Comparação dos ensaios de microtração, push-out e pull-out na avaliação da adesão entre pino de fibra e dentina radicular por meio da mensuração da resistência de união / Evaluation of different bond strengh tests on fiber posts'adhesion

Este estudo comparou os ensaios de microtração, pull-out e push-out, na habilidade de medir a resistência de união (RU) entre pinos de fibra e dentina radicular, e também analisou o comportamento de diversos tipos de condicionamento dentinário (ácido fosfórico 37% ou monômero acídico) em diferentes profundidades de dentina radicular. Foram utilizados 18 dentes uniradiculares, endodonticamente tratados. Em metade deles, aplicou-se o sistema adesivo Optbond Solo Plus (Kerr) (OS) e na outra metade o Optbond Solo Self Ecth (Kerr) (OSE). Na fixação dos pinos em ambos os grupos foi utilizado o cimento resinoso Variolink II (Bisco). Para testar a RU, os dois grupos foram divididos em três subgrupos, nos quais todos os corpos-de-prova tinham 1 mm de espessura de dentina radicular. No subgrupo Mi foi usado o ensaio de microtração, no subgrupo Pl o ensaio de pull-out e no Ps o push-out. Tanto no ensaio de Ps quanto no Pl, os corpos-de-prova eram em forma de disco com forças aplicadas sobre o centro do pino. Já para o ensaio de microtração, os discos de dentina contendo os pinos receberam entalhes bilaterais diametralmente opostos, adquirindo formato final de ampulheta. Todos os testes foram realizados em uma máquina de ensaios universais (Kratos/Brasil) com velocidade de 0,5 mm/min. Apenas a comparação entre os diferentes ensaios mostrou diferença estatística significante (Mi = 5,93 ± 2,00a; Pl = 6,11 ± 2,82a; Ps = 9,50 ± 4,05b). Independente de outras variáveis, o tipo de ensaio pode influenciar nos valor.

Influence of five home whitening gels and a remineralizing gel on the enamel and dentin ultrastructure and hardness.

PURPOSE: To investigate the influence of calcium phosphate enhanced home whitening agents on human enamel and dentin surface microhardness and ultramorphology. METHODS: Five intact molars crowns were used for ultrastructural analysis and five for microhardness test. Each resulting coronal structure was cut in slices. After measuring baseline Knoop Hardness Number (KHN) of the enamel and dentin, the slices were divided into six experimental groups and one control (n= 5). G1= 15% carbamide peroxide (CP); G2= 16% CP; G3= Ca and PO4 (remineralizing agent); G4= 16% CP with Ca and PO4; G5= 7.5% hydrogen peroxide (HP) with Ca and PO4; G6=7.5% HP with Ca. After each daily session of treatment, specimens were stored in distilled water (37 degrees C) until the next session. Products were applied for 2 weeks, according to manufacturers' instructions. Additional KHN weredetermined. RESULTS: Conventional whitening agents (G1; G2) and the gel with Ca (G6), caused KHN decrease (P< 0.05).The remineralizing and whitening agents with Ca and PO4 (G3; G4; G5) did not change KHN. A change of morphology was observed on enamel and dentin surfaces in G1; G2; G5.

Análise microestrutural do esmalte tratado com peróxido de hidrogênio e carbamida / Effects of hydrogen peroxide and carbamide peroxide on enamel morphology

