Resumo O objetivo neste estudo foi avaliar o efeito da direção da corrente elétrica na resistência da união resina composta-dentina usando três sistemas adesivos. Dentes molares humanos foram distribuídos de acordo com o sistema adesivo (dois passos autocondicionante - Clearfil SE Bond, Kuraray [CSE]; e um passo autocondicionante - Single Bond Universal, 3M ESPE [SBU]; e dois passos convencional - Adper Single Bond 2, 3M ESPE [SB2]), a direção da corrente elétrica (sem corrente elétrica - controle, correntes elétricas direta e reversa - 35µA) e tempo de armazenamento (24h - imediato e 6 meses). Blocos de resina composta (Filtek Z350XT, 3M ESPE) foram aderidos à dentina. Amostras de dentina-resina foram produzidas e armazenadas em água destilada a 37ºC por 24 horas e 6 meses para o teste de resistência da união à microtração (µTBS) (n = 10; ~12 palitos por dente). Os padrões de fratura foram analisados em estereomicroscópio e classificados em falhas coesiva na dentina, coesiva na resina, adesiva ou mista. A penetração do adesivo na dentina e a formação da camada híbrida foram avaliadas em microscópio eletrônico de varredura (MEV). Os dados foram submetidos à ANOVA três fatores seguidos pelo teste post hoc de Tukey (α = 0,05). Não houve diferenças na µTBS quando os sistemas adesivos foram aplicados sob as correntes elétricas direta e reversa, mas ambas as correntes elétricas aumentaram a µTBS para todos os sistemas adesivos. SBU apresentou os menores valores de µTBS para o grupo controle em ambos os tempos de armazenamento e para a corrente elétrica direta em 6 meses de armazenamento. Falhas adesivas foram mais frequente em todos os grupos. A corrente elétrica formou longos tags resinosos para todos os sistemas adesivos. O armazenamento por 6 meses não diminuiu significativamente os valores de µTBS. Ambos os sentidos da corrente elétrica (cargas positivas e negativas) a 35µA podem aumentar a µTBS dos sistemas adesivos testados à dentina.

Abstract Thisstudy aimed to evaluate the effect of the electric current direction application on the resin composite-dentin bond strength using three adhesive systems. Human molar teeth were distributed according to the adhesive system (two-step self-etch - Clearfil SE Bond, Kuraray [CSE]; one-step self-etch - Single Bond Universal, 3M ESPE [SBU]; and two-step etch-and-rinse - Adper Single Bond 2, 3M ESPE [SB2]), electric current direction (without electric current - control, direct and reverse electric currents - 35µA), and storage time (24h - immediate and 6 months). Resin composite blocks (Filtek Z350XT, 3M ESPE) were bonded to dentin. The teeth/resin composites specimens were stored in distilled water at 37ºC for 24 hours and 6 months for the microtensile bond strength (µTBS) test (n = 10; ~12 sticks for each tooth). Failure patterns were analyzed on a stereomicroscope and classified as cohesive-dentin, cohesive-resin, adhesive or mixed. Adhesive penetration into dentin and hybrid layer formation were evaluated in a scanning electron microscope (n = 6). Data were submitted to a three-way ANOVA followed by Tukey’s post hoc test (α = 0.05). There are no differences in µTBS when the adhesive systems were applied under direct and reverse electric currents, but both electric currents increased the µTBS for all adhesive systems. SBU showed the lowest µTBS values for control groups in both storage times and direct electric current in 6 months of storage. The adhesive failure pattern was more frequently observed in all groups. The electric current formed long resin tags for all adhesive systems. Storage for 6 months did not significantly decrease µTBS values. Both directions of electric current (positive and negative charges) at 35µA can increase the µTBS of the adhesive systems tested to dentin.

