Assessment of influence of LED curing units used on microhardness of resin-modified glass ionomer sealants

Aim: Resin modified glass ionomer (RMGI) is class of material that can be used as sealant for preventing and arresting the progression of caries in pits and fissures. As these are hybrid materials, their properties can be affected by factors related to the polymerization process. Therefore, this study aimed to evaluate the influence of different generations of LED curing units (Elipar DeepCure-L and VALO Grand) on Knoop microhardness values (KHN) of RMGI sealants (Clinpro XT and Vitremer). Methods: Forty cylindrical specimens (6mm ø x 1 mm high) were prepared according to the manufacturer's instructions and divided into four groups (n=10) according to the type of RMGI and LED used. The KHN of the top surface of each sample was calculated 7 days after light-curing. Data were submitted to two-way ANOVA (α = 0.05). Results: Vitremer had higher KHN values than Clinpro XT after using both LEDs (p<0.0001), but especially when light-cured with the use of VALO Grand (p<0.0001). Whereas the KHN value of Clinpro was not influenced by the LED device (p>0.05). Conclusions: Top surface microhardness values of RGMI sealants were affected by both material composition and generations of LED curing units used. Third generation LED curing units seemed to be more efficient for the polymerization of RMGI-based sealants

Effect of conventional and power office bleaching with diode laser and led light on enamel microhardness

Aim: The present study aimed to asses enamel microhardness after office bleaching with diode laser and LED light compared to the conventional bleaching procedure. Methods: Thirty-nine human premolar teeth were collected and randomly divided into three groups regarding of the bleaching technique. Group 1: Snow O bleaching gel with LED light-curing unit; Group 2: Snow L bleaching gel with diode laser irradiation; and Group 3: Opalescence Boost bleaching gel with no light source in group 3. Enamel surface changes were evaluated in one tooth in each study group and one intact tooth as a reference under a scanning electron microscope (SEM). In the remaining samples (n=12), enamel microhardness was determined by Vickers microhardness test before and after bleaching. Data were analyzed with repeated-measures ANOVA to compare microhardness changes, followed by post hoc Tukey tests at the 0.05 significance level. Results: Enamel microhardness decreased in all the groups after bleaching, with the maximum decrease in microhardness in the Snow O bleaching group with LED light, which was significantly higher than the other groups (P=0.002). The two other groups did not exhibit any significant difference in microhardness decrease (P>0.05). Conclusion:Based on the limitations of this study, it can be concluded power bleaching with 980nm diode laser was less time-consuming compare to conventional bleaching procedure and yielded better outcomes in terms of enamel surface microhardness compared to the use of an LED light-curing unit

Effect of Light-Curing Unit Type and Bulk-Fill Composite Resins with Different Photoinitiators on Marginal Gaps of Class II Restorations

Abstract Objective: To evaluate the effect of two types of light-curing units (second and third generations) and two types of bulk-fill composite resins with different photoinitiators - Tetric N-Ceram Bulk Fill (TNCB) and Xtra Fil (XTF) on gap formation at the gingival margins of Cl II restorations. Material and Methods: Fifty-six standard Cl II cavities were prepared on the mesial and distal surfaces of premolar teeth, with the gingival margin of the cavities 1 mm apical to the CEJ. The samples were randomly assigned to two groups based on the composite resin type and two subgroups based on the light-curing unit type and restored. After 5000 rounds of thermocycling, gingival margin gap in each sample was measured in µm under an electron microscope at ×2000 magnification. Data were analyzed by two-way ANOVA and Tukey tests (α=0.05). Results: Marginal gaps of TNCB composite resin were significantly smaller than those of XTF composite resin (p<0.001). There were no significant differences between the two light-curing units in each group (p=0.887 with XTF and p=0.999 with TNCB). Conclusion: The gaps at gingival margins of Cl II cavities with TNCB bulk-fill composite were smaller than XTF composite resin. Both composite resins can be cured with both the second- and third-generation LEDs (AU).

Novo sistema de retentor pré-fabricado perfurado e de iluminador em fibra óptica: estudo da resistência mecânica frente a variação dos cimentos resinosos / New system of hollow prefabricated post and optical fiber illuminator: study of the mechanical strength by varying resin cements

