Effect of Polywave and Monowave Light Curing Units on the Microtensile Bond Strength and Failure Types of Different Bulk-Fill Resin Composites: An in vitro Study.

Aim: This study aimed to evaluate the effects of polywave and monowave light-emitting diode curing units on the microtensile bond strength and failure types of three bulk-fill resin composites. Materials and Methods: This in vitro experimental study was performed on 180 microbars obtained from human third molars and were distributed into 12 groups according to the type of bulk-fill resin composite and the light-curing unit. Third molars were restored using Filtek One Bulk Fill Restorative, Tetric® N-Ceram Bulk Fill, and Opus Bulk Fill resin composites was light-cured with Elipar Deep Cure L and Valo in three modes: standard, high power, and extra power. Subsequently, microtensile analysis was carried out with a universal testing machine and the type of failure with an optical stereomicroscope. For statistical analysis, the Kruskal-Wallis H-test was used, with the Bonferroni post hoc test and Fisher's exact test, considering a significance of p<0.05. Results: There were significant differences in the microtensile bond strength between the Filtek One Bulk Fill restorative and Opus Bulk-Fill (p = 0.042) when light was cured with the polywave unit at standard power. On the other hand, the Filtek One Bulk Fill Restorative and Opus Bulk Fill resins showed significant differences in microtensile bond strength when light was cured with the monowave unit compared with the polywave unit (p<0.05). Conclusion: The presence of alternative photoinitiator systems that are more reactive than camphorquinone produced higher microtensile bond strength in Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins when light-cured with a high and standard polywave unit, respectively, compared to Filtek One Bulk Fill resins. Finally, Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins had the highest percentage of mixed failures, while Filtek One Bulk Fill resin had adhesive failures, which was related to its lower microtensile bond strength.

Evaluation of the ceramic laminate veneer-tooth interface after different resin cement excess removal techniques.

OBJECTIVES: To compare, in vitro, resin cement excess removal techniques at the veneer-tooth interface. MATERIALS AND METHODS: Anterior human teeth were restored with ceramic veneers and randomly divided according to the following techniques (n = 10): removal of excess resin cement with brush and dental floss, followed by light-curing with Valo (Group 1) or Elipar (Group 2) for 1 min and 40 s; tack-curing with Valo (Group 3) or Elipar (Group 4) for 1 s; and tack-curing with Valo (Group 5) or Elipar (Group 6) for 5 s. The tack-curing was followed by removal of excess with probe and dental floss and light-curing for 1 min and 40 s. The area of excess resin cement (mm2) was measured in micro-CT images using AutoCAD program. The failures at the cervical margin in the X, Y, and Z axes (µm) of greater value were measured using the DataViewer program. The specimens were submitted to microleakage with 2% basic fuchsin. RESULTS: According to the Kruskal-Wallis and multiple comparison test, the highest area of excess resin cement was found in Group 1 (5.06 mm2), which did not differ statistically from Groups 2 (3.70 mm2) and 5 (2.19 mm2). Groups 2, 3 (1.73 mm2), 4 (1.14 mm2), and 5 (2.18 mm2) did not differ statistically. Group 6 (0.77 mm2) obtained the lowest value, which did not differ statistically from Groups 3 and 4. According to the Kruskal-Wallis and Dunn test, there was no significant difference in failures in X (p = 0.981), Y (p = 0.860), and Z (p = 0.638) axes and no significant difference in microleakage (p = 0.203) among the groups. CONCLUSIONS: Tack-curing for 1 s or 5 s, followed by removal of excess resin cement using a probe and a dental floss, tended to result in a lower amount of excess material around the margin. CLINICAL RELEVANCE: The technique used for resin cement excess removal influences the amount of excess leaved at the veneer-tooth interface. Tack-curing for 1 s or 5 s is recommended to mitigate the excess resin cement.

Effect of four different mono and multi-wave light-curing units on the Knoop hardness of veneer resin composites.

OBJECTIVES: To evaluate the effect of mono and multi-wave light-curing units (LCUs) on the Knoop hardness of resin-based composites (RBC) that use different photoinitiators. METHODS: Central incisor-shaped specimens 12 mm long, 9 mm wide, and 1.5 mm thick were made from 2 RBCs that use different photoinitiators: Tetric N-Ceram (Ivoclar Vivadent) - and Vittra APS (FGM), both A2E shade. They were light-cured with 4 different LCUs: two claimed to be multi-wave - VALO Grand (Ultradent) and Emitter Now Duo (Schuster); and two were monowave - Radii Xpert (SDI) and Elipar DeepCure-L (3 M Oral Care) using 2 different light exposure protocols: one 40 s exposure centered over the specimen; and two 20 s light exposures that delivered light from two positions to better cover the entire tooth. 16 groups with 10 specimens in each group were made. The Knoop hardness (KH, kg/mm2) was measured at the top and bottom of the specimen in the center and at the cervical, incisal, mesial, and distal peripheral regions. The active tip diameters (mm) and spectral radiant powers (mW/nm) of the LCUs were measured with and without the interposition of the RBC, as well as the radiant exposure beam profiles (J/cm²) delivered to the top of the RBCs. The data was analyzed using Three-way ANOVA and Tukey's tests (α = 0.05). RESULTS: The VALO Grand (1029 mW) emitted twice the power of the Radii Xpert (500 mW). The KH values of VI and TN resin composite specimens were significantly affected by the LCU used (p < .001), the measurement location (p < .001), and the surface of the specimen (p < .001). LCUs with wider tip diameters produced greater Knoop hardness values at the peripheries of the 12 mm of long, 9 mm wide specimens. In general, the VALO Grand produced the highest KH values, followed by Elipar DeepCure-L, then by Radii Xpert. The Emitter Now Duo LCU produced the lowest values. Exposing the veneers from two locations reduced the differences between the LCUs and the effect of the measurement location. Only the VALO Grand could fully cover the composite veneer with light when the two locations were used. SIGNIFICANCE: The light tip must cover the entire restoration to photocure the RBC beneath the light tip.