ABSTRACT This study evaluated the physico-mechanical properties of experimental composite resins made with different resin matrix and light-curing units. Experimental composite groups were divided according to monomers (BisGMA + TEGDMA-BT and BisGMA + BisEMA + UDMA + TEGDMA-BBUT) and photoinitiator system (camphorquinone-CQ and 1-phenyl-1,2-propanedione-PPD). A quartz tungsten halogen (QTH) or light-emitting diode (LED) were used to light cure all materials. Knoop microhardness (n = 10) was determined using Knoop microhardness test. Compressive strength, diametral tensile strength, and Young modulus (n = 7) were obtained using a universal testing machine at crosshead speed of 1.0 mm/min. The data were submitted to a three-way ANOVA and the Tukey post-hoc test (α = 0.05). QTH presented the highest total irradiance values and similar total radiant exposure to LED. For the compressive strength test, BT-PPD light-cured with LED group showed the lowest mean value. BT-CQ light-cured with LED group exhibited the lowest diametral tensile strength results. The BBUT-composite resins presented lowest Young modulus values, with no statistical difference between light-curing units (QTH and LED) and photoinitiators system (CQ and PPD). Application of QTH or LED in BT-based composite resins with PPD photoinitiator generated suitable results regarding the physico-mechanical properties.

ABSTRACT The aim of this study was to evaluate the depth of cure of conventional (Filtek Z350 and Esthet-X HD) and bulk fill resins composites (Filtek bulk fill flow and SDR) using different photoactivation methods. Samples were made using five disc-shaped matrices (1 mm high and 8 mm central diameter) with interposed polyester strips. The samples were photoactivated using different methods [continuous high-irradiance light (LCA), continuous low-irradiance light (LCB), and soft-start (SS)], maintaining 24 J/cm2 radiant exposure. After 24h, Knoop microhardness test was performed at 5 depths (surface, 1 mm, 2 mm, 3 mm and 4 mm). The Knoop microhardness were analyzed by ANOVA two-way and Tukey’s test (5%). Conventional resins presented the highest results up to 2 mm depth, except for Esthet-X photoactived by LCB, which showed significant lower Knoop hardness from 2 mm depth. Bulk fill resins photoactivated with LCA and SS had the highest results in 4 mm depth. The LCA and SS photoactivation methods produce suitable photoactivation in conventional composites up to 2 mm and bulk fill up to 4 mm depth and the bulk fill composites present higher polymerization depth than conventional composites.

Resumo O objetivo neste estudo foi avaliar o impacto de diferentes diâmetros de pinos de fibra de vidro (PFVs) na resistência de união à dentina. Quarenta dentes humanos unirradiculares foram tratados endodonticamente e utilizados para cimentação de PFVs (White Post DC, FGM) com diferentes diâmetros (n=10): P1 - ø 1,6 mm coronal x 0,85 mm apical; P2 - ø 1,8 mm coronal x 1,05 mm apical; P5 - ø 1,4 mm coronal x 0,65 mm apical; e PC - pino número 0,5 individualizado com resina composta (Tetric Ceram A2, Ivoclair Vivadent). Todos os PFVs foram cimentados no canal radicular usando cimento resinoso dual (Variolink II, Ivoclar Vivadent). As raízes foram seccionadas em três secções (cervical, média e apical) e submetidas ao teste push-out. Os modos de falha de todos os espécimes foram classificados em falha adesiva entre o cimento resinoso e pino, falha adesiva entre dentina e cimento resinoso, falha coesiva no cimento resinoso, pino ou dentina e falha mista. Os dados foram analisados com ANOVA two-way e teste de Tukey (a=0,05). Os maiores valores de resistência da união foram apresentados para os grupos P2 e PC. Não houve diferença estatisticamente significante entre os terços dos PFVs cimentados na raiz para cada grupo. Os grupos P2, P5 e PC apresentaram predominantemente falha adesiva entre a dentina e o cimento resinoso. Para o grupo P1, o tipo de falha mais prevalente foi a adesiva entre cimento resinoso e pino. Pode-se concluir que o pino de fibra de vidro bem adaptado ao canal radicular apresentou os maiores valores de resistência da união, independentemente do terço dos PFVs.

