Microhardness, Color Stability and Microstructural Analysis of Prefabricated Composite Resin Veneers / Estudo da Microdureza, Estabilidade de cor e Microestrutura de Facetas Pré-Fabricadas de Resina Composta

The aim of the work was to determine Knoop microhardness (KH), color stability (ΔE00) and microstructure of prefabricated composite resin veneers (PCRVs). Two PCRVs systems (Componeer Brilliant New Generation, Coltene, Altstätten, Switzerland; and Direct Veneer, Edelweiss, Wolfurt, Austria) were tested. KH was measured at the buccal surface of the PCRVs. Color analyze was evaluated by a spectrophotometer and ΔE00 calculated using CIEDE2000 formula. Microstructure of the PCRVs was characterized using scanning electron microscopy (SEM). Data of KH and ΔE00 were subjected to One-way ANOVA followed by Tukey post hoc test (α=0.05). Componeer (KH = 46) and Edelweiss (KH = 43) presented statistical similar hardness results (p>0.05). Componeer (ΔE00water= 0.1 and ΔE00coffee= 13.4) showed lower ΔE00 than Edelweiss (ΔE00water= 0.5 and ΔE00coffee= 18.7). SEM-images indicated similar microstructures of the PCRVs tested. Although PCRVs present similar microhardness and microstructure, Componeer showed higher color stability and lower extrinsic pigmentation to coffee in comparison to Edelweiss. Direct composite resin veneer treatment might be simplified with PCRVs. However, the high pigmentation observed in the PCRVs could generate aesthetic failures over the time. (AU)

O objetivo do trabalho foi determinar a microdureza Knoop (KH), estabilidade de cor (ΔE00) e a microestrutura de facetas de resina composta pré-fabricadas. Os sistemas de facetas Componeer e Edelweiss foram testados. Para cada sistema, a microdureza foi avaliada na superfície vestibular das facetas. A análise da estabilidade de cor foi feita mediante o emprego de um espectrofotômetro e a alteração de cor foi calculada seguindo a fórmula determinada pelo CIEDE2000. A microestrutura dos sistemas foi observada e caracterizada a partir de um microscópio eletrônico de varredura. Os resultados de microdureza e alteração de cor foram submetidos a análise de variância de um fator complementados pelo teste de Tukey (α=0,05). Os sistemas de facetas pré-fabricadas de resina composta apresentaram valores estatisticamente similares de microdureza (p>0,05). O grupo Componeer apresentou uma alteração de cor inferior em relação ao grupo Edelweiss. Os dois sistemas apresentaram uma elevada pigmentação após imersão em solução com café. A microestrutura dos sistemas se mostrou similar em função da avaliação das imagens em microscopia. Apesar dos sistemas apresentarem microdureza e microestrutura similares, o sistema Componeer gerou menor alteração de cor com menor pigmentação a bebida corante empregada em comparação ao sistema Edelweiss. A técnica de facetas dentárias pode ser simplificada utilizando um sistema de facetas pré-fabricadas de resina composta. Todavia, a elevada pigmentação observada no presente estudo deve ser levada em consideração já que o tratamento com esse tipo faceta tende a ser um procedimento estético com durabilidade elevada. (AU)

Physicochemical and morphological characterization of a glass ceramic treated with different ceramic primers and post-silanization protocols.

OBJECTIVE: Evaluate the effect of different ceramic primers and post-silanization protocols on physicochemical and morphological characteristics of a lithium disilicate glass ceramic. METHODS: Lithium disilicate ceramic (IPS e-max CAD) plaques (6 × 10 × 2 mm) were divided into 3 groups according to the ceramic primer used: (1) Silane (RelyX Ceramic Primer-RL); (2) Silane + MDP (Clearfil Ceramic Primer Plus-CP); (3) Self-etching ceramic primer (Monobond Etch and Prime-MB). Specimens from each group were distributed into 5 sub-groups according to post-silanization protocols: (a) Treated as recommended by the manufacturer (MR), (b) MR + Additional drying with air at room temperature for 30 s (RTA), (c) MR + additional drying with hot air for 30 s (HT), (d) MR + Surface rinsing with water at room temperature for 10 s and drying with air at room temperature for 30 s (WT), and (e) Specimens were not silanized (NS). Surface free energy (SFE) was determined using static contact angles measurements with water and diiodomethane. SFE data were submitted to Friedman followed by Wilcoxon post-hoc test (α = 0.05). Morphology was analyzed using scanning electron microscopy. Elemental composition and chemical interactions were determined with X-ray photoelectron spectroscopy analysis. RESULTS: RL presented the highest SFE (62.4 mN/m) followed by CP (59.7 mN/m). Post-silanization protocols resulted in similar SFE, but WT and HT induced the highest water contact angles when using CP and RL. CP modified ceramics' surface morphology compared to the etched and RL treated groups. The presence of water was identified on CP treated specimen. All analyzed primers formed siloxane bonds with ceramic surface. SIGNIFICANCE: Ceramic primers resulted in different surface free energy and morphology, but siloxane bonds were identified for all tested solutions. HT and WT protocols should be used with RL and CP primers. MB was not influenced by the different silanization protocols.