Delayed light-curing of dual-cure bulk-fill composites on internal adaptation and depth of cure.

OBJECTIVE: To evaluate the effect of delayed light-curing of dual-cure bulk-fill composites on internal adaptation and microhardness (KHN) in depth. MATERIALS AND METHODS: Bulk-fill composites were placed in 35 box-shaped preparations and cured according to the following protocols (n = 5): Filtek Bulk-Fill light-cured immediately after insertion (FBF); Bulk-EZ light-cured immediately after insertion (BEZ-I); Bulk-EZ light-cured 90 s after insertion (BEZ-DP); Bulk-EZ self-cured (BEZ-SC); HyperFIL light-cured immediately after insertion (HF-I); HyperFIL light-cured 90 s after insertion (HF-DP); HyperFIL self-cured (HF-SC). After 24 h, the samples were axially sectioned, and the internal adaptation was evaluated using replicas under a scanning electron microscope. The KHN was evaluated at six depths (0.3 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm). The statistical analysis was performed using α = 0.05. RESULTS: The KHN significantly decreased with depth, except in self-curing mode, when it was similar at all depths. Delayed light-curing significantly increased the KHN at higher depths. The internal adaptation was material-dependent. Light-curing did not influence the internal adaptation of HyperFIL, whereas delayed light-curing significantly reduced the internal gaps (%) of Bulk-EZ. CONCLUSION: Delayed light-curing improved the depth of cure of dual-cure resin composites. Light-curing did not influence the internal adaptation of HyperFIL, but delayed light-curing improved the internal adaptation of Bulk-EZ. CLINICAL SIGNIFICANCE: Light-curing is fundamental for improving the mechanical properties of dual-cure resin composites. Moreover, depending on the dual-cure resin composite, the delay in light-curing can reduce the internal gaps.

Effect of thickness of CAD/CAM materials on light transmission and resin cement polymerization using a blue light-emitting diode light-curing unit.

OBJECTIVE: Evaluate the effect of thickness of high-translucency (HT) CAD/CAM materials on irradiance and beam profile from a blue light-emitting diode light-curing unit (LCU) and on the degree of conversion (DC) and maximum polymerization rate (Rpmax ) of a light-cured resin cement (LCC). MATERIAL AND METHODS: The direct output from the LCU, the light transmission and irradiance ratio (IR) through one conventional composite and nine HT CAD/CAM materials (0.5, 1.0, 1.5, or 2.0-mm thick; n = 5) were measured with a integrating sphere coupled to a spectrometer. The light beam was assessed with a beam profiler camera. The DC at 600 s and the Rpmax of one LCC was determined using a Fourier transform infrared spectrometer (n = 5). Data were analyzed by ANOVA followed by Tukey's tests, and Dunnett's test was also used for irradiance data (α = 0.05). RESULTS: A significant decrease in irradiance through all materials occurred as thickness increased. Thin CAD/CAM materials improved light homogeneity, which decreased with the increase in thickness. The DC of the LCC directly exposed to light was the same as when exposed to 45%, 25%, 15%, or 5% IRs. Rpmax decreased with the decrease in IR. CONCLUSIONS: Although the HT CAD/CAM materials reduced the irradiance from the LCU, minor effects were observed in the LCC's DC. CLINICAL SIGNIFICANCE: Despite the light attenuation of blue light through different CAD/CAM materials that were up to 2-mm thick, the degree of conversion of one brand of light-cured resin cement was clinically acceptable when the LCU was used for 30 s.

Resistência ao cisalhamento de bráquetes colados com diferentes fotopolimerizadores led de alta potência / Shear strength of brackets bonded with different high-power led light curing

Resumo OBJETIVO: Avaliar a resistência ao cisalhamento e o Índice de Remanescente Adesivo (IRA) de bráquetes metálicos colados com três diferentes fotopolimerizadores LED de alta potência, quando comparados ao LED convencional. MATERIAIS E MÉTODOS: 80 incisivos bovinos foram divididos aleatoriamente em 4 grupos (n=20), nos quais foram realizadas colagens dos bráquetes utilizando-se os seguintes LEDs de alta potência por 3s: Grupo 1 ­ LEDX ­ T 2400, Orthometric; Grupo 2 ­ Flashmax P4 PRO Ortho, Rock Moutain Orthodontics; Grupo 3 ­ VALO CORDLESS, Ultradent e Grupo 4 ­ LED convencional por 40s (controle) POLY-WIRELESS, Kavo. O teste de resistência ao cisalhamento foi realizado utilizando-se uma máquina de ensaio universal (AME-2kN, Oswaldo Filizola, São Paulo, Brasil) com velocidade de 0,5mm/min e célula de carga de 50N. A determinação da diferença estatística entre os grupos em relação ao cisalhamento foi realizada usando-se a análise de variância (ANOVA). Para avaliação do IRA, foi aplicado o teste Kruskal-Wallis. RESULTADOS: O grupo 2 apresentou resistência ao cisalhamento significativamente superior aos demais LEDs de alta potência e foi similar ao LED convencional. Em relação ao IRA, houve diferença estatisticamente significante entre os grupos e o único que não diferiu do grupo controle foi o 2, enquanto os demais LEDs de alta potência (Grupos 1 e 3) apresentaram mais falhas adesivas entre a resina e o esmalte. CONCLUSÃO: Houve diferença entre os três tipos de fotopolimerizadores LED de terceira geração, sendo que maior resistência ao cisalhamento e menos falhas adesivas foram observadas no LED que apresentou maior potência (AU)

