The role of surface sealants in the roughness of composites after a simulated toothbrushing test.

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.

Influence of glutaraldehyde priming on bond strength of an experimental adhesive system applied to wet and dry dentine.

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.

Comparative analysis of the shrinkage stress of composite resins.

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.

Comparative analysis of the shrinkage stress of composite resins

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.

Fluoride release of six restorative materials in water and pH-cycling solutions

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.

Effect of toothbrushing abrasion on weight and surface roughness of pH-cycled resin cements and indirect restorative materials.

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.

Fluoride release of six restorative materials in water and pH-cycling solutions.

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.

Resinas compostas: histórico e evolução / Composite resins: history and evolution

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

Avaliação da qualidade de radicais livres remanescentes em duas resinas compostas pelo método de ressonância paramagnética eletrônica / Evaluation of remaining double bonds of two resin composites by eletron spin resonance analysis

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

Avaliação da influência da configuração cavitária na adaptação de resinas compostas em preparos de classe II (MOD) / Evaluation of the influence of cavity design on the adaptation of resin composites in class II

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

Atividade antimicrobiana de materiais restauradores e selantes / Inhibitory activity of restorative materials and sealants

Avaliou-se a atividade inibitória de diferentes materiais restauradores e selantes de fóssulas e fissuras sobre microrganismos cariogênicos através do método de difusão em ágar, empregado-se o ágar Mueller-Hinton acrescido de 5 por cento de sangue desfribrinado de carneiro. Verificou-se que a maioria dos materiais testados apresentou alguma atividade inibitória frente aos microrganismos isolados, particularmente os cimentos ionoméricos. As resinas compostas, à exceção do Dyract, não evidenciaram atividade antimicrobiana

Evaluating a method of artificially hypermineralizing dentin to simulate natural conditions in bonding studies.

PURPOSE: This study tested an in vitro model of dentin hypermineralization, aiming to simulate naturally hypermineralized dentin for bond strength studies. The effect on bond strength of a double-etching treatment on the artificially hypermineralized substrate was also evaluated. MATERIALS AND METHODS: Extracted human third molars were selected and 2 groups were formed: a group of 3 teeth, called N (normal dentin) and a group of 6 teeth, called H (hypermineralized dentin). Occlusal surfaces were ground flat to expose midcoronal dentin. Group H was subjected to artificial hypermineralization and subdivided into 2 subgroups: Ht and Hd. The exposed dentinal surfaces of group N and subgroup Ht were etched with 37% phosphoric acid for 15 s prior to bonding with Single Bond adhesive. Dentin of the subgroup Hd was etched twice (double etching) prior to bonding with Single Bond. A 4-mm-high Z100 composite buildup was created on each tooth and, after 24 h water storage, bond strengths were evaluated by the microtensile method. The data between group N and subgroup Ht and between subgroups Ht and Hd were compared using the Student's t test (alpha = 0.05). RESULTS: No significant difference was observed between bond strengths of group N and subgroup Ht (p = 0.108). Subgroup Hd was statistically different from Ht (p < 0.0001). CONCLUSIONS: Bond strengths of Single Bond to artificially hypermineralized dentin did not differ statistically from those to normal dentin substrate. The double etching approach significantly reduced bond strengths of artificially hypermineralized dentin.

Evaluation of the roughness and mass loss of the flowable composites after simulated toothbrushing abrasion.

The purpose of this study was to measure mass loss and surface roughness changes of different brands of flowable resin composites after a simulated toothbrushing test. The null hypotheses were that there would be no differences in mass loss and no significant changes in surface roughness after this test and that there would be no correlation between the two variables. The tested materials were Aeliteflo (Bisco), Flow-It (Pentron), Flow-It LF (Pentron), Natural Flow (DFL) and Wave (SDI). Z100 (3M/ESPE) microhybrid and Silux Plus (3M/ESPE) microfilled resin composites were used as control materials. Twelve specimens (5 mm in diameter, 3 mm thick) of each material were prepared according to manufacturers' instructions. Toothbrushing abrasion was performed on all specimens from each of the materials using a simulator. The percentage mass loss and surface roughness were assessed before and after 100,000 brushstrokes, using a Sartorius analytical balance of 0.0001 g accuracy and a Hommel Tester T1000, respectively. The measurements of both properties were statistically compared by paired t-test and Tukey's test (p < 0.05). All materials presented a statistically significant mass loss comparing initial and final values, with the exception of Flow-It LF. However, no difference was revealed when comparing the mass loss of the different tested materials. All materials became rougher and Wave presented statistically higher roughness compared to the other resin composites. Flowable resin composites did not seem to be superior to the control groups, and they can be expected to wear by mass loss and to have an increased roughness of surface after toothbrushing action. The anticipated null hypotheses were partially accepted.