Abstract The aim of this study was to evaluate the effect of different glass fiber posts (GFPs) diameters on the push-out bond strength to dentin. Forty unirradicular human teeth were endodontically treated and used for cementation of GFPs (White Post DC, FGM) with different diameters (n=10): P1 - ø 1.6 mm coronal x 0.85 mm apical; P2 - ø 1.8 mm coronal x 1.05 mm apical; P5 - ø 1.4 mm coronal x 0.65 mm apical; and PC - customized post number 0.5 with composite resin (Tetric Ceram A2, Ivoclair Vivadent). All GFPs were cemented into the root canal using a dual-curing luting composite (Variolink II, Ivoclar Vivadent). One slice (1.7 mm) of each root third of cemented GFP (cervical, middle, and apical) was submitted to push-out testing. Failure modes of all specimens were classified as: adhesive failure between resin cement and post; adhesive failure between dentin and resin cement; cohesive failure within resin cement, post or dentin; and mixed failure. The data were analyzed with two-way ANOVA and Tukey’s test (a=0.05). The highest bond strength values were presented for the P2 and PC groups. There was no statistically significant difference between the GFP thirds in each group. The groups P2, P5, and PC showed predominantly adhesive failure. For P1, the most prevalent type of failure was adhesive between resin cement and post. It may be concluded that a glass fiber post that is well adapted to the root canal presents higher bond strength values, regardless of GFP third.

Resumo O objetivo foi avaliar a influência da concentração e proporção de canforoquinona (CQ)/amina terciária (DABE) na resistência à flexão (RF), módulo flexural (MF), grau de conversão (GC), amarelamento (AM), sorpção (SA) e solubilidade em água (SL) de compósitos experimentais. Blendas acrilatas foram preparadas com diferentes concentrações e proporções de CQ/DABE em peso, como segue: (CQ/DABE%): 0,4/0,4% (C1); 0,4/0,8% (C2); 0,6/0,6% (C3); 0,6/1,2% (C4); 0,8/0,8% (C5); 0,8/1,6% (C6); 1,0/1,0% (C7); 1,0/2,0% (C8); 1,5/1,5% (C9); 1,5/3,0% (C10). Para RF e MF, espécimes retangulares (7x2x1 mm, n=10) foram fotoativados com LED de pico único (Radii Cal) por 20 s e testados em máquina Instron (0,5 mm/min). Após, o GC dos mesmos espécimes (fragmentos) foi mensurado por FTIR. Para AM, discos de compósito (5x2 mm, n=10) foram preparados, fotoativados por 20 s e imediatamente avaliados em espectrofotômetro, considerando o aspecto b do sistema CIEL*a*b*. Para SA e SL, discos de compósito (5x0,5 mm, n=5) foram preparados e seus volumes calculados (mm³). Após desidratação, as amostras foram pesadas e armazenadas em água destilada por 7 dias, pesadas e novamente desidratadas e pesadas, para se calcular o SA e SL. Os dados foram submetidos a one-way ANOVA e teste de Tukey (5%). Os grupos C8, C9 e C10 mostraram maior GC, MF e AM, comparado aos outros grupos. No entanto, RF e SA foram similares entre todos os grupos. Ainda, C1, C2 e C3 apresentaram maior SL em 7 dias comparado aos outros grupos. Em geral, maiores concentrações de CQ promoveram melhores propriedades físico-mecânicas; no entanto, levaram ao maior amarelamento dos compósitos.

