Applications of collagen extrafibrillar demineralization in dentin bonding / 中华口腔医学杂志

The existing dentin bonding systems based on acid-etching technique lead to the loss of both extrafibrillar and intrafibrillar minerals from dentin collagen, causing excessive demineralization. Because resin monomers can not infiltrate the intrafibrillar spaces of demineralized collagen matrix, degradation of exposed collagen and resin hydrolysis subsequently occur within the hybrid layer, which seriously jeopardizing the longevity of resin-dentin bonding. Collagen extrafibrillar demineralization can effectively avoid the structural defects within the resin-dentin interface caused by acid-etching technique and improve the durability of resin-dentin bonding, by preserving intrafibrillar minerals and selectively demineralizing extrafibrillar dentin. The mechanism and research progress of collagen extrafibrillar demineralization in dentin bonding are reviewed in the paper.

Clinical follow-up at 18 months of two bulk fill occlusal composite resins: a double-blind randomized clinical study / Seguimiento clínico a 18 meses de dos resinas compuestas oclusales bulk fill: estudio clínico aleatorio doble ciego

Objetive: To compare the clinical behavior of two types of Bulk Fill composite resins and a nanohybrid resin at 18 months in occlusal restorations. Material and Methods: Three occlusal restorations were performed in each one of the 55 participants. They were randomly distributed into three groups, TN: Tetric-N-Ceram Bulk-Fill, FK: Filtek Bulk-Fill, and Z350: Filtek Z350XT. Adhesive techniques and restorative procedures were performed according to the manufacturer's instructions for each restorative material used. In TN and FK an increment of 4mm was applied, and in Z350 increments of ≤2mm depth were applied. Two calibrated operators evaluated the restorations at baseline and at 18 months using the FDI World Dental Federations system (1: excellent, 2: good, 3: satisfactory, 4: unsatisfactory, 5: poor) for clinical marginal staining (MS) properties, fracture-retention (FR), superficial texture (ST), marginal integrity (MI), postoperative sensitivity (PS) and caries (C). Kruskal-Wallis and Wilcoxon were used to compare the 3 groups at 18 months (5% significance). Results: 38 patients with a total of 114 restorations were assessed, being evaluated with excellent clinical behavior; MI, 78.9% in Z350, 89.51% in TN and 81.6% in FK; ST 73.5% in Z350, 86.8% in TN, and 84.2% in FK; MS 84.2% in Z350, 84.2% in TN, and 91.2% in FK; PS 100% in Z350 and 97.3% in TN and FK; in C and FR, 100% in the 3 groups. There were no significant differences between the three groups (p>0.05). Conclusion: The three resins studied presented a good clinical performance at 18 months without showing significant differences in the clinical properties evaluated.

Objetivo: Comparar el comportamiento clínico a 18 meses en restauraciones oclusales entre dos tipos de resinas compuestas Bulk Fill y una resina nanohíbrida. Material y Métodos: En 55 participantes se realizaron 3 restauraciones oclusales en cada paciente, distribuidas aleatoriamente en 3 grupos, TN: Tetric-N-Ceram Bulk-Fill, FK: Filtek Bulk-Fill y Z350: Filtek Z350XT. Las técnicas adhesivas y procedimientos restauradores fueron realizados según las instrucciones de los fabricantes de cada material restaurador utilizado. En TN y FK se aplicó un incremento de 4mm y en Z350 se aplicó incrementos ≤ 2 mm de profundidad. Dos operadores calibrados evaluaron las restauraciones al baseline y a los 18 meses mediante el sistema FDI World Dental Federations (1: excelente, 2: aceptable, 3: suficiente, 4: insatisfactorio, 5: inaceptable) en las propiedades clínicas de tinción marginal (TM), fractura-retención (FR), textura superficial (TS), integridad marginal (IM), sensibilidad postoperatoria (SP) y caries (C). Se utilizó Kruskal-Wallis y Wilcoxon para la comparación de los 3 grupos a 18 meses (significancia de 5%). Resultados: Se controlaron 38 pacientes con un total de 114 restauraciones, siendo evaluados con comportamiento clínico excelente; IM, 78.9% en Z350, 89.51% en TN y 81.6% en FK; TS 73.5%, en Z350, 86.8% en TN y 84.2% en FK; TM, 84.2% en Z350, 84.2% en TN y 91.2% en FK; SP 100% en Z350 y 97,3% en TN y FK; en C y FR 100% en los 3 grupos. No hubo diferencias significativas entre los 3 grupos (p>0,05). Conclusión: Las 3 resinas estudiadas presentaron un buen desempeño clínico a 18 meses sin mostrar diferencias significativas en las propiedades clínicas evaluadas.