Objetivo: Avaliar, no microscópio eletrônico de varredura, a morfologia do esmalte humano tratado por duas diferentes técnicas clareadoras que empregam peróxido de hidrogênio e peróxido de carbamida. Métodos: Foram selecionados dez dentes terceiros molares superiores e divididos aleatoriamente em dois grupos (n=5). Cada coroa dental foi seccionada ao meio, no sentido mésio-distal, sendo produzidos dois espécimes, um referente à face vestibular (clareado) e outro referente à face palatina (controle). Desta forma, cinco espécimes serviram como controle e seus pares foram submetidos às seguintes técnicas clareadoras: G1 - clareamento de consultório com peróxido de hidrogênio a 35% (FGM, Whiteness HP, Joinville, Brasil) e aplicação de luz através de um aparelho de LED/Laser (DMC Equipamentos, Whitening Lase II, São Carlos, Brasil) e G2 - clareamento caseiro com peróxido de carbamida a 16% (FGM, Whiteness HP, Joinville, Brasil). Durante todo o experimento, os espécimes foram armazenados em saliva artificial a 37ºC. Após as técnicas clareadoras terem sido concluídas, os espécimes foram analisados no microscópio eletrônico de varredura. Resultados: As imagens obtidas revelaram alterações não uniformes no esmalte superficial clareado pelas duas técnicas. Não houve diferença no grau de alteração morfológica provocado pelo peróxido de hidrogênio a 35% se comparado ao peróxido de carbamida a 16%. Conclusão: Os agentes clareadores em baixa e alta concentração foram capazes de provocar alterações morfológicas na superfície do esmalte dental.

Objective: This study used a scanning electron microscope to assess the effects of two bleaching techniques, one using hydrogen peroxide and another using carbamide peroxide, on the surface of human enamel.Methods: Ten upper third molar teeth were selected and divided into two groups (n=5). Each tooth crown was sectioned in the mesiodistal axis. The buccal face was bleached and the lingual face was used as control. Thus, five specimens served as controls and their pairs were subjected to the following bleaching techniques: G1-external bleaching with 35% hydrogen peroxide (FGM, Whiteness HP, Joinville, Brazil) and use of a LED/Laser device (DMC Equipamentos, Whitening Lase II, São Carlos, Brazil) and G2-external bleaching with 16% carbamide peroxide (Whiteness Perfect-FGM). The specimens were kept in artificial saliva at 37ºC during the entire experiment. After the bleaching treatment for each group was completed, the specimens were analyzed by a scanning electron microscope. Results: Scanning electron microscopy revealed nonuniform changes in the enamels treated with hydrogen peroxide and carbamide peroxide. The degree of morphological changes obtained by treatment with 35% hydrogen peroxide or 16% carbamide peroxide did not differ. Conclusion: Bleaching agents in low and high concentrations were able to induce morphological changes on the enamel surface.

Efeito de diferentes géis clareadores sobre a dentina humana: análise microestrutural e de dureza / Effect af different whitening agents an human dentin: microstructural analysis and hardness

Objetivos: investigar a influência da adição de cálcio e fosfato a géis clareadores, comparando-os a clareadores convencionais (com nitrato de potássio e flúor) sobre a microestrutura e dureza da dentina humana. Materiais e Métodos: 5 coras de molares foram utilizadas para análise microestrutural e mais 5 para ensaio de dureza. Cada coroa foi seccionada em fatias de dentina, divididas entre 5 grupos experimentais e um controle. Medidas inicias de dureza foram tomadas. Em seguida, foram aplicados diferentes tratamentos: GC=Grupo Controle (sem tratamento); Opal-peróxido de carbamida (PC) 150Ja com nitrato de potássio e flúor; WT =PC 160Ja com nitrato de potássio e flúor; NWACP=PC 160Ja com Ca e P04; DW ACP=peróxido de hidrogênio (PH) 7.50Ja com Ca e P04; WC Ca=PH 7.50Ja com Ca. Após cada sessão diária de clareamento, os espécimes eram armazenados em água deionizada (37°C) até a próxima sessão. Os produtos foram aplicados durante 14 dias, conforme instrução dos fabricantes. Então, os espécimes foram preparados para análise microestrutural e medidas adicionais de dureza foram determinadas. Resultados: clareadores Opal, WT e WC Ca causaram desobstrução de túbulos dentinários e redução de dureza na dentina (p

