34: e018, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32187304

RESUMEN

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.


Asunto(s)
Silicatos de Aluminio/química , Recubrimiento Dental Adhesivo/métodos , Ácido Fluorhídrico/química , Ácidos Fosfóricos/química , Compuestos de Potasio/química , Análisis de Varianza , Porcelana Dental/química , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Valores de Referencia , Reproducibilidad de los Resultados , Cementos de Resina/química , Resistencia al Corte/efectos de los fármacos , Silanos/química , Propiedades de Superficie , Factores de Tiempo
3.
Braz Oral Res ; 34: e004, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32022223

RESUMEN

The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.


Asunto(s)
Cerámica/química , Diseño Asistido por Computadora , Porcelana Dental/química , Vidrio/química , Análisis de Varianza , Recubrimiento Dental Adhesivo/métodos , Resistencia Flexional , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Porosidad , Valores de Referencia , Reproducibilidad de los Resultados , Cementos de Resina/química , Resistencia al Corte , Propiedades de Superficie , Difracción de Rayos X
4.
Niger J Clin Pract ; 23(1): 1-6, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31929199

RESUMEN

Objective: The aim of this study was to evaluate the marginal adaptation and fracture resistance of feldspathic and Polymer-Infiltrated Ceramic Network (PICN) CAD/CAM endocrowns for maxillary premolars. Materials and Methods: Twenty extracted human permanent maxillary premolars were randomly divided into two groups (n = 10); Group CEREC (GC), which was produced by feldspathic ceramic and the Group Enamic (GE), which was produced by PICN. All teeth were endodontically treated and decoronated horizontally at 2 mm above the cemento-enamel junction. Endocrown preparations were done with 4 mm depth into the pulp chamber. Endocrowns were manufactured using CAD/CAM from ceramic blocks. Following adhesive cementation, all specimens were subjected to thermocycling. Marginal adaptation evaluated under SEM at 200 × magnification. Each specimen was fixed in a universal testing machine and a compressive load was applied at 45° to long axis of the teeth until failure. Failure load was recorded and failure modes were evaluated. Statistical analyses were performed with SPSS 19.0 software and data were compared using Mann-Whitney U test. Results: There were no significant differences in the marginal adaptation between two groups (P > 0.05). GE presented significantly higher fracture resistance when compared to GC (P < 0.05). Failure pattern was similar and characterized by the tooth-ceramic fracture on the force-applied side. Conclusions: CAD/CAM fabricated feldspathic ceramic and PICN endocrowns provide sufficient marginal adaptation, but the PICN endocrowns shows higher fracture resistance than the feldspathic ceramic endocrowns.


Asunto(s)
Diente Premolar/fisiopatología , Cerámica/química , Coronas , Porcelana Dental/química , Diseño de Prótesis Dental/métodos , Polímeros , Fracturas de los Dientes/fisiopatología , Diseño Asistido por Computadora , Preparación de la Cavidad Dental/métodos , Porcelana Dental/uso terapéutico , Diseño de Prótesis Dental/efectos adversos , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Cementos de Resina , Estrés Mecánico , Cuello del Diente/lesiones
5.
Braz Oral Res ; 33: e121, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31939500

RESUMEN

The objective of the study was to analyze the surface area (SA) of the wear caused by simulated chewing on human enamel and opposing restorative material, namely: composite resin (CR), porcelain fused to metal (PFM), lithium disilicate (LD), or monolithic zirconia (MZr). Forty-eight premolars were selected as enamel specimens and divided randomly into 4 groups (n = 48; n =12) used as antagonists in chewing simulation (250,000 loading cycles) against one of the four selected test materials. Enamel and material specimens were scanned and evaluated under digital microscope, and wear SA (mm2) were recorded. Descriptive statistics, paired t-test, one-way ANOVA, and post-hoc Tukey-HSD tests were used for statistics (p < 0.05). The smallest and largest SA were exhibited by enamel against LD (0.80 mm2) and PFM (1.74 mm2), respectively. PFM (3.48 mm2) showed the largest SA and CR (2.28 mm2) showed the smallest SA. Paired t-test for SA values showed significant difference (p < 0.05) in all wear comparisons between materials and enamel antagonists. The wear of materials were greater than that of their respective enamel antagonists (p < 0.05). One-way ANOVA of the logarithmic means of wear SA revealed significant differences (P<0.05). Post-hoc Tukey test revealed significance for PFM (p < 0.05) with other materials. Wear of all test materials was greater compared to the wear of enamel antagonists. PFM and LD caused the largest and the smallest enamel wear, respectively. CR, LD, and MZr are more resistant than PFM to wear after simulated chewing against enamel.


