Abstract This study was aimed at analyzing the surface properties of a universal resin composite and evaluating the effect of preheating on its physicochemical properties. Two commercial resin composites were used under two conditions: Filtek Universal Restorative (UR); UR preheated (URH); Filtek Supreme (FS) and FS preheated (FSH). The film thickness (FT) test (n = 10) was done using two glass slabs under compression. Flexural strength (FLS) and modulus (FLM) were evaluated using a three-point flexion test (n = 10). Polymerization shrinkage stress (PSS) was evaluated in a universal testing machine (n = 5). Gap width (GW) between composite and mold was measured in internally polished metallic molds (n = 10). The degree of conversion (DC) was evaluated by Fourier Transform Infrared spectroscopy (n = 3). The morphology of the filler particles was checked by scanning electron microscope (SEM) and EDX analysis. Surface gloss (SG) and surface roughness (SR) were evaluated before and after mechanical brushing (n = 10). The outcomes were submitted to 2-way ANOVA and Tukey's test (α = 0.05). Lower mean values of FT were observed for the preheated groups when compared to the non-preheated groups. URH and FSH showed higher mean values of FLS and FLM when compared with UR and FS. No differences were observed between groups in the PSS test. The GW was higher for the UR and FS groups when compared with URH and FSH. The DC was higher for preheated resin composites when compared to the non-preheated groups. The SR of the UR composite was higher than the FS after mechanical brushing, while the SG was higher for the FS groups. In conclusion, the universal resin composite tested generally presented similar physicochemical properties compared with the nanofilled resin composite and either similar or slightly inferior surface properties. The preheating improved or maintained all properties evaluated.

Resumo Neste estudo avaliou-se propriedades físico-químicas e de superfície de um compósito universal pré-aquecido e comparado a um compósito convencional. Foram utilizados dois compósitos comerciais: Filtek Universal Restorative (UR); UR pré-aquecido (URH); Filtek Supreme (FS) e FS pré-aquecido (FSH). O teste de espessura de película (EP) (n = 10) foi feito usando duas placas de vidro sob compressão. A resistência à flexão (RF) e o módulo flexural (MF) foram avaliados por meio do teste de flexão de três pontos (n = 10). A tensão de contração de polimerização (TCP) foi avaliada em uma máquina de teste universal (n = 8). A largura da fenda (LF) entre o compósito e o molde foi medida em moldes metálicos polidos internamente (n = 10). O grau de conversão (GC) foi avaliado por espectroscopia de infravermelho com transformada de Fourier (n = 3). A morfologia das partículas de carga foi observada em microscopia eletrônica de varredura (MEV) e sua composição em EDX. Brilho superficial (BS) e rugosidade superficial (RS) foram avaliados antes e após escovação mecânica (n=10). Os resultados foram submetidos à ANOVA 2-fatores e as médias comparadas pelo teste de Tukey (α = 0,05). Menores valores médios de EP foram observados para os grupos pré-aquecidos quando comparados aos grupos não pré-aquecidos. URH e FSH apresentaram maiores valores médios de RF e MF quando comparados com UR e FS. Não foram observadas diferenças entre os grupos no teste TCP. A LF foi maior para os grupos UR e FS quando comparados com URH e FSH. O GC foi maior para os compósitos pré-aquecidos quando comparados aos não pré-aquecidos. A RS do compósito UR foi maior que o FS após a escovação mecânica, enquanto o BS foi maior para os grupos FS. Em conclusão, o compósito universal testado geralmente apresentou propriedades físico-químicas semelhantes em comparação ao compósito nanoparticulado e propriedades de superfície semelhantes ou ligeiramente inferiores. O pré-aquecimento melhorou ou manteve todas as propriedades avaliadas.

Abstract This study aimed to evaluate the effect of an elastomeric urethane monomer (Exothane-24) in different concentrations on physicochemical properties, gap formation, and polymerization shrinkage stress of experimental resin composites. All experimental composites were prepared with 50 wt.% of Bis-GMA and 50 wt.% of TEGDMA, to which 0 wt.% (control), 10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.% of Exothane-24 were added. Filler particles (65 wt.%) were then added to these resin matrixes. Ultimate tensile strength (UTS: n = 10), flexural strength (FS: n = 10), flexural modulus (FM: n = 10), hardness (H: n = 10), hardness reduction (HR: n = 10), degree of conversion (DC: n = 5), gap width (GW: n = 10), and polymerization shrinkage stress in Class I (SS-I: n = 10) and Class II (SS-II: n = 10) simulated configuration. All test data were analyzed using one-way ANOVA and Tukey’s test (α = 0.05; β= 0.2). Exothane-24 in all concentrations decreased the H, HR, DC, GW, SS-I, and SS-II (p < 0.05) without affecting the UTS, and FS (p > 0.05). Reduction in FM was observed only in the Exothane 40% and 30% groups compared to the control (p < 0.05). Exothane-24 at concentrations 20% and 30% seems suitable since it reduced GW and polymerization SS without affecting the properties of the composite resins tested, except for H.