O presente estudo teve por objetivo avaliar a resistência à flexão de um pino experimental de fibra de vidro vazado, e a resistência adesiva entre este pino experimental à dentina radicular, associando a utilização de um dispositivo iluminador em fibra óptica, sob o processo de envelhecimento, além de determinar a distribuição de tensão pela Análise de Elementos Finitos (FEA). O pino experimental e o dispositivo iluminador de fibra óptica têm por finalidade aumentar a efetividade de fotoativação dos cimentos resinosos nos terços médios e apicais dos canais radiculares. Para o teste de flexão de 3 pontos, estritamente do pino de fibra de vidro, as amostras foram divididas em 4 grupos (n=10): pino convencional (pc), pino experimental sem preenchimento (pp), com preenchimento de cimento resinoso (ppc) e com preenchimento de fibra óptica (ppf). Para o teste de resistência adesiva Pull-out, 100 raízes de dentes bovinos foram restauradas com retentores intrarradiculares e coroas de resina composta, distribuídos em 10 grupos (n=10), tendo como variáveis: o tipo de pino de fibra de vidro [convencional (C) ou perfurado (P)], o sistema de fotoativação [com ou sem o iluminador de fibra óptica (O)], o tipo de cimento resinoso [fotoativado (F) ou polimerização dual (D)] e o envelhecimento das amostras [com e sem ciclagem mecânica (C)]. O processo de envelhecimento foi realizado através da ciclagem mecânica e as amostras foram submetidas ao teste de resistência adesiva Pull-out. A análise do modo de falha foi realizada em Estereomicroscópio. A Análise em Elementos Finitos avaliou a distribuição de tensão pela análise de von Mises, deformação total e tensão máxima principal no Software Ansys 19.3. A análise estatística foi constituída pelo teste de normalidade Shapiro-Wilk, análise de variância (ANOVA) 1, 2 e 3 fatores e teste Tukey 5%. As médias e desvios padrão de resistência à flexão foram (MPa): pc = 677 ± 81,1; ppc = 419 ± 23,2; ppf = 200 ± 32,5 e pp = 177 ± 32,8. As médias e desvios padrão de resistência adesiva foram (MPa): CD = 12,2 ± 1,21; PD = 11,1 ± 1,32; PF = 10,9 ± 1,29; POD = 13,7 ± 1,16; POF = 11,9 ± 1,48; CDC = 10,1 ± 1,33; PDC = 9,25 ± 1,11; PFC = 8,37 ± 1,25; PODC = 10,8 ± 0,95 e POFC = 9,82 ± 1,02. Os resultados do modo de falha foram: adesiva entre pino e cimento (56%), mista predominantemente adesiva entre cimento e dentina (22%), adesiva entre cimento e dentina (14%) e a mista predominantemente adesiva entre pino e cimento (8%). Concluiu-se que entre os pinos experimentais, o grupo do pino perfurado preenchido com cimento resinoso obteve o maior valor de resistência à flexão, a utilização do dispositivo iluminador aumentou os resultados de resistência adesiva nos grupos dos pinos perfurados e não houve diferença na distribuição de tensões entre os grupos. (AU)

The present study aimed to evaluate the flexural strength of an experimental hollow glass fiber post, and the bond strength between this experimental post and root dentin, associating the use of an optical fiber illuminating device, under the aging process, in addition to determine the stress distribution by Finite Element Analysis (FEA). The experimental post and optical fiber illuminating device are intended to increase the polymerization effectiveness of resin cements in the middle and apical regions of root canals. For the 3-point bending test, strictly of the fiber post, the samples were divided into 4 groups (n=10): conventional post (pc), experimental post without filling (pp), with resin cement filling (ppc) and with optical fiber filling (ppf). For the Pull-out test, 100 roots of bovine teeth were restored with intraradicular retainers and composite resin crowns, distributed into 10 groups (n=10), with the following variables: glass fiber post type [conventional (C) or hollow (P)], the photocuring system [with or without the optical fiber illuminating device (O)], the type of resin cement [light cured (F) or dual cured (D)] and aging of the samples [with and without mechanical cycling (C)]. The aging process was performed by mechanical cycling and the samples were submitted to the Pull-out bond strength test. Failure mode analysis was performed using a stereomicroscope. Finite Element Analysis evaluated the stress distribution by von Mises analysis, total strain and maximum principal stress in Ansys Software 19.3. Statistical analysis consisted of the Shapiro-Wilk normality test, 1-, 2- and 3-way analysis of variance (ANOVA) and Tukey test 5%. The means and standard deviations of flexural strength were (MPa): pc = 677 ± 81.1; ppc = 419 ± 23.2; ppf = 200 ± 32.5 and pp = 177 ± 32.8. The means and standard deviations of bond strength were (MPa): CD = 12.2 ± 1.21; PD = 11.1 ± 1.32; PF = 10.9 ± 1.29; POD = 13.7 ± 1.16; POF = 11.9 ± 1.48; CDC = 10.1 ± 1.33; PDC = 9.25 ± 1.11; PFC = 8.37 ± 1.25; PODC = 10.8 ± 0.95 and POFC = 9.82 ± 1.02. The failure mode results were: adhesive between post and cement (56%), mixed predominantly adhesive between cement and dentin (22%), adhesive between cement and dentin (14%) and mixed predominantly adhesive between post and cement (8 %). It was concluded that among the experimental posts, the hollow post group filled with resin cement obtained the highest flexural strength value, the use of the illuminating device increased the results of bond strength in the hollow post groups and there was no difference in the stress distribution among the groups (AU)

Errors in light-emitting diodes positioning when curing bulk fill and incremental composites: impact on properties after aging.