Abstract OBJECTIVE: To evaluate shear strength and Adhesive Remnant Index (ARI) of metallic brackets bonded to three types of high-power LED light curing, when compared to conventional LED. MATERIALS AND METHODS: 80 bovine incisors were divided into 4 groups (n = 20), in which brackets were bonded using the following high-power LEDs for 3s: Group 1 ­ LEDX ­ T 2400, Orthometric; Group 2 ­ Flashmax P4 PRO Ortho, Rock Mountain Orthodontics; Group 3 ­ VALO CORDLESS, Ultradent; and Group 4 ­ conventional LED for 40s (control) POLY-WIRELESS, Kavo. The shear strength test was performed using a universal test machine (AME-2kN, Oswaldo Filizola, São Paulo, Brasil) with 0.5 mm/min speed and 50N load cell. The determination of statistical difference between the groups in relation to shear strength was performed using analysis of variance (ANOVA). The Kruskal-Wallis test was used to assess the IRA. RESULTS: Group 2 showed shear strength significantly higher than other high-power LEDs and was similar to conventional LED. Regarding ARI, there was a statistically significant difference between the groups and the only one that did not differ from the control group was 2, while the other high-power LEDs (Groups 1 and 3) had more adhesive failures between the resin and the enamel. CONCLUSION: There was a difference between the three types of third generation LED light curing agents, with greater shear strength and less adhesive failures observed in the LED that presented higher power. (AU)

Light-curing of calcium hydroxide-based liners: pH analysis and calcium ion release / Fotoativação de forradores a base de hidróxido de cálcio: análise de pH e liberação de íons cálcio

Objective: Compare the pH values and calcium ion release of calcium hydroxide-based liner materials before and after light-curing. Material and Methods: The materials evaluated were: hydrox-cal white (HW), hydrox-cal dentin (HD), Biocal (BC) and UltraBlend Plus (UB). 120 samples of the liner materials were inserted into a PVC tube (n=15). The samples from HW+A, HD+A, BC+A and UB+A were subjected to photoactivation. The other groups HW+N, HD+N, BC+N and UB+N were only inserted in a glass tube with deionized water. The pH was measured 24 hours and 14 days after the inclusion of the samples with the aid of a pH meter. The calcium release was analyzed with the aid of an atomic absorption spectophotometer at 24h and 14 days. The results were submitted to the Shapiro-Wilk test, followed by ANOVA and Tukey test (p=0.05). Results: In 24h, the groups that were not light cured showed the highest pH values (p<0.05). In 14 days, BC+N and BC+A demonstrated the lowest pH values. The groups that were not light cured also showed higher calcium release values in 24h and 14 days (p<0.05). Conclusion: Photoactivation of calcium hydroxide-based liner materials negatively interferes with calcium ion release, as well as with pH.(AU)

Objetivo: Comparar os valores de pH e liberação de íons cálcio de materiais forradores à base de hidróxido de cálcio antes e depois da fotopolimerização. Material e métodos: Os materiais avaliados foram: Hidrox-cal branco (HW), Hidrox-cal dentina (HD), Biocal (BC) e UltraBlend Plus (UB). 120 amostras dos materiais de revestimento foram inseridas em um tubo de PVC (n=15). As amostras de HW +A, HD+A, BC+A e UB+A foram submetidas à fotoativação. Os demais grupos HW +N, HD+N, BC+N e UB+N foram inseridos apenas em um tubo de vidro com água deionizada. O pH foi medido 24 horas e 14 dias após a inclusão das amostras com o auxílio de um medidor de pH. A liberação de cálcio foi analisada com o auxílio de um espectrofotômetro de absorção atômica em 24h e 14 dias. Os resultados foram submetidos ao teste de Shapiro-Wilk, seguido de ANOVA e teste de Tukey (p=0,05). Resultados: Em 24h, os grupos não fotopolimerizados apresentaram os maiores valores de pH (p<0,05). Em 14 dias, BC+N e BC+A apresentaram os menores valores de pH. Os grupos não fotopolimerizados também apresentaram maiores valores de liberação de cálcio em 24h e 14 dias (p<0,05). Conclusão: A fotoativação de materiais de revestimento à base de hidróxido de cálcio interfere negativamente na liberação de íons cálcio e no pH (AU)

Color stability and degree of conversion of amine-free dual cured resin cement used with two different translucencies of lithium disilicate ceramics / Estabilidade de cor e grau de conversão de cimento resinoso dual sem amina usado com duas translucidezes diferentes de cerâmica de dissilicato de lítio

Objective: The present study aims to evaluate the color stability and degree of conversion of amine-free dual cured resin cement compared to light cured and amine-containing dual cured resin cements used with two different translucencies of thin esthetic restorations. Material and Methods: A total of 120 specimens were prepared for color stability testing (n=60). The specimens were divided into three main groups according to the resin cement type. Group 1: amine-free dual cured, Group 2: light cured, Group 3: amine-containing dual cured. Each group was further subdivided according to the ceramic translucency into two subgroups: high and low translucency. Color stability was assessed by a spectrophotometer before and after thermal aging. For the degree of conversion assessment (n=60), Fourier transform infrared spectroscopy was used at three different time intervals. Statistical analysis was performed using multi-factorial ANOVA, followed by one-way ANOVA with Bonferroni correction. Results: Amine-containing resin cement showed significantly higher ΔEab and ΔE00in both translucencies (4.5±0.3, 3.5±0.3 respectively for high translucency ceramic and 3.8±0.4, 3.0±0.3 respectively for low translucency) than the other tested cements (p<0.001). The highest degree of conversion (DC) was shown after 2 weeks by the amine-free dual cured resin cement (86.27±0.74). Conclusion: Amine-free dual cured resin cement can be an alternative to light cured one for cementation of thin veneers since it showed comparable color stability and high degree of conversion (AU)