Effect of liners on composite resin microleakage after selective carious lesion removal: an experimental study / Efecto de los recubrimiento en la microfiltración de resina compuesta después de la eliminación selectiva de lesiones cariosas: un estudio experimental

Objetive: To evaluate microleakage of composite resins (CR) placed over different cavitary liners after managing deep caries lesions through selective removal of soft carious tissue to soft dentin (SRCT-S). Material and Methods: Fifty four human teeth were collected for microleakage testing. Each assay comprised ICDAS 5 or ICDAS 6 carious lesions and sound teeth for controls. Sound teeth were prepared with cavities that mirrored the carious teeth cavities, which were prepared with SRCT-S. Sound and carious teeth were further randomly assigned to one of the three experimental groups: Group A: universal adhesive (UA) + CR, Group B: glass ionomer cement liner + UA + CR, and Group C: calcium hydroxide + UA+ CR. Occlusal microleakage (OM) and cervical microleakage (CM) was classified within one of 5 depth categories. ANOVA and Chi-square tests were computed (p<0.05). Results: OM and CM were similarly distributed across subgroups (p>0.05). All Group C samples with carious lesions presented some degree of microleakage. However, no statistically significant differences were observed between groups and within each group (p>0.05). Conclusion: Teeth restored with CR after SRCT-S using calcium hydroxide as a liner material seem to exhibit higher microleakage than those restored using glass ionomer or UA alone. Further clinical research is needed to deepen these findings. Clinical significance: The application of calcium hydroxide as a liner under a composite resin may reduce the longevity of a restoration after performing selective or partial removal of carious tissues. Clinicians should rethink the need of using calcium hydroxide for this application, albeit the lack of clinical evidence.

Objetivo: Evaluar la microfiltración de resinas compuestas (RC) colocadas sobre diferentes liners cavitarios después del manejo de lesiones de caries profundas mediante la remoción selectiva de tejido cariado blando hasta dentina blanda (SRCT-S). Material y Métodos: Se recolectaron 54 dientes humanos para pruebas de microfiltración. Cada ensayo comprendía lesiones cariosas ICDAS 5 o ICDAS 6 y dientes sanos para los controles. Se prepararon dientes sanos con cavidades que reflejaban las cavidades de los dientes cariados, que se prepararon con SRCT-S. Los dientes sanos y cariados se asignaron al azar a uno de los tres grupos experimentales: Grupo A: adhesivo universal (AU) + RC, Grupo B: revestimiento de cemento de ionómero de vidrio + AU + RC, y Grupo C: hidróxido de calcio + AU+ RC. La microfiltración oclusal (MO) y la microfiltración cervical (MC) se clasificaron dentro de una de las 5 categorías de profundidad. Se calcularon las pruebas ANOVA y Chi-cuadrado (p<0,05). Resultados: La MO y MC se distribuyeron de manera similar en los subgrupos (p> 0,05). Todas las muestras del Grupo C con lesiones cariosas presentaron algún grado de microfiltración. Sin embargo, no se observaron diferencias estadísticamente significativas entre grupos y dentro de cada grupo (p>0,05). Conclusión: Los dientes restaurados con RC después de SRCT-S usando hidróxido de calcio como material de revestimiento parecen exhibir una mayor microfiltración que aquellos restaurados usando ionómero de vidrio o AU solo. Se necesita más investigación clínica para profundizar estos hallazgos. Relevancia clínica: la aplicación de hidróxido de calcio como revestimiento debajo de una resina compuesta puede reducir la longevidad de una restauración después de realizar la eliminación selectiva o parcial de los tejidos cariados. Los médicos deberían reconsiderar la necesidad de usar hidróxido de calcio para esta aplicación, aunque no haya evidencia clínica.