OBJECTIVES: This study aimed to evaluate the effect of improper positioning single-peak and multi-peak lights on color change, microhardness of bottom and top, and surface topography of bulk fill and incremental composites after artificial aging for 1 year. MATERIALS AND METHODS: Bulk fill and incremental composites were cured using multi-peak and single-peak light-emitting diode (LED) following 4 clinical conditions: (1) optimal condition (no angulation or tip displacement), (2) tip-displacement (2 mm), (3) slight tip angulation (α = 20°) and (4) moderate tip angulation (α = 35°). After 1-year of water aging, the specimens were analyzed for color changes (ΔE), Vickers hardness, surface topography (Ra, Rt, and Rv), and scanning electron microscopy. RESULTS: For samples cured by single-peak LED, the improper positioning significantly increases the color change compared to the optimal position regardless of the type of composite (p < 0.001). For multi-peak LED, the type of resin composite and the curing condition displayed a significant effect on ΔE (p < 0.001). For both LEDs, the Vickers hardness and bottom/top ratio of Vickers hardness were affected by the type of composite and the curing condition (p < 0.01). CONCLUSIONS: The bulk fill composite presented greater resistance to wear, higher color stability, and better microhardness than the incremental composite when subjected to improper curing. The multi-peak LED improves curing under improper conditions compared to single-peak LED. Prevention of errors when curing composites requires the attention of all personnel involved in the patient's care once the clinical relevance of the appropriate polymerization reflects on reliable long-term outcomes.

Fuentes de luz de uso clínico en el pre grado: 7 años de seguimento / Light curing units in the undergraduate dental clinics: 7 years of follow-up

RESUMEN Objetivo: Realizar, durante siete años ininterrumpidos, un control y seguimiento de las fuentes de luz disponibles en las clínicas odontológicas de pre graado de una Institución de Enseñanza Superior Pública Brasileña. Material y métodos: Durante el período comprendido entre 2011-2017 se evaluó el control de calidad de las fuentes de luz de la Facultad de Odontología de la Universidad Federal de Goiás a través del análisis de su estado de conservación y de su densidad de potencia (mW/cm2). Los datos obtenidos se sometieron a un análisis estadístico descritpivo y a las pruebas de Levene, Shapiro-Wilk, Kruskal-Wallis, Dunn y Chi-cuadrado (P<0,05). Resultados: No se observaron diferencias estadísticas significativas del estado de conservación de las fuentes de luz entre los años 2012, 2016 y 2017 (p>0,05). Sí se observaron diferencias estadísticas significativas entre los valores de densidad de potência entre dichos años (p<0,0001). En las comparaciones por pares, los valores de densidad de potencia para los años 2011 (p<0,01) y 2012 (p<0,05) fueron estadísticamente diferentes de los años 2015, 2016 y 2017. Conclusiones: Comparativamente se observó una mejora sustancial del estado de conservación de las fuentes de luz en los cuatro años iniciales de evaluaciones, con una disminución en el quinto año y una estabilización en los dos últimos años. Durante los siete años de estudio de la densidad de potencia de las fuentes de luz se observó en un aumento gradual de la misma con una estabilización de los resultados a partir del quinto año de control de calidad.

SUMMARY Objetive: To monitor the light curing units available at undergraduate dental clinics of a Brazilian Public Higher Education Institution for seven uninterrupted years. Materials and methods: In the period between 2011-2017, the quality control of light curing units at the Faculty of Dentistry, Federal University of Goiás, was evaluated by analyzing their state of conservation and power density (mW/cm2). Data obtained were subjected to descriptive statistical analysis and Levene, Shapiro-Wilk, Kruskal-Wallis, Dunn and Chi-square tests (P <0.05). Results: Regarding the conservation status of the light curing units, comparatively, there was no statistically significant difference between the years 2012, 2016 and 2017 (p> 0.05). Statistically significant differences were found for power density values between years (p <0.0001). In pairwise comparisons, the power density values for the years 2011 (p <0.01) and 2012 (p <0.05) were statistically different from the years 2015, 2016 and 2017. Conclusions: A significant improvement in the state of conservation of light curing units was observed in the initial four years of evaluations, with a decline in the fifth year and stabilization in the last two years. Regarding the power density of the light curing units, a gradual increase was observed in the seven years of study, with stabilization of the results after the fifth year of quality control.

Polywave And Monowave Light-Curing Units Effects On Polymerization Efficiency Of Different Photoinitiators / Efeito Da Unidade De Cura Por Luz Polywave E Monowave Na Eficiência De Polimerização De Diferentes Fotoiniciadores

Objective: The objective of this study was to characterize and correlate the absorption spectra of three photoinitiators [camphorquinone (CQ), diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) and phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO)], using second or third-generation light curing units (LCU), and to evaluate the degree of conversion and the physical properties of an experimental resin adhesive. Material and methods: Second-generation (Radii-cal® and Emitter D®) and third-generation (Valo® Cordless and Bluephase N®) LCU were assessed regarding spectrum and irradiance rate of emitted light. Also, the photoinitiators (CQ, TPO and BAPO) were characterized by a light absorption spectrum assessed by UV-Vis spectroscopy, degree of conversion and yellowing effect. Statistical analyzes considered two-way ANOVA and post-hoc Tukey test. Results: BAPO presented higher reactivity compared to TPO. Regarding degree of conversion of the photoinitiators activated by different light-curing units, the Emitter D® device promoted a high degree of conversion. BAPO presented the highest yellowing effect values. Conclusions: The emission and absorption characteristics of the photoinitiators were different. The polymerization reaction activated by the second-generation light-curing unit was reduced when using an experimental resin with photoinitiator TPO, and the third-generation light-curing unit showed a higher polymerization potential regardless of the photoinitiator. (AU)