Objetivo: O presente estudo tem como objetivo avaliar a estabilidade de cor e o grau de conversão do cimento resinoso dual sem amina em comparação com cimentos resinosos fotopolimerizáveis contendo amina usados com duas translucidezes diferentes em restaurações estéticas definitivas. Material e Métodos: Um total de 120 espécimes foram preparados para teste de estabilidade de cor (n=60). Os espécimes foram divididos em três grupos principais de acordo com o tipo de cimento resinoso. Grupo 1: polimerização dupla sem amina, Grupo 2: fotopolimerização, Grupo 3: polimerização dupla contendo amina. Cada grupo foi ainda subdividido de acordo com a translucidez da cerâmica em dois subgrupos: alta e baixa translucidez. A estabilidade da cor foi avaliada por um espectrofotômetro antes e após o envelhecimento térmico. Para a avaliação do grau de conversão (n=60), a espectroscopia de infravermelho com transformada de Fourier foi usada em três intervalos de tempo diferentes. A análise estatística foi realizada usando ANOVA multifatorial, seguida de ANOVA um faot com correção de Bonferroni. Resultados: O cimento resinoso contendo amina apresentou ΔEab e ΔE00 significativamente maiores em ambas as translucidezes (4,5±0,3, 3,5±0,3 respectivamente para cerâmica de alta translucidez e 3,8±0,4, 3,0±0,3 respectivamente para baixa translucidez) do que os outros cimentos testados (p< 0,001). O maior grau de conversão (DC) foi mostrado após 2 semanas pelo cimento resinoso dual sem amina (86,27±0,74). Conclusão: O cimento resinoso dual sem amina pode ser uma alternativa ao cimento polimerizável na restauração de facetas finas, uma vez que apresentou estabilidade de cor comparável e alto grau de conversão. (AU).

Impact of photoinitiator quality on chemical-mechanical properties of dental adhesives under different light intensities / Impacto da qualidade de fotoiniciadores nas propriedades químico mecânicas de adesivos dentais sob diferentes intensidades de luz

Objective: Evaluate the mechanical properties of experimental adhesive models with different photoinitiators (PI) polymerized by LED units of different power densities. Material and Methods: Three groups of adhesive models based on HEMA/BisGMA (45/55) were prepared in association with different PI combinations: G2 (control) ­ 2 PI: 0.5% CQ, 0.5% EDMAB; G3 - 3 PI: 0.5% CQ; 0.5% DMAEMA, 0.5% DPIHP; G4 - 4 PI: 0.5% CQ; 0.5% EDMAB; 0.5% DMAEMA; 0.5% DPIHP. The three formulations were polymerized at two different LED power densities: 550 mW/cm2 and 1200 mW/cm2. The degree of conversion (DC) of adhesive monomers was monitored in situ through the FTIR for 600 s. Specimens were prepared for each formulation for analysis mong adhesive systems (G2

Objetivo: Avaliar as propriedades mecânicas de modelos adesivos experimentais com diferentes fotoiniciadores (PI) polimerizados por unidades de LED de diferentes densidades de energia. Material e Métodos: Três grupos de modelos adesivos baseados em HEMA/BisGMA (45/55) foram preparados em associação com diferentes combinações de PI: G2 (controle) ­ 2 PI: 0,5% CQ, 0,5% EDMAB; G3 - 3PI: 0,5% CQ; 0,5% DMAEMA, 0,5% DPIHP; G4 - 4 PI: 0,5% CQ; 0,5% EDMAB; 0,5% DMAEMA; 0,5% DPIHP. As três formulações foram polimerizadas em duas densidades de potência de LED: 550 mW/cm2 e 1200 mW/cm2. O grau de conversão (DC) dos monômeros adesivos foi monitorado in situ através do FTIR durante 600 s. Amostras foram preparadas para cada formulação para análise de resistência à flexão (FS), módulo de elasticidade (ME), sorção (SOR) e solubilidade (SOL). Os dados foram submetidos aos testes ANOVA 2-fatores e Tukey (5%). Resultados: DC: houve diferença significativa entre os sistemas adesivos (G2

Effects of shades of a multilayered zirconia on light transmission, monomer conversion, and bond strength of resin cement.

OBJECTIVE: To evaluate the influence of shades of a multilayered zirconia on light transmission, resin cement degree of conversion, and shear bond strength of resin cement. MATERIALS AND METHODS: The light transmission through opaque (OPQ) and translucent (TNS) regions of Katana UTML zirconia (Kuraray Noritake Dental) were evaluated for using a spectroradiometer (n = 5). Degree of conversion of dual-cure resin cement (Panavia V5, Kuraray Noritake Dental) was measured after light-activation through OPQ or TNS regions and direct exposure. Composition of the zirconia was analyzed with energy dispersive x-ray spectroscopy (EDS). Shear bond strength (SBS) was evaluated on the OPQ and TNS regions after 24 h and 1 year from specimen preparation (n = 15). RESULTS: The OPQ region produced higher irradiance loss (95.1%) than TNS one (92.9%), and lower degree of conversion (52.4%) than TNS (71.2%) at 24 h post-light activation. EDS analysis did not show differences on the microstructure of the OPQ and TNS regions. There were no significant differences on the SBS between zirconia regions. For both zirconia regions, a significant reduction on the SBS occurred after aging, being 31.7% for OPQ and 38% for TNS. CONCLUSION: Both OPQ and TNS regions affected the light transmission through the multilayered zirconia. The OPQ region yielded the highest light attenuation and the lowest degree of conversion of resin cement. Different regions of the zirconia did not influence the SBS. Clinical significance Although opaque and translucent regions of the multilayered zirconia reduced the light transmission from LED curing unit and the degree of conversion of resin cement, the regions did not affect the resin cement adhesion.