Influence of sonic vibration and cement type on the bond strength of fiberglass posts after aging / Influencia de la vibración sónica y el tipo de cemento en la fuerza de unión de los postes de fibra de vidrio después del envejecimiento

Introduction: This study evaluated the influence of sonic vibration and thermocycling on the bond strength of fiberglass posts using conventional dual-cured and self-adhesive resin cements. Material and Methods: Ninety-six single-rooted endodontically treated teeth were divided randomly into eight groups according to the cement used (dual-cured or self-adhesive resin cement), use of sonic vibration during post accommodation, and aging conditions (24h in distilled water or 5,000 thermal cycles). The fiberglass posts (White Post DC1, FGM) were cleaned with alcohol, treated with silane and cemented with dual-cured (Allcem Core, FGM) or with self-adhesive resin cement (seT, SDI). For groups in which sonic vibration was used, the posts were accommodated, and sonic vibration was applied for 10 s using a special tip placed on top of the post (Sonic Smart Device, FGM). Pull-out tests were performed after storage in distilled water for 24h at 37°C or after thermocycling (5000 cycles, at 5°C and 55°C). The results were evaluated using three-way ANOVA and Tukey's test (α=0.05). Results: Significant differences were not observed between the bond strengths of dual-cured (87.93±41.81 N) and self-adhesive cement (82.53±41.43 N). Bond strength for the sonic vibration groups (100.36±42.35 N) was significantly higher than for groups without sonic vibration (70.13±34.90 N). There were significant differences between specimens subjected to thermocycling (98.33±39.42 N) and those stored for 24h in distilled water (72.16±39.67 N). Conclusion: It can be concluded that both sonic vibration and thermocycling significantly improved bond strength of fiberglass posts with the two evaluated resin cements.

Introducción: Este estudio evaluó la influencia de la vibración sónica y el termociclado en la fuerza de unión de los postes de fibra de vidrio utilizando cementos de resina autoadhesivos y de curado dual convencionales Material y Métodos: Se dividieron aleatoriamente noventa y seis dientes tratados endodónticamente de raíz única en ocho grupos según el cemento utilizado (cemento de resina de curado dual o autoadhesivo), el uso de vibración sónica durante la acomodación posterior y las condiciones de envejecimiento (24 horas agua destilada o 5.000 ciclos térmicos). Los postes de fibra de vidrio (White Post DC1, FGM) se limpiaron con alcohol, se trataron con silano y se cementaron con cemento de curado dual (Allcem Core, FGM) o con cemento de resina autoadhesivo (seT, SDI). Para los grupos en los que se utilizó vibración sónica, se acomodaron los postes y se aplicó la vibración sónica durante 10 s utilizando una punta especial colocada en la parte superior del poste (Sonic Smart Device, FGM). Las pruebas de extracción se realizaron después del almacenamiento en agua destilada durante 24 horas a 37ºC o después del termociclado (5000 ciclos, a 5ºC y 55ºC). Los resultados se evaluaron mediante ANOVA de tres vías y la prueba de Tukey (α = 0.05). Resultados: No se observaron diferencias significativas entre las resistencias de adhesión del cemento de curado dual (87,93 ± 41,81 N) y el cemento autoadhesivo (82,53 ± 41,43 N). La fuerza de unión para los grupos de vibración sónica (100,36 ± 42,35 N) fue significativamente mayor que para los grupos sin vibración sónica (70,13 ± 34,90 N). Hubo diferencias significativas entre los especímenes sometidos a termociclado (98,33 ± 39,42 N) y los almacenados durante 24 h en agua destilada (72,16 ± 39,67 N). Conclusión: Se puede concluir que tanto la vibración sónica como el termociclado mejoraron significativamente la fuerza de unión de los postes de fibra de vidrio con los dos cementos de resina evaluados.