Objetivo: Caracterizar e correlacionar os espectros de absorção de três fotoiniciadores [canforoquinona (CQ), difenil 2,4,6-trimetilbenzil óxido de fosfina (TPO) e óxido de di (2,4,6-trimetilbenzil) difenil fosfina (BAPO)], com unidades de fotoativação (LCU) de segunda ou terceira geração, e avaliar o grau de conversão e as propriedades físicas de um adesivo experimental. Material e métodos: LCU de segunda geração (Radii-cal® e Emitter D®) e terceira geração (Valo® Cordless e Bluephase N®) foram avaliadas quanto ao espectro e taxa de irradiância da luz emitida. Além disso, os fotoiniciadores (CQ, TPO e BAPO) foram caracterizados por um espectro de absorção de luz avaliado por espectroscopia UV-Vis, avaliado o grau de conversão dos adesivos e efeito de amarelamento. A análise estatística empregada foi ANOVA duas vias e teste post-hoc de Tukey. Resultados: BAPO apresentou maior reatividade comparado ao TPO. Em relação ao grau de conversão dos fotoiniciadores ativados por diferentes aparelhos fotopolimerizadores, o dispositivo Emitter D® promoveu um alto grau de conversão. BAPO apresentou os maiores valores de efeito de amarelamento. Conclusões: As características de emissão e absorção dos fotoiniciadores foram diferentes. A reação de polimerização ativada pelas unidades de fotopolimerização de segunda geração foi reduzida com o uso de uma resina experimental com fotoiniciador TPO. As unidades de fotopolimerização de terceira geração apresentaram maior potencial de polimerização independentemente do fotoiniciador. (AU)

Produção científica em laser / LED na odontologia brasileira no período de 2015 a 2019 / Scientific production in laser / LED in Brazilian dentistry from 2015 to 2019

Objetivo:Investigar o perfil das publicações brasileiras em laser/LED de 2015 a 2019. Métodos: Foi realizado um estudo observacional, por meio de documentação indireta, através da análise dos trabalhos apresentados nas reuniões do SBPqO de 2015 a 2019. Os estudos foram classificados quanto à instituição de ensino dos pesquisadores, estado de origem da pesquisa, especialidade odontológica e tipo de estudo. Resultados: Foram identificados 563 resumos. A maior parte foi concentrada em 2019 (21,7%), sendo os lasers operando em baixa potência os mais utilizados (54,1%). O Estado de São Paulo concentrou a maioria dos resumos (67,3%), com a região Sudeste contendo o maior número de trabalhos (76,9%). Em relação à instituição de ensino, as universidades estaduais produziram a maioria dos estudos (47.8%). A especialidade de Dentística foi a que mais realizou pesquisas em laser/LED (21,7%). A maioria dos resumos (73,7%) era do tipo de pesquisa laboratorial básica. A maioria dos trabalhos selecionados não recebeu apoio financeiro (54,7%). Dentre as agências financiadoras mencionadas, as Fundações de Amparo à Pesquisa foram as mais prevalentes (26,6%). Grande parte dos trabalhos não citou o Comitê de Ética em Pesquisa (97,5%). Houve associação estatisticamente significativa entre as instituições públicas e o recebimento de fomento (p < 0,005). Conclusão: A maior parte dos resumos foi concentrada em 2019, com maior número de pesquisas no Estado de São Paulo, realizadas em instituições Públicas e na especialidade de Dentística. Foi observado um número maior de estudos do tipo laboratorial. Além disso, a maioria dos estudos não recebeu fomento para pesquisa.

Aim: To determine the profile of Brazilian publications in laser/ LED from 2015 to 2019. Methods: A retrospective observational study was conducted, using indirect documentation to analyze the papers presented at SBPqO meetings from 2015 to 2019. Results: 563 abstracts involving the use of laser/LED were evaluated and subsequently classified according to higher education research institution, state where the research was conducted, dental specialty, and type of study. Most of the abstracts involving the laser/LED were concentrated in 2019 (21.7%), with low-power lasers being the most frequently used (54.1%). Most of the abstracts were concentrated in the State of São Paulo (67.3%), with the Southeast region containing the largest number of works (76.9%). Regarding the higher education institution, the state universities produced a larger number of the studies (47.8%). Restorative dentistry was the specialty that most developed studies in the laser/LED area (21.7%). Most abstracts (73.7%) were classified as basic laboratory research. Most of the selected studies received no financial support (54.7%). Among the funding agencies mentioned, the Research Support Foundations were the most prevalent (26.6%). Most studies did not mention the Research Ethics Committee (97.5%). There was a statistically significant association between public institutions and the receipt of funding (p < 0.005). Conclusion: Most of the abstracts were identified in 2019, with a greater number of studies conducted in the State of São Paulo, in state institutions across the country, and in the specialty area of restorative dentistry. Laboratory-type studies were the most prevalent. Moreover, most studies received no funding for research.

