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This study evaluated the effect of using two different pre-heating methods on the three resin-based composite (RBCs). Three paste viscosity bulk-fill RBCs (VisCalor Bulk [VC]; VOCO; x-tra fil Caps [XF], VOCO; Filtek One Bulk Fill [FO], 3 M) were pre-heated using either a VisCalor Dispenser (VOCO) to 65 °C, or the Caps Warmer (VOCO) to 37 °C, 54 °C, or 68 °C. The temperature inside the capsules and cavity was monitored before and after insertion into the matrix. Within 30 s of inserting the RBC, they were light-activated using a VALO (Ultradent) curing light for 20 s. The post-gel shrinkage (Shr - %), Flexural Strength (FS - MPa), Elastic Modulus (E - MPa), degree of conversion (DC - %), Knoop Hardness (KH - N/mm

This study evaluated the effect of the design of the light-curing unit (LCU) and mouth opening on the properties of bulk-fill resin-based composites (RBCs).Eighty molars received a mesio-occlusal-distal preparation and were restored using two different bulk-fill RBCs, Opus Bulk Fill APS (FGM) and Filtek Bulk Fill One (3M Oral Care), using two different designs of LCU, straight (Valo Cordless [Ultradent]) and angled (Radii-Cal [SDI]). Two mouth openings of 25 and 45 mm at the incisors were used. Forty samples were sectioned mesiodistally. One half was immersed in tetrahydrofuran to examine the effect of the solvent on the RBCs (SE), and the other half to measure the degree of conversion (DC) in proximal and occlusal boxes using Fourier Transform Infrared spectroscopy. The other 40 samples were subjected to thermomechanical fatigue and immersed in silver nitrate to examine the gingival margin integrity (GMI) using SEM. The irradiance (mW/cm2) and emission spectrum (mW/cm2/nm) from the LCUs were measured using a MARC Resin Calibrator (BlueLight Analytics). DC data were analyzed by 3-way ANOVA and Tukey's test; SE and GMI were analyzed by an ANOVA on Ranks and Dunn test (α = 0.05).The DC values were similar in the occlusal and proximal boxes when using Valo Cordless , irrespective of RBC and the mouth opening used. Lower DC values were measured in proximal boxes when using Radii-Cal. The mouth opening had a greater effect on the irradiance delivered by Radii-Cal. Radii-Cal with 25-mm mouth opening had greater SE and GMI values, whereas the SE and GMI values obtained with Valo Cordless were unaffected by mouth opening.The choice of LCU did not influence the properties of tested bulk-fill RBCs when the 45-mm mouth opening was used. However, when using the 25-mm mouth opening, the choice of LCU did influence the properties of the RBCs.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico Avaliar o efeito do pré-aquecimento de diferentes resinas compostas bulk fill em diferentes temperaturas e métodos de aquecimento nas propriedades mecânicas expressas por resistência à flexão, módulo de elasticidade, grau de conversão, dureza Knoop, contração pós-gel e tensão de contração. Três resinas compostas bulk fill de consistência regular disponíveis em cápsulas (FO - Filtek One Bulk Fill, 3M-ESPE; VC - VisCalor Bulk, VOCO; XF - x-tra Fil, VOCO) foram pré-aquecidas usando VisCalor Dispenser (VOCO) a 65oC e Caps Warmer (VOCO) a 37oC, 54oC e 68oC. Todos os materiais foram ativados por luz usando uma LCU multi espectos (VALO Cordless, Ultradent) por 20 segundos. A contração pós-gel (Shr, %) foi calculada usando um extensômetro. A resistência à flexão (FS, MPa), módulo de elasticidade (E, MPa) foram calculados pelo teste de flexão de 3 pontos. O grau de conversão (DC, %) usando FTIR e dureza Knoop (KNH, N / mm2) foram testados nas superfícies superiores. A resistência à tração diametral (DTS) e a resistência à compressão (CS) foram determinadas (n = 10). As tensões de contração foram analisadas usando a análise tridimensional de elementos finitos. Os dados foram analisados por ANOVA de dois fatores e testes de Tukey (α = 0,05). Os diferentes processos de aquecimento e temperaturas não influenciaram nas propriedades mecânicas testadas. Os valores de FS não foram influenciados pelos métodos de aquecimento, temperatura e tipo de resina composta testada. FO apresentou os menores valores de E, DC e KNH, VC apresentou valores intermediários e XF apresentou os maiores valores. Os valores de DTS e CS não foram influenciados pelos métodos de aquecimento, temperaturas e tipo de resina composta testada. O processo de aquecimento a 65oC realizado com um dispensador e a 68oC e 54oC realizado com tampas mais quentes resultou em menos tensão de encolhimento do que o pré-aquecimento a 37oC usando tampas mais quentes, independentemente do composto de resina bulk fill. O método VisCalor possui as tensões mais baixas. O novo dispensador de aquecimento testado demonstrou eficiência na produção de aquecimento de resinas compostas, sem influenciar as propriedades mecânicas. O aquecimento de compósitos de resina de enchimento viscosos a granel em temperaturas mais elevadas (54oC, 65oC e 68oC) reduziu a tensão de retração em comparação ao aquecimento a 37oC. To evaluate the effect of the preheating of different bulk fill composites at different temperatures and heating methods on the mechanical properties expressed by flexural strength, modulus of elasticity, degree of conversion, Knoop hardness, post-gel contraction and contraction stress. Three bulk fill composite resins of regular consistency available in capsules (FO - Filtek One Bulk Fill, 3M-ESPE; VC - VisCalor Bulk, VOCO; XF - x-tra Fil, VOCO) were preheated using VisCalor Dispenser (VOCO) a 65oC and Caps Warmer (VOCO) at 37oC, 54oC and 68oC. All materials were activated by light using a multipeak LCU (VALO Cordless, Ultradent) for 20 seconds. Post-gel contraction (Shr, %) was calculated using an extensometer. Flexural strength (FS, MPa), modulus of elasticity (E, MPa) were calculated by the 3-point flexion test. The degree of conversion (DC, %) using FTIR and Knoop hardness (KNH, N / mm2) were tested on the upper surfaces. The diametrical tensile strength (DTS) and the compressive strength (CS) were determined (n = 10). The contraction stresses were analyzed using three- dimensional finite element analysis. The data were analyzed by two-way ANOVA and Tukey's tests (α = 0.05). The different heating processes and temperatures did not influence the tested mechanical properties. The FS values were not influenced by the heating methods, temperature and type of composite resin tested. FO presented the lowest values of E, DC and KNH, VC presented intermediate values and XF presented the highest values. The DTS and CS values were not influenced by the heating methods, temperatures and type of composite resin tested. The heating process at 65oC performed with a dispenser and at 68oC and 54oC performed with warmer covers resulted in less shrinkage tension than preheating at 37oC using warmer covers, regardless of the bulk-fill resin compound. The VisCalor method has the lowest stresses. The new tested heating dispenser demonstrated efficiency in producing heating of composite resins, without influencing the mechanical properties. The heating of bulk viscous filler resin composites at higher temperatures (54 oC, 65oC and 68oC) reduced the shrinkage tension compared to heating at 37oC. Dissertação (Mestrado)