Abstract The aim in this study was to evaluate the influence of different ratio of camphorquinone/tertiary amine concentration on the flexural strength (FS), elastic modulus (EM), degree of conversion (DC), yellowing (YL), water sorption (WS) and water solubility (WSL) of experimental composites. Thus, acrylate blends were prepared with different camphorquinone (CQ) and amine (DABE) concentrations and ratios by weight: (CQ/DABE%): 0.4/0.4% (C1), 0.4/0.8% (C2), 0.6/0.6% (C3), 0.6/1.2% (C4), 0.8/0.8% (C5), 0.8/1.6% (C6), 1.0/1.0% (C7), 1.0/2.0% (C8), 1.5/1.5% (C9), 1.5/3.0% (C10). For the FS and EM, rectangular specimens (7x2x1 mm, n=10) were photo-activated by single-peak LED for 20 s and tested at Instron (0.5 mm/min). Then, the same specimens were evaluated by FTIR for DC measurement. For YL, disks (5x2 mm, n=10) were prepared, light-cured for 20 s and evaluated in spectrophotometer using the b aspect of the CIEL*a*b* system. For WS and WSL, the volume of the samples was calculated (mm³). For WS and WSL, composites disks (5x0.5 mm, n=5) were prepared. After desiccation, the specimens were stored in distilled water for 7 days and again desiccated, in order to measure the WS and WSL. Data were submitted to one-way ANOVA and Tukey’s test (5%). The groups C8, C9 and C10 showed higher DC, EM and YL means, compared to other composites. Therefore, the FS and WS values were similar among all groups. Also, C1, C2 and C3 presented higher WSL in 7 days, compared to other composites. In general, higher concentrations of camphorquinone promoted higher physical-mechanical properties; however, inducing higher yellowing effect for the experimental composites

RESUMO Objetivo: Avaliar e comparar a precisão dimensional de três técnicas de moldagem: dupla mistura, reembasamento e moldeira individual. Métodos: Um modelo metálico inferior parcialmente edêntulo foi fabricado com pontos de referência nos dentes e usado para fazer as moldagens. As distâncias ântero-posteriores e transversais foram medidas. Todas as moldagens foram feitas com um silicone por adição utilizando moldeiras metálicas (técnicas da dupla mistura e reembasamento) ou de resina acrílica (técnica da moldeira individual). Na técnica da moldeira individual foi utilizado apenas o elastômero de viscosidade leve e nas técnicas da dupla mistura e reembasamento foram usados os elastômeros nas viscosidades denso e leve. Após os procedimentos de moldagem, a precisão dimensional de cada técnica de moldagem foi avaliada aferindo os modelos de gesso (n = 5) em um microscópio comparador com 30x de aumento e 0,5 µm de precisão. Os dados foram analisados estatisticamente por ANOVA dois fatores e teste de Tukey (p<0,05). Resultados: Os modelos de gesso feitos com todas as técnicas de moldagem apresentaram alterações lineares negativas (contração). As distâncias ântero-posteriores apresentaram maiores alterações dimensionais que as distâncias transversais. O lado parcialmente edêntulo teve maior contração que o lado ântero-posterior oposto. Conclusão: Não foram encontradas diferenças entre as técnicas de moldagem, mas foram observadas significantes alterações dimensionais.

ABSTRACT Objective: The purpose of this in vitro study was to assess and compare the dimensional accuracy of three impression techniques: 1-step putty/light-body, 2-step putty/light-body, and the monophase technique. Methods: A partially edentulous standard stainless steel mandibular arch cast with reference points on the teeth was used to make the impressions. The anteroposterior and transverse distances were measured. All impressions were made with a polyvinyl siloxane using stock metallic (1- and 2-step putty/light-body techniques) or acrylic resin (monophase technique) trays. The monophase impressions were made using a light-body material and the 1- and 2-step putty/light-body impressions with putty and light-body materials. After impression procedures, the accuracy of each technique was assessed measuring the stone casts (n = 5) poured from the impressions using a microscope at 30x magnification and at 0.5 µm accuracy. The data were analyzed statistically using 2-way ANOVA and Tukey's test (p<0.05). Results: Stone casts made by all techniques had significantly negative linear changes (shrinkage). The anteroposterior distances showed more dimensional changes than the transverse distances. The edentulous side showed more shrinkage than the anteroposterior side. Conclusion: No differences between the impression techniques were found, but significant dimensional changes were observed.