Evaluation of the roughness and mass loss of the flowable composites after simulated toothbrushing abrasion

O objetivo deste estudo foi mensurar a perda de massa e as alterações de rugosidade superficial de diferentes marcas de resinas compostas "flow" após teste de escovação simulada. A hipótese nula testada foi de que não haveria diferença de massa e rugosidade de superfície após o teste e de que não haveria correlação entre essas variáveis. Os materiais testados foram: Aeliteflo (Bisco), Flow-It (Pentron), Flow-It LF (Pentron), Natural Flow (DFL) e Wave (SDI). As resinas compostas Z100 (3M/ESPE) e Silux Plus (3M/ESPE) foram utilizadas como controle. Doze espécimes (5 mm de diâmetro, 3 mm de espessura) de cada material foram confeccionados de acordo com as instruções do fabricante. O teste foi conduzido em uma máquina de escovação simulada, em todos os espécimes de todos os materiais, totalizando 100.000 ciclos. Antes e depois do teste, a massa e a rugosidade de cada material foram aferidas por uma balança analítica Sartorius de 0,0001 g de precisão e pelo equipamento Hommel Tester T1000, respectivamente. Os valores obtidos foram comparados pelos testes t-pareado e Tukey (p < 0,05). Todos os materiais apresentaram diferenças estatísticas de perda de massa entre os valores iniciais e finais, com exceção da resina Flow-It LF. Entretanto, nenhuma diferença foi observada quando se comparou a porcentagem de perda de massa entre os diferentes materiais testados. Todos os materiais tornaram-se mais rugosos, sendo Wave, estatisticamente, o mais rugoso. As resinas compostas "flow" não demonstraram superioridade em relação aos materiais de controle, devendo-se esperar o desgaste por perda de massa do material e maior rugosidade após a ação da escovação. A hipótese nula antecipada foi parcialmente aceita.

Wear and superficial roughness of glass ionomer cements used as sealants, after simulated toothbrushing

O presente estudo foi conduzido "in vitro" com o intuito de constatar as propriedades (desgaste e rugosidade) dos CIV, as quais influenciam na sua indicaçäo como material selador de fossas e fissuras. Os materiais empregados foram Fuji Plus, Ketac Molar e Vitremer (duas proporçöes: 1:1 e 1/4:1). O selante Delton foi controle. A determinaçäo do desgaste foi obtida através da quantidade de massa perdida após a escovaçäo e a rugosidade através da análise quantitativa da superfície. Os resultados mostraram que o Vitremer diluído e o Fuji Plus apresentaram maior grau de desgaste e maior aumento de rugosidade. Apesar de clinicamente se encontrar um maior uso dos CIV cimentantes ou diluídos como forma alternativa para material selador; este trabalho permitiu concluir que estes possuem propriedades bastante inferiores quando comparados aos ionômeros restauradores que, por sua vez, possuem resultados semelhantes ao selante resinoso

Adaptaçäo marginal e dureza de resinas compostas: influência de métodos de fotoativaçäo: avaliaçäo da adptaçäo com moldes de elestômeros / Marginal adaptation and hardness of composite resins: influence of light activation methods: adaptation evaluation by elastomeric impressions

Este estudo comparou a utilizaçäo de uma técnica de fotoativaçäo contínua com uma seqüencial em duas etapas, começando com baixa intensidade de luz seguida de uma intensidade maior e utilizando duas resinas compostas. A interferência dos métodos de ativaçäo foi analisada näo só quanto à formaçäo de fendas marginais (f.m.) mas, também, quanto ao grau de polimerizaçäo, com a avaliaçäo da dureza Vickers. Paralelamente, foi verificada a viabilidade de um método simplificado de moldes de polivinilsiloxana para a medida das de fendas. Foram mensuradas as f.m. formadas na interface de restaurações com a dentina, usando as resinas compostas Z100 e Solitaire, em cavidades cilíndricas de molares humanosrecém-extraídos, através da microscopia óptica, feita diretamente nesses espécimes e, indiretamente nosmoldes. Concluiu-se que as f.m. foram menores e a dureza no topo foi maior, quando se utilizou a ativaçäo seqüencial, com a intensidade inicial de 180 mW/cm2 por 20 segundos, seguida de 650 mW/cm2 por 40 segundos; a resina Z100 teve melhor desempenho com relaçäo às fendas e à dureza Vickers tanto no topo quanto na base; na espessura de 2 mm, ambas as resinas mostraram valores médios de dureza menores na superfície de base que na de topo; finalmente, a técnica indireta, com a utilizaçäo dos moldes, para as medidas, foi considerada viável, uma vez que os resultados obtidos com ela foram coincidentes com os da técnica direta

Wear and superficial roughness of glass ionomer cements used as sealants, after simulated toothbrushing.