Objectives: Investigate the influence of calcium and phosphate enhanced whitening agents, comparing them to conventional whitening agents (potassium nitrate and fluoride) on human dentin surface hardness and micromorphology. Materiais and Methods: 5 molars crowns were used for microstructural analysis and another 5 for hardness test. Each crown was cut in slices, divided into five experimental groups and one control.lnitial hardness measures were taken. Then, different treatments were applied: CG=control group (no treatmentl; Opal= 15% carbamide peroxide (CP) with potassium nitrate and fluoride; WT = 16% CP with potassium nitrate and fluoride; NW ACP= 16% CP with Ca and P04; DW ACP=7.5% hydrogen peroxide (HP) with Ca and P04; WC Ca = 7.5% HP with Ca. After each daily session of treatment, specimens were stored in distilled water (37°C) until the next session. Products were applied for 14 days, according to manufacturers' instructions. Specimens were prepared for microstructural analysis and additional hardness measures were determined. Results: Opal, WT and WC Ca presented dentinal tubules opened and hardness decrease (p

Influence of curing light attenuation caused by aesthetic indirect restorative materials on resin cement polymerization.

OBJECTIVES: To verify the effect of interposing different indirect restorative materials on degree of conversion (DC), hardness, and flexural strength of a dual-cure resin cement. METHODS: Discs (2 mm-thick, n=5) of four indirect restorative materials were manufactured: a layered glass-ceramic (GC); a heat-pressed lithium disilicate-based glass-ceramic veneered with the layered glass-ceramic (LD); a micro-hybrid (MH); and a micro-filled (MF) indirect composite resin. The light transmittance of these materials was determined using a double-beam spectrophotometer with an integrating sphere. Bar-shaped specimens of a dual-cure resin cement (Nexus 2/SDS Kerr), with (dual-cure mode) and without the catalyst paste (light-cure mode), were photoactivated through the discs using either a quartz-tungsten-halogen (QTH) or a light-emitting diode (LED) unit. As a control, specimens were photoactivated without the interposed discs. Specimens were stored at 37 masculineC for 24h before being submitted to FT-Raman spectrometry (n=3), Knoop microhardness (n=6) and three-point bending (n=6) tests. Data were analyzed by ANOVA/Tukey's test (alpha=0.05). RESULTS: MH presented the highest transmittance. The DC was lower in light-cure mode than in dual-cure mode. All restorative materials reduced the cement microhardness in light-cure mode. GC and LD with QTH and GC with LED decreased the strength of the cement for both activation modes compared to the controls. Curing units did not affect DC or microhardness, except when the dual-cure cement was photoactivated through LD (LED>QTH). Flexural strength was higher with QTH compared to LED. CONCLUSIONS: Differences in transmittance among the restorative materials significantly influenced cement DC and flexural strength, regardless of the activation mode, as well as the microhardness of the resin cement tested in light-cure mode. Microhardness was not impaired by the interposed materials when the resin cement was used in dual-cure mode.

Two-year clinical wear performance of two polyacid-modified resin composites (compomers) in posterior permanent teeth

Aim: The aim was to compare the clinical wear of two compomers (F2000; 3M/ESPE and Dyract AP; Dentsply) placed in occlusal cavities in permanent molars within a two-year follow-up period using an indirect method of evaluation. Methods: Twenty-one patients, whose treatment plans included Class I restorations, were selected. Each patient received two occlusal Class I restorations in permanent molars. One and 2 years after placement of the restorations, the 21 teeth restored with each material were submitted to wear evaluation. Polyvinylsiloxane impressions were taken and casts were made (baseline, 1 year and 2 years). The casts were classified by comparative evaluation using sets of 18 calibrated standard models (0 to 900 ìm), according to Leinfelder’s indirect method. Paired and unpaired t-tests were used for comparisons between the evaluations for the same material and between materials for each evaluation period, respectively. Results: The occlusal wear was higher after 2 years than after 1 year (p<0.001). The t-test demonstrated that the wear values, after 1 year, were similar for both compomers (F2000=17.6 ìm and Dyract AP=12.8 ìm). However, after 2 years, F2000 restorations (40.6 ìm) suffered significantly more wear (p<0.05) than Dyract AP restorations (29.8 ìm). Although compomers performed similarly after 1 year, Dyract showed less occlusal wear after 2 years. All occlusal Class I compomer restorations presented more occlusal wear after 2 years, but were considered as clinically acceptable within the evaluation period. Conclusions: The mean wear values found for both compomers do not indicate the need for either repair or replacement of the restorations.

