Effect of at-home bleaching gels with different thickeners on the physical properties of a composite resin without bisphenol A.

OBJECTIVE: To investigate, in vitro, the influence of at-home bleaching with 16% carbamide peroxide (CP) gels containing different thickeners on the color, gloss, roughness, and microhardness of a composite resin with bisphenol A (BPA) and without bisphenol A (BPA-free). MATERIAL AND METHODS: Cylindrical samples (7 × 2 mm) of a composite resin with BPA (Filtek Z350 XT®; 3M/ESPE) and composite resin BPA-free (Vittra APS®; FGM) were subdivided into six subgroups (n = 12), according to the bleaching gel used: no bleaching (control), commercial gel with 16% CP and carbopol, experimental gel with 16% CP and carbopol, experimental gel with 16% CP and natrosol, experimental gel with carbopol and experimental gel with natrosol. At the end of the experimental phase, the specimens were analyzed for color (ΔE*ab and ΔE00 ), surface roughness (Ra), gloss (GU), and surface microhardness (SMH). The data for all analyzes were submitted to Levene's test, Shapiro-Wilk's test and ANOVA. RESULTS: For ΔE*ab and ΔE00 no statistically significant differences were found between all groups evaluated. Bleaching with experimental 16% CP gel with carbopol resulted in the lowest GU values for both composite resins evaluated. 16% CP experimental gel with natrosol resulted in higher Ra for the BPA composite resin and the bleaching with natrosol resulted in higher Ra for BPA-free. About 16% CP experimental gel with carbopol and 16% CP experimental gel with natrosol resulted in the lowest final SMH for composite resin with BPA. For the BPA-free composite resin, no differences were found between the groups in SMH for the same resin, however they presented the lowest values compared with all others groups. CONCLUSION: The effects on physical properties are dependent on the composition of the composite resin and the thickener/bleaching gel used. The BPA-free composite resin showed less changes after exposure to bleaching agent, although its initial physical properties were worse compared to a bleached BPA. CLINICAL RELEVANCE: The hydrogen peroxide and thickener of the at-home bleaching gel does impact the properties of composites with BPA or BPA-free such as gloss, roughness and surface microhardness, extremely important factors for maintaining an aesthetically and physically satisfactory restoration. BPA-free composite resins have inferior properties after at-home bleaching with different thickeners.

Knoop hardness and effectiveness of dual-cured luting systems and flowable resin to bond leucite-reinforced ceramic to enamel.

PURPOSE: The aim of this study was to evaluate the Knoop microhardness and microshear bond strength (MSBS) of dual-cured luting systems and flowable resin bonded to leucite-reinforced ceramics and enamel. MATERIALS AND METHODS: Eighty bovine incisors were randomly divided into four groups per test (microhardness and microshear; n = 10) according to the bonding procedure: Excite DSC/Variolink, Clearfil SE Bond/Panavia F, Adper Scotchbond Multi-Purpose Plus/RelyX ARC, and Adper Single Bond 2/Filtek Z350 Flow. For the KHN measurement, the cement was applied on the enamel surface and light-cured through a ceramic disk (5 mm diameter × 1.2 mm thick). Five indentations were performed in each specimen and measured at HMV-2. For the microshear test, two cylinders of a leucite-reinforced ceramic (1 mm diameter × 2 mm height) were bonded to the enamel substrate in accordance with the bonding procedures previously established. One cylinder was tested 24 hours after cementation, and the other was subjected to thermocycling (2000 cycles) and then submitted to an MSBS test. The data from the hardness and bond strength tests were subjected to one- and two-way repeated-measures analysis of variance (ANOVA), respectively, and to Tukey's test (α= 0.05). RESULTS: Scotchbond/RelyX ARC presented higher values of bond strength, while Single Bond/Z350 Flow showed lower values. The thermocycling promoted a reduction in the bond strength values for all groups. Panavia F presented higher values of KHN, and the flowable resin presented the lowest. RelyX ARC and Variolink presented intermediate values on hardness evaluation. CONCLUSIONS: For ceramic cementation, dual-cured resin luting systems promoted more reliable bonding and microhardness values than the flowable resin.