Resumo Este estudo teve como objetivo avaliar o efeito de um monômero elastomérico de uretano (Exothane-24) em diferentes concentrações em propriedades físico-químicas, formação de fenda e tensão de contração de polimerização de resinas compostas experimentais. Todos os compósitos experimentais foram preparados com 50% em peso de Bis-GMA e 50% em peso de TEGDMA, nos quais 0% (controle), 10%, 20%, 30% e 40% em peso de Exothane-24 foram adicionados. Partículas de carga (65% em peso) foram então adicionadas as matrizes resinosas. Resistência coesiva (RC: n = 10), resistência à flexão (RF: n = 10), módulo de flexão (MF: n = 10), dureza (D: n = 10), redução de dureza (RD: n = 10), grau de conversão (GC: n = 5), largura de fenda (LF: n = 10) e tensão de contração de polimerização em simulações de cavidades Classe I (TC-I: n = 10) e Classe II (TC-II: n = 10). Todos os dados do teste foram analisados usando one-way ANOVA e teste de Tukey (α = 0,05; β = 0,2). O Exothane-24 em todas as concentrações diminuiu a D, RD, GC, LF, TC-I e TC-II (p < 0,05) sem afetar o RC e RF (p > 0,05). A redução da MF foi observada apenas nos grupos Exothane 40% e 30% em relação ao controle (p < 0,05). O Exothane-24 nas concentrações de 20% e 30% pareceu ser adequado, pois reduziu LF e TC de polimerização sem afetar as propriedades das resinas compostas testadas, exceto para D.

ABSTRACT: This in silico study aimed to evaluate the biomechanical behavior of a full-arch implant-supported prosthesis on titanium and zirconia monotype implants. A 3D mandible containing 1.0 mm thick cortical and cancellous bone was modeled. Four dental implants (3.3 x 10 mm) were inserted into the jaw model in each model. The implants consisted of Titanium (Ti-S group) and Zirconia Monotype/one-piece (Zr-S group). Fixed full-arch implant-supported prostheses were cemented onto the implant. The models were exported to the analysis software and divided into meshes composed of nodes and tetrahedral elements. All materials were considered isotropic, elastic, and homogeneous. Therefore, all contacts were considered bonded, the mandible model was fixed in all directions, applying a static structural axial load of 300 N on the bottom of the fossa of the left mola r teeth. Microstrain and von-Mises stress (MPa) were adopted as failure criteria. Comparable stress and strain values were shown in the peri-implant bone for both groups. However, the Ti-S group presented a lower stress value (1,155.8 MPa) than the Zr-S group (1,334.2 MPa). Regarding bone tissues, the Ti-S group presented 612 µε and the Zr-S group presented 254 µε. The highest strain peak was observed in bone tissues around the implant closer to the load for both groups. Evaluating monotype zirconia and titanium implants, it is suggested that the greater the rigidity of the implant, the greater the concentration of internal stre sses and the less dissipation to the surrounding tissues. Therefore, monotype ceramic implants composed of yttrium-stabilized tetragonal polycrystalline zirconia may be a viable alternative to titanium implants for full-arch prostheses.