Early and 24-hour bond strength and degree of conversion of etch-and-rinse and self-etch adhesives.

PURPOSE: To evaluate early and 24-hour microtensile bond strength (microTBS) and the degree of conversion (DC) of one representative adhesive system from each of the four current bonding approaches. METHODS: 40 human molars were sectioned occluso-gingivally into two halves. Resin composite was bonded incrementally to flat, mid-coronal dentin, using the adhesives Adper Scotchbond MP (MP); Adper Scotchbond 2 (SB); Clearfil SE Bond (SE); and Adper Prompt L-Pop (LP) according to the respective manufacturer's instructions (n = 10). One half was immediately sectioned into sticks and subjected to muTBS test. As the sectioning process took approximately 1 hour, the results were designated as 1-hour bond strengths. The other half was stored in distilled water at 37 degrees C for 24 hours before being sectioned and tested. The DC of these systems was measured using Fourier Transform-Raman spectroscopy in three periods: immediately, 1 and 24 hours after polymerization. Data were analyzed with ANOVA and Tukey's tests. RESULTS: There were no significant differences between the 1-hour and 24-hour bond strengths (P > 0.05), or among the DC measured immediately, 1 hour and 24 hours after polymerization (P > 0.05). However, significant differences were observed among adhesives (P < 0.05). microTBS values obtained, in MPa (1 hour/24 hour), were: SB (48.6 + 1.3/48.4 + 3.5) = SE (51.9 + 4.7/53.3 +/- 2.9) > MP (35.3 +/- 10.9/38.6 + 6.7) > LP (25.5 + 1.1/26.0 + 1.5). The DC, in percentage (immediately/1 hour/24 hour), were: SE (81/82/87) > MP (79/77/81) > SB (60/63/65) > LP (39/37/42).

Effects of surface treatments and storage times on the tensile bond strength of adhesive cements to noble and base metal alloys.

This work evaluated two resin cements and a glass-ionomer cement and their bond strength to gold-palladium (Au-Pd), silver-palladium (Ag-Pd), and nickel-chromium-beryllium (Ni-Cr-Be) alloys, utilizing three surface treatments over a period of six months. Eight hundred ten pieces were cast (in a button shape flat surfaces) in one of three alloys. Each alloy group was assigned to three other groups, based on the surface treatment utilized. Specimens were fabricated by bonding similar buttons in using one of three adhesive cements. The 405 pairs were thermocycled and stored in saline solution (0.9% NaCl) at 37 degrees C. The tensile bond strengths were measured in a universal testing machine after storage times of 2, 90, or 180 days. The highest mean bond strength value was obtained with the base metal alloy (10.9 +/- 8.6 MPa). In terms of surface treatment, oxidation resulted in the highest mean bond strength (13.7 +/- 7.3 MPa), followed by sandblasting (10.3 +/- 5.5 MPa) and polishing (3.0 +/- 6.4 MPa). Panavia Ex (13.2 +/- 9.3 MPa) showed significantly higher bond strengths than the other two cements, although the storage time reduced all bond strengths significantly.

Influência do tipo de substrato entinário na resistência de união a microtração - estudo ôin vitroõ / Influence of the dentin type in the microtensile bond strength