Asunto(s)
Resinas Compuestas/química , Esmalte Dental/química , Porcelana Dental/química , Masticación , Aleaciones de Cerámica y Metal/química , Desgaste de los Dientes/etiología , Circonio/química , Adolescente , Adulto , Análisis de Varianza , Pulido Dental/métodos , Humanos , Procesamiento de Imagen Asistido por Computador , Ensayo de Materiales , Microscopía/instrumentación , Valores de Referencia , Estadísticas no Paramétricas , Propiedades de Superficie , Adulto Joven
6.
J Appl Biomater Funct Mater ; 17(4): 2280800019836832, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31621471

RESUMEN

BACKGROUND: This in-vitro study examined the impact of storage solution, storage duration, and storage temperature on discoloration of three tooth-colored CAD/CAM materials for final restorations. METHODS: Specimens (N = 288; n = 96 per material) with a thickness of 1 ± 0.03 mm of the following CAD/CAM materials were fabricated: resin composite (Lava Ultimate, 3M), polymer-infiltrated ceramic (VITA Enamic, VITA Zahnfabrik), and leucite ceramic (IPS Empress CAD, Ivoclar Vivadent). After baseline measurement, specimens were stored in red wine, curry solution, cress solution, and distilled water at 37°C or 55°C. The discoloration was measured using a spectrophotometer (Lambda 35 Perkin Elmer, Perkin Elmer Inc.) after 1 and 7 days storage. Data were analyzed using four-way ANOVA followed by the Scheffé post-hoc test and partial eta squared (ηP²) test (p < 0.05). RESULTS: The highest influence on ∆E was exerted by storage duration (ηP² = 0.295, p < 0.001), followed by storage solution (ηP² = 0.171, p < 0.001), CAD/CAM material (ηP² = 0.049, p < 0.001), and storage temperature (ηP² = 0.033, p < 0.001). Specimens stored for 7 days in staining solutions showed more discoloration than those stored for just 1 day. Higher ∆E values were achieved for specimens stored in curry solution, followed by red wine, cress solution, and distilled water. Resin composite Lava Ultimate showed larger ∆E values compared with the resin hybrid ceramic VITA Enamic and leucite ceramic IPS Empress CAD. Specimens stored at 37°C showed significantly less discoloration than those stored at 55°C. CONCLUSIONS: The degree of coloration of the materials depends on food and temperature and was most pronounced with Lava Ultimate.


Asunto(s)
Resinas Acrílicas/química , Silicatos de Aluminio/química , Cerámica/química , Resinas Compuestas/química , Porcelana Dental/química , Calor , Poliuretanos/química , Diente , Color , Humanos , Propiedades de Superficie
7.
J Dent ; 90: 103210, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31600535

RESUMEN

OBJECTIVES: The present study examined the effects of Na+→K+ ion-exchange on the wear performance of feldspathic veneering porcelain. METHODS: Bar and disk specimens were prepared using IPS classic as the feldspathic veneering porcelain. After ion-exchange by immersion of the specimens in melted KNO3 at two temperatures for different time-periods, the bars were tested for flexural strength and Vickers surface hardness. The disks were paired with zirconia antagonists and tested with a pin-on-disk tribometer with 10 N for 70☓104 wear cycles in artificial saliva. Wear analysis of the porcelain and zirconia was performed using 3D profilometer and analysed with one-way analysis of variance and Tukey's post-hoc pairwise comparison procedures. Worn surfaces were examined with scanning electron microscopy. RESULTS: The feldspathic veneering porcelain exhibited strong time-dependent wear behaviour, with typical running-in and steady wear stages. Ion-exchange treatments at 380 °C and 440 °C both enhanced the mechanical properties, decreased the wear rates of running-in wear and steady wear. The wear performance of porcelain treated by ion-exchange at lower temperature (380 °C) was improved significantly, especially reducing the wear rate of the running-in stage. CONCLUSION: A thicker ion-exchange layer with less stress relaxation may be obtained by ion-exchange at lower exchange temperature for a long processing time. Such a protocol improves the wear performance of the porcelain effectively. CLINICAL SIGNIFICANCE: Restorations with veneering porcelain may fail prematurely due to excessive wear. It important to improve the wear performance of the porcelain. Ion-exchange has the potential to strengthen dental veneering porcelain. Understanding the effect of ion-exchange on the wear performance of porcelain provides insight improving the wear performance of these restorations.