RESUMEN: El objetivo de este estudio in silico fue evaluar el comportamiento biomecánico de una prótesis implanto soportada de arcada completa sobre implantes monotipo de titanio y zirconia. Se modeló una mandíbula en 3D que contenía tejido óseo cortical y esponjoso de 1,0 mm de espesor. En cada modelo, se insertaron cuatro implantes dentales (3,3 x 10 mm) en el modelo de mandíbula. Los implantes consistieron en Monotipo de Titanio y Zirconia. Sobre el implante se cementaron prótesis implanto soportadas de arcada completa fija. Los modelos se exportaron al software de análisis y se dividieron en mallas compuestas por nodos y elementos tetraédricos. Todos los materiales se consideraron isotrópicos, elásticos y homogéneos. Por lo tanto, todos los contactos se consideraron cementados, el modelo mandibular se fijó en todas las direcciones, aplicando una carga vertical estructural estática de 300 N en el fondo de la fosa de los dientes molares izquierdos. Se seleccionaron la microesfuerzo y la tensión de Von-Mises (MPa) como criterios de falla. Se mostraron valores de tensión y deformación comparables en el hueso periimplantario para ambos grupos. Sin embargo, el grupo Ti-S presentó un valor de estrés menor (1.155,8 MPa) que el grupo Zr-S (1.334,2 MPa). En cuanto a los tejidos óseos, el grupo Ti-S presentó 612 µε y el grupo Zr-S presentó 254 µε. La mayor concentración de deformación en el tejido óseo se observó en los tejidos alrededor del implante más cerca de la carga para ambos grupos. Al evaluar los implantes monotípicos de zirconia y titanio, se sugiere que cuanto mayor sea la rigidez del implante, mayor será la concentración de tensiones internas y menor la disipación a los tejidos circundantes. Por lo tanto, los implantes cerámicos monotipo compuestos de zirconia policristalina tetragonal estabilizada con itrio pueden ser una alternativa viable a los implantes de titanio para prótesis de arcada completa.

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.

Resumo Foi desenvolvido um novo dispositivo para permitir a visualização e medição da angulação canina ao mesmo tempo que se visualiza e mede a força transmitida aos dentes adjacentes. Este estudo avaliou o ângulo de inclinação mesiodistal dos braquetes caninos superiores, a deflexão do fio, e os seus efeitos nos dentes adjacentes com cinco diferentes desenhos de ranhuras dos caninos superiores. Os fios (0,020" e 0,019" x 0,025") foram testados em cinco diferentes tipos de braquetes e ângulos distais. A força aplicada aos dentes adjacentes foi medida a medida que o ângulo era aumentado, e as suas consequências foram observadas também nas regiões posterior e anterior. A tensão da força (gf) foi medida em uma máquina de ensaio universal (Instron). Os dados foram submetidos ao teste ANOVA 3 fatores e Tukey (α=0,05). Para ambos os arcos, independentemente do tipo de dente e tipo de braquete, os valores médios de tensão mais elevados foram mostrados pelo ângulo de 20°, seguido pelos ângulos de 15°, 10°, e 5°, que diferiram estatisticamente entre si. Em geral, para ângulos de 5°, 10° e 15°, os braquetes convencionais e versáteis apresentaram valores de força significativamente mais elevados em todos os dentes, braquetes tip-edge e controle apresentaram os mais baixos. Os maiores valores de força foram observados nos incisivos centrais e laterais com braquetes convencionais e versáteis e no primeiro e segundo pré-molares com braquetes auto-ligantes passivo e controle. Os braquetes convencionais apresentaram as forças mais elevadas, os braquetes controle e tip-edge apresentaram os valores mais baixos. Os dentes que sofreram as maiores forças foram os incisivos laterais, e os que sofreram menos foram os segundos pré-molares.

Abstract A new device was developed to enable the visualization and measurement of canine angulation while at the same time visualizing and measuring the force transmitted to adjacent teeth. This study aimed to evaluate the mesiodistal tilt angle of the upper canine brackets, the wire deflection, and its effects on adjacent teeth with five different slot designs of upper canines. Wires (0.020” and 0.019” x 0.025”) were tested on different five bracket types at five different distal angles. The force applied to adjacent teeth was measured as the angle was increased, and its consequences were observed in the posterior and anterior regions as well. The force tension (gf) was measured in a universal testing machine. Data were submitted to a 3-way ANOVA and Tukey’s test (α=0.05). For both arches, regardless of the type of tooth and bracket type, the highest means tension mean values were shown by the 20° angle, followed by the 15°,10°, and 5° angles, which differed statistically among themselves. Overall, for 5°, 10°, and 15° angles, conventional and versatile brackets showed significantly higher force values in all teeth, tip-edge and control brackets showed the lowest. The highest force values were observed in central and lateral incisors with conventional and versatile brackets and on first and second premolar teeth with self-ligating passive and control brackets. Conventional brackets presented the highest forces, tip-edge and control brackets showed the lowest. The teeth that suffered the greatest forces were lateral incisors, and those that suffered the least were second premolars.