Physicochemical Properties and Microshear Bond Strength of Experimental Self-adhesive Resin Cements to Dentin or Yttria-stabilized Tetragonal Zirconia Polycrystal.

PURPOSE: To determine the degree of conversion (DC), physicochemical properties, and microshear bond strength (µSBS) of experimental self-adhesive resin cements (SARCs) to dentin and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic. MATERIALS AND METHODS: Dual-curing cements were formulated with UDMA, HEMA, bis-GMA, and TEG-DMA as the organic matrix. 2MP (bis 2-(methacryloyloxy)-ethyl-phosphate) and GDMAP (1,3-glycerol dimethacrylate phosphate) were added to impart self-adhesive characteristics. A control group was formulated without self-etch methacrylates. Silanized particles were incorporated. Photoactivation was carried out using an LED light-curing unit (1200 mW/cm2) for 20 s. Infrared spectroscopy assessed the DC immediately and after 24 h. pH was analyzed in real time and recorded after 48 h. Water sorption (Wsp), water solubility (Wsl), and film thickness measurements followed ISO 4049. µSBS of the cements to dentin and Y-TZP was evaluated immediately and after 3 months of water storage. Y-TZP was also tested without a surface treatment and after tribochemical silica coating with subsequent application of a silane agent. The fractures patterns were classified as adhesive, cohesive, and mixed. Data were submitted to analyses of variance and Tukey's tests (α = 0.05). RESULTS: Control (91.7%) and 2MP (92.0%) groups generated the highest DC after 24 h. 2MP (pH = 3.6) showed the lowest pH followed by GDMAP (pH = 4.7) and control (pH = 6.4) after 48 h. The control cement exhibited lower Wsp (41.0 µg/mm3) and Wsl (4.3 µg/mm3) than the other groups. Film thickness was statistically similar (p = 0.266) for all cements. Control (27.0 MPa) and GDMAP (24.1 MPa) showed higher µSBS to dentin than 2MP (13.7 MPa) after water storage. Mixed fractures were predominant in dentin. For all cements, the µSBS to Y-TZP was < 3.0 MPa after water storage, independent of the surface treatment. CONCLUSION: The results of DC, pH, Wsp and Wsl were material dependent. Only the film thickness was statistically similar for all groups. The cement formulated with GDMAP maintained the bond strengths to dentin even after aging. However, none of the groups were able to generate satisfactory bond strength to Y-TZP, independent of the surface treatment.

Depth of cure of bulk fill resin composites: A systematic review.

OBJECTIVE: To evaluate scientific evidence regarding depth of cure of bulk-fill resin composites (BFRCs) and related factors. MATERIAL AND METHODS: PubMed/Medline, Embase, Scopus, and ISI Web of Science databases were accessed from October 2016 to May 2017. Investigations published in English language, assessing depth of cure of BFRCs by microhardness test and/or degree of conversion (DC) were included. Studies using exclusively ISO 4049, employing specimens deepness less than 4 mm, as well as those not reporting exposure time and/or irradiance from light curing units (LCUs) were excluded. RESULTS: In total, 742 studies were found from which 33 were included. From 21 studies evaluating BFRCs microhardness, 10 showed acceptable bottom/top ratios (≥0.8) for all tested materials. However, material-dependent results and non-satisfactory bottom/top microhardness ratios (<0.8) were reported in 9 and 2 investigations, respectively. From 19 studies that assessed DC, 11 showed acceptable results (≥50%) for all tested BFRCs, while 8 studies reported material-dependent outcomes. Overall, irradiance from LCUs ranged from 650 to 1330 mW/cm2 and exposure time from 5 to 60 seconds. Favorable depth of cure results were observed with the use of LCUs emitting irradiance ≥1000 mW/cm2 and exposure times ≥20 seconds. CONCLUSIONS: High depth of cure rates by BFRCs, depends on some factors as material, irradiance and exposure time. Polywave LCUs were useful but not essential on polymerizing alternative photoinitiator-containing BFRC. CLINICAL SIGNIFICANCE: LED curing devices (polywave or monowave) displaying an irradiance ≥1000 mW/cm2 and 20 seconds of exposure time are imperative to accomplish successful polymerization of most BFRCs.

