O objetivo deste estudo foi realizar uma revisão crítica da literatura sobre os fatores que podem interferir nos resultados do teste de microtração de sistemas adesivos ao esmalte ou dentina. Foram utilizados trabalhos publicados nas bases de dados eletrônicas MEDLINE e BBO, em inglês, espanhol ou português, entre julho de 1994 e setembro de 2009, referências destes artigos, além de dissertações e teses disponíveis em bancos de dados eletrônicos de universidades brasileiras enfocando o estudo das variáveis que podem influenciar cada fase da execução do ensaio de microtração. A estratégia de busca incluiu os termos: microtração e teste; microtração e ensaio; microtensile e test e parameters; microtensile e test e factors; microtensile e specimen; microtracción e espécimen. Os 25 artigos selecionados demonstraram que mesmo após a padronização de parâmetros do ensaio, as alterações encontradas na dentina podem ser responsáveis pela variação do resultado. Uma maneira de reduzir esta influência seria utilizar os valores de resistência coesiva da dentina adjacente à interface adesiva como padrão de comparação, porém mais estudos são necessários. Aspectos relativos à análise dos dados devem ser levados em consideração quando se compara os estudos.

The aim of this study was to provide a critical review of the literature regarding factors that can interfere with microtensile test results for enamel and dentin adhesive systems. Primarily, reports in English, Spanish, or Portuguese that were published between July 1994 and September 2009 and are catalogued in MEDLINE and BBO were used. Additionally, we compiled relevant articles found in the references of these articles and dissertations and theses available in electronic databases of Brazilian universities that examined factors that can influence implementation of the microtensile test at each stage. The search strategy included searching for the following key term groups: microtensile and test; microtensile and assay; microtensile and test and parameters; microtensile and test and factors; microtensile and specimen; microtraccón and especimen. We reviewed 25 selected articles and found that they showed that even after adjustment of test parameters, changes found in the dentin could be responsible for variations observed amongst results. This influence could potentially be reduced by using the cohesive strength value of dentin adjacent to the adhesive interface as a standard for comparison, but more studies are needed to confirm whether such an approach would be reliable. Data analysis methodology should be taken into account when comparing studies.

O objetivo deste estudo foi avaliar a influência da microestrutura e da composição de ligas básicas quanto à resistência de união (RU) a um agente cimentante resinoso. Foram usadas as seguintes ligas: Supreme Cast-V (SC), Tilite Star (TS), Wiron 99 (W9), VeraBond II (VBII), VeraBond (VB), Remanium (RM) and IPS d.SIGN 30 (IPS). Cinco padrões em cera (13 mm de diâmetro e 4 mm de altura) para cada uma das ligas básicas foram incluídos e fundidos em uma máquina de fundição. As amostras foram então embutidas em resina, polidas com lixas e jateadas. Após a limpeza das superfícies, seis cilindros de tygon tube (0,5 mm de altura e 0,75 mm de diâmetro) foram colocados sobre a superficie da liga e preenchida com cimento resinoso (Panavia F), o excesso foi removido antes da fotoativação. Após armazenagem (24 h/37ºC), cada amostra foi ensaiada por microcisalhamento a 0,5 mm/min. Os dados foram tratados por análise de variância para e medidas repetidas e teste Tukey (α=0,05). Para avaliar a microesturutura, as mesmas amostras foram polidas e condicionadas com solução específica. Os valores mais altos da RU (média/desvio padrão em MPa) foram encontrados para as ligas com estrutura dendrítica, formação eutética e precipitados: VB (30,6/1,7), TS (29,8/0,9), SC (30,6/1,7), com exceção da IPS (31,1/0,9) que apresentou alto valor de RU, mas sem formação eutética. As ligas W9 (28,1/1,5), VBII (25,9/2,0) and RM (25,9/0,9) apresentaram os menores valores de RU e ausência de formação eutética. Pode-se inferir que os valores mais elevados de resistência de união ao cimento resinoso fotoativado ocorre com as ligas que apresentam formação de eutético.

The aim of this study was to evaluate the influence of microstructure and composition of basic alloys on their microshear bond strength (µSBS) to resin luting cement. The alloys used were: Supreme Cast-V (SC), Tilite Star (TS), Wiron 99 (W9), VeraBond II (VBII), VeraBond (VB), Remanium (RM) and IPS d.SIGN 30 (IPS). Five wax patterns (13mm in diameter and 4mm height) were invested, and cast in a centrifugal casting machine for each basic alloy. The specimens were embedded in resin, polished with a SiC paper and sandblasted. After cleaning the metal surfaces, six tygon tubes (0.5 mm height and 0.75 mm in diameter) were placed on each alloy surface, the resin cement (Panavia F) was inserted, and the excess was removed before light-curing. After storage (24 h/37°C), the specimens were subjected to µSBS testing (0.5 mm/min). The data were subjected to a one-way repeated measures analysis of variance and Turkey's test (α=0.05). After polishing, their microstructures were revealed with specific conditioners. The highest µSBS (mean/standard deviation in MPa) were observed in the alloys with dendritic structure, eutectic formation or precipitation: VB (30.6/1.7), TS (29.8/0.9), SC (30.6/1.7), with the exception of IPS (31.1/0.9) which showed high µSBS but no eutectic formation. The W9 (28.1/1.5), VBII (25.9/2.0) and RM (25.9/0.9) showed the lowest µSBS and no eutectic formation. It seems that alloys with eutectic formation provide the highest µSBS values when bonded to a light-cured resin luting cement.