Influence of customization and light-curing device on the bond strength of glass fiber posts - in vitro study / Influência da reanatomização e do aparelho fotopolimerizador na resistência de união de pinos de fibra de vidro - estudo in vitro

Introduction: Endodontically treated teeth are usually affected by extensive structure loss requiring the use of intraradicular posts to provide retention and restoration. Objective: An in vitro assessment was performed on the bonding of glass fiber posts to the root dentin. Material and method: Ninety (n = 10) single bovine roots were used in a 3 x 3 x 3 factorial study with subdivided plots: post customization varying the presence and type of resin (without customization, conventional resin, and Bulk Fill resin), light-curing device (Valo, Radii-Cal, Rainbow), and root third (cervical, middle, and apical). Result: For the customization factor, Tukey's test (5%) showed the superiority of the Bulk Fill (8.16 MPa) and Z350 (7.40 MPa) groups compared to the control group (4.92 MPa), without differing from each other. All light-curing devices differed, showing the superiority of Valo (9.36 MPa), Radii (6.96 MPa) as an intermediate, and the inferiority of Rainbow (4.17 MPa). The cervical root third (7.81 MPa) was superior, the apical third was inferior (5.80 MPa), and the middle third (6.88 MPa) was an intermediate without differing from the others. Conclusion: The customization of glass fiber posts increases the bond strength to the root dentin, regardless of the resin used. There was a compromise in the apical third and when using light-curing devices with lower light intensity.

Introdução: Dentes com extensa perda de estrutura podem comprometer a retenção das restaurações ao remanescente dental, onde pinos intraradiculares são indicados. Objetivo: Avaliou-se in vitro a união de pinos de fibra de vidro à dentina radicular em função de diferentes modos de reanatomização, fotopolimerizadores e regionalização radicular. Material e método: Noventa (n=10) raízes bovinas uniradiculares foram usadas num estudo fatorial 3 x 3 x 3 com parcelas subdivididas: Reanatomização do pino, variando a presença e tipo de resina (Sem reanatomização, Resina Convencional e Resina Bulkfill); Fotopolimerizador (Valo, Radii-cal, Rainbow); e Terço radicular (cervical, médio e apical). Resultado: O teste de Tukey (5%) evidenciou para o Fator Reanatomização superioridade dos grupos BulkFill (8.16MPa) e Z350 (7.40MPa) ao grupo Controle (4.92MPa), sem diferirem entre si. Todos os fotopolimerizadores diferiram entre si, com superioridade de Valo (9.36MPa), Radii (6.96MPa) intermediário, e inferioridade de Raiwbow (4.17MPa). O terço radicular cervical (7.81MPa) foi superior e o apical inferior (5.80MPa), com o terço médio (6.88MPa) intermediário e sem diferir dos demais. Conclusão: Conclui-se que a reanatomização de pinos de fibra de vidro aumenta a resistência de união à dentina radicular, independentemente da resina utilizada, havendo prejuízo no terço apical e quando são empregados fotopolimerizadores com menor intensidade luminosa.

Can bulk-fill compromise the curing potential in deep cavities? / Bulkfill pode comprometer o potencial de polimerização em cavidades profundas?

Objective: To determine the effect of the restorative technique, material's opacity and the selected light sources on the curing potential (CP) in deep cavities. Material and Methods: The radiant exitance (mW/cm2) of two light curing units (Bluephase G2 and Radii-Cal) was determined at 0 and 8 mm distance from a power meter sensor (Ophir). Two bulk-fill composites of regular consistency (Opus, FGM; and Filtek One, 3M) and a conventional one (Sirius-Z, DFL) were considered and the level of their opacity were determined by a sphere-based spectrophotometer (SP60, X-Rite). The degree of C=C conversion (DC) was determined by spectroscopy (FTIR-ATR) at 0.05 and 8 mm depths and the CP considered the ratio between them. The "incremental technique" considered 4 increments of 2mm thickness each, whereas the "bulk-fill technique considered 2 increments of 4mm-thickness. Data were submitted to analysis of variance and Tukey's test (95%). Pearson's correlation tests were performed to calculate the possible relation between curing potential and materials' opacity. Results: With the incremental technique it was possible to achieve high CP regardless of the light source. The CP of bulk-fill composites was dependent on the light source, whereas Radii-Cal compromised the DC at 8 mm for both materials. The correlation between opacity and CP was dependent on the light source (r = 0.891707246 for Radii-Cal; r = 0.515703768 for Bluephase G2). Conclusion: The bulk-fill technique was dependent on the light source while the incremental was not. The influence of materials' opacity was dependent on the light curing unit.(AU)

Objetivo: Determinar o efeito da técnica restauradora, a opacidade do material e as fontes de luz selecionadas sobre o potencial de cura (PC) em cavidades profundas. Materiais e métodos: A saída radiante (mW/cm2) de duas unidades de cura por luz (Bluephase G2 e Radii-Cal) foi determinada a 0 e 8 mm de distância de um sensor de potência (Ophir). Dois compósistos bulkfill de consistência regular (Opus, FGM; e Filtek One, 3M) e um convencional (Sirius-Z, DFL) foram considerados e o nível de sua opacidade foi determinado por um espectrofotômetro (SP60, X-Rite). O grau de conversão C=C (DC) foi determinado por espectroscopia (FTIR-ATR) a 0,05 e 8 mm de profundidade e o PC considerou a relação entre eles. A técnica incremental considerou 4 incrementos de 2 mm de espessura cada, enquanto que a técnica bulkfill considerou 2 incrementos de 4 mm de espessura. Os dados foram submetidos à análise de variância e ao teste de Tukey (95%). Os testes de correlação de Pearson foram realizados para calcular a possível relação entre o potencial de cura e a opacidade dos materiais. Resultados: Com a técnica incremental foi possível obter um PC elevado, independentemente da fonte de luz. O PC de compósitos bulkfill foi dependente da fonte de luz, enquanto que Radii-Cal comprometeu o DC em 8 mm para ambos os materiais. A correlação entre opacidade e PC foi dependente da fonte de luz (r = 0,891707246 para Radii-Cal; r = 0,515703768 para Bluephase G2). Conclusão: O potencial de polimerização para a técnica bulkfill foi dependente da fonte de luz, enquanto para a técnica incremental não. A influência da opacidade dos materiais sobre a capacidade de polimerização foi dependente da unidade de fotoativação. (AU)