The effect of curing light and chemical catalyst on the degree of conversion of two dual cured resin luting cements.

The aim of this study was to evaluate the influence of different curing lights and chemical catalysts on the degree of conversion of resin luting cements. A total of 60 disk-shaped specimens of RelyX ARC or Panavia F of diameter 5 mm and thickness 0.5 mm were prepared and the respective chemical catalyst (Scotchbond Multi-Purpose Plus or ED Primer) was added. The specimens were light-cured using different curing units (an argon ion laser, an LED or a quartz-tungsten-halogen light) through shade A2 composite disks of diameter 10 mm and thickness 2 mm. After 24 h of dry storage at 37°C, the degree of conversion of the resin luting cements was measured by Fourier-transformed infrared spectroscopy. For statistical analysis, ANOVA and the Tukey test were used, with p ≤ 0.05. Panavia F when used without catalyst and cured using the LED or the argon ion laser showed degree of conversion values significantly lower than RelyX ARC, with and without catalyst, and cured with any of the light sources. Therefore, the degree of conversion of Panavia F with ED Primer cured with the quartz-tungsten-halogen light was significantly different from that of RelyX ARC regardless of the use of the chemical catalyst and light curing source. In conclusion, RelyX ARC can be cured satisfactorily with the argon ion laser, LED or quartz-tungsten-halogen light with or without a chemical catalyst. To obtain a satisfactory degree of conversion, Panavia F luting cement should be used with ED Primer and cured with halogen light.

Adhesion, Mechanical Properties, and Microstructure of Resin-matrix CAD-CAM Ceramics.

PURPOSE: To investigate the effects of 1-year water storage and surface treatments on shear bond strength (SBS) of two composite cements bonded to resin matrix CAD-CAM ceramics (RMCs) and on the mechanical properties of RMCs. MATERIALS AND METHODS: Three types of RMCs were tested: 1. polymer-infiltrated hybrid ceramic (PIHC, Enamic, VITA Zahnfabrik); 2. resin nanoceramic (RNC, Lava Ultimate, 3M Oral Care); and 3. flexible hybrid ceramic (FHC, Cerasmart, GC). One indirect laboratory composite (ILC, Epricord, Kuraray Noritake) was used as control. For each material, 60 plates (14 x 7 x 1 mm) were prepared for the SBS test and submitted to three different surface treatments: following manufacturer's instructions, non-thermal atmospheric plasma application (30 s), and plasma + bonding agent. Two composite cements were tested: RelyX Ultimate (3M Oral Care) and Panavia V5 (Kurarary Noritake). Two resin cylinders (1.5 mm diameter x 1.5 mm height) were bonded to each plate (n = 10), with one tested after 24-h storage in distilled water and the other after 1 year of storage in distilled water. Twenty rectangular bars (12 x 2 x 1 mm) of each indirect material were prepared and submitted to the 3-point flexural test after 24-h or 1-year water storage to determine the elastic modulus (EM) and flexural strength (FS) (n = 10). Fractured samples were also examined with SEM and energy dispersive x-ray spectroscopy (EDS). SBS data were analyzed by four-way ANOVA, and EM and FS data by two-way ANOVA, followed by Tukey's post-hoc test (α = 0.05). RESULTS: Groups treated in accordance with manufacturer's instructions exhibited higher SBS than did plasma and plasma + bonding agent groups for all indirect materials, composite cements, and storage periods tested. In general, RelyX Ultimate displayed higher mean SBS than did Panavia V5, except for some groups of ILC where manufacturer's instructions were followed. After 1-year storage in water, all groups exhibited a significant reduction in SBS, except for some groups that following manufacturer's instructions. ILC showed the lowest values of EM and FS. Among the CAD-CAM materials, FHC exhibited the lowest EM and highest FS means, while PIHC possessed the highest EM and lowest FS means for both storage periods. CONCLUSIONS: In general, following the respective manufacturer's instructions yielded the best bond strength results. For most materials, 1-year water storage decreased bond strength of composite cements to RMCs, as well as their FS, while increasing their EM. Microstructure and composition influenced the mechanical properties studied.

