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OBJECTIVES: To evaluate the influence of two surface sealants (BisCover/Single Bond) and three application techniques (unsealed/conventional/co-polymerization) on the roughness of two composites (Filtek Z250/Z350) after the toothbrushing test. METHODS: Seventy-two rectangular specimens (5 mm x10 mm x 3 mm) were fabricated and assigned into 12 groups (n=6). Each sample was subjected to three random roughness readings at baseline, after 100,000 (intermediate), and 200,000 (final) toothbrushing strokes. Roughness (R) at each stage was obtained by the arithmetic mean of the reading of each specimen. Sealant removal was qualitatively examined (optical microscope) and classified into scores (0-3). Data were analyzed by Student's paired t-test, two-way ANOVA/Tukey's test, and by Wilcoxon, Kruskal-Wallis and Miller's test (alpha=0.05). RESULTS: Z250 groups at baseline did not differ statistically from each other. Unsealed Z350 at baseline had lower R values. All the unsealed groups presented gradual decrease in R from baseline to final brushing. From baseline to the intermediate stage, Z250 co-polymerized groups presented a significant reduction in R (score 3). Conventionally sealed groups had no significant changes in R (scores 2-0.8). From baseline to the intermediate stage, the conventionally sealed Z350 Single Bond group had an increase in R (score 1.5). In the final stage, all the conventionally sealed groups presented a reduction in R (scores 0.7-0). Co-polymerized Single Bond groups had a significant reduction in R (scores 2.5-2.7), and co-polymerized BisCover groups an increase in R (scores 2.8-3). CONCLUSIONS: At any brushing stage, sealed composites presented superior performance when compared with unsealed composites.

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OBJECTIVES: This study tested the following null hypotheses: (1) there is no difference in resin-dentine bond strength when an experimental glutaraldehyde primer solution is added prior to bonding procedures and (2) there is no difference in resin-dentine bond strength when experimental glutaraldehyde/adhesive system is applied under dry or wet demineralized dentine conditions. METHODS: Extracted human maxillary third molars were selected. Flat, mid-coronal dentine was exposed for bonding and four groups were formed. Two groups were designated for the dry and two for the wet dentine technique: DRY: (1) Group GD: acid etching+glutaraldehyde primer (primer A)+HEMA/ethanol primer (primer B)-under dried dentine+unfilled resin; (2) Group D: the same as GD, except for primer A application; WET: (3) Group GW: the same as GD, but primer B was applied under wet dentine condition; (4) Group W: the same as GW, except for primer A application. The bonding resin was light-cured and a resin core was built up on the adhesive layer. Teeth were then prepared for microtensile bond testing to evaluate bond strength. The data obtained were submitted to ANOVA and Tukey's test (alpha=0.05). RESULTS: Glutaraldehyde primer application significantly improved resin-dentine bond strength. No significant difference was observed when the same experimental adhesive system was applied under either dry or wet dentine conditions. These results allow the first null hypothesis to be rejected and the second to be accepted. CONCLUSION: Glutaraldehyde may affect demineralized dentine properties leading to improved resin bonding to wet and dry substrates.

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The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). The obtained contraction forces were: Grandio = 12.18 +/- 0.428N; Filtek Z 250 = 11.80 +/- 0.760N; Filtek Supreme = 11.80 +/- 0.707 N; and Admira = 11.89 +/- 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 +/- 0.0357%; Filtek Supreme = 0.36 +/- 0.0438%; Admira = 0.25 +/- 0.0346% and Grandio = 0.16 +/- 0.008%. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 +/- 2.160 microm; Filtek Supreme = 10.66 +/- 1.211 microm; Admira = 11.16 +/- 2.041 microm and Grandio = 10.50 +/- 1.224 microm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation.

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The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). The obtained contraction forces were: Grandio = 12.18 ± 0.428N; Filtek Z 250 = 11.80 ± 0.760N; Filtek Supreme = 11.80 ± 0.707 N; and Admira = 11.89 ± 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 ± 0.0357 percent; Filtek Supreme = 0.36 ± 0.0438 percent; Admira = 0.25 ± 0.0346 percent and Grandio = 0.16 ± 0.008 percent. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 ± 2.160 µm; Filtek Supreme = 10.66 ± 1.211µm; Admira = 11.16 ± 2.041 µm and Grandio = 10.50 ± 1.224 µm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation.

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The fluoride release of restorative materials in deionized water has been the subject of many studies, but the behavior of these materials under conditions of acid challenge that simulates the oral cavity, needs to be further explored. Therefore, the aim of this study was to evaluate the fluoride release of restorative materials in two storage protocols: deionized water and pH-cycling system (demineralizing solution-pH 4.3 and remineralizing solution-pH 7.0) for 15 days. Eight disks of each material (Vitremer™-positive control, Dyract AP, Ariston pHc, Definite®, Tetric®Ceram and Z100-negative control) were prepared (11.0 mm x 1.5 mm) and suspended individually in 4.0 mL of each solution, which were daily changed. Daily fluoride release was analyzed with an ion specific electrode (Orion 9609) by the direct method or after HMDS-facilitated diffusion, following 1, 7 and 15 days. The values obtained were converted into µgF/mm² and the data analyzed by ANOVA and Tukey's test (p< 0.05). The results showed that all materials released more fluoride in the pH-cycling system, except for Ariston pHc which maintained a constant release during the experiment. The highest fluoride release was presented by the positive control, Vitremer™ in pH-cycling and by Ariston pHc, in deionized water. The negative control Z100 and the resins Definite® and Tetric®Ceram did not present statistically significant differences.