Effect of two processing techniques used to manufacture lithium disilicate ceramics on the degree of conversion and microshear bond strength of resin cement / Efeito de duas técnicas de processamento utilizadas na fabricação da cerâmica de dissilicato de lítio no grau de conversão e na resistência de união ao microcisalhamento do cimento resinoso

ABSTRACT 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.

RESUMO O objetivo do presente estudo foi comparar o efeito de duas técnicas de processamento da cerâmica de dissilicato de lítio (prensada e CAD/CAM) no grau de conversão do cimento resinoso quando fotoativado e na resistência de união ao microcisalhamento do cimento resinoso às cerâmicas. Foram fabricados dois discos de cerâmica: um pela técnica prensada e outro pela técnica CAD/CAM. Cinco amostras de cimento resinoso Variolink Veneer foram fotoativadas através de cada disco cerâmico e submetidas à espectroscopia no infravermelho por transformada de Fourier com reflectância total para avaliar seu grau de conversão. Para avaliar a resistência de união ao microcisalhamento, foram preparadas 20 barras de cerâmicas: 10 utilizando a técnica prensada e 10 utilizando a técnica CAD/CAM. As barras foram tratadas com partículas de Al2O3 (50 μm), com ácido fluorídrico a 10% por 20 s e submetidas à aplicação do RelyX Ceramic Primer. Em seguida, o adesivo multiuso Adper Scotchbond foi aplicado nas barras e fotoativado por 10 s. Dois tubos de plástico de 1 mm de comprimento foram colocados em cada barra e preenchidos com cimento resinoso Variolink Veneer. Cada cilindro foi fotoativado por 20 s. Os tubos de plástico foram removidos e a resistência de união ao microcisalhamento de cada cilindro foi testada. Os dados de grau de conversão (%) e resistência de união ao microcisalhamento (MPa) foram submetidos ao teste t de Student (α = 0,05). Tanto o grau de conversão do cimento resinoso fotoativado através da cerâmica quanto a resistência de união do cimento resinoso à cerâmica foram estatisticamente maiores no grupo em que a cerâmica foi confeccionada pela técnica CAD/CAM (44,74% e 22,18 MPa) do que no grupo em que a cerâmica foi confeccionada pela técnica prensada (25,71% e 19,83 MPa). As técnicas de processamento de cerâmica dissilicada de lítio afetaram o grau de conversão do cimento resinoso quando fotoativado através das cerâmicas e a resistência de união do microcisalhamento do cimento resinoso às cerâmicas.

Microstructural and mechanical analysis of two CAD-CAM lithium disilicate glass-reinforced ceramics

Abstract 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.

Adhesive resistance of a copaiba oil-based dentin biomodifier

Abstract This study analyzed the effect of prior application of copaiba oil (CO) emulsions as a dentin cleaning substance on microleakage and microtensile adhesive strength. Twenty-five premolars and sixty-four molars were used for microleakage and microtensile assays. For the microleakage assays, specimens with standard class V cavities were divided (n = 5), according to the tested CO emulsions: CO10%X, CO10%Y, and CO10%Z, as well as chlorhexidine 2% (CHX) and distilled water (DW), as positive and negative controls, respectively. Restorations were performed using the Adper Single Bond® and/or Clearfil SE Bond® systems. Cervical, occlusal, distal and mesial sections were assessed for tracer penetration degree at the composite/tooth interface. For the microtensile assay, healthy molars were divided into sixteen groups, in which artificial caries were induced in half of the groups. Dentin surfaces were treated with CO10%X and CO10%Y, CHX and DW. Microtensile bond strength was measured by fixing each sample to the plate of a universal testing machine operated at a speed of 0.5 mm/minute until failure. Dentin treated with CO10%X showed a lower infiltration rate than dentin treated with the other CO emulsions, CHX2% and DW. According to the microtensile assay, both healthy and affected dentin treated with CO10%X and Adper Single Bond® adhesive system presented higher adhesive strength. CO emulsion, used as a dentin biomodifier, interfered positively in microleakage and improved adhesive strength after acid etching in the Adper Single Bond® adhesive system, or before applying the Clearfil SE Bond® self-etching system.