Este estudo avaliou a resistência de união entre o conjunto resina composta/adesivo e diferentes tipos de substrato dentinário. Quinze molares humanos extraídos foram divididos em três grupos de acordo com o tipo de dentina: 5 dentes com dentina afetada por cárie (C), 5 restaurados com amálgama (R) e 5 dentes hígidos (H). Todos os dentes tiveram suasuperfície oclusal desgastada até expor uma superfície dentinária plana. As diferentes superfícies foram condicionadas com ácido fosfórico a 37% (3M ESPE), seguindo-se a aplicação e fotopolimerização do adesivo Single Bond (3M ESPE)para a imediata inserção de incrementos de 1 mm de resina composta (Z250 û 3M ESPE) até atingir 4 mm de altura.Após 24 horas de armazenagem em água destilada (37ºC), os corpos-de-prova em forma de palito com secção transversal de 1 mm2 de área foram submetidos ao ensaio de microtração (Instron). A análise estatística (ANOVA/Tukey) revelou que o fator substrato interferiu na resistência adesiva (p<0,05), com a dentina hígida (42,0±7,1 MPaa) proporcionandomaiores valores que a dentina restaurada (37,1±4,7 MPab) e que a cariada (37,7±4,8 MPab).

Influence of cavity dimensions, insertion technique and adhesive system on microleakage of Class V restorations.

BACKGROUND: The authors evaluated the influence of cavity dimensions, insertion technique and adhesive system on microleakage of Class composite restorations. METHODS: The authors prepared cylindrical cavities with enamel margins of 3-millimeter diameter by 1-mm depth or 6-mm diameter by 2-mm depth on the labial surface of bovine incisors. They defined experimental groups (n = 15) according to cavity size, insertion technique (bulk or incremental) and adhesive system applied (Single Bond, 3M ESPE, St. Paul, Minn., or Excite, Ivoclar Vivadent, Amherst, N.Y.). They restored preparations with Tetric Ceram (Ivoclar Vivadent). After 36 hours' storage in distilled water at 37 C, specimens were submitted to microleakage using 50 percent silver nitrate as tracer. Teeth were sectioned twice and dye penetration on the axial wall was determined in millimeters. RESULTS: The authors analyzed the data using analysis of variance/Tukey test (a = .05). For large restorations, the use of Single Bond resulted in higher microleakage than Excite (1.56 +/- standard deviation [SD] 0.26 mm and 0.63 +/- SD 0.56 mm, respectively; P < .001), whereas for small restorations there was no statistical difference between adhesives (Excite: 0.47 +/- SD 0.28 mm; Single Bond: 0.46 +/- SD 0.28 mm). CONCLUSION: The choice of adhesive system influenced microleakage only for large restorations. Incremental insertion of the composite did not affect dye penetration. CLINICAL IMPLICATIONS: Microleakage of composite restorations cannot be predicted only on the basis of the restorations' dimensions. In large restorations, it also depends on the choice of adhesive system, whereas in small restorations, the adhesive used does not seem to be an influential factor. Incremental insertion did not seem to reduce restorations' microleakage.

A novel method to obtain microtensile specimens minimizing cut flaws.

Cutting procedures conventionally used for microtensile specimens' preparation induce mechanical stress and attrition, leading to cracks in dental structure. Enamel is mainly affected due to its high module of elasticity and brittleness. As an alternative to the conventional diamond saw, a diamond wire was used for cutting. The two techniques were compared in efficacy in the preparation of two different sample shapes. Forty human molars, flattened in dentin or enamel, were used for sample preparation. After bonding procedures, resin block was built incrementally. Half of the teeth were cut using a diamond disc and the other half using a diamond wire, obtaining slabs and stick-shaped specimens. Slabs were then shaped to obtain hourglass samples. Five samples from each subgroup were randomly selected for Scanning electron microscopy (SEM) analysis. Remaining samples underwent microtensile test and the results were analyzed, including/excluding premature failures (pf), with three-way ANOVA and Tukey test, performed separately, by substrate. On dentin, only the exclusion of pf showed a significant higher bond strength values than when pf were included (p < 0.05); however, on enamel, all factors (equipment, shape and including/excluding pf) had a significant effect on bond strength (p<0.05). The most remarkable finding from SEM was the incidence of specimens' cracks and defects when diamond blade was used. Scratches and cracks in the hourglass-shaped specimens were also detected. In both cases, enamel was more affected than dentin.