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OBJECTIVE: To evaluate wear resistance, by weight loss and roughness changes, of resin cements and indirect restorative materials to toothbrushing and toothbrushing associated with pH-challenge simulation. METHOD AND MATERIALS: The following materials were studied: Enforce resin cement (Dentsply), Rely X resin cement (3M ESPE), Variolink II resin cement (Ivoclar/Vivadent), Artglass indirect resin composite (Heraeus Kulzer), and Duceram Plus porcelain (Degussa). Twenty cylindrical specimens were prepared for each material for a total of 10 groups (n = 10). After finishing and polishing, the specimens were subjected to toothbrushing. One group of each material was pH cycled before abrasion. For toothbrushing, a machine containing soft-bristle tips, dentifrice, and water was used. One hundred thousand brushing cycles were performed. Weight loss was determined as the percentage difference between initial (before brushing) and final (after brushing) measurements. Roughness changes were evaluated by the difference between initial and final measurements. Data were analyzed with the paired t test, 2-way ANOVA, and Tukey test (alpha = 0.05). RESULTS: Paired t test showed significant differences in weight loss and roughness after toothbrushing (P <.01). Statistically significant differences were found among materials for both weight loss, which ranged from 0.34% (Duceram Plus) to 1.85% (Enforce/pH), and roughness changes, which ranged from -0.03 microm (Duceram Plus) to 0.29 microm (Rely X/pH). CONCLUSIONS: Among cements, Variolink II exhibited the least weight loss and roughness increase. Of all materials, Duceram Plus porcelain presented the lowest weight loss and became smoother after abrasion. pH cycling had no influence on material weight or roughness changes after abrasion.

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The fluoride release of restorative materials in deionized water has been the subject of many studies, but the behavior of these materials under conditions of acid challenge that simulates the oral cavity, needs to be further explored. Therefore, the aim of this study was to evaluate the fluoride release of restorative materials in two storage protocols: deionized water and pH-cycling system (demineralizing solution-pH 4.3 and remineralizing solution-pH 7.0) for 15 days. Eight disks of each material (Vitremer-positive control, Dyract AP, Ariston pHc, Definite, TetricCeram and Z100-negative control) were prepared (11.0 mm x 1.5 mm) and suspended individually in 4.0 mL of each solution, which were daily changed. Daily fluoride release was analyzed with an ion specific electrode (Orion 9609) by the direct method or after HMDS-facilitated diffusion, following 1, 7 and 15 days. The values obtained were converted into microgF/mm(2) and the data analyzed by ANOVA and Tukey's test (p< 0.05). The results showed that all materials released more fluoride in the pH-cycling system, except for Ariston pHc which maintained a constant release during the experiment. The highest fluoride release was presented by the positive control, Vitremer in pH-cycling and by Ariston pHc, in deionized water. The negative control Z100 and the resins Definite and TetricCeram did not present statistically significant differences.

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A procura de materiais restauradores estéticos começou com o emprego das restaurações feitas em porcelana fundida, passou pela utilização do cimento de silicato, das resinas acrílicas quimicamente ativadas e pequenas tentativas de usar as resinas epóxicas. Com a síntese do BIS-GMA por Bowen, em 1958, todo o esforço passou a ser feito na pesquisa de resinas poliméricas. Porém, mesmo tendo sido pesquisados e comercializados muitos tipos de polímeros, todos eles têm sido derivados do modelo simples do metilmetacrilato polimerizado por radicais livres. As diversas deficiências desses materiais levaram ao desenvolvimento de muitas modificações. Os problemas mecânicos têm sido diminuídos com o emprego de cargas inorgânicas que, por sua vez, aumentam a dificuldade da mistura dos componentes pelo Dentista. Para contornar esse problema, foram formuladas as resinas ativadas por luz. Os materiais à base de resinas adquirem cada vez mais importância na Odontologia moderna e o conhecimento da forma mais correta de seu emprego pelos Dentistas, assim como o empenho em seu constante aperfeiçoamento pelos pesquisadores, são da maior importância para o seu futuro como material restaurador

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O objetivo do presente estudo foi avaliar o número de radicais livres de duas resinas compostas, utilizando o método de Ressonância Paramagnética Eletrônica (RPE). Foram utilizadas três técnicas de fotoativação: 1) 150mW/cm² durante 20s + 300mW/cm² durante 20s + 600 mW/cm² durante 20s; 2) 150mW/cm² durante 20s + 600mW/cm² durante 40s e 3) 600mW/cm² durante 60s. Os materiais utilizados foram as resinas Z100 (3M) e Definite (Degussa). Foram confeccinadas duas amostras, para cada condição. As leituras foram realizadas nos períodos de uma hora, um dia e um mês. Nos intervalos de tempo, as amostras foram armazenadas a seco, em potes plásticos pretos. Pela análise dos resultados, pôde-se constatar: valores numericamente semelhantes, para ambos os materiais, espessuras e técnicas de fotoativação; foi visível também o decaimento deles em função do tempo. Em razão, provavelmente, das diferenças de composição entre os materiais etudados, não foi possível estabelecer uma correlação entre os resultados de dureza superficial e aqueles dos radicais livres

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Avaliou-se a adaptação de resinas compostas às paredes axial e cervical de preparos do tipo classe II (MOD) em função da configuração cavitária (ângulos vivos ou arredondados), empregando-se três sistemas restauradores adesivos (Fill Magic/Unibond, Z250/Single Bond e P60/Single Bond). A partir dos dados obtidos aplicou-se a análise estatística utilizando o "Wilcoxon Matched Pairs Test", com nível de significância p<0.05. Concluiu-se que não houve diferença estatisticamente significante entre a conformação cavitária de ângulos vivos e arredondados em relação à extensão das fendas nas paredes axial e cervical, a configuração cavitária de ângulos arredondados apresentou valores estatisticamente inferiores aos obtidos pela configuração em ângulos vivos para os sistemas Fill Magic/Unibond e Z250/Single Bond

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