Evaluation of intensity standards of tungsten-halogen and led curing units / Evaluación de estándares de intensidad de unidades de curado tugsteno-halógenas y leds

Current evidence indicates that the minimum light intensity of photo curing units required to polymerize in a reliable way a composite resin, in increments of 2mm, is 300mW/cm2. The recent introduction of new generations of composite resin materials for large volume increments, partially contrasts with ISO 4049 (2009), calling for the use of light intensity of 1,000mW/cm2. Therefore, it is considered relevant to carry out periodic measurements of the emission intensity of light-curing units of clinical use. The aim of this study was to test the intensity [mW/cm2] of a representative sample of tungsten-halogen and LED photopolymerization units used in private and public health service in different areas of the Valparaíso Region in Chile. This was achieved through the use of dental radiometers, without considering the variables of intensity modification over time (either spontaneously, by undesirable inherent characteristics of the device, or by programs of intensity modification in time), or the density of accumulated power needed. This in vitro diagnostic test, evaluated a sample of 507 units, 107 halogen and 400 LED, for a period of around one month, using two radiometers as measuring instruments. For LED units the Bluephase Meter® radiometer, from Ivoclar-VivadentTM was used, and for halogen units we used the Coltolux® from ColténeTM. As a result, 85% of the LED and halogen units achieved the minimum requirements of intensity needed for the polymerization of conventional dental biomaterials. However, only 25% from the tested units achieved a power density of 1,000mW/cm2.

Light transmittance of CAD/CAM ceramics with different shades and thicknesses and microhardness of the underlying light-cured resin cement.

OBJECTIVES: The aim of this in vitro study was to evaluate the effects of the thickness and shade of 3 types of computer-aided design/computer-aided manufacturing (CAD/CAM) materials. MATERIALS AND METHODS: A total of 120 specimens of 2 shades (A1 and A3) and 2 thicknesses (1 and 2 mm) were fabricated using VITA Mark II (VM; VITA Zahnfabrik), IPS e.max CAD (IE; IvoclarVivadent), and VITA Suprinity (VS; VITA Zahnfabrik) (n = 10 per subgroup). The amount of light transmission through the ceramic specimens was measured by a radiometer (Optilux, Kerr). Light-cured resin cement samples (Choice 2, Bisco) were fabricated in a Teflon mold and activated through the various ceramics with different shades and thicknesses using an LED unit (Bluephase, IvoclarVivadent). In the control group, the resin cement sample was directly light-cured without any ceramic. Vickers microhardness indentations were made on the resin surfaces (KoopaPazhoohesh) after 24 hours of dark storage in a 37°C incubator. Data were analyzed using analysis of variance followed by the Tukey post hoc test (α = 0.05). RESULTS: Ceramic thickness and shade had significant effects on light transmission and the microhardness of all specimens (p < 0.05). The mean values of light transmittance and microhardness of the resin cement in the VM group were significantly higher than those observed in the IE and VS groups. The lowest microhardness was observed in the VS group, due to the lowest level of light transmission (p < 0.05). CONCLUSION: Greater thickness and darker shades of the 3 types of CAD/CAM ceramics significantly decreased the microhardness of the underlying resin cement.

Real-time Temperature Monitoring During Light-Curing of Experimental Composites.

OBJECTIVE: To investigate the real-time temperature rise during light-curing of experimental composite materials containing bioactive glass 45S5 (BG) and compare it to the temperature rise in three commercial composites. MATERIALS AND METHODS: Five light-curable composite materials containing 0-40 wt% of BG and a total filler load of 70 wt% were prepared. Cylindrical composite specimens 6 mm in diameter and 2 mm thick were cured using Bluephase G2 (Ivoclar Vivadent) at 1200 mW/cm2 for 30 s. The rise in temperature during light-curing was measured at the bottom of the specimens using a T-type thermocouple at the data collection rate of 20 s -1. An additional illumination for 30 s was performed after the specimen temperature returned to the baseline in order to record the temperature rise due to the heating from the curing unit. Statistical analysis was performed using the one-way ANOVA and Pearson correlation analysis with α=0.05. RESULTS: Temperature rise during light-curing of experimental composites amounted to 12.2-14.0 °C and was comparable to that of the flowable commercial composite (12.5 °C) but higher than that of nano- and micro-hybrid commercial composites (9.6-10.3 °C). The temperature rise during the second illumination was similar for all composites (7.8-9.1 °C). In experimental composites, the temperature rise which was attributable to the polymerization exotherm amounted to 3.1-5.8 °C and was negatively correlated to the BG fraction (R2=0.94). Times at which temperature reached maximum values were in the range of 6.5-19.8 s and were positively correlated to the BG fraction (R2=0.98). CONCLUSIONS: Temperature rise during light-curing of experimental composites was comparable to that of commercial composites, suggesting that the amount of heat released is tolerable by dental pulp.