Effects of desensitizing products on the reduction of pain sensitivity caused by in-office tooth bleaching: a 24-week follow-up.

OBJECTIVE: To clinically assess the effect of desensitizing gels and dentifrices on the reduction in pain sensitivity and color variation during tooth bleaching. METHODOLOGY: A total of 108 volunteers were randomly separated into the following groups of n=12: GT/S-glycerine and thickener/sucralose; NF/S-potassium nitrate and sodium fluoride/sucralose; NA/S-potassium nitrate and arginine/sucralose; GT/AC-glycerine and thickener/arginine and calcium carbonate; NF/AC-potassium nitrate and sodium fluoride/arginine and calcium carbonate; NA/AC-potassium nitrate and arginine/arginine and calcium carbonate; GT/PN-glycerine and thickener/potassium nitrate; NF/PN-potassium nitrate and sodium fluoride/potassium nitrate; and NA/PN-potassium nitrate and arginine/potassium nitrate. Sensitivity was assessed with the numerical analogue scale, and color variation (ΔE) was measured with a spectrophotometer. The sensitivity values obtained were subjected to a multivariate analysis of variance (MANOVA) and color variation values were subjected to a randomized analysis of variance (p<0.05). RESULTS: The NF/AC, NA/AC, NF/PN, and NA/PN groups presented lower sensitivity values and reduced sensitivity compared to those of the other groups throughout the clinical sessions. None of the groups showed sensitivity at the 24-week assessment. Statistically, no significant difference were observed in the color values among the groups four weeks after the beginning of bleaching (p=0.074). Additionally, the color assessment of all groups was statistically similar four weeks (p=0.084) and 24 weeks (p=0.118) after the beginning. CONCLUSION: Our results indicate that adding NF/S, NA/S, NF/AC, and NA/AC desensitizers to tooth bleaching protocols reduces pain sensitivity without affecting its effectiveness.

Surface roughness evaluation and whitening efficiency on tooth enamel after using whitening toothpaste: a randomized double-blinded study

The aim of this randomized double-blinded study was to evaluate the enamel surface roughness and color change after one month of whitening toothpaste use and the color stability obtained 1 month after its interruption. 30 volunteers were divided into 3 groups (n = 10) corresponding to the dentifrices: 1) Colgate Total 12 Clean Mint (TD) (Control), 2) Colgate Luminous White (LW) and 3) Sensodyne Whitening Extra Fresh (SB). The volunteers were impression with addition silicone to obtain an epoxy resin replica of the upper central incisor for the initial surface roughness evaluation using a profilometer and the initial color of the incisors and canines was evaluated with a spectrophotometer after one week of wash-out. After 1 month, the color of the central incisors and canines was measured again, and the volunteers were molded to obtain a second replica to the final roughness analysis. Data were submitted to ANOVA-one way (p≤0.05). The results showed that there was no statistical difference between the dentifrices for color difference and surface roughness for all the studied conditions. It was possible to conclude that the whitening dentifrices used in this study were not able to alter the initial color of the teeth and did not cause changes in the surface roughness of enamel.

Effects of desensitizing products on the reduction of pain sensitivity caused by in-office tooth bleaching: a 24-week follow-up