Asunto(s)
Porcelana Dental/química , Coronas con Frente Estético , Circonio/química , Alisadura de la Restauración Dental , Análisis del Estrés Dental , Dureza , Humanos , Ensayo de Materiales , Propiedades de Superficie
8.
Braz Oral Res ; 33: e041, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31508723

RESUMEN

The objective of this study was to evaluate the effect of the hydrofluoridric acid (HF) concentration and time of acid conditioning on bond strength of three glass ceramics to a resin cement. Thus, fifty blocks (10 mm x 5 mm x 2 mm) of each ceramic (LDCAD: IPS e.max CAD; LCAD: IPS Empress CAD and LDHP: IPS e.max Press) were made and embedded in acrylic resin. The surfaces were polished with sandpaper (#600, 800, 1000, and 1200 grits) and blocks were randomly divided into 15 groups (n = 10) according to the following factors: Concentration of HF (10% and 5%), conditioning time (20 s and 60 s) and ceramic (LDCAD, LDHP, and L). After conditioning, silane (Prosil / FGM) was applied and after 2 min, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block using a Teflon strip as matrix and light cured for 40 s (1,200 mW/cm2). Then, the samples were thermocycled (10,000 cycles, 5/55°C, 30s) and submitted to the shear bond test (50 KgF, 0.5 mm/min). The data (MPa) were analyzed with 3-way ANOVA and Tukey's test (5%). Failure analysis was performed using a stereomicroscope (20x) and a scanning electron microscope (SEM). ANOVA revealed that the "concentration" factor (p = 0.01) and the interaction "acid concentration X ceramic" (p = 0.009) had a significant effect, however, the "ceramic" (p = 0.897) and "conditioning time" (p = 0.260) factors did not influence the results. The LDHP10%60s (10.98 MPa)aA* group presented significantly higher bond strength than LDHP10%20s (6.57 MPa)bA, LCAD5%20s (6,90 ±3,5)aB and LDHP5%60s (5.66 ± 2,9MPa)aA* groups (Tukey). Failure analysis revealed that 100% of specimens had mixed failure. In conclusion, etching with 5% HF for 20 seconds is recommended for lithium disilicate and leucite-reinforced CAD/CAM ceramics. However, for pressed lithium disilicate ceramic, 10% HF for 60 s showed significantly higher bond strength to resin cement.


Asunto(s)
Grabado Ácido Dental , Cerámica/química , Recubrimiento Dental Adhesivo/métodos , Ácido Fluorhídrico/administración & dosificación , Porcelana Dental/química , Análisis del Estrés Dental , Ácido Fluorhídrico/química , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Cementos de Resina/química , Resistencia al Corte , Propiedades de Superficie , Factores de Tiempo
9.
Braz Oral Res ; 33: e009, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31508728

RESUMEN

This study investigates the color correspondence of resin cements and try-in pastes, and the color stability of bonded lithium disilicate ceramic disks. Resin composite disks were fabricated (n = 36) to serve as the background for lithium disilicate disks prepared in two thicknesses (0.5 and 1.0 mm, n = 18 each). Two brands were used for try-in and cement procedures: Variolink Veneer and AllCem Veneer. For baseline, water was applied between the ceramic disks and their respective backgrounds to achieve the control group. This set was subjected to color measurement using an intraoral measurement device (T0). The try-in was inserted between background and ceramic, and this set was subjected to color measurement (T1). After adhesive procedures, the ceramic disk was placed under cement, and color measurement was performed with uncured cement (T2) and 24 h after light-curing (T3). Each set was immersed in distilled water and thermal-cycled, with color measurement being performed after 10,000 (T4) and 20,000 (T5) cycles. Color differences were calculated by CIELab (rEab) and CIEDE2000 (rE00). Data were analyzed by two-way ANOVA for repeated measurements and Tukey's test (α=5%). There was color correspondence of try-in and resin cement for the Variolink system, regardless of the ceramic thickness (p > 0.05). For the AllCem system, the thickness significantly influenced the color measurement (p < 0.001). The Variolink system also demonstrated color stability after 20,000 thermal cycles with rEab < 3.46 and rE00 < 2.25. It was concluded that the color correspondence between a try-in and its respective cement may vary according to resin cement composition.