Influence of alumina air-abrasion for highly translucent partially stabilized zirconia on flexural strength, surface properties, and bond strength of resin cement

Abstract Objective This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. Methodology Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. Results The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. Conclusion Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.

Does use of silane-containing universal adhesive eliminate the need for silane application in direct composite repair?

Abstract This in vitro study aimed to evaluate the effect of a silane-containing universal adhesive used with or without a silane agent on the repair bond strength between aged and new composites. Forty nanohybrid composite resin blocks were stored in distilled water for 14 d and thermo-cycled. Sandpaper ground, etched, and rinsed speciments were randomly assigned into four experimental groups: silane + two-step etch-and-rinse adhesive system, two-step etch-and-rinse adhesive system, silane + silane-containing universal adhesive system, and silane-containing universal adhesive system. Blocks were repaired using the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile testing. Ten unaged, non-repaired composite blocks were used as a reference group to evaluate the cohesive strength of the composite. Two-way ANOVA and Tukey's tests were used to analyze average µTBS. One-way ANOVA and Dunnet post-hoc tests were used to compare the cohesive strength values and bond strength obtained in the repaired groups (α = 0.05). The µTBS values were higher for the silane-containing universal adhesive compared to the two-step etch-and-rinse adhesive system (p = 0.002). Silane application improved the repair bond strength (p = 0.03). The repair bond strength ranged from 39.3 to 65.8% of the cohesive strength of the reference group. Using universal silane-containing adhesive improved the repair bond strength of composite resin compared to two-step etch-and-rinse adhesive. However, it still required prior application of a silane agent for best direct composite resin repair outcomes.

Effect of ethanol-wet bonding on porosity and retention of fiberglass post to root dentin

Abstract: This in vitro study aimed to assess the effects of different pretreatments used to adapt glass-fiber posts cemented to root canals with different resin cements, regarding porosity percentage and bond strength. Twelve bovine incisor roots were prepared with Largo drills. After post space preparation, the specimens were randomized into two types of pretreatment groups (n = 3): water-wet bonding and ethanol-wet bonding. After the post were cemented, the roots were stored in 100% humidity at room temperature for 7 days. The samples were scanned by microcomputed tomography (micro-CT). Images were reconstructed by NRecon software, and CTAn software was used to analyze the porosity percentage (%) at the luting interface. Evaluation of the push-out bond strength was performed by serially cutting the roots, and submitting the slices to testing. Additionally, the resin cement post-gel shrinkage values (%) were measured using the strain-gauge method (n = 10). Data were analyzed by two-way ANOVA, Tukey's test and Student's t test (a = 0.05). The roots prepared with ethanol-wet bonding using RelyX™ U200 had significantly lower porosity in the coronal and apical thirds (p < 0.05). The group prepared with ethanol-wet bonding using RelyX™ ARC presented better bond strength results in the coronal and apical thirds (p < 0.05). RelyX™ ARC (0.97%) produced a higher post-gel shrinkage value than RelyX™ U200 (0.77%). Canals pretreated with ethanol-wet bonding presented better outcomes in regard to porosity percentage and push-out bond strength.

Adhesive resistance of a copaiba oil-based dentin biomodifier

Abstract This study analyzed the effect of prior application of copaiba oil (CO) emulsions as a dentin cleaning substance on microleakage and microtensile adhesive strength. Twenty-five premolars and sixty-four molars were used for microleakage and microtensile assays. For the microleakage assays, specimens with standard class V cavities were divided (n = 5), according to the tested CO emulsions: CO10%X, CO10%Y, and CO10%Z, as well as chlorhexidine 2% (CHX) and distilled water (DW), as positive and negative controls, respectively. Restorations were performed using the Adper Single Bond® and/or Clearfil SE Bond® systems. Cervical, occlusal, distal and mesial sections were assessed for tracer penetration degree at the composite/tooth interface. For the microtensile assay, healthy molars were divided into sixteen groups, in which artificial caries were induced in half of the groups. Dentin surfaces were treated with CO10%X and CO10%Y, CHX and DW. Microtensile bond strength was measured by fixing each sample to the plate of a universal testing machine operated at a speed of 0.5 mm/minute until failure. Dentin treated with CO10%X showed a lower infiltration rate than dentin treated with the other CO emulsions, CHX2% and DW. According to the microtensile assay, both healthy and affected dentin treated with CO10%X and Adper Single Bond® adhesive system presented higher adhesive strength. CO emulsion, used as a dentin biomodifier, interfered positively in microleakage and improved adhesive strength after acid etching in the Adper Single Bond® adhesive system, or before applying the Clearfil SE Bond® self-etching system.