Abstract Objective To clinically assess the effect of desensitizing gels and dentifrices on the reduction in pain sensitivity and color variation during tooth bleaching. Methodology A total of 108 volunteers were randomly separated into the following groups of n=12: GT/S-glycerine and thickener/sucralose; NF/S-potassium nitrate and sodium fluoride/sucralose; NA/S-potassium nitrate and arginine/sucralose; GT/AC-glycerine and thickener/arginine and calcium carbonate; NF/AC-potassium nitrate and sodium fluoride/arginine and calcium carbonate; NA/AC-potassium nitrate and arginine/arginine and calcium carbonate; GT/PN-glycerine and thickener/potassium nitrate; NF/PN-potassium nitrate and sodium fluoride/potassium nitrate; and NA/PN-potassium nitrate and arginine/potassium nitrate. Sensitivity was assessed with the numerical analogue scale, and color variation (ΔE) was measured with a spectrophotometer. The sensitivity values obtained were subjected to a multivariate analysis of variance (MANOVA) and color variation values were subjected to a randomized analysis of variance (p<0.05). Results The NF/AC, NA/AC, NF/PN, and NA/PN groups presented lower sensitivity values and reduced sensitivity compared to those of the other groups throughout the clinical sessions. None of the groups showed sensitivity at the 24-week assessment. Statistically, no significant difference were observed in the color values among the groups four weeks after the beginning of bleaching (p=0.074). Additionally, the color assessment of all groups was statistically similar four weeks (p=0.084) and 24 weeks (p=0.118) after the beginning. Conclusion Our results indicate that adding NF/S, NA/S, NF/AC, and NA/AC desensitizers to tooth bleaching protocols reduces pain sensitivity without affecting its effectiveness.

Effects of primer excess on marginal adaptation, nanoleakage and bond strength of adhesive systems after aging

There is no consensus about the amount of primer inserted into the cavity. Aim: This study aimed to evaluate the effects of the amount of primer used on dentin microtensile bond strength (µTBs), nanoleakage and marginal sealing, following thermomechanical aging. Methods: 48 human third molars were selected and a box-shaped class I cavity was constructed to maintain enamel margins. Teeth were randomly assigned to 6 experimental groups (n=8). For the bonding protocols of the restorative procedure, two adhesive systems were used: three-step etch-and-rinse and two-step self-etch. Epoxy resin replicas of the occlusal surface were made, and the specimens were submitted to thermomechanical aging. Newer replicas were obtained after thermomechanical aging, and marginal adaptation was observed using SEM. To obtain sections (0.7 x 0.7 mm) for testing at a tension of 0.5 mm/min, teeth were serially sectioned in the buccallingual direction, parallel to the occlusal surface. Failure mode was then obtained. For nanoleakage evaluation, one section of each tooth was immersed in AgNO3 and evaluated using SEM. The µTBs data were submitted to a two-way ANOVA and Tukey's test (α= 0.05) Results: One drop of primer promoted higher µTBs than two or three drops. Besides, the three-step etch-and-rinse promoted greater µTBs (19.78) than the two-step self-etch adhesive (12.23). The increase in the amount of primer was directly proportional to the increase of infiltration. All groups exhibited more gaps after thermomechanical aging. Conclusion: Using an excess of primer is not recommended because it reduces the µTBs and forms an unsatisfactory hybrid layer

Influence of whitening dentifrices and mechanical brushing on color change and surface roughness of bulk fill resins

The use of whitening dentifrices during oral hygiene may cause surface modifications such as color change (ΔE) and increase surface roughness (Ra) of composite resin. Aim: This study aimed to evaluate the effect of whitening dentifrices and mechanical brushing on color change and surface roughness of Bulk Fill (Filtek Bulk Fill - F) and (Aura Bulk Fill - A) composite resins. Materials and methods: Sixty cylindrical specimens were fabricated of each composite resin. After initial color evaluations (Konica Minolta CM-700d), with D65 standard illuminant, and the surface roughness (Surfcorder SE 1700, Kosalab), the specimens were assigned (n=10) according to the whitening dentifrice used: True White (T), Colgate Total 12 Professional Whitening (D), Luminous White Advanced (L). Specimens were submitted to mechanical brushing (10,000 cycles); new color and surface roughness evaluations were taken. Data were analyzed by ANOVA, Duncan test and Dunnet test were used to identify differences between groups (α=5%). Results: The results showed that the tooth brushing time promoted a significant increase in ΔE of the FT group. The FD group exhibited intermediate values of ΔE and was similar to all groups tested. There was a significant increase in the surface roughness of the AD and AT groups after the mechanical tooth brushing. Conclusion: The results showed no significant changes were observed in surface roughness for F groups after toothbrushing. It be concluded that the color change and surface roughness of the composite resins after toothbrushing are dependent on the interaction between the composition of the composite resin and the characteristics of the dentifrice

Diametral tensile strength of composite resins submitted to different activation techniques.