Asunto(s)
Color , Porcelana Dental/química , Cementos de Resina/química , Cerámica/química , Coronas con Frente Estético , Técnicas In Vitro , Ensayo de Materiales , Pomadas/química
10.
Biomed Mater Eng ; 30(4): 365-374, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31476141

RESUMEN

BACKGROUND: Ceramic crown that fires the layering porcelain on zirconia corping is starting to be used due to aesthetic requirements. However, many ceramics are used, but wear characteristics are often unknown. OBJECTIVE: This study was performed to investigate the wear of human enamel by porcelains, and to determine the influence of porcelain hardness, surface roughness and crystal of porcelain on the enamel wear. METHODS: Enamel specimens were prepared from extracted human molar teeth. Porcelain specimens were prepared from Deguceram Gold, Vita Omega 900, and Cercon Ceram Kiss. Enamel wear volume was calculated and the porcelain wear depth, surface roughness and Vickers hardness was measured. Moreover, the observation of a crystal by scanning electron microscope and the crystal by X-ray diffraction were identified. RESULTS: Omega 900 showed the smallest enamel wear volume and porcelain wear depth. The Vickers hardnesses of Omega 900 and Cercon Ceram Kiss were almost identical. Leucite was detected from Deguceram Gold and Omega 900, and Silica and Silicon Nitride were detected from Cercon Ceram Kiss. CONCLUSIONS: The enamel wear is influenced not by the hardness of the porcelain but by the surface roughness, the size and shape of the crystal.


Asunto(s)
Coronas , Esmalte Dental/anatomía & histología , Porcelana Dental/química , Coronas/efectos adversos , Cristalización , Esmalte Dental/química , Porcelana Dental/efectos adversos , Alisadura de la Restauración Dental/efectos adversos , Dureza , Humanos , Ensayo de Materiales , Propiedades de Superficie , Difracción de Rayos X
11.
J Mech Behav Biomed Mater ; 100: 103389, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31398693

RESUMEN

The present study elucidates the mechanical performance of different designs of resin-bonded fixed dental prostheses made of lithium disilicate simulating masticatory loads of anterior or canine guidance. A three-dimensional model of maxilla was constructed containing central incisor and canine teeth, with edentulous space of the lateral incisor. Three designs of prosthesis were created: retained in central incisor (1-I), retained in canine (1-C) and fixed in both teeth (2-IC). The computational analysis was performed for load in canine and central incisor separately (100N, 45°). The tensile and shear stresses were calculated for the resin-bonded fixed dental prosthesis, bonding surface of each retainer and cement layer using 3D finite element analysis. The 20 highest stress values were analyzed using two-way ANOVA and post-hoc Tukey test, all with α = 5%. The computational analysis showed that 2-retainer resin-bonded fixed dental prosthesis presented the worst prognosis regardless of the mandibular movement. ANOVA showed that Mandibular movement*Retainer interaction influenced on the tensile and shear stresses values (p < 0.01). Higher stresses were observed in the connector region for all groups (13-82.2 MPa; 11-70.2 MPa). In order to reduce the stress concentration in the resin-bonded fixed dental prosthesis and the retainer made of lithium disilicate, the occlusion may serve as the selection criteria of the unitary abutment for better sustainability.


Asunto(s)
Porcelana Dental/química , Prótesis Dental , Análisis del Estrés Dental/métodos , Imagenología Tridimensional/métodos , Aparatos Ortodóncicos Fijos , Resinas Sintéticas , Simulación por Computador , Diente Canino/fisiología , Análisis de Elementos Finitos , Humanos , Incisivo/fisiología , Mandíbula/fisiología , Ensayo de Materiales , Maxilar , Pronóstico , Resistencia al Corte , Estrés Mecánico , Resistencia a la Tracción , Diente/fisiología
12.
PLoS One ; 14(8): e0220551, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31393888