Prefabricated resin veneer: A case report of a simplified restorative technique.

Background: the aim of the study was to describe the step-by-step of clinical cases using prefabricated composite resin veneers (PCRVs), manufactured with the composite Brilliant New Generation (Coltene, Altstätten, Switzerland). Direct composite veneers presented some drawback as the difficult of execution and color instability of the composite over the time. The simplified application of the PCRVs presented as an interesting alternative in cases of smile asymmetry, large deficient restorations and discolored tooth. In the present investigation, the complete description of the PCRVs technique can help the dentist during the planning and execution of treatments with the Componeer system. Conclusion: the treatment with Componeer Brilliant NG showed excellent aesthetic results. PCRVs technique is simpler than direct composite veneers. The specific characteristics of the system can promote results with greater aesthetic longevity. It is important to highlight that this procedure does not replace the already established veneer technique with dental ceramics. Clinical implication: PCRVs presented an excellent surface gloss. Their dimensions based on the golden ratio facilitate the technique and turns as an excellent alternative in the aesthetic restorative treatment in the anterior region.

Effect of Ceramic Interposition and Post-activation Times on Knoop Hardness of Different Shades of Resin Cement

Abstract The aim of this study was to evaluate Knoop hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microhardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 ºC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p<0.0001), mode of activation (p<0.001), post-cure time (p<0.0001) and depth (p<0.0001) were detected. No significant interactions (p>0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop hardness. Indirect activation through a ceramic material reduced significantly Knoop hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop hardness.

Resumo O objetivo deste estudo foi avaliar a dureza Knoop de diferentes cores de um cimento resinoso fotoativado diretamente ou através da interposição de um disco de cerâmica, medindo 15 min ou 24 h após exposição à luz, em diferentes profundidades. Amostras do cimento resinoso (Variolink Veneer) em sete cores foram fabricados num molde de elastômero, coberto com tira de poliéster, seguido de um disco cerâmico (IPS e.max Press) com 0.7 mm de espessura e fotoativado por 20 s com o aparelho LED (IPS e.max Press). O cimento resinoso fotoativado foi transversalmente desgastado na porção média e os valores de microdureza Knoop foram obtidos após 15 min após exposição à luz e após armazenagem em água deionizada à 37 °C por 24 h. Cinco penetrações foram feitas na secção transversal à 100 e 700 μm da superfície de topo. Dez amostras foram confeccionadas para cada condição de teste. Os dados foram submetidos à Análise de Variância em esquema de parcelas subdivididas (cor, tempo pós-ativação, modo de ativação e profundidade), seguido pelo teste de Tukey post hoc (α=0,05). Diferença significante para a cor (p<0,0001), modo de ativação (p<0,001), tempo pós-ativação (p<0,0001) e profundidade (p<0,0001) foi detectada. Nenhuma interação significante foi encontrada (p>0,05), exceto para a interação cor x tempo pós-ativação (p<0,0045) e modo de ativação x tempo pós-ativação (p<0,0003). A cor do cimento resinoso teve significante efeito na dureza Knoop. A ativação indireta através do material cerâmico reduziu significativamente a dureza Knoop. A dureza Knoop aumentou significativamente após 24 h em todas as cores do cimento comparados aos valores obtidos após 15 min. A profundidade do cimento resinoso reduziu significativamente os valores de dureza Knoop.

Effect of Ceramic Interposition and Post-activation Times on Knoop Hardness of Different Shades of Resin Cement.

The aim of this study was to evaluate Knoop hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microhardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 ºC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 µm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p<0.0001), mode of activation (p<0.001), post-cure time (p<0.0001) and depth (p<0.0001) were detected. No significant interactions (p>0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop hardness. Indirect activation through a ceramic material reduced significantly Knoop hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop hardness.