Hydrofluoric acid concentration, time and use of phosphoric acid on the bond strength of feldspathic ceramics

Abstract 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.

Comparison of the Polymerization Shrinkage of Eclipse Resin for Prostheses with Conventional Acrylic Resins / Comparación de la Contracción de Polimerización de la Resina Eclipse para Prótesis con Resinas Acrílicas Convencionales

ABSTRACT: The objective of this study was to compare the polymerization shrinkage of Eclipse photopolymerization resin for prosthesis based on urethane dimethacrylate (UDMA) with that of three heat-cured acrylic resins based on polymethyl methacrylate (PMMA) after the polymerization process and immersion in water. A total of 40 prostheses were fabricated on a standard metallic upper edentulous model: group 1, Eclipse; group 2, Triplex hot; group 3, Veracril; and group 4, Lucitone 199. Subsequently, the polymerization contraction was tested using a microscope in which measurements were made in micrometres at 3 points located in the middle parts of the right and left sides and the middle part of the palate at three time points once the prosthesis was completed, after 30 days of immersion in water for 8 hours a day at a temperature of 37 °C, and after cutting the prosthesis at the level of the second premolar. ANOVA revealed that the contraction of the polymerization no statistically significant differences between the groups, (P> 0.05). The type of resin and its interaction with the processing method behaves similarly for all test resins. The Veracril heat-cured resin obtained the lowest contraction value in the three measurements (mm) and the highest value was obtained with the Eclipse photopolymerization resin. The Eclipse resin exhibited no lower polymerization shrinkage compared to conventional acrylic resins based on polymethyl methacrylate (PMMA), however it was not significantly affected by immersion in water.

RESUMEN: El objetivo de este estudio fue comparar la contracción de polimerización de la resina de fotopolimerización Eclipse para prótesis basadas en dimetacrilato de uretano (UDMA) con la de tres resinas acrílicas curadas con calor a base de polimetacrilato de metilo (PMMA) después del proceso de polimerización e inmersión en agua. Se fabricaron un total de 40 prótesis en un modelo edéntulo superior metálico estándar: grupo 1, Eclipse; grupo 2, triplex caliente; grupo 3, veracril; y grupo 4, Lucitone 199. Posteriormente, la contracción de la polimerización se probó utilizando un microscopio en el que se realizaron mediciones en micrometros en 3 puntos ubicados en las partes medias de los lados derecho e izquierdo y la parte media del paladar en tres puntos de tiempo una vez la prótesis se completó, después de 30 días de inmersión en agua durante 8 horas al día a una temperatura de 37 °C, y después de cortar la prótesis a nivel del segundo premolar. ANOVA reveló que la contracción de la polimerización no presenta diferencias estadísticamente significativas entre los grupos, (P> 0,05). El tipo de resina y su interacción con el método de procesamiento se comportan de manera similar para todas las resinas de prueba. La resina curada con calor Veracril obtuvo el valor de contracción más bajo en las tres mediciones (mm) y el valor más alto se obtuvo con la resina de fotopolimerización Eclipse. La resina Eclipse no mostró una contracción de polimerización menor en comparación con las resinas acrílicas convencionales basadas en polimetilmetacrilato (PMMA), sin embargo, no se vio afectada significativamente por la inmersión en agua.