RESUMEN

The purpose of the investigation was to analyze fracture resistance and mode of failure of zirconium oxide (zirconia) abutments placed on dental implants bearing crowns of different esthetic materials: zirconia, lithium disilicate (LDS), and nano-ceramic resin, for replacing single teeth in the anterior sector. Eighty implant-abutment-crown units were divided into four groups: Group T-MC (control): 20 metal-ceramic crowns cemented onto titanium abutments; Group Z-Z: 20 zirconia crowns on zirconia abutments; Group Z-LD: 20 lithium disilicate crowns on zirconia abutments; and Group Z-NCR: 20 nano-ceramic resin crowns on zirconia abutments. Specimens underwent a fatiguing process (dynamic loading and thermocycling), followed by static loading to evaluate mechanical fracture resistance, and the mode of failure produced. Mean fracture resistance values were: Control Group T-MC, 575.85±120.01 N; Group Z-Z 459.64±66.52 N; Group Z-LD, 531.77±34.10 N; and Group Z-NCR, 587.05±59.27 N. In Group T-MC, fracture occurred in the prosthetic fixing screw in 100% of specimens. In Group Z-Z, 80% of fractures occurred in the fixing screw, 15% in the abutment, and 5% in the abutment and crown. In Group Z-LD, 60% of fractures were produced in the fixing screw and 40% in the abutment. In Group Z-NCR, 70% of fractures were produced in the fixing screw and 30% in the abutment. All the abutments and crowns analyzed have the potential to withstand the physiological occlusal forces to which they would be subject in the anterior region. Lithium disilicate and nano-ceramic resin crowns cemented onto zirconia abutments are a good restoration alternative for single implants in the anterior sector.


Asunto(s)
Coronas , Implantes Dentales , Fracaso de la Restauración Dental , Ensayo de Materiales , Circonio/química , Cemento Dental/química , Porcelana Dental/química , Humanos
13.
J Dent ; 89: 103178, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31394121

RESUMEN

OBJECTIVES: The purpose of this prospective study was to evaluate the clinical long-term outcome over 15 or more years of crown-retained fixed dental prostheses (FDPs) made from a lithium disilicate ceramic (IPS e.max Press, Ivoclar Vivadent AG). METHODS: Thirty-six three-unit FDPs replacing anterior (16%) and posterior (84%) teeth were inserted in 28 patients. Abutment teeth were prepared following a standardized protocol. The size of the proximal connector of the FDPs was 12 mm² (anterior) or 16 mm² (posterior). FDPs were cemented either conventionally with glass-ionomer cement (n = 19) or adhesively with composite resin (n = 17). The following parameters were evaluated at baseline, 6 months after cementation and then annually (at abutment and contralateral teeth): probing pocket depth, plaque index, bleeding on probing, and tooth vitality. RESULTS: Three FDPs were defined as drop-outs. The mean observation period of the remaining 33 FDPs was 167 months (range: 79-225 months). The survival rate (survival being defined as FDPs remaining in place either with or without complications) according to Kaplan-Meier was 48.6% after 15 years. The success rate (success being defined as free of complications and remaining unchanged) was 30.9% after 15 years. CONCLUSIONS: Fatigue and crack propagation caused by clinical aging in monolithic lithium disilicate ceramics seem to take considerable time, as shown by the presented survival and success rates after 15 years. Further long-term studies are necessary to evaluate the reliability of FDPs made from other all-ceramic materials over a period of 15 or more years.


Asunto(s)
Cerámica/química , Porcelana Dental/química , Fracaso de la Restauración Dental , Dentadura Parcial Fija , Humanos , Estimación de Kaplan-Meier , Estudios Prospectivos , Reproducibilidad de los Resultados , Tasa de Supervivencia , Resultado del Tratamiento , Circonio
14.
BMC Oral Health ; 19(1): 178, 2019 08 06.
Artículo en Inglés | MEDLINE | ID: mdl-31387557