Resumo O objetivo foi investigar o efeito do inibidor de polimerização BHT no grau de conversão (GC), resistência à flexão (RF), módulo de flexão (MF), microdureza Knoop (KH) e redução da microdureza (RKH), e consistência de um compósito experimental contendo diferentes concentrações de BHT (% em peso): C0 - controle (0%); C0,01 (0,01%); C0,025 (0,025%); C0,05 (0,05%); C0,1 (0,1%); e C0,5 (0,5%). Para o teste de consistência, os compósitos foram testados imediatamente após serem expostos à luz de um refletor odontológico por 0, 20, 40 e 60 s. Os dados relativos a GC, RF, MF, KH e RKH foram submetidos a one-way ANOVA, enquanto os dados de consistência foram submetidos a two-way ANOVA; os valores médios foram comparados (teste de Tukey; α = 0,05). As análises de KH, RF e MF não mostraram diferença significativa entre os compósitos testados. Para GC, C0 apresentou o maior valor médio e diferiu apenas de C0,5. Para a RKH, C0,5 apresentou o menor valor médio e diferiu de C0 e C0,01. A análise de consistência não mostrou diferença entre C0,05, C0,1 e C0,5, considerando-se 0 e 20 s de exposição à luz, enquanto C0, C0,01 e C0,025 apresentaram maiores valores médios a 0 s quando comparados a 20 s. A polimerização ocorreu dentro de 40 s de exposição à luz para C0, C0.01, C0.025 e C0.05 e dentro de 60 s para C0.1. Em conclusão, as concentrações de BHT não tiveram influência significativa sobre RF, MF e KH. Quanto maior a concentração de BHT, maior o tempo de manuseio sob luz, com melhora significativa da RKH, mas diminuição da GC. Portanto, o compósito contendo 0,1 % de BHT apresentou os melhores resultados entre as demais concentrações testadas.

Abstract This study investigated the effect of butylated hydroxytoluene (BHT) inhibitor on degree of conversion (DC), flexural strength (FS), flexural modulus (FM), Knoop microhardness (KH), microhardness reduction (HR), and consistency of experimental resin composites at different BHT concentrations: C0 (control-0%); C0.01 (0.01%); C0.025 (0.025%); C0.05 (0.05%); C0.1 (0.1%); and C0.5 (0.5%). For the consistency, the composites were tested immediately after being exposed to a dental chair headlight (0, 20, 40 and 60 s). Data concerning DC, FS, FM, KH, and HR were submitted to one-way ANOVA, while the consistency data was submitted to 2-way ANOVA; mean values were then compared (Tukey’s test; α=0.05). The KH, FS and FM analyses showed no significant difference among the composites tested. For DC, C0 showed the highest mean value (74.2%) and differed only from C0.5 (67.2%). For HR, C0.5 showed the lowest mean (13.09%) value and differed from C0 (26.4%) and C0.01 (24.87). The consistency analysis showed no difference among C0.05, C0.1 and C0.5, considering 0 and 20 s of light exposure, while C0 (14.07 mm), C0.01 (13.97 mm), and C0.025 (14.18 mm) showed higher mean values at 0 s when compared to 20 s (12.67, 12.77 and 13.05 mm, respectivelly). Polymerization occurred within 40 s of light exposure for C0, C0.01, C0.025, and C0.05 and within 60 s for C0.1. In conclusion, the BHT concentrations had no significant influence on FS, FM and KH. The higher the BHT concentration, the longer was its handling time under light, with a significant improvement in the HR, but a decrease in DC. Therefore, BHT at 0.1% showed the best outcomes concerning all the BHT concentrations tested.

Abstract This study aimed to evaluate the effect of light attenuation through ceramic veneers and resin cement on degree of conversion (DC), cohesive strength (CS), and microshear bond strength (μSBS) of experimental adhesive systems. Experimental etch-and-rinse and self-etch adhesives were combined with different ratios of camphorquinone (CQ) and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiators: CQ-only; 3CQ:1TPO; 1CQ:1TPO; 1CQ:3TPO and TPO-only. Square-shaped ceramic veneer (IPS Empress Esthetic, Ivoclar Vivadent) (n = 10; 10mm long x 10mm wide x 0.5mm thick) and resin cement specimens (Variolink Esthetic LC, Ivoclar Vivadent) (n = 10; 10 mm long x 10 mm wide and 0.3 mm thick) were prepared. Light transmittance of a multiple-peak LED (Bluephase G2, Ivoclar Vivadent) was measured through restorative materials using a spectrometer (n = 5). Adhesive specimens were analyzed for DC, CS, and μSBS by light-curing the adhesive with or without (control) ceramic veneer, and with resin cement fixed to output region of the light-curing tip (n = 10). Data were submitted to ANOVA and Tukey’s test (α = 0.05). Total light transmittance through the restorative materials was attenuated, and this attenuation was more evident for the violet spectrum. The DC for the TPO groups in ratios up to 1CQ:1TPO was similar to the control. 1CQ:3TPO showed lower values for CS. μSBS was reduced for all groups with light attenuation, but lower values were observed for 1CQ:3TPO and TPO-only. In conclusion, light transmission was reduced with interposed restorative materials. Adhesives combined with CQ and TPO up to 1CQ:1TPO showed greater cure efficiency and mechanical properties compared with a higher amount of TPO.