To describe a method of measuring the molar cusp deformation using micro-computed tomography (micro-CT), the propagation of enamel cracks using transillumination, and the effects of hygroscopic expansion after incremental and bulk-filling resin composite restorations.Twenty human molars received standardized Class II mesio-occlusal-distal cavity preparations. They were restored with either a bulk-fill resin composite, X-tra fil (XTRA), or a conventional resin composite, Filtek Z100 (Z100). The resin composites were tested for post-gel shrinkage using a strain gauge method. Cusp deformation (CD) was evaluated using the images obtained using a micro-CT protocol and using a strain-gauge method. Enamel cracks were detected using transillumination.The post-gel shrinkage of Z100 was higher than XTRA (P 0.001). The amount of cusp deformation produced using Z100 was higher compared to XTRA, irrespective of the measurement method used (P 0.001). The thinner lingual cusp always had a higher CD than the buccal cusp, irrespective of the measurement method (P 0.001). A positive correlation (r = 0.78) was found between cusp deformation measured by micro-CT or by the strain-gauge method. After hygroscopic expansion of the resin composite, the cusp displacement recovered around 85% (P 0.001). After restoration, Z100 produced more cracks than XTRA (P = 0.012).Micro-CT was an effective method for evaluating the cusp deformation. Transillumination was effective for detecting enamel cracks. There were fewer negative effects of polymerization shrinkage in bulk-fill resin restorations using XTRA than for the conventional incremental filling technique using conventional composite resin Z100.Shrinkage and cusp deformation are directly related to the formation of enamel cracks. Cusp deformation and crack propagation may increase the risk of tooth fracture.