RESUMEN

BACKGROUND: The aim of this study was to evaluate the effect of universal adhesives (UA) and silane on the microtensile bond strength (µTBS) of resin cement to a hybrid ceramic Vita Enamic (VE). METHODS: VE specimens were acid etched using hydrofluoric acid (HF) and were assigned to three groups (n = 10) based on the applied bonding technique. In group 1 (S), a silane-based primer was used as a surface treatment prior to the application of a resin cement (Variolink Esthetic DC). In group 2, a silane-containing UA, Clearfil Universal Bond (CUB) was used for the surface treatment, and in group 3, A silane-free UA, Tetric N-Bond Universal (TNU) was used for surface treatment. Resin cement build-ups were prepared. The bonded specimens were sectioned into resin-ceramic beams. Half of the beams of each group were stored for 24 h at 37 °C and the other half were subjected to a thermo-cycling aging. The microtensile bond strength (µTBS) was measured at a crosshead speed of 0.5 mm/min. Failure modes were assessed accordingly. Data were analyzed using a) two-way analysis of variance ANOVA followed by one-way ANOVA and Tukey tests between groups and b) independent t-test to detect differences (α = 0.05) for each group. The surface topographies of the ceramic surface were evaluated using scanning electron microscopy. RESULTS: The results showed that silane-based primer (S) application resulted in significantly higher (p < 0.05) µTBS values after 24 h and after thermocycling compared to both silane-containing UA (CUB) and silane-free UA (TNU). The µTBS values of all groups were significantly reduced after thermocycling. No statistically significant difference was observed between the µTBS of CUB and TNU after 24 h. However, TNU showed significantly higher µTBS after thermocycling. Different failure modes were observed, and adhesive failure was the most common in all groups. Marked surface topographic changes were observed following HF etching. CONCLUSION: It is concluded that, the UAs tested cannot be recommended as substitutes to the silanization of Hybrid ceramic.


Asunto(s)
Cerámica/química , Recubrimiento Dental Adhesivo , Cementos de Resina/química , Grabado Ácido Dental , Cementos Dentales , Grabado Dental/métodos , Porcelana Dental/química , Análisis del Estrés Dental , Estética Dental , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Resistencia a la Tracción
15.
J Appl Oral Sci ; 27: e20180351, 2019 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-31365707

RESUMEN

OBJECTIVE: Since the transmittance of ceramics can influence the degree of conversion (DC) of resin cements, ceramics composition and shade should be considered in the selection of resin cement. This in vitro study aimed to evaluate the effect of the transmittance of different composition, opacities and shades of ceramics on the degree of conversion of two dual-cured resin cements. METHODOLOGY: Sixty discs were prepared from low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, and zirconia ceramic (Z). Each group was subdivided into 5 subgroups (n=4) in shades A2, A3.5, B2, C2 and D3. The transmittance measurement was performed in a spectrophotometer. The Variolink II and Rely X U200 resin cements were photoactivated by LED (1400 mW/cm2) for 40 s through the ceramic discs and without the discs (control group). The DC was measured with infrared FTIR spectroscopy, immediately after light activation. Data were analyzed with Kruskall-Wallis and one-way ANOVA, following post-hoc comparisons by Tukey test and Pearson's correlation test (P<0.05). RESULTS: LT ceramic exhibited higher transmittance values compared to MO and Z ceramics. LTA2 and LTB2 showed statistically higher transmittance values compared to MOA2, MOA3.5 and ZA3.5. For Variolink II, the ceramic interposition did not influence the DC, since there were no statistical differences between groups with ceramic interposition and the control group. For Rely X U200 cement, the interposition of some ceramics types/shades (LTA3.5, MOA2, MOA3.5 and ZA3.5) significantly decreased the DC values compared to control group. A positive correlation was found between the ceramic transmittance and DC values of both tested cements. Conclusions. The transmittance and DC values of the cements were influenced by composition and shades of the ceramics. The higher the transmittance of ceramics, the higher the DC values for both cements.


Asunto(s)
Porcelana Dental/química , Cementos de Resina/química , Circonio/química , Análisis de Varianza , Luces de Curación Dental , Curación por Luz de Adhesivos Dentales , Ensayo de Materiales , Transición de Fase , Polimerizacion , Valores de Referencia , Reproducibilidad de los Resultados , Espectrofotometría/métodos , Estadísticas no Paramétricas
16.
J Mech Behav Biomed Mater ; 100: 103401, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31445400