Resumo O objetivo neste estudo in vitro foi mensurar as fendas e a profundidade de polimerização de compósitos resinosos bulk-fill duais inseridos em preparos em forma de caixa. Os preparos em forma de caixa (4 mm de profundidade) foram realizados em quinze terceiros molares e separados em 3 grupos, de acordo com o compósito resinoso (n = 5): Bulk-fill dual BulkEZ (BEZ); Bulk-fill dual HyperFIL (HF); Tetric Evoceram Bulk-fill (TETRIC). O comprimento das fendas (%) foi avaliado na interface dente-restauração por meio de micro-tomografia computadorizada (µCT). As restaurações foram seccionadas e o grau de conversão (GC) e microdureza Knoop foram avaliados em cinco profundidades (0,3, 1, 2, 3 e 4 mm). Os dados de microdureza foram avaliados estatisticamente por meio de valores absolutos e relativos (porcentagens de microdureza em relação ao topo). O comprimento das fendas (%) aumentou na seguinte ordem: BEZ = TETRIC <HF. O percentual de microdureza em relação ao topo diminuiu significativamente a partir de 2 mm para TETRIC e 3 mm para HF. BEZ apresentou percentuais de microdureza e de GC constantes em todas as profundidades, enquanto HF e TETRIC apresentaram decréscimo significativo no GC em 4 mm. Os compósitos resinosos bulk-fill duais não reduziram as fendas formadas quando comparados a um compósito bulk-fill fotopolimerizável; entretanto, os mesmos podem melhorar a profundidade de polimerização em restaurações de incremento único.

Abstract This in vitro study aimed to evaluate the gaps length and depth of cure of dual-cure bulk-fill resin composites inserted in box-shaped preparations. Box-shaped preparations (4 mm deep) were made in fifteen human third-molars and divided into three groups according to the resin composites (n=5): Dual-cure bulk-fill BulkEZ (BEZ); Dual-cure bulk-fill HyperFIL (HF); and Tetric Evoceram Bulk-fill (TETRIC), as control. Gaps length (%) was evaluated in tooth-restoration interface with micro-computed tomography (µCT). The restorations were sectioned, and the degree of conversion (DC) and Knoop microhardness were evaluated at five depths (0.3, 1, 2, 3, and 4 mm). Microhardness data were statistically evaluated using absolute values (KHN) and relative values (microhardness percentages in relation to top). Gaps length (%) increased in the following order: BEZ=TETRIC<HF. The microhardness percentages in relation to top significantly decreased from 2 mm for TETRIC and 3 mm for HF. BEZ had constant microhardness and DC at all depths, while HF and TETRIC presented a significant decrease on DC at 4 mm. Dual-cure bulk-fill composites did not reduce gaps compared to light-cure bulk-fill, but they can improve depth of cure of bulk-filled restorations.

Resumo O objetivo deste estudo foi avaliar o efeito da lei de reciprocidade de um diodo emissor de luz (LED) multi-wave na transmitância de luz (LT), profundidade de cura (DOC) e grau de conversão em profundidade (DC) de um compósito bulk fill. Material e Métodos: Um compósito bulk fill (EvoCeram®, Ivoclar Vivadent) foi fotoativado utilizando um LED multi-wave (VALO ™ Cordless, Ultradent). O LED foi previamente caracterizado usando um espectrofotômetro para padronizar o tempo de exposição utilizando os modos Standard ou Xtra-Power com a mesma dose de energia de 20 J/cm 2. A LT foi avaliada através de amostras do compósito bulk fill a cada milímetro até 4 mm de profundidade. O DOC foi avaliado de acordo com a ISO 4049. O DC foi realizado em forma de mapeamento da seção transversal longitudinal central de cada amostra do teste de DOC utilizando microscopia FT-NIR. Os dados foram analisados estatisticamente de acordo com o delineamento experimental (α=0,05; ß=0,2). A exposição radiante na faixa de comprimento de onda violeta para os modos Standard e Xtra-Power foi de 4,5 e 5,0 J/cm2, respectivamente; e para a faixa de comprimento de onda azul, a exposição radiante para os modos Standard e Xtra-Power foi de 15,5 e 15,0 J/cm2, respectivamente. Não houve diferença estatística no DOC utilizando os modos de fotopolimerização Standard ou Xtra-Power, mas o DOC foi menor do que o reivindicado pelo fabricante (4 mm). O DC não foi afetado significativamente pelo modo de fotopolimerização até 4 mm de profundidade (p>0,05). De acordo com a lei de reciprocidade da exposição, a redução no tempo de exposição utilizando a mesma exposição radiante não afetou a profundidade de cura do compósito bulk fill.