The aim of this study was to evaluate the diametral tensile strength (DTS) of composite resins submitted to different curing techniques. Four composite resins were tested in this study: Targis (Ivoclar), Solidex (Shofu), Charisma (Heraeus-Kulzer) and Filtek Z250 (3M Espe). Sixty-four cylindrical specimens were prepared and divided into eight groups according to each polymerization technique (n = 8). The indirect composite resins (Targis and Solidex) were polymerized with their respective curing systems (Targis Power and EDG-lux); Charisma and Filtek Z250 were light-cured with conventional polymerization (halogen light) and additionally, with post-curing systems. Specimens were stored in artificial saliva at 37 degrees C for one week. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). The data were statistically analyzed by ANOVA and Duncan tests. The results were (MPa): Z250/EDG-lux: 69.04 feminine; Z250/Targis Power: 68.57 feminine; Z250/conventional polymerization: 60.75b; Charisma/Targis Power: 52.34c; Charisma/conventional polymerization: 49.17c; Charisma/EDG-lux: 47.98c; Solidex: 36.62d; Targis: 32.86d. The results reveal that the post-cured Z250 composite resin showed the highest DTS means. Charisma composite presented no significant differences when activation techniques were compared. Direct composite resins presented higher DTS values than indirect resins.

Influence of composite restorative materials and light-curing units on diametrical tensile strength.

The aim of this study was to evaluate the diametrical tensile strength (DTS) of three light-curing photo-activated composites with two different light curing units (LCU). Three types of dental restorative composites were used in this study: micro filled A110 (3M Espe); P60 (3M Espe) for posterior restorations, and micro-hybrid Charisma (Heraeus-Kulzer). The two LCUs were: halogen light (HAL) (Degulux, Degussa) and blue light emitting diode (LED) (Ultrablue, DMC). Resin composite specimens were inserted incrementally into a Teflon split mold measuring 3 mm in depth and 6 mm in internal diameter, and cured using either LCU (n = 10). Specimens were placed into a dark bottle containing distilled water at 37 degrees C for 7 days. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). Data were submitted to two-way ANOVA and Tukey's test. Results were (MPa): A110/HAL: 276.50 +/- 62.94a; A110/LED: 306.01 +/- 65.16a; P60/HAL: 568.29 +/- 60.77b and P60/LED: 543.01 +/- 83.65b; Charisma/HAL: 430.94 +/- 67.28c; Charisma/LED: 435.52 +/- 105.12c. Results suggested that no significant difference in DTS was obtained with LCUs for the same composite. However, resin composite restorative materials presented different DTS.

Influence of selective acid etching on microtensile bond strength of a self-adhesive resin cement to enamel and dentin

Aim: To evaluate the selective acid etching of enamel and dentin on microtensile bond strength (¦ÌTBS) of a self-adhesive resin cement. Methods: Forty-eight bovine teeth were selected and had the buccal surface ground to obtain a flat dentin (n=24) or enamel (n=24) surface. Z250 composite resin blocks (4 x 3 x 8 mm) were prepared for cementation at enamel and dentin. Each substrate received three experimental resin cementation strategies: 1) 37% phosphoric acid etching before the application of RelyX Unicem; 2) application of RelyX Unicem alone; 3) RelyX ARC as a control. Samples were light-cured using a halogen light (Optilux 501, 700mW/cm2), for 40 s. Hourglass-shaped specimens were obtained and submitted to a tensile strength at a crosshead speed of 0.5 mm/min in a universal testing machine. For statistical analysis, data were submitted to ANOVA and Tukey¡¯s test at a pre-set alpha (¨¢=0.05). Results: RelyX Unicem showed similar bond strength value (16.5 MPa) when compared to the pretreatment with acid etching (11.9 Mpa) and to the conventional resin cement (18.1 MPa) for enamel. All luting strategies presented similar dentin bond strength, but significantly lower than enamel bond strength. Conclusions: Acid etching prior to RelyX Unicem application did not improve microtensile bond strength for enamel and dentin.