RESUMEN

This study compared the fatigue performance and the stress distribution of endodontically treated molars restored with endocrowns obtained with lithium disilicate glass-ceramic or a polymer-infiltrated ceramic network, both processed by CAD-CAM, and direct composite restorations. Forty-eight human mandibular molars were randomly assigned into 03 groups (n = 16) and restored with endocrowns (LD - lithium disilicate glass-ceramic or PICN - polymer-infiltrated ceramic network) or with direct composite restorations. Fatigue testing followed a step-stress approach (initial maximum load of 200 N and 5000 cycles, incremental step load of 200N and 10,000 cycles/step, being the specimens loaded until failure or to a maximum of 135,000 cycles at 2800 N). The fatigue failure load and number of cycles until failure were recorded and statistically analyzed. Fractographic and finite element (FEA) analyzes were conducted as well. There were no differences in fatigue failure load, number of cycles until fracture and mean survival probabilities among groups. However, indirect endocrowns had higher mechanical structural reliability, and LD restorations lasted more time before start to failing. FEA showed that the stress concentration in tooth tissues was higher for the resin composite, followed by PICN and LD in a decreasing order. Almost all fractures were restricted to the restorative material (without tooth involvement), and origins were identified at occlusal surface. The type of restoration did not influence the fatigue failure load, number of cycles until fracture and mean survival probabilities of the restorative strategies. Despite that, the mechanical structural reliability of endocrowns, especially those made of lithium disilicate, was higher and lasted more time before start to failing.


Asunto(s)
Cerámica , Coronas , Porcelana Dental/química , Fracaso de la Restauración Dental , Polímeros/química , Resinas Sintéticas/química , Resinas Compuestas/química , Fuerza Compresiva , Diseño Asistido por Computadora , Restauración Dental Permanente , Análisis del Estrés Dental , Análisis de Elementos Finitos , Vidrio , Humanos , Imagenología Tridimensional , Estimación de Kaplan-Meier , Litio , Ensayo de Materiales , Diente Molar/fisiología , Falla de Prótesis , Reproducibilidad de los Resultados , Cementos de Resina/química , Estrés Mecánico , Propiedades de Superficie
17.
Int Orthod ; 17(4): 726-732, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31466931

RESUMEN

AIM: This study sought to determine whether a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets is achievable to CAD/CAM (Computer-Aided Design/Manufacturing) lithium silicate infused with zirconia and whether a chemical pre-treatment bonding protocol produced a higher shear bond strength. MATERIALS AND METHODS: Twenty lithium silicate infused with zirconia (CELTRA® DUO) samples, twenty zirconia samples, and twenty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular left first molar. The samples were split into two test groups, one of which received a chemical pre-treatment protocol (hydrofluoric acid etch). Shear bond strength testing was conducted and the mean, maximum, minimal, and standard deviation SBS values for each were calculated and recorded in MPa. An Adhesive Resin Index (ARI) score was also assigned to each sample to assess the mode of bond failure. RESULTS: SBS of the lithium silicate infused with zirconia groups were significantly less than the chemically pre-treated lithium disilicate group, however both materials, when chemical pre-treatment protocol was used, were not statistically different than the enamel control. CONCLUSIONS: Orthodontic bonding to lithium silicate infused with zirconia yielded a weaker shear bond strength than bonding to traditional lithium disilicate, however, when the surface was pre-treated with hydrofluoric acid etch it provides a bond strength that is within an acceptable clinical range.


Asunto(s)
Cerámica/química , Recubrimiento Dental Adhesivo/métodos , Litio/química , Soportes Ortodóncicos , Resistencia al Corte , Silicatos/química , Circonio/química , Grabado Ácido Dental/métodos , Diseño Asistido por Computadora , Esmalte Dental , Porcelana Dental/química , Humanos , Ácido Fluorhídrico , Estrés Mecánico , Propiedades de Superficie
18.
Photodiagnosis Photodyn Ther ; 28: 273-276, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31419581

RESUMEN

AIM: To evaluate the shear bond strength (SBS) and modes of lithium disilicate ceramics (LDC) photosensitized by Er,Cr:YSGG (ECL) and fractional carbon dioxide (CO2) laser bonded to metallic bracket compared to traditional conditioning methods. MATERIAL AND METHOD: Fifty LDC discs were polished and randomly allocated into 5 groups (n = 10) each. Group 1 were photosensitized with ECL + Silane (S). Group 2 were irradiated using CO2 laser + S. In group 3 LDC discs were treated with aluminium trioxide (Al2O3) air abrasion (AA). Moreover, samples in group 4 and 5 were conditioned with Hydrofluoric acid (HFA)+ S (Control) and Self-Etch Glass Ceramic Primer (SEGCP). Following conditioning regimen fifty maxillary central incisor brackets were pasted on LDC using adhesive material. SBS testing was performed by mounting the specimens on a universal testing machine. After debonding, sheared surface was examined under stereomicroscope to classify failure mode using adhesive remnant index (ARI). Mean and standard deviation (SD) were compared by analysis of variance (ANOVA) and Tukey multiple comparison test at a significance level of p = 0.05. RESULTS: Among the conditioning groups the highest SBS values were presented by HFA + S (21.08 ±â€¯1.06). The lowest SBS values were displayed by AA Al2O3 (12.61 ±â€¯0.45). SBS of samples conditioned with SEGCP showed significant difference amongst all experimental groups (16.76 ±â€¯0.81). CONCLUSION: LDC photosensitized with CO2 and ECL has a potential to be recommended in clinical settings alternate to HFA + S when bonded to metallic bracket.