Avaliação do nível de conhecimento de acadêmicos de Odontologia sobre fotopolimerização / Evaluation of the knowledge of dental students on light curing

O sucesso clínico de materiais resinosos é dependente de uma adequada polimerização. Diversos materiais fotoativados são utilizados frequentemente nas clínicas-escola de Odontologia. O objetivo desse estudo foi avaliar o nível de conhecimento dos acadêmicos do 10º período de Odontologia do Centro Universitário Maurício de Nassau, Recife/PE,sobre fotopolimerização, por meio de questionário. Os dados foram tabulados e analisados por meio de estatísticas descritivas, teste Qui-quadrado de Pearson e teste Exato de Fischer, com nível de significância de 5% (p<0,05). Os resultados demonstram que 83,8%dos estudantesnão possuem fotopolimerizador, 72,9% não conhecem a potência do aparelho, 56,2% não sabem qual é a potência mínima ideal e apenas 8,5% sabem o nome do aparelho aferidor da irradiância / potência. Além disso, 48,5% não sabem o comprimento de onda ideal para fotoativação de resina composta e 69,2% desconhecemo tipo de aparelho que utilizam (monowaveou poliwave).Em relação ao tempo de fotopolimerização, 60,8% afirmaram utilizar20 segundos em resinas compostas convencionais e 38,5% utilizam por40 segundos em resinas compostas Bulk-fill. Embora 84,6% afirmem usar aparelhos fotopolimerizadores frequentemente, apenas 26,9% sabem a distância ideal da ponteira à restauração. Além disso, 51,5% relataram que fazem a limpeza e desinfecção com álcool 70GL e 45,4% usam barreira plástica. Nesse contexto, pode-se concluir que o nível do conhecimento dos acadêmicos em relação à fotopolimerização foi insatisfatório, exigindo uma abordagem e avaliaçãomais efetivaspara que os discentes tenham consciência da importância clínica deste procedimento e suas consequências (AU).

The clinical success of resin materials depends on adequate curing. Several light cured materials are frequently used in dental school clinics. This study aimed to assess the knowledge of students from the 10th period of Dentistry at Maurício de Nassau University Center, Recife/PE, about light curing, using a questionnaire. Data were tabulated and analyzed by descriptive statistics, Pearson chi-square test and Fisher exact test, at a significance level of 5% (p<0.05). The results show that 83.8% of studentsdo not have a light curing unit, 72.9% do not know the device power, 56.2% do not know the ideal minimum power and only 8.5% know the name of the device that measures the irradiance/power. Also, 48.5% do not know the ideal wavelength for light curing of composite resin and 69.2% do not know the type of device they use (monowave or polywave). Regarding the light curing time, 60.8% stated they used 20 seconds in conventional composite resins and 38.5% used 40 seconds in bulk-fill composite resins. Although 84.6% stated that they use light curing units frequently, only 26.9% know the ideal distance from the tip to the restoration. Additionally, 51.5% reported performing cleaning and disinfection with 70GL alcohol and 45.4% use a plastic barrier. In this context, it can be concluded that the knowledge of students regarding light curing was unsatisfactory, requiring a more effective approach and evaluation so that the students may be aware of the clinical importance of this procedure and its consequences (AU).

Effect of ceramic thicknesses and opacities on water sorption and solubility of a light-curing resin cement by different units

Aim: This study evaluated the water sorption and solubility of a light-cured resin cement, under four thicknesses and four opacities of a lithium disilicate ceramic, also considering three light-emitting diode (LED) units. Methods: A total of 288 specimens of a resin cement (AllCem Veneer Trans ­ FGM) were prepared, 96 samples were light-cured by each of the three light curing units (Valo ­ Ultradent / Radii-Cal ­ SDI / Bluephase II ­ Ivoclar Vivadent), divided into 16 experimental conditions, according to the opacities of the ceramic: High Opacity (HO), Medium Opacity (MO), Low Translucency (LT), High Translucency (HT), and thicknesses (0.3, 0.8, 1.5, and 2.0 mm) (n = 6). The specimens were weighed at three different times: Mass M1 (after making the specimens), M2 (after 7 days of storage in water), and M3 (after dissection cycle), for calculating water sorption and solubility. Results: The higher thickness of the ceramic (2.0 mm) significantly increased the values of water sorption (44.0± 4.0) and solubility (7.8±0.6), compared to lower thicknesses. Also, the ceramic of higher opacity (HO) generated the highest values of sorption and solubility when compared to the other opacities, regardless of the thickness tested (ANOVA-3 factors / Tukey's test, α = 0.05). There was no influence of light curing units. Conclusion: Higher thicknesses and opacities of the ceramic increased the water sorption and solubility of the tested light-cured resin cement

Shrinkage Stress and Temperature Variation in Resin Composites Cured via Different Photoactivation Methods: Insights for Standardisation of the Photopolymerisation.