Light transmittance of CAD/CAM ceramics with different shades and thicknesses and microhardness of the underlying light-cured resin cement

OBJECTIVES: The aim of this in vitro study was to evaluate the effects of the thickness and shade of 3 types of computer-aided design/computer-aided manufacturing (CAD/CAM) materials. MATERIALS AND METHODS: A total of 120 specimens of 2 shades (A1 and A3) and 2 thicknesses (1 and 2 mm) were fabricated using VITA Mark II (VM; VITA Zahnfabrik), IPS e.max CAD (IE; IvoclarVivadent), and VITA Suprinity (VS; VITA Zahnfabrik) (n = 10 per subgroup). The amount of light transmission through the ceramic specimens was measured by a radiometer (Optilux, Kerr). Light-cured resin cement samples (Choice 2, Bisco) were fabricated in a Teflon mold and activated through the various ceramics with different shades and thicknesses using an LED unit (Bluephase, IvoclarVivadent). In the control group, the resin cement sample was directly light-cured without any ceramic. Vickers microhardness indentations were made on the resin surfaces (KoopaPazhoohesh) after 24 hours of dark storage in a 37°C incubator. Data were analyzed using analysis of variance followed by the Tukey post hoc test (α = 0.05). RESULTS: Ceramic thickness and shade had significant effects on light transmission and the microhardness of all specimens (p < 0.05). The mean values of light transmittance and microhardness of the resin cement in the VM group were significantly higher than those observed in the IE and VS groups. The lowest microhardness was observed in the VS group, due to the lowest level of light transmission (p < 0.05). CONCLUSION: Greater thickness and darker shades of the 3 types of CAD/CAM ceramics significantly decreased the microhardness of the underlying resin cement.

Light curing in dentistry and clinical implications: a literature review

Abstract Contemporary dentistry literally cannot be performed without use of resin-based restorative materials. With the success of bonding resin materials to tooth structures, an even wider scope of clinical applications has arisen for these lines of products. Understanding of the basic events occurring in any dental polymerization mechanism, regardless of the mode of activating the process, will allow clinicians to both better appreciate the tremendous improvements that have been made over the years, and will also provide valuable information on differences among strategies manufacturers use to optimize product performance, as well as factors under the control of the clinician, whereby they can influence the long-term outcome of their restorative procedures.

Efficiency of polymerization of bulk-fill composite resins: a systematic review

Abstract This systematic review assessed the literature to evaluate the efficiency of polymerization of bulk-fill composite resins at 4 mm restoration depth. PubMed, Cochrane, Scopus and Web of Science databases were searched with no restrictions on year, publication status, or article's language. Selection criteria included studies that evaluated bulk-fill composite resin when inserted in a minimum thickness of 4 mm, followed by curing according to the manufacturers' instructions; presented sound statistical data; and comparison with a control group and/or a reference measurement of quality of polymerization. The evidence level was evaluated by qualitative scoring system and classified as high-, moderate- and low- evidence level. A total of 534 articles were retrieved in the initial search. After the review process, only 10 full-text articles met the inclusion criteria. Most articles included (80%) were classified as high evidence level. Among several techniques, microhardness was the most frequently method performed by the studies included in this systematic review. Irrespective to the "in vitro" method performed, bulk fill RBCs were partially likely to fulfill the important requirement regarding properly curing in 4 mm of cavity depth measured by depth of cure and / or degree of conversion. In general, low viscosities BFCs performed better regarding polymerization efficiency compared to the high viscosities BFCs.

Water sorption and solubility of bulk-fill composites polymerized with a third generation LED LCU

Abstract The aim of this study was to compare the degree of water sorption and solubility in bulk-fills after curing with a polywave light source. A total of 120 disc-shaped specimens (8 mm diameter; 4 mm depth) were prepared from three regular bulk-fill materials (X-tra Fil, Tetric N-Ceram Bulk Fill, SonicFill), and a control material (Filtek Z250), cured in 3 different modes (standard: 1000 mW/cm2-20 s; high power: 1400 mW/cm2-12 s; xtra power: 3200 mW/cm2-6 s) using a third generation light-emitting diode light curing unit. Water sorption and solubility levels of the specimens were measured according to the ISO 4049:2009 specification after storing in distilled water for 30 days. Data were analyzed using two-way ANOVA and Tukey's post-hoc test (p < 0.05). The Z250 sample exposed to high power presented a higher sorption compared to the X-tra Fil and SonicFill samples. In xtra power mode, the values of Z250 and SonicFill were similar to each other and higher compared to those of X-tra Fil. Only SonicFill exhibited significantly different sorption values depending on the curing mode, the highest of which was achieved when using the xtra power mode. The highest solubility values were obtained for SonicFill. No statistically significant differences were found among other groups. No significant correlation was detected between water sorption and solubility. The traditional composite group exhibited a higher water sorption values than the bulk-fills. The reduction in polymerization time significantly increased the sorption of SonicFill. SonicFill showed the highest water solubility value among the composites tested.