Asunto(s)
Cerámica/química , Recubrimiento Dental Adhesivo/métodos , Porcelana Dental/química , Ácido Fluorhídrico/química , Soportes Ortodóncicos , Silanos/química , Abrasión Dental por Aire , Aluminio/química , Láseres de Gas , Láseres de Estado Sólido , Resistencia al Corte , Propiedades de Superficie
19.
J Mech Behav Biomed Mater ; 100: 103394, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31419749

RESUMEN

Chemical strengthening of a lithium disilicate (LD) parent glass with stoichiometric composition and the corresponding glass-ceramic by Li+/Na+ exchange was investigated. The ion-exchange was performed in a molten NaNO3 salt bath at 380 °C below the glass transition temperature over a wide time range from 3.75 to 480 min. It was found that strength of both the glass and glass-ceramic could be significantly enhanced after very short time treatment (3.75-15 min); however, significant strength decreases occurred similarly for the glass and glass-ceramic with further increasing the treatment time to obtain a greater ion-exchanged depth. Morphology analysis of the ion-exchanged surfaces revealed that the over-long treatment would induce surface failure for the glass, or LD crystal micro-cracking in the ion-exchanged region for the glass-ceramic. The strong time-dependence of the strengthening was attributed to dual effects of the ion-exchange. Besides the conventional "stuffing effect" of ion-exchange, the thermal expansion increase of surface layer induced by Li+/Na+ exchange might be a critical factor to be considered for strengthening the LD glass and glass-ceramic. With prolonging the processing time, the dual effects would change the surface residual stress from compressive into tensile, resulting in surface failure and undesirable strength degradation.


Asunto(s)
Cerámica/química , Porcelana Dental/química , Ensayo de Materiales , Sodio/química , Propiedades de Superficie , Rastreo Diferencial de Calorimetría , Cromatografía por Intercambio Iónico , Iones , Modelos Estadísticos , Estrés Mecánico , Temperatura , Resistencia a la Tracción , Factores de Tiempo , Difracción de Rayos X
20.
Biomed Res Int ; 2019: 7485409, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31355280

RESUMEN

Objective of Study: To investigate, using the FEM, the influence of different notching angles on a zirconium dioxide coping with the aim of establishing the optimal connection conditions with veneering ceramic. Materials and Methods: To calculate the stresses in the connection between zirconia coping and veneering ceramic, a model comprising grooves cut perpendicular was adopted. Such a notch profile was used to design the shape and spacing of the grooves on an FEM model simulating a zirconium dioxide coping. For discretization purposes we used twenty-node solid BRICK elements featuring intermediate nodes with three degrees of freedom in each node. The model was divided into 117 745 finished elements and 439 131 nodes. The problem was solved with a GLU type contact. The same load F = 1N divided by the number of nodes on the external surface was applied to each node of the outer surface of the base. In subsequent computing variants the F load changed the orientation by angle α from 0° to 45° every 15°. Results: The highest level of material strain occurs at angle α = 0° σred  max =309 MPa and the lowest at angle α = 45° σred  max =220 MPa. The highest positive stress pressure occurs at angle α = 0° pmax=251 MPa, pmin=-354 MPa and the lowest at angle α = 15°, pmax=171 MPa, pmin=-186 MPa. In the case of tangential stresses on the coping-veneering ceramic connection, the highest values were noted at angle α = 15° τmax=44,4 MPa and the lowest at angle α = 45° τmax=32,7 MPa. Conclusions: To reduce the load on the zirconia-veneering ceramic connection, the notches should be made at an angle of α = 45°.


Asunto(s)
Cerámica/química , Porcelana Dental/química , Circonio/química , Análisis de Elementos Finitos , Ensayo de Materiales , Estrés Mecánico
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