The literature has shown that there is no consensus regarding the best resin composite photoactivation protocol. This study evaluated the efficiency of the conventional, soft-start, pulse-delay and exponential protocols for photoactivation of resin composites in reducing the shrinkage stress and temperature variation during the photopolymerisation. The photoactivation processes were performed using a photocuring unit and a smartphone app developed to control the irradiance according each photoactivation protocol. These photoactivation methods were evaluated applying photoactivation energies recommended by the resins manufactures. Three brands of resin composites were analysed: Z-250, Charisma and Ultrafill. The cure effectiveness was evaluated through depth of cure experiments. All results were statistically evaluated using one-way and multi-factor analysis of variance (ANOVA). The use of exponential and pulse-delay methods resulted in a significant reduction of the shrinkage stress for all evaluated resins; however, the pulse-delay method required too long a photoactivation time. The increases on the temperature were lower when the exponential photoactivation was applied; however, the temperature variation for all photoactivation protocols was not enough to cause damage in the restoration area. The evaluation of the depth of cure showed that all photoactivation protocols resulted in cured resins with equivalent hardness, indicating that the choice of an alternative photoactivation protocol did not harm the polymerisation. In this way, the results showed the exponential protocol as the best photoactivation technique for practical applications.

Microhardness homogeneity of RBCs light-cured with a multiple-peak LED and surface characterization after wear

Abstract This in vitro study evaluated the effect of the beam homogeneity of a multiple-peak light-curing unit on the surface microhardness and the effect of toothbrushing wear on the microhardness, surface roughness, roughness profile, volume loss, and gloss retention of incremental and bulk-fill resin-based composites (RBCs). A LED light-curing unit (VALO) with four LEDs at the tip end (405, 445, 465A, and 465B nm emission peak) was used according to each manufacturer-recommended time to obtain disks (n=10) of six RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra, and Filtek Bulk Fill. Microhardness values were obtained according to each LED positioning of the light-curing unit on the top surface of the RBCs and were analyzed before and after toothbrushing regarding microhardness, surface roughness, roughness profile, volume loss, and gloss retention. Microhardness was considered homogeneous on the top surface regardless of the type of RBC or wavelength tested (p>0.05). Overall, toothbrushing did not reduce the microhardness of the RBCs but influenced the gloss values for most RBCs (p<0.001). Charisma Classic presented the greatest surface roughness and roughness profile after toothbrushing (p<0.05). Volume loss did not differ among RBCs (p>0.05). In conclusion, different wavelengths of the LED did not affect the top surface microhardness, regardless of the RBCs tested; and bulk-fill composites presented similar surface changes (microhardness, surface roughness, roughness profile, volume loss, and gloss retention) when compared to conventional composites after toothbrushing.

Resumo Este estudo in vitro avaliou a homogeneidade do feixe de um fotopolimerizador de múltiplos picos na microdureza superficial e o efeito da escovação na microdureza, rugosidade superficial, perfil de rugosidade, perda de volume e retenção do brilho de compósitos a base de resina (RBCs) incrementais ou bulk-fill. Um fotopolimerizador LED (VALO) com quatro LEDs na ponteira (405, 445, 465A e 465B nm de pico de emissão) foi usado de acordo com o tempo recomendado por cada fabricante para obtenção de discos (n=10) de seis RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra e Filtek Bulk Fill. Os valores de microdureza foram obtidos seguindo o posicionamento de cada LED na superfície superior das amostras e foram analisados antes e após a escovação quanto a microdureza, rugosidade superficial, perfil de rugosidade, perda de volume e retenção do brilho. A microdureza foi considerada homogênea no topo da superfície, independentemente do tipo de RBCs ou comprimento de onda testados (p>0.05). No geral, a escovação não reduziu a microdureza das RBCs, mas influenciou o brilho para a maioria das RBCs (p<0.001). Charisma Classic apresentou os maiores valores de rugosidade superficial e perfil de rugosidade após a escovação (p<0.05). A perda de volume não diferiu entre as RBCs (p>0.05). Em conclusão, os diferentes comprimentos de onda do LED não alteraram a microdureza do topo da superfície, independentemente das RBCs testadas; e as resinas bulk-fill apresentaram alterações superficiais similares (microdureza, rugosidade superficial, perfil de rugosidade, perda de volume e manutenção do brilho) quando comparadas às resinas convencionais após a escovação.

Light and viscosity effects on the curing potential of bulk-fill composites placed in deep cavities.

To determine the influence of light curing units (LCUs) and material viscosity on the degree of conversion (DC) of bulk-fill (BF) resin-based composites (RBCs) placed in deep cavity preparations. Four LCUs were tested: Valo cordless, Bluephase-G2, Poly wireless and Radii-cal. Light irradiance was determined at 0 mm and 6 mm distance to the reading sensor. The following RBCs were considered: Filtek BF, Filtek BF Flow, Opus BF, Opus BF Flow, Tetric N-Ceram BF and Surefil SDR Flow. Sirius-Z was used with the incremental technique. DC (n = 3) was evaluated by spectroscopy both at top and bottom regions of deep preparations with 6 mm depth. The data were submitted to ANOVA and Tukey's test (α = 0.05). Pearson's correlation (95%) was used to verify the relation between the LCUs and the curing potential of RBCs. The DC at 6 mm depth was reduced when Opus BF, Opus BF Flow and Tetric N-Ceram BF were activated with Radii-cal. There was a positive correlation between the LCU irradiance and the bottom/top conversion ratios. The materials' viscosities did not affect the curing potential. Bulk-fill composites did not present higher curing potential than the conventional composite used with the incremental technique; the most important aspect of the LCU was the irradiance ratio; and the materials' viscosity did not affect the curing potential as a function of depth. Radii-cal negatively impacted the degree of conversion at 6 mm depth for most bulk-fill resin composites. Depending on the brand, bulk-fill composites may present reduced curing potential due to the light source when placed in deep cavities. Dentists should avoid LCU with acrylic tips to photoactivate bulk-fill resin-based composites.

Effects of Different Light-curing Modes on the Compressive Strengths of Nanohybrid Resin-based Composites: A Comparative In Vitro Study.