ABSTRACT Objective To evaluate the influence of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental resin-based materials photoactivated using different light curing units (LCUs). Material and Methods Experimental resin-based materials with the same organic matrix (60:40 wt% BisGMA:TEGDMA) were mechanically blended using a centrifugal mixing device. To this blend, different photoinitiator systems were added in equimolar concentrations with aliphatic amine doubled by wt%: 0.4 wt% CQ; 0.38 wt% PPD; or 0.2 wt% CQ and 0.19 wt% PPD. The degree of conversion (DC), flexural strength (FS), Young’s modulus (YM), Knoop hardness (KNH), crosslinking density (CLD), and yellowing (Y) were evaluated (n=10). All samples were light cured with the following LCUs: a halogen lamp (XL 2500), a monowave LED (Radii), or a polywave LED (Valo) with 16 J/cm2. The results were analysed by two-way ANOVA and Tukey’s test (α=0.05). Results No statistical differences were found between the different photoinitiator systems to KNH, CLS, FS, and YM properties (p≥0.05). PPD/CQ association showed the higher DC values compared with CQ and PPD isolated systems when photoactivated by a polywave LED (p≤0.05). Y values were highest for the CQ compared with the PPD systems (p≤0.05). Conclusion PPD isolated system promoted similar chemical and mechanical properties and less yellowing compared with the CQ isolated system, regardless of the LCU used.

Resumo Este estudo avaliou a resistência de união (BS) de cimentos resinosos experimentais formulados com diferentes fotoiniciadores, quando ativados através de cerâmica, por dois tipos de fontes luminosas (LCUs). Foram preparadas sete formulações com diferentes concentrações em peso (wt) de canforquinona (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; C4P4: 0,4%CQ e 0,4%PPD. Duas LCUs foram usadas: uma com luz halógena (QTH - 850 mW/cm²) e uma com diodo emissor de luz (LED - 1300 mW/cm²). A BS foi avaliada por teste de microtração. Os dados foram submetidos a ANOVA a dois fatores e Teste de Tukey (α=0,05). Isolando o tipo de fotoiniciador, não houve diferenças significativas na BS. Três cimentos mostraram diferenças significativas: a BS foi maior para P5 e C5 com QTH; e para C4P1 com LED. Para a QTH, P5 exibiu a maior e C1P4 a menor BS. Para LED, C4P1 exibiu a maior BS de todos os outros cimentos testados. Conclusão: PPD é altamente viável em formulações de cimentos resinosos fotopolimerizáveis, reduzindo ou eliminando a CQ que é amarelada, sem comprometer a resistência de união. Além disso, tanto LED quanto QTH são efetivas para polimerizar os cimentos contendo PPD ou CQ.

Abstract This study evaluated the bond strength (BS) of experimental resin cements formulated with different photoinitiators when activated by two kinds of light-curing units (LCUs) through a ceramic material. Seven resin blends with different camphorquinone (CQ) and/or phenylpropanedione (PPD) concentrations (weight) were prepared: C5: 0.5% CQ; C8: 0.8% CQ; P5: 0.5% PPD; P8: 0.8% PPD; C1P4: 0.1% CQ and 0.4% PPD; C4P1: 0.4% CQ and 0.1% PPD; C4P4: 0.4% CQ and 0.4% PPD. Two LCUs were used: one quartz-tungsten-halogen (QTH - 850 mW/cm²) and one light-emitting diode (LED - 1300 mW/cm²). The microtensile bond strength of each blend was assessed. Data were submitted to two-way ANOVA and Tukey's test (α=0.05). The BS values did not exhibit significant differences for LCUs, regardless of the photoinitiator type. Three cements showed significant differences: P5 and C5 had higher BS with QTH, and C4P1 with LED. For QTH, P5 showed the highest and C1P4 the lowest BS. For the LED, C4P1 showed the highest BS of all the cements. The results indicated that PPD was a viable alternative in the formulation of photocured resin cements, reducing or eliminating CQ that is yellowish without impairing the bond strength. Furthermore, both LED and QTH were effective in curing resin cements that contain PPD or CQ.