Avaliação de dureza knoop de resina composta ativada por diferentes fontes de luz / Knoop hardness of composites polymerized by differents light curing units

O objetivo deste estudo foi avaliar a influência das fontes fotoativadoras LED pulsante (LD13 - GGDent) ou halógena(Optilux 501 - Demetron) na microdureza Knoop da resina composta Z250 (3MESPE) na cor A3, em três profundidades distintas. Para tanto, foram confeccionadas 20 cavidades classe I em terceiros molares humanos, separados em 2 grupos (n=10). As cavidades foram preparadas utilizando-se broca 245 (KG Sorensen) nas dimensões de 3 x 4 x 3mm e as restaurações foram confeccionadas em três incrementos oblíquos, sendo a fotoativação de cada incremento realizada com 20s em modo contínuo para fonte halógena ou 60s para fonte LED (10s em modo pulsante e 50s em modo contínuo). Em seguida, as amostras foram armazenadas por sete dias em 100% umidade relativa na temperatura de 37°C + 1. Apóso período de armazenagem, as coroas foram seccionadas no sentido mésio-distal em cortadeira metalográfica. As raízes foram seccionadas logo abaixo da junção cemento-esmalte e perpendicularmente ao longo eixo do dente, sendo então descartadas. As hemicoroas foram incluídas em resina de poliestireno e a superfície que continha a restauração recebeuacabamento com lixas de óxido de alumínio nas granulações de 600, 1200 e 2000 e polimento com discos de feltro e pastas diamantadas com granulações de 6, 3 e 1 μm. O ensaio de microdureza Knoop foi realizado com carga de 25gdurante 20s. Foram realizadas 15 penetrações em cada hemicoroa, sendo 5 em cada profundidade estudada. Os dados foram transformados em número de dureza Knoop (KHN), submetidos à Análise de Variância e comparados pelo teste de Variação Múltipla de Tukey (5%). Os resultados obtidos revelaram que não houve diferença estatística significativa entre as profundidades estudadas. A maior média de dureza obtida foi com a fonte LED (82,98), apresentando diferença estatística significativa com a fonte halógena (61,27). Pode-se concluir que a densidade de energia dos aparelhosinfluenciou nos resultados de dureza obtidos.

Diametral tensile strength of composite resins submitted to different activation techniques / Resistência à tração diametral de compósitos resinosos submetidos a diferentes técnicas de ativação

The aim of this study was to evaluate the diametral tensile strength (DTS) of composite resins submitted to different curing techniques. Four composite resins were tested in this study: Targis (Ivoclar), Solidex (Shofu), Charisma (Heraeus-Kulzer) and Filtek Z250 (3M Espe). Sixty-four cylindrical specimens were prepared and divided into eight groups according to each polymerization technique (n = 8). The indirect composite resins (Targis and Solidex) were polymerized with their respective curing systems (Targis Power and EDG-lux); Charisma and Filtek Z250 were light-cured with conventional polymerization (halogen light) and additionally, with post-curing systems. Specimens were stored in artificial saliva at 37°C for one week. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). The data were statistically analyzed by ANOVA and Duncan tests. The results were (MPa): Z250/EDG-lux: 69.04ª; Z250/Targis Power: 68.57ª; Z250/conventional polymerization: 60.75b; Charisma/Targis Power: 52.34c; Charisma/conventional polymerization: 49.17c; Charisma/EDG-lux: 47.98c; Solidex: 36.62d; Targis: 32.86d. The results reveal that the post-cured Z250 composite resin showed the highest DTS means. Charisma composite presented no significant differences when activation techniques were compared. Direct composite resins presented higher DTS values than indirect resins.