Objectives Curing lights cannot be sterilized and should be covered with an infection control barrier. This study evaluated the effect of barriers when applied correctly and incorrectly on the radiant power (mW), irradiance (mW/cm2), emission spectrum (mW/nm), and beam profile from a multi-peak light-curing unit (LCU). Methods Five plastic barriers (VALO Grand, Ultradent; TIDIShield, TIDI Products; Disposa-Shield, Dentsply Sirona; Cure Sleeve, Kerr; Stretch and Seal, Betty Crocker) and one latex-based barrier (Curelastic, Steri-Shield) were tested. The radiant power (mW) and emission spectrum (mW/nm) from one multi-peak LCU (VALO Grand, Ultradent) was measured using an integrating sphere. LCU tip internal diameter (mm) was measured, then the tip area and irradiance (mW/cm2) were calculated. The beam profiles were measured using a laser beam profiler. Results When applied correctly, the plastic barriers reduced the radiant power output by 5–8%, and the latex-based barrier by 16%. When the plastic seam or barrier opaque face was positioned over the LCU tip, the power output was reduced by 8–11%. When the plastic barriers were wrinkled, the power output was significantly reduced by 14–26%. The wrinkled latex-based barrier reduced by 28%, and further reduced the violet light. The beam profiles illustrated the importance of correctly barrier use without wrinkles over the tip. Conclusions Plastic barriers applied correctly reduced the light output (mW) by 5–8%. The barriers applied incorrectly significantly reduced the light output by 14–26%. The latex-based barrier wrinkled also reduced the amount of violet light. Clinical relevance Infection control curing light barriers should be used to prevent cross-infection between patients. However, they must be applied correctly to reduce their negative effects on the light output.

O objetivo foi propor método para mensuração da deflexão de cúspide utilizando microtomografia computadorizada (micro-CT) e de trincas em esmalte utilizando transiluminação de restaurações de resina composta. Vinte molares humanos receberam preparos padronizados classe II e restaurações com resina composta de incremento único (Xtrafil - XTRA) ou resina convencional (Filtek Z100 - Z100). Contração pós-gel das resinas compostas foi mensurada utilizando método de Extensometria. Deformação de cúspide foi mensurada por meio de novo protocolo empregando micro-CT e validado pelo método de extensometria. Trincas em esmalte foram detectadas pelo método de transiluminação. Contração pós-gél de Z100 foi superior a XTRA. Deformação de cúspide para Z100 foi superior à XTRA, independentemente dos métodos. A cúspide lingual apresentou maior deformação do que a vestibular. Os métodos de deformação de cúspide por micro-CT e Extensometria apresentaram alta correlação (r 0,78). A expansão higroscópica recuperou significativamente a deformação de cúspide, porém resultou em ampliação de trincas. Z100 resultou em maior ocorrência de trincas com maior extensão que XTRA. As trincas foram predominantemente horizontais, localizadas na região correspondente à base da cavidade, envolvendo principalmente o centro e a região distal. O método que emprega micro-CT provou ser viável e eficaz para avaliar deflexão de cúspide, assim como a transiluminação para detecção de trincas.Palavras-chave: Resinas Compostas. Polimerização. Microtomografia.

Avaliou-se o efeito da fonte de luz e microcirculação pulpar (MP) simulada na geração de calor na câmara pulpar (CP) sob restaurações de resina composta inseridas em incremento único. Duas fontes de luz multi espectros (Bluephase G2, Ivoclar e VALO Cordless, Ultradent) foram caracterizadas com MARC-Resin Calibrator (BlueLight), a potência radiante com medidor de potência de laboratório e grau de conversão (GC) foi avaliado, utilizando FTIR. 40 molares humanos tiveram a coroa seccionada gerando preparo oclusal plano com 2 mm de dentina. Restaurações foram feitas com sistema adesivo auto-condicionante (Clearfil SE Bond, Kuraray) e resina composta bulk fill fluida (SDR, Dentsply) ou regular (AURA, SDI). A temperatura na CP foi medida com termopar tipo-J, na presença ou ausência de MP. Os dados foram analisados com ANOVA e teste Tukey (a0,05). A irradiância e a potência sofreram atenuação significativa com 3 mm de resina composta sobre os 2 mm de dentina remanescente. Bluephase obteve maior irradiância e potência que o VALO. As resinas e fontes de luz avaliadas influenciaram o GC, porém com valores que confirmam adequada polimerização. Simulação da MP reduziu o aumento de temperatura na CP. Maior aumento de temperatura ocorreu na fotoativação do adesivo. As fontes de luz foram diferentes com o VALO resultando em menor variação de temperatura na ativação do adesivo apenas na ausência de MP. SDR permitiu maior transmissão de luz e alcançou maior GC que AURA. O ponto crítico de temperatura foi na fotoativação do sistema adesivo, sendo que a presença de MP minimiza estes efeitos.Palavras-chave: Temperature. Dental Pulp Cavity. Adhesives.