We compared polymerization stress in two commercial composites and three experimental composites made using camphorquinone (CQ) and/or phenylpropanedione (PPD) as photoinitiators. The internal surfaces of photoelastic resin discs with cylindrical cavities were roughened and treated with adhesive. Composites were divided into five groups: two commercial composites (Filtek Silorane and Filtek Z250) and three experimental composites with CQ/amine, CQ/PPD/amine, and PPD/amine. Composites were photopolymerized inside cavities, and subjected to photoelastic analysis immediately and at 24 hours and 7 days later using a plane polariscope. Stress created by Silorane (3.08 ± 0.09 MPa) was similar to that of Z250 (3.19 ± 0.13 MPa) immediately after photopolymerization (p > 0.05). After 24 hours and 7 days, Z250 (3.53 ± 0.15 and 3.69 ± 0.10 MPa, respectively) showed higher stress than Silorane (3.19 ± 0.10 and 3.16 ± 0.10 MPa, respectively). Qualitative analysis immediately after photopolymerization showed composite/CQ promoted higher stress than PPD, but stress levels at other evaluated times were statistically similar, varying between 3.45 ± 0.11 MPa and 3.92 ± 0.13 MPa. At 24 hours and 7 days, Silorane created the lowest stress. All photoinitiators created comparable tensions during polymerization.

The aim of this study was to evaluate: (i) the absorption of photo-initiators and emission spectra of light curing units (LCUs); and (ii) the degree of conversion (DC) of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ) and/ or 1-phenyl-1,2-propanedione (PPD) were prepared. Dimethylaminoethyl methacrylate (DMAEMA) was used as co-initiator. Each mixture was loaded with 65 wt% of silanated filler particles. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE) and two lightemitting diode (LED) LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent) were used for activation procedures. Irradiance (mW/cm²) was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000). The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G). DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to two-way ANOVA and Tukey's test (5%). No significant difference was found for DC values when using LED LCUs regardless of the photo-initiator type. However, PPD showed significantly lower DC values than composites with CQ when irradiated with QTH. PPD produced DC values similar to those of CQ, but it was dependent on the LCU type.

This study evaluated weight loss and surface roughening after toothbrushing of different resin composites: one packable (Solitaire 2, Heraeus Kulzer), one microhybrid (Charisma, Heraeus Kulzer), one nanohybrid (Simile, Pentron) and one microfilled (Durafill VS, Heraeus Kulzer). Cylindrical specimens (n = 20) were prepared. Half of the samples were submitted to 60,000 strokes, at 4 Hz, with a dentifrice-water slurry. Control samples (n = 10) remained stored at 37°C. Pre- and post-abrasion parameters for weight (mg) and surface roughness (Ra, µm) were determined on an analytical balance and a surface profilometer. Data were separately submitted to Repeated Measures ANOVA and Tukey's test (a = 0.05). Percentages of weight loss were analyzed by ANOVA and Tukey's test (a = 0.05). The relationship between both evaluations was assessed by Pearson's test (a = 0.05). The means (%) for weight loss (standard deviation) were 0.65(0.2), 0.93(0.2), 1.25(0.6) and 1.25(0.4) for Simile, Durafill, Charisma and Solitaire, respectively. Baseline roughness means ranged from 0.065(0.01), 0.071(0.01), 0.066(0.02) and 0.074(0.01) for Simile, Durafill, Charisma and Solitaire, respectively, to 0.105(0.04), 0.117(0.03), 0.161(0.03) and 0.214(0.07) after testing. The composites with larger fillers presented higher weight loss and roughening than the finer materials (p < 0.05). For both evaluations, control specimens showed no significant alteration. No significant relationship between loss of weight and roughness alteration was detected (r = 0.322, p = 0.429).