Six month follow-up of two bulk-fill composites in non-carious cervical lesions: double blind randomized clinical trial / Evaluación clínica a 6 meses de restauraciones cervicales en lesiones no cariosas con resinas compuestas bulk-fill: estudio aleatorio doble ciego

Objective: To assess the six-month clinical outcome of restorations of non-carious cervical lesions (NCCL) with two composite resins: Bulk-Fill and nanohybrid resin. Materials and methods: Fifty-one patients, with three NCCLs each, were randomly allocated into three restoration groups: Tetric-N-Ceram Bulk-Fill (TB); Filtek Bulk-Fill (FB); y Filtek Z350XT (Z350). Adhesive techniques and restorative procedures were performed according to the manufacturers' instructions for the different materials. A 4mm increment was applied in TB and FB, and increments of ≤2mm depth were applied in Z350. Restorations were assessed by two calibrated examiners at baseline and at six months according to the FDI World Dental Federation guidelines (1: excellent, 2: acceptable, 3: sufficient, 4: unsatisfactory, 5: unacceptable) in Marginal Staining (MS), Fracture-Retention (FR), Marginal Adaptation (MA), Postoperative Sensitivity (S) and Caries (C). Wilcoxon test was used for the comparison between baseline and 6 months, and Kruskal-Wallis for the comparison of the three groups at six months (95% significance). Results: Forty-six patients with a total of 138 restorations attended a check-up at six months and were evaluated with excellent clinical outcome. In MS, 91.2% for Z350 and 97.8% for FB and TB; in FR, 97.8% for Z350 and 100% for FB and TB; in MA, 95.6% for Z350, 97.8% for FB and 100% for TN; in S, 95.6% for all three groups; and 100% for C. No statistically significant differences were found between the three groups nor in the comparison between the baseline and 6 months (p>0.05) Conclusion: No significant differences are observed between the three groups of resins in the parameters of MS, MA, S, FR and C regarding clinical outcome at six months.

Objetivo: Evaluar el comportamiento clínico a 6 meses en restauraciones de lesiones cervicales no cariosas (LCNC) con dos resinas compuestas Bulk-Fill y una resina nanohíbrida. Materiales y métodos: En 51 pacientes se restauraron 3 LCNC distribuidas aleatoriamente en 3 grupos, TB: Tetric-N-Ceram Bulk-Fill, FB: Filtek Bulk-Fill y Z350: Filtek Z350XT. Las técnicas adhesivas y procedimientos restauradores fueron realizados según las instrucciones de los fabricantes para los diferentes materiales. En TB y FB se aplicó un incremento de 4mm y en Z350 se aplicó incrementos ≤2mm de profundidad. Dos operadores calibrados evaluaron las restauraciones al baseline y 6 meses mediante los criterios clínicos FDI (1: excelente, 2: aceptable, 3: suficiente, 4: insatisfactorio, 5: inaceptable) en Tinción Marginal (TM), Fractura-Retención (FR), Adaptación Marginal (AM), Sensibilidad Postoperatoria (S) y Caries (C). Se utilizó Wilcoxon para la comparación entre baseline ­ 6 meses y Kruskal-Wallis para la comparación de los 3 grupos a 6 meses (significancia de 95%). Resultados: A los 6 meses asistieron 46 pacientes con un total de 138 restauraciones siendo evaluados con comportamiento clínico excelente; en TM 91,2% para Z350 y 97,8% para FB y TB; en FR, Z350 presentó 97,8% y en FB y TB el 100%; en AM, 95,6% para Z350, 97,8% para FB y 100% para TN; en S presentó 95,6% para los tres grupos; en C se presentó el 100%. No hubo diferencias estadísticamente significativas entre los 3 grupos y en la comparación de baseline - 6 meses (p>0.05). Conclusión: No existen diferencias significativas en el comportamiento clínico a 6 meses entre los 3 grupos de resinas en los parámetros TM, AM, S, FR Y C.