OBJECTIVE: To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated. MATERIAL AND METHODS: A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled) and three brands of silver nitrate salt (Merck, Synth or Cennabras) at 0, 1, 2, 24, 48, 72, 96 and 168 h after preparation, and storage in transparent or dark bottles. Ionic silver was assayed according to the post-preparation times (2, 24, 48, 72, 96, 168 h) and concentrations (1, 5, 25, 50%) of solutions by atomic emission spectrometry. For each sample of each condition, three readings were obtained for calculating the mean value. Class V cavities were prepared with enamel margins on primary and permanent teeth and restored with the adhesive systems OptiBond FL or OptiBond SOLO Plus SE and the composite resin Filtek Z-250. After nail polish coverage, the permanent teeth were immersed in 25% or 50% AgNO3 solution and the primary teeth in 5% or 50% AgNO3 solutions for microleakage evaluation. ANOVA and the Tukey's test were used for data analyses (α=5%). RESULTS: The mean pH of the solutions ranged from neutral to alkaline (7.9±2.2 to 11.8±0.9). Mean ionic silver content differed depending on the concentration of the solution (4.75±0.5 to 293±15.3 ppm). In the microleakage test, significant difference was only observed for the adhesive system factor (p=0.000). CONCLUSIONS: Under the tested experimental conditions and based on the obtained results, it may be concluded that the aqueous AgNO3 solutions: have neutral/alkaline pH and service life of up to 168 h; the level of ionic silver is proportional to the concentration of the solution; even at 5% concentration, the solutions were capable of indicating loss of marginal seal in the composite restorations; the 3-step conventional adhesive system had better performance regarding microleakage in enamel on primary and permanent teeth.

The aim of this study was to evaluate in vitro the marginal sealing of two adhesive systems and to analyze the influence of human and bovine substrates on marginal microleakage in enamel. Rectangular-shaped class V cavities (4 mm wide x 2 mm high x 2 mm deep) were made as follows: 8 cavities were prepared on the buccal and lingual surfaces of the human teeth with margins located on enamel and 16 cavities were prepared on the buccal surfaces of the bovine teeth. The cavities were randomly assigned to 4 groups of 8 cavities according to the adhesive system and substrate: G1 - Prime & Bond 2.1 (Dentsply)/human substrate; G2 - Adhese (Ivoclar/Vivadent)/human substrate; G3 - Prime & Bond 2.1 (Dentsply)/bovine substrate; G4 - Adhese (Ivoclar/Vivadent)/bovine substrate. The cavities were filled with microhybrid composite resin (Fillmagic) and after polishing/finishing procedures, the teeth were subjected to a thermocycling regimen of 500 cycles with 1-min immersions in water at 55° ±2°C and 5° ± 2°C. Next, the teeth were coated with two layers of nail polish to within 1 mm of the margin, submerged in a 50% silver nitrate solution for 2 h, rinsed thoroughly in running tap and immersed in developing solution for 8 h. The restorations were bisected resulting in 16 specimens. Microleakage was observed under a stereomicroscope at x25 and recorded using four-point (0-3) scoring system. The data were analyzed statistically by the Mann Whitney U-test at 5% significance level. Leakage was present in all specimens and there was statistically significant difference between the adhesive systems. Adhese self-etching system showed significantly more leakage in both substrates (human - p= 0.0001 and bovine - p= 0.0031). There was no statistically significant difference between human and bovine substrates for either of the adhesive systems based on different bonding mechanisms (Prime & Bond 2.1 - p= 0.6923 and Adhese - p= 0.6109). Neither of the adhesive systems was capable to completely prevent microleakage and the self-etching system was more susceptible to microleakage.

The use of composite resins in dentistry is well accepted for restoring anterior and posterior teeth. Many polishing protocols have been evaluated for their effect on the surface roughness of restorative materials. This study compared the effect of different polishing systems on the surface roughness of microhybrid composites. Thirty-six specimens were prepared for each composite $#91;Charisma® (Heraeus Kulzer), Fill Magic® (Vigodent), TPH Spectrum® (Dentsply), Z100® (3M/ESPE) and Z250® (3M/ESPE)] and submitted to surface treatment with Enhance® and PoGo® (Dentsply) points, sequential Sof-Lex XT® aluminum oxide disks (3M/ESPE), and felt disks (TDV) combined with Excel® diamond polishing paste (TDV). Average surface roughness (Ra) was measured with a mechanical roughness tester. The data were analyzed by two-way ANOVA with repetition of the factorial design and the Tukey-Kramer test (p<0.01). The F-test result for treatments and resins was high (p<0.0001 for both), indicating that the effect of the treatment applied to the specimen surface and the effect of the type of resin on surface roughness was highly significant. Regarding the interaction between polishing system and type of resin used, a p value of 0.0002 was obtained, indicating a statistically significant difference. A Ra of 1.3663 was obtained for the Sof-Lex/TPH Spectrum interaction. In contrast, the Ra for the felt disk+paste/Z250 interactions was 0.1846. In conclusion, Sof-Lex polishing system produced a higher surface roughness on TPH Spectrum resin when compared to the other interactions.