Abstract The objective of this study was to evaluate the effect of the exposure reciprocity law of a multi-wave light-emitting diode (LED) on the light transmittance (LT), depth of cure (DOC) and degree of conversion in-depth (DC) of a bulk fill composite. A bulk fill composite (EvoCeram® bulk fill, Ivoclar Vivadent) was photoactivated using the multi-wave LED (VALO™ Cordless, Ultradent). The LED was previously characterized using a spectrophotometer to standardize the time of exposure when using the Standard or Xtra-Power modes with the same radiant exposure of 20J/cm2. LT was evaluated through samples of the bulk fill composite every millimeter till 4 mm in-depth. DOC was evaluated according to the ISO 4049. DC of the central longitudinal cross-section from each sample of the DOC test was mapped using FT-NIR microscopy. Data were statistically analyzed according to the experimental design (α=0.05; ß=0.2). The radiant exposure in the violet wavelength range for Standard and Xtra-Power was 4.5 and 5.0 J/cm2, respectively; for the blue wavelength range the radiant exposure for Standard and Xtra-Power was 15.5 and 15.0 J/cm2, respectively. There was no statistical difference in the DOC using Standard or Xtra-Power light-curing modes, but the DOC was lower than the claimed by the manufacturer (4 mm). The DC was not significantly affected by the light-curing mode up to 4 mm in depth (p>0.05). According to exposure reciprocity law, the reduction in exposure time using the same radiant exposure did not affect the depth of cure of the bulk fill composite.

ABSTRACT The aim of this study was to verify the effectiveness of alternative techniques for measuring the linear dimensional change of molds obtained by different impression materials. A stainless-steel die containing three lines was used to get the impressions. The impression materials were handled according to the manufacturers' instructions. After gelation/polymerization time, the molds (n=12) were stored for 30 minutes and the lines were subsequently measured using: a microscope (Olympus Measuring Microscope STM; Olympus Optical Co) with a 30x magnification (MM, control group), a digital caliper (Mitutoyo Digimatic; Kawasaki) (DC) and digitization using a digital camera (Canon EOS Rebel 3Ti; Canon) (DI). For each mold, a mean of the length of the lines was obtained. For each impression material, the difference in the length between the metallic matrix and the mold was considered as linear dimensional change (%). The data were submitted to the non-parametric Kolmogorov-Smirnov test, followed by one-way Analysis of Variance (ANOVA) for each material, and the means were compared by the Tukey test (α=0.05). The DI group promoted values of dimensional accuracy without significant differences with the control group (MM), except for the putty-body condensation silicone. The DC group showed significant differences for MM and DI groups for all impression materials tested. The DI group showed to be a reliable methodology (Standard error of the mean <10%) to measure the linear dimensional change of all impression materials. The DI group presented molds with linear dimensional change values without significant differences with MM group, except for the putty-body addition silicone. The digitization is a reliable methodology to evaluate the linear dimensional changes of molds made with impression materials, except for the putty-body elastomeric impression materials.

Abstract Camphorquinone is the most conventionally used photoinitiator in Dentistry. Although different alternative photoinitiators have been proposed, no photoinitiator was capable of completely substituting camphorquinone. The combination of photoinitiators has been considered the best alternative. Objectives: To evaluate the effect of combining Norrish type I and II photoinitiators on the cure efficiency of dental resin-based composites. Methodology: Experimental composites were produced containing different photoinitiator systems: Norrish type I-only, mono-alkyl phosphine oxide (TPO); Norrish type II-only, camphorquinone (CQ); or its combination, CQ and TPO, in a 1: 1 molar ratio. UV-vis absorption spectrophotometry was performed to assess the consumption of each photoinitiator after curing (n=3). A multi-wave LED (Bluephase® G2, Ivoclar Vivadent) was pre-characterized and used with a radiant exposure of 24 J/cm2. The degree of conversion was evaluated by Raman spectrometry, and the elution of the monomers by nuclear magnetic resonance analysis (n=3). Data were analyzed using ANOVA and Tukey's test (α=0.05; β=0.2). Results: The combination of CQ and TPO increased the consumption of the photoinitiator system compared to CQ-only (p=0.001), but presented similar consumption compared to TPO-only (p=0.52). There was no significant difference in the degree of conversion between the composites regardless of the photoinitiator system (p=0.81). However, the elution of the monomers was reduced when both photoinitiators were combined. TPO-based material presented the highest elution of monomers. Conclusions: The combination of the photoinitiator systems seems to be beneficial for the cure efficiency of dental resin-based composites.