O objetivo do trabalho foi avaliar a resistência à tração diametral (DTS) de compósitos submetidos a diferentes técnicas de polimerização. Foram testados quatro compósitos neste estudo: Targis (Ivoclar), Solidex (Shofu), Charisma (Heraeus-Kulzer) e Filtek Z250 (3M Espe). Foram confeccionados 64 corpos-de-prova cilíndricos, que foram divididos em 8 grupos de acordo com a técnica de polimerização (n = 8). Os compósitos indiretos (Targis e Solidex) foram polimerizados com seus respectivos sistemas de ativação (Targis Power e EDG-lux); Charisma e Filtek Z250 foram fotoativados com polimerização convencional (luz halógena) e, adicionalmente, com sistemas de polimerização adicional. Os corpos-de-prova foram armazenados em saliva artificial a 37°C por uma semana. Ensaio de DTS foi realizado em Máquina Universal de Ensaios Instron (0,5 mm/min). Os dados foram analisados estatisticamente pelos testes ANOVA e Duncan. Os resultados foram (MPa): Z250/EDG-lux: 69,04ª; Z250/Targis Power: 68,57ª; Z250/polimerização convencional: 60,75b; Charisma/Targis Power: 52,34c; Charisma/polimerização convencional: 49,17c; Charisma/EDG-lux: 47,98c; Solidex: 36,62d; Targis: 32,86d. Os resultados indicaram que o compósito Z250 polimerizado adicionalmente mostrou os maiores valores de DTS. O compósito Charisma não apresentou diferenças significativas quando foram comparadas diferentes técnicas de polimerização. Compósitos diretos apresentaram maiores valores de DTS que os compósitos indiretos.

Influence of composite restorative materials and light-curing units on diametrical tensile strength

O objetivo deste estudo foi avaliar a resistência à tracão diametral (DTS) de três compósitos fotoativados com dois aparelhos de fotoativacão (LCU). Os compósitos utilizados neste estudo foram: resina de micropartículas A110 (3M Espe); P60 (3M Espe), indicada para restauracões posteriores, e micro-híbrida Charisma (Heraeus-Kulzer). As fontes de luz foram: halógena (HAL) - Degulux (Degussa) e luz emitida por diodos (LED) - Ultrablue (DMC). As amostras foram confeccionadas através de dois incrementos inseridos em uma matriz de Teflon bipartida medindo 3 mm de profundidade e 6 mm de diâmetro interno e foram fotoativadas pelas LCUs (n = 10). As amostras foram armazenadas dentro de recipientes escuros contendo água destilada a 37ºC por 7 dias. O ensaio de DTS foi realizado com a Máquina de Ensaio Universal Instron com velocidade de 0,5 mm/min. Os dados obtidos foram submetidos à Análise de Variância e ao teste de Tukey. Os resultados foram (MPa): A110/HAL: 276,50 n 62,94a; A110/LED: 306,01 n 65,16a; P60/HAL: 568,29 n 60,77b e P60/LED: 543,01 n 83,65b; Charisma/HAL: 430,94 n 67,28c; Charisma/LED: 435,52 n 105,12c. Desta forma, os resultados indicaram que não houve diferenca significativa de DTS em relacão aos aparelhos para uma mesma resina. Entretanto, entre os materiais ocorreram diferencas significativas nos valores de DTS.

Comparaçäo da resistência de uniäo entre adesivos dentinários convencionais e de frasco único / Comparison of bond strength conventional three-step and one bottle dentin adhesives

Os primeiros adesivos dentinários hidrófilos caracterizavam-se pela aplicaçäo separada do primer e do bond na tentativa de reduzir o número de frascos do sistema e simplificar etapas na técnica restauradora. O objetivo deste estudo foi comparar a resistência ao cisalhamento dos adesivos convencionais e de frasco único. Foram utilizados os sistemas adesivos Scotchbond MP Plus (SB) e All Bond 2 (AB), e os adesivos de frasco único One Step (OS) e Prime & Bond 2.0 (PB). As superfícies dentinárias foram obtidas de pré-molares humanos extraídos. As médias de resistência ao cisalhamento, em MPa, foram: SB- 22,99 ñ 9,39; AB- 22,26 ñ 7,23; OS- 21,62 ñ 6,04 e PB- 23,43 ñ 9,05. A ANOVA indicou nenhuma diferença significativa na resistência de uniäo entre os adesivos (p > 0,05). Os resultados sugerem que sistemas adesivos convencionais e de frasco único apresentam similares médias de resistência ao cisalhamento