OBJECTIVE: To evaluate the effects of polymerization conducted by using LED lamps of different wavelengths (polywave and monowave) on the compressive strengths of nanohybrid composite resins Filtek™ Bulk Fill - 3M and 3M™ Filtek™ Z350 XT. MATERIALS AND METHODS: The study was prospective, experimental in vitro, and comparative. The sample consisted of nanohybrid composite resins. The sample size (n) was 100 specimens, divided into 10 groups. CRIS (Checklist for Reporting In-vitro Studies) Guidelines were used for writing this article. RESULTS: There were statistically significant differences between all groups with P < 0.001. Group 2 (nanohybrid composite resin blocks 3M™ Filtek™ Z350 XT with Monowave LED lamps) showed the highest compressive strength of 238.36±34.69N; CI (213.55-263.18) N. This was followed by Group 4 (nanohybrid composite resin blocks 3M™ Filtek™ Z350 XT with Poliwave LED lamps, High Power) and Group 6 (nanohybrid composite resin blocks 3M™ Filtek™ Z350 XT with Poliwave LED lamps, Soft Star), with compressive strengths of 222.33 ± 53.09N, and 209.21 ± 22.52N, respectively. CONCLUSIONS: Significant differences were found between the compressive strengths of 3M™ Filtek™ Z350 XT and Filtek™ Bulk Fill - 3M resins, and that of resins photopolymerized with monowave and polywave LED lamps and halogen light. Thus, the types of light and lamp directly influence the compressive strengths of the composite resins.

Effect of Light Sources on Bond Strength of Different Composite Resins Repaired with Bulk-Fill Composite / Efecto del tipo de fuente luz en la resistencia adhesiva de distintas resinas compuestas reparados con una resina bulk-fill

Abstract: The aim of this study was to evaluate and compare the effects of different light sources on shear bond strength when bulk-fill composite was used for the repair of different composite resins. A total of 126 samples made from six resin composites with different properties were aged (thermal-cycling with 5000 cycle), exposed to the same surface treatments and adhesive procedure. Then, they were repaired with a bulk-fill composite. At the polymerization step, each group was divided into three subgroups (n=7) and light cured with a QTH light source for 40s and two different LED light sources for 20s. Subsequently, the specimens were aged in distilled water at 37 ºC for 4 weeks and then subjected to shear bond strength test. Then, the specimens were examined under a stereomicroscope to identify modes of failure and visualized by Scanning Electron Microscope. Data obtained from the study were analyzed using ANOVA and Tukey HSD Test (α=0.05). In all groups, the light curing units had an impact on shear bond strength (p<0.05). Among the study groups, the greatest bond strength values were observed in the specimens repaired using the LED and the specimens repaired with the QTH light curing unit had the lowest bond strength values. It was concluded that the content of composite resins and light curing units may influence bond strength of different composites repaired with the bulk-fill composite.

Resumen: El objetivo de este estudio fue evaluar y comparar los efectos de diferentes fuentes de luz sobre la resistencia de la unión al cizallamiento cuando se utiliza una resina bulk-fill para la reparación de diferentes resinas compuestas. Se envejecieron un total de 126 muestras fabricadas con seis compuestos de resina con diferentes propiedades (ciclo térmico con 5000 ciclos), expuestas a los mismos tratamientos de superficie y procedimiento adhesivo. Luego, fueron reparadas con una resina bulk- fill. En el paso de polimerización, cada grupo fue dividido en tres subgrupos (n=7) y fotopolimerizado con una fuente de luz QTH por 40s y dos fuentes de luz LED por 20s. Posteriormente, los especímenes se envejecieron en agua destilada a 37 ºC durante 4 semanas y luego se sometieron a una prueba de resistencia adhesiva de cizalla. Luego, los especímenes fueron examinados bajo un estereomicroscopio para identificar los modos de falla y visualizados por el Microscopio Electrónico de Barrido. Los datos obtenidos del estudio fueron analizados usando el ANOVA y la prueba Tukey HSD (α=0.05). En todos los grupos, las unidades de fotopolimerización tuvieron un impacto en la fuerza de adhesión al cizallamiento (p<0,05). Entre los grupos de estudio, los mayores valores de fuerza de adhesión se observaron en los especímenes reparados utilizando el LED y los especímenes reparados con la unidad de fotopolimerización QTH tuvieron los valores de fuerza de adhesión más bajos. Se llegó a la conclusión de que el contenido de las resinas compuestas y las unidades de fotopolimerización pueden influir en la fuerza de adhesión de los diferentes compuestos reparados con resinas bulk-fill.

Flexural strength and microhardness of bulk-fill restorative materials.

BACKGROUND: Bulk-fill materials can facilitate the restorative procedure mainly for deep and wide posterior cavities. The purpose of this study was to evaluate flexural strength (biaxial flexural strength [BFS]) and microhardness (Knoop microhardness [KHN]) at different depths of bulk-fill materials. METHODS: Five bulk-fill materials were tested: two light-curable composite resins, one dual-cure composite, one bioactive restorative, and a high-viscosity glass ionomer. A conventional composite was used as control. BFS and KHN were tested at different depths. Data was analyzed by two- and one-way ANOVAs, respectively and Tukey's post-hoc (α=0.05). RESULTS: The high-viscosity glass ionomer material presented the lowest BFS at all depths. KHN for the two light-curable and the dual-cure bulk-fill resin composites was reduced following an increase in restoration depth, while the conventional composite, the bioactive material, and the high-viscosity glass ionomer were not affected. CONCLUSION: There are differences in the properties of the tested materials at 4 mm depth, showing that the studied properties of some materials vary according to the cavity depth, although the results are material dependent. CLINICAL SIGNIFICANCE: Mechanical properties of light-cured, bulk-fill materials may be affected by inadequate polymerization. Clinicians should consider complementary strategies to achieve adequate polymerization at high-increment depths.