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.

Resumo O objetivo neste estudo foi avaliar a influência do pré-aquecimento, conteúdo de carga e espessura da cerâmica na espessura da película, resistência de união ao microcisalhamento, grau de conversão e alteração de cor na cimentação de cerâmicas. Dois compósitos experimentais foram preparados (Bis-GMA / UDMA / BisEMA / TEGDMA), com diferentes quantidades de carga (65% ou 50% em peso), simulando um compósito convencional e um fluido. O fluido (F) foi usado à temperatura ambiente e o convencional, à temperatura ambiente (C) ou pré-aquecido (CPH). Foram preparados discos de cerâmica com diferentes espessuras (0,4mm, 0,8mm, 1,5mm). A espessura da película foi avaliada de acordo com a ISO 4049 (n=10). A resistência de união ao microcisalhamento (n=10) foi avaliada em esmalte utilizando espécimes fotopolimerizados através da cerâmica. O grau de conversão foi avaliado usando espectroscopia Raman. A alteração de cor das restaurações cerâmicas (n=10) foi avaliada por espectrofotometria. Os resultados foram submetidos à ANOVA 2- fatores e ao teste post hoc de Tukey (a=5%). Para espessura de película foi utilizada a ANOVA 1-fator (a=5%). O grupo C apresentou maior espessura de película; o CPH produziu uma espessura semelhante ao F. Todos os compósitos mostraram resistência de união ao microcisalhamento similares. O grau de conversão do F foi maior que C e CPH. O grau de conversão dos compósitos fotoativados através 0,4 mm foi maior que dos compósitos fotoativados através de cerâmicas mais espessas. O grupo C apresentou a maior mudança de cor, enquanto o CPH apresentou mudança de cor semelhante ao F. Em conclusão, compósitos convencionais pré-aquecidos assim como compósitos fluídos, parecem ser uma alternativa em potencial para cimentar laminados cerâmicos.

Abstract The aim of this study was to evaluate of pre-heating, filler contents and ceramic thickness on film thickness, microshear bond strength, degree of conversion and color change on ceramic veneers. Two experimental composites were prepared (Bis-GMA/UDMA/BisEMA/ TEGDMA), with different amounts of filler (65% or 50%wt) simulating a conventional and a flowable composite. The flowable (F) was used at room temperature and, the conventional either at room temperature (C) or pre-heated (CPH). Disk-shaped ceramics with different thickness (0.4 mm, 0.8 mm, 1.5 mm) were prepared. The film thickness was evaluated according to the ISO 4049 (n=10). The microshear bond strength (n=10) was evaluated in enamel using tubing specimens light-cured through the ceramic veneer. The degree of conversion was evaluated using Raman spectroscopy. The color change of the ceramic restorations (n=10) was evaluated by spectrophotometry. The results were submitted to 2-way ANOVA and Tukey’s post hoc test (a=5%). For the film thickness 1-way ANOVA was used (a=5%). The C presented the thicker film thickness; the CPH produced a similar film thickness in comparison to the F. All composites showed similar microshear bond strength. The degree of conversion of the F was higher than the C and CPH. The degree of conversion of the composites photo-activated through a 0.4 mm was higher than the composites photo-activated through thicker ceramics. The C showed the highest color change, while the CPH showed similar color change to the F. In conclusion, pre-heated conventional composites seem to be a potential alternative to lute ceramic veneers such as the flowable composites.