Bond strengths of various resin cements to different ceramics

Abstract This study evaluates the shear bond strength (SBS) of various resin cements to different ceramics. Composite resin cylinders of Z100 were fabricated and cemented to disks of feldspathic ceramic (Creation), leucite-reinforced feldspathic ceramic (Empress I), and densely sintered aluminum oxide ceramic (Procera AllCeram) using five resin cements: Panavia F (PAN), RelyX ARC (ARC), RelyX Unicem (RXU), RelyX Veneer, and Variolink II. SBS was measured after three days of water storage (baseline) and after artificial aging (180 days of water storage along with 12,000 thermal cycles). Failure mode of fractured specimens also was evaluated. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (α=0.05). RXU showed 1) the lowest baseline median SBS to feldspathic ceramic, which was not statistically different from PAN; 2) the lowest median baseline SBS to leucite-reinforced feldspathic and densely sintered aluminum-oxide ceramics. All cements performed similarly after aging, except for ARC (median 0.0 MPa) and PAN (median 16.2 MPa) in the densely sintered aluminum-oxide ceramic group. Resin cements perform differently when bonded to different ceramic substrates. While all test resin cements worked similarly in the long-term to feldspathic and leucite-reinforced feldspathic ceramics, only the MDP-containing resin cement provided durable bonds to densely sintered aluminum-oxide ceramic.

Influence of the composition and shades of ceramics on light transmission and degree of conversion of dual-cured resin cements

Abstract 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.

Fatigue survival and damage modes of lithium disilicate and resin nanoceramic crowns

Abstract Polymer-based composite materials have been proposed as an alternative for single unit restorations, due to their resilient and shock absorbing behavior, in contrast to the brittleness of ceramic materials that could result in failure by fracture. Objective: To evaluate the fatigue strength and damage modes of monolithic posterior resin nanoceramic and lithium disilicate glass ceramic crowns. Methodology: Twenty-six resin nanoceramic (RNC) and lithium disilicate glass ceramic (LD) 2 mm monolithic crowns (n=13) were cemented on composite resin replicas of a prepared tooth and subjected to cyclic load with lithium disilicate indenters for 2 million cycles. Specimens and indenters were inspected every 500,000 cycles and suspended when presenting fractures or debonding. Surviving specimens were embedded in epoxy resin, polished and subsurface damage was analyzed. Specimens presenting fractures or severe subsurface damage were considered as failures. Survival data was subjected to Fisher's exact test; damage modes were subjected to Mann-Whitney test (p<0.05). Results: There were no debonding, cohesive or catastrophic failures. Considering subsurface damage, 53.8% of RNC and 46.2% of LD crowns survived the fatigue test, presenting no statistical difference. Chief damage modes were radial cracks for RNC and inner cone cracks for LD, presenting no statistical difference. Conclusions: The results suggest that if debonding issues can be resolved, resin nanoceramic figures can be an alternative to posterior crowns. Although distinct, damage modes revealed potential to cause bulk fracture in both glass ceramic and resin nanoceramic crowns.

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen

Abstract Objective This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and Methods Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.

Microtensile bond strength of root canal dentin treated with adhesive and fiber-reinforced post systems

Abstract Nowadays, demand for esthetic restorations has risen considerably; thus, nonmetal esthetic posts made of either high-strength ceramics or reinforced resins, such as fiber-reinforced resin posts, have become more and more popular. Important characteristics of fiber-reinforced posts involve a modulus of elasticity similar to dentin and their ability to be cemented by an adhesive technique. A total of 36 maxillary incisors were divided into four groups. In this study, four adhesively luted fiber-reinforced (glass fiber, quartz glass fiber, zirconia glass fiber and woven polyethylene fiber ribbon) post systems were used. Post spaces were prepared by employing drills according to the protocol established for each group, and each post was adhesively luted with one of three adhesive systems. Three segments per root apical to the cementoenamel junction (CEJ) were obtained by sectioning the root under distilled water with a carbon spare saw. The samples (total of 108 sections) were 2.0±0.1 mm in thickness and they were stored individually in black film canisters with sterile distilled water. In order to determine the bond strength, the bonding area of each specimen was measured, and specimens were attached to a device to test microtensile strength at a speed of 1 mm/min. The analyses revealed no statistically significant differences between the adhesive systems and fiber-reinforced posts. (P> 0.05). However, the coronal portion of the root dentin had the highest bond strength. Adhesive systems used along with fiber-reinforced resin posts demonstrated reliable bonding.

Effect of hydrofluoric acid concentration and etching time on resin-bond strength to different glass ceramics

Abstract: 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.