The purpose of this study was to evaluate, in vitro, the properties (wear and roughness) of glass ionomer cements that could influence their indication as pit and fissure sealants. The utilized materials were Fuji Plus, Ketac-Molar and Vitremer (in two different proportions: 1:1 and :1). The resin-based sealant Delton was used as control. By means of an electronic balance (precision of 10-4 g), wear was measured in function of weight loss after simulated toothbrushing. Superficial roughness was determined by means of a surface roughness-measuring apparatus. The results revealed that diluted Vitremer and Fuji Plus were less resistant to toothbrushing abrasion and had the greatest increase in superficial roughness. Although in clinical situations luting or diluted ionomer cements are often utilized as alternatives to resin-based sealants, the resultsof this study revealed that the properties of those cements are worse than those of restorative ionomers, whichpresented results similar to those of the evaluated resin sealant.

Utilização de uma espátula vibratória na preparação de gessos dos tipos III e IV: influência sobre algumas propriedades / The use of a vibratory spatula in the preparation of plaster types III and IV: the influence on some properties

Considerando a grande importância da espatulação no preparo dos gessos odontológicos, o autor idealizou uma espátula vibratória e realizou ensaios de verificação do tempo de presa, resistência à compressão e abrasão e fidelidade na reprodução de pormenores, comparando com os de uma espátula mecânico-manual e de uma espátula manual

Resistências de uniäo de cinco cimentos utilizados em ortodontia / Bond strength of five cements for orthodontic use

A resistência de uniäo de cinco cimentos disponíveis no mercado e utilizados na fixaçäo de bráquetes ortodônticos (Concise Ortodôntico, Fuji Ortho LC, Vitremer, Dyract e Transbond XT) foi estudada. Foram utilizados 50 dentes pré-molares superiores humanos, hígidos, recém extraídos, conservados em soluçäo de Cloramina T a 1 por cento e água até o momento de sua utilizaçäo. Os dentes tiveram suas raízes seccionadas em nível da junçäo cemento-esmalte, sendo posteriormente incluídos em resina epóxica, com auxílio de matrizes de silicona, e depois armazenados em água deionizada até o momento da fixaçäo dos bráquetes. Previamente à fixaçäo foi realizada profilaxia com pasta de pedra pomes e água, utilizando-se taça de borracha em motor de baixa rotaçäo. Os materiais foram utilizados de acordo com as instruçöes dos respectivos fabricantes. Após fixaçäo dos bráquetes, os corpos de prova foram armazenados em água deionizada à 37ºC durante 24 horas. Os testes de cisalhamento foram realizados com auxílio de uma Máquina de Ensaios Universal Kratos, com velocidade de 0,5mm/minuto. Os resultados foram analisados estatisticamente, o que permitiu concluir que: a) todos os cimentos atingiram valores aceitáveis à prática ortodôntica; b) com exceçäo dos grupos Concise Ortodôntico x Transbond XT e Fuji Ortho LC x Transbond XT, houve diferença estatística significante entre todos os outros grupos, c) as falhas adesivas ocorreram, na maioria das vezes (66 por cento), na interface cimento/bráquete

Cimentos de ionômeros de vidro convencionais e modificados: influência de adesivos, e da umidade, sobre a adesäo a dentina / Conventional and modified glass-ionomer cements: influence of adhesives and wetness, on bonding to dentin

A influência de adesivos e da umidade dentinária na resistência ao cisalhamento da uniäo entre dentina e materiais restauradores diretos, foi avaliada neste trabalho. Os materiais restauradores testados foram: cimento de ionômero de vidro (C.I.V.) convencional, C.I.V. modificado com resina, resina composta modificada com poliácidos e resina composta. No trabalho foram utilizados 240 pré-molares e molares humanos extraídos, que tiveram uma de suas superfícies proximais desgastadas, sobre a qual foram aplicados os sistemas adesivos e os materiais restauradores. Os espécimes foram divididos em 4 grupos experimentais, de acordo com o material usado para o tratamento da dentina, como segue: I) adesivo próprio indicado pelo fabricante; II) sistema adesivo experimental Gluma C; III) sistema adesivo Prime & Bond 2.0; e IV) sistema adesivo Scotchbond MP. As técnicas de secagem da dentina foram jato de ar por 5 segundos, considerada "técnica seca", e lenço de papel aplicado duas vezes sobre a dentina, considerada "técnica úmida". Os espécimes foram testados em máquina universal de testes. Os adesivos (grupos II e III) melhoraram significantemente a adesäo quando comparados com o adesivo próprio. A técnica de secagem da dentida considerada úmida promoveu resultados significantemente melhores que a considerada seca (p<0,01)