Resumo O objetivo nesse estudo foi utilizar o isobornil metacrilato (IBOMA) como monômero combinante ou substituinte na matriz resinosa de resinas compostas odontológicas. Para tanto, a matriz resinosa foi formulada com 60 % em peso de BisGMA e 40 % em peso de monômero diluente. O TEGDMA foi utilizado como único monômero diluente para o grupo controle com 40 % em peso, enquanto a substituição total de TEGDMA foi feita com 40 % em peso de IBOMA. Na combinação de IBOMA e TEGDMA foram utilizados 20 % em peso de cada monômero. Na matriz resinosa, 65 % em peso de partículas de carga foi adicionado. O grau de conversão (GC) utilizando FT-IR, a resistência flexural (RF), o módulo flexural (MF), a contração de polimerização por formação de gap (FG) utilizando Microscopia Confocal à Laser, a Dureza Knoop (DK) e a degradação em solvente (DS) foram avaliados. Todos os dados foram analisados utilizando ANOVA e teste de Tukey (α=0.05; b=0.2). Os resultados demonstraram que reduzindo ou substituindo o TEGDMA utilizando o IBOMA não afetou o GC (p=0.085), a RF (p=0.886) ou o MF (p=0.414). Ainda, quando o IBOMA foi utilizado como um monômero combinante ou substituinte, menor FG foi observada em comparação ao controle contendo apenas TEGDMA como monômero diluente (p=0.032). Contudo, apesar de todos os compósitos terem apresentados redução na DK durante o teste de DS, a combinação de IBOMA e TEGDMA demonstrou uma redução na DK similar ao grupo (p=0.001), enquanto a substituição total de TEGDMA com IBOMA reduziu a DK após DS (p=0.041). Dessa forma, a combinação do IBOMA e TEGDMA parece reduzir DS e a FG sem afetar as propriedades de resinas compostas.

Abstract The aim of this study was to use the isobornyl methacrylate (IBOMA) as a combining or substituent diluent monomer in the resin matrix of dental resin composites. Thus, the resin matrix was formulated with 60 wt% of BisGMA and 40 wt% of diluent monomers. TEGDMA as the only diluent monomer was used as control with 40 wt%, while total substitution of TEGDMA was done with 40 wt% of IBOMA. The combination of IBOMA and TEGDMA was done with 20 wt% of each monomer. To the resin matrix, 65 wt% of filler particles was added. Degree of conversion (DC) using FT-IR, flexural strength (FS), flexural modulus (FM), polymerization shrinkage by gap formation (GF), Knoop hardness (KH) and solvent degradation (SD) were evaluated. Data were analyzed using ANOVA and Tukey’s test (α=0.05; b=0.2). The results showed that reducing or substituting TEGDMA using IBOMA did not affect the DC (0.085), FS (p=0.886) or FM (p=0.414). Also, when IBOMA was used, lower GF was found in comparison to the control containing only TEGDMA as the diluent monomer (p=0.032). However, even though all composites presented reduction in KH during the SD test, the combination of IBOMA and TEGDMA showed similar reduction in KHN in comparison to the control group (p=0.001), while the total substitution of TEGDMA with IBOMA decreased KHN after SD (p=0.041). Thus, the combination of IBOMA and TEGDMA seem to reduce SD and GF without affecting the properties of resin composites.

Abstract The main of the study was quantify the effect of two ceramics with two underlying resin cements on apparent fluorescence levels. Buccal surfaces of two bovine incisors were ground flat producing one enamel and one dentin substrate. The veneers were fabricated (0.5 and 1.0 mm thickness) using two ceramics (IPSe.max Press and IPSe.max Zirpress, Ivoclar Vivadent). Veneers were cemented using either light-cured (Variolink II, Ivoclar Vivadent) or self-adhesive dual (Rely X U200, 3M ESPE) cement. The layered Control group materials had no cement application. Semi-quantitative fluorescence image analysis (Matlabs software, Matworks) involved processing the images as captured under each daylight (DL, Gretagmacbeth) and ultraviolet illuminants (UVA, Sylvania) within a neutral-gray lightbox (Macbeth Spectral Light). Statistical analysis of the quantitative fluorescence values was performed using two-way ANOVA and Tukey’s test (p < 0.05). The e.max Zirpress on the dentin substrate produced greater fluorescence (p < 0.05) when subjected to UV illumination and more fluorescence (p < 0.05) than e.max Press in both cement groups. Light-cured cement produced higher (p < 0.05) fluorescence than the dual-cement with e.max Press on enamel under UV illumination. The fluorescence for e.max Press on the dentin substrate was greater (p < 0.05) than for e.max Zirpress using dual self-adhesive cement subjected to daylight illumination. Thus, it is possible to conclude that the combination of ceramic and cement produce definite, significant effects on the apparent fluorescence, vital quality for restorative dentistry.