Análise da dureza de um novo material restaurador para ART: Glass Carbomer / Analysis of the hardness of a new restorative material for ART: Glass Carbomer

Objetivo: Este estudo avaliou a microdureza de dois materiais ionoméricos - Glass Carbomer (GC-GCP Dental) e Riva Light Cure (RL-SDI) - em combinação com quatro unidades fotopolimerizadoras (Carbo LED lamp, GCP-Dental; Demi LED curing light, Kerr; Poli Wireless, Kavo; Radii Plus, SDI). Material e método: Foram confeccionados 80 corpos de prova seguindo a orientação dos fabricantes, sendo 40 para cada material ionomérico e, para cada 10 corpos de prova, uma das unidades fotopolimerizadoras foi utilizada. Após sete dias de armazenamento em água destilada e temperatura ambiente, os 80 corpos de prova foram submetidos ao teste de microdureza Vickers (microdurômetro HMV 2T). Cinco indentações foram realizadas em cada corpo de prova (centro, extremidades direita e esquerda, e superior e inferior). O ensaio foi realizado sob uma carga de 100 gramas, com tempo de penetração de dez segundos. Resultado: Independentemente da unidade fotopolimerizadora, o Riva Light Cure (RL-SDI) apresentou menor microdureza que o material Glass Carbomer (GC-GCP-Dental). A microdureza do Glass Carbomer (GC-GCP-Dental) foi influenciada pelo tipo de unidade fotopolimerizadora utilizada como fonte de calor. A análise de variância e o Teste de Tuckey (p< 0,05) mostraram que a interação dos fatores material vs.unidade fotopolimerizadora (p< 0,001) e os fatores principais material (p< 0,001) e unidade fotopolimerizadora (p=0,002) foram estatisticamente significantes. Conclusão: O material ionomérico Glass Cabomer (GCP- Dental) apresentou valor de microdureza significativamente superior quando comparado com o cimento de ionômero de vidro modificado por resina Riva Light Cure (SDI), independentemente da unidade fotopolimerizadora utilizada.

Objective: This study evaluated the microhardness of two encapsulated ionomer materials - Glass Carbomer (GC-GCP Dental) and Riva Light Cure (RL-SDI) in combination with four light curing units (Carbo LED lamp, GCP-Dental, Demi LED curing light, Kerr, Poli Wireless, Kavo, Radii Plus, SDI). Material and method: Eighty specimens were prepared following the manufacturer's guidelines, 40 for each ionomer material and for 10 specimens, one light curing unit was used. After 7 days of storage in distilled water and at room temperature, 80 specimens were tested with the Vickers hardness (microhardness HMV 2T, Shimadzu, Japan). Five indentations were performed on each specimen (center, right, left, top and bottom). The test was carried out under a load of 100 g, with a 10 second penetration time. Result: Independent of the curing unit the Riva Light Cure (RL-SDI) obtained the lower hardness than the material Glass Carbomer (GC-GCP-Dental). The microhardness of Glass Carbomer (GC-GCP-Dental) was influenced by the type of curing unit used as a heat treatment. The analysis of variance and Tukey test (p< 0.05) showed that the interaction of factors material vs. curing unit (p< 0.001), the main factor material (p< 0.001) and curing unit (p=0.002) were statistically significant. Conclusion: The ionomeric material Glass Carbomer (GCP-Dental) had significantly higher hardness value when compared with glass ionomer modified by resin Riva Light Cure (SDI), regardless of the light curing unit used.

Effect of new innovative restorative carbomised glass cement on intrapulpal temperature rise: an ex-vivo study

Abstract This study aimed to evaluate the temperature changes that occurred in the pulp chamber when using GCP Glass Carbomer Fill (GCP) and two different resin-modified glass-ionomer (RGI) restorative materials at different dentin thicknesses. A standardized Class I occlusal cavity with 1 mm or 2 mm dentin thickness was prepared in the extracted human molar teeth. RGI and GCP fills were placed in the cavities and cured with two different light-curing units. This study included a total of 120 samples, with 20 samples in each group. The pulp microcirculation method was used for measuring the intrapulpal temperature changes. Statistical analysis was performed using the two-way ANOVA and Tukey HSD multiple comparison tests. Statistically significant differences were observed between 1 mm and 2 mm dentin thicknesses (p < 0.001). The GCP groups (both 1 mm and 2 mm dentin thicknesses) exhibited higher temperatures than the other groups (p < 0.001), and Fuji II LC and Photac Fil Quick Aplicap showed similar values (p > 0.05). The highest temperature changes were observed with 1 mm dentin thickness. While RGI materials in both dentin thicknesses did not cause temperature changes that were harmful to the pulp, GCP CarboLED LCU caused the highest intrapulpal temperature rise, and these values were borderline harmful to the dental pulp.

Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time.

OBJECTIVES: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. MATERIALS AND METHODS: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (µSBS) of composite resin to enamel was measured. RESULTS: The mean µSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). CONCLUSION: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the µSBS.

Changes in irradiance and energy density in relation to different curing distances

The present study aimed to assess the influence of curing distance on the loss of irradiance and power density of four curing light devices. The behavior in terms of power density of four different dental curing devices was analyzed (Valo, Elipar 2, Radii-Cal, and Optilux-401) using three different distances of photopolymerization (0 mm, 4 mm, and 8 mm). All devices had their power density measured using a MARC simulator. Ten measurements were made per device at each distance. The total amount of energy delivered and the required curing time to achieve 16 J/cm2 of energy was also calculated. Data were statistically analyzed with one-way analysis of variance and Tukey’s tests (p < 0.05). The curing distance significantly interfered with the loss of power density for all curing light devices, with the farthest distance generating the lowest power density and consequently the longer time to achieve an energy density of 16 J/cm2 (p < 0.01). Comparison of devices showed that Valo, in extra power mode, showed the best results at all distances, followed by Valo in high power mode, Valo in standard mode, Elipar 2, Radii-Cal, and Optilux-401 halogen lamp (p < 0.01). These findings indicate that all curing lights induced a significant loss of irradiance and total energy when the light was emitted farther from the probe. The Valo device in extra power mode showed the highest power density and the shortest time to achieve an energy density of 16 J/cm2 at all curing distances.

Influence of photoinitiators and light sources on the degree of conversion of experimental resin cements / Influência de fotoiniciadores e fontes de luz no grau de conversão de cimentos resinosos experimentais

Objetivo: O objetivo deste estudo foi avaliar o grau de conversão (DC) de sete cimentos resinosos experimentais formulados com diferentes fotoiniciadores, quando ativados por duas fontes luminosas (LCUs) atravessando a cerâmica. Material e Métodos: Sete formulações foram preparadas com diferentes concentrações (em peso) de Canforoquinona (CQ) e/ou Fenilpropanodiona (PPD): C5: 0,5% CQ; C8: 0,8% CQ; P5: 0,5% PPD; P8: 0,8% PPD; C1P4: 0,1% CQ e 0,4% PPD; C4P1: 0,4% CQ e 0,1% PPD; e C4P4: 0,4% CQ e 0,4% PPD. Cada mistura foi carregada com 65% em peso de partículas de carga silanizada. Foram usadas duas fontes luminosas para a fotoativação: uma de luz halógena de quartzo-tungstênio (QTH) e uma de diodo emissor de luz (LED). A irradiância (mW/cm²) foi calculada pela potência média de saída dividida pela área da ponta do aparelho. DC foi obtido por espectroscopia de infravermelho transformada de Fourier. Os dados foram submetidos a ANOVA 2-Fatores e ao teste de Tukey (5%). Resultados: Os valores de DC não exibiram diferenças significativas para LCUs, independente do tipo de fotoiniciador. O maior DC foi observado para o cimento P8, e o menor para C5. Valores intermediários de DC foram observados nos demais cimentos. No entanto, quando usado QTH, P8 diferiu dos cimentos C1P4, C4P1 e C5; e quando o LED foi empregado, P8 diferiu apenas de C4P1 e C5. Conclusão: Portanto, PPD é uma alternativa viável para o desenvolvimento de cimentos resinosos fotoativados, e a associação PPD/CQ também pode ser viável, uma vez que C4P4 foi semelhante a P8.

Objective: The aim of this study was to evaluate the degree of conversion (DC) ofseven experimentalresin cements formulated with different photoinitiators when activated by two light-curing units (LCUs) through ceramic material. Material and Methods: Seven resin blends with different camphorquinone (CQ) and/or phenyl propanedione (PPD) ratios were prepared: C5: 0.5% wt CQ; C8: 0.8% wt CQ; P5: 0.5% wt PPD; P8: 0.8% wt PPD; C1P4: 0.1% wt CQ and 0.4% wt PPD; C4P1: 0.4% wt CQ and 0.1% wt PPD; and C4P4: 0.4% wt CQ and 0.4% wt PPD. Each mixture was loaded with 65% wt of silanized filler particles. For photoactivation procedures, two LCUs were used: a quartz-tungsten-halogen (QTH) and a light emitting diode (LED). Irradiance (mW/ cm²) was calculated by the ratio of the output power by the area of the tip. DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to a two-way ANOVA and Tukey’s test (5%). Results: DC values do not show significant differences for LCUs regardless of the photoinitiator type. The highest DC was found for experimental cement P8 and the lowest for C5. Intermediate DC values were found for the other cements. However, when QTH was used, P8 exhibited differences among C1P4, C4P1 and C5; whereas when LED was used, P8 differed only for C4P1 and C5. Conclusion: Thus, PPD is a viable alternative for the manufacture of photoactivated cements, and the PPD/CQ association may also be viable since C4P4 was similar to P8.