Estudo da distância intercanina no processo de identificação de marcas de mordidas humanas / Intercanine distance study in the identification process of human bite marks

O objetivo deste trabalho foi avaliar se existe diferença significativa entre a distância intercanina, referenciada nas pontas de cúspides, e a maior distância que envolve os caninos, referenciada no abaulamento presente nas superfícies vestibulares. A amostra deste trabalho foi composta por 50 pares de modelos de gesso. Com o uso de um paquímetro digital foram feitas as mensurações, as quais foram comparadas através do teste estatístico t de Student. Após avaliação dos dados, concluiu-se que existe diferença significativa (p < 0,001) entre as distâncias estudadas, devendo o perito estar atento ao tipo de alimento que contém a marca de mordida. Nos alimentos macios, em que ocorre a penetração total ou parcial das unidades dentárias, a mensuração deverá se basear na maior distância que envolve os caninos.

An evaluation of the compression strength of gypsum according to proportion and manipulation / Resistência à compressão de gessos em função do proporcionamento e manipulação

This study evaluated the compression strength of gypsum type IV and V according to 2 variables: 1) water proportioned randomly or as recommended by the manufacturer and 2) according to 3 (three) different groups of operators (dentists, technicians and dental students). 180 specimens, produced according to ADA regulation nr. 25 underwent, after seven days (dry resistance), the compression strength test in an universal testing machine. After statistical analyses of the data, there was no statistical significant difference regarding the group of operators. Regarding the variable proportion, the specimens manufactured using a random proportion of water/gypsum powder presented a lower compression value (626,2 Kgf/cm2) when compared to the group where the amount of water/gypsum powder followed the recommendation of the manufacturer (741,7 Kgf/cm2). This difference was statistically significant (p<0.01)

Resistência à microtração e avaliação por microscopia eletrônica de varredura da interface entre um adesivo com "primer" autocondicionante e esmalte ou dentina / Microtensile strength and SEM evaluation of the interface between an adhesive with self-eatching primer and enamel or dentin

O objetivo do presente estudo foi avaliar, por teste de microtração, a resitência de união do adesivo com "primer" autocondicionante Clearfil SE Bond (Kuraray Medical Inc.) ao substrato (esmalte ou dentina); e verificar, através de MEV, a integridade da interface entre adesivo e substrato antes do teste de microtração. Quatorze molares humanos hígidos foram aleatoriamente divididos em dois grupos (n=7) de acordo com o substrato a ser usado: dentina ou esmalte. Após a aplicação do sistema adesivo, um bloco de resina composta (Tetric Ceran - Ivoclar Vivadent, Schaan, Liechtenstein) de aproximadamente 5 x 5 x 5 mm foi construído sobre o dente, sendo cada incremento fotoativado por 40 segundos com 60mW/cm² (Optilux 401 - Demetron Research Corporation). Após 24 horas, os blocos dente/adesivo/resina foram seccionados, obtendo-se corpos de prova em forma de palito, com área de união de aproximadamente 0,8mm². Foram obtidos 156 corpos-de-prova, sendo que 120 palitos foram usados para o teste de microtração e 36 foram preparados para análise em microscopia eletrônica de varredura. A média de resistência de união (MPa) em dentina foi de 44,5 (+/-7,7) e em esmalte, 38,9 (+/-4,8), sendo estatisticamente semelhantes entre si. A análise em MEV mostrou presença de bolhas e/ou microtrincas na interface adesiva e no substrato, principalmente em esmalte

Resistência de união à dentina de peças metálicas obtidas por fundição convencional e por eletrodeposição de ouro / Dentin bond strength of conventional and gold electroformed castings

A proposta deste estudo foi avaliar a resistência de união entre dentina e peças metálicas obtidas por fundição convencional e por eletrodeposição de ouro, usando 2 sistemas de cimentação. Superfícies planas foram preparadas em dentina de 30 molares humanos e similares. Vinte cilindros (5mm de altura x 3mm de diâmetro) foram fundidos em liga de AU-Pt, 20 em liga de Co-Cr e 20 cilindros (7mm de altura x 3 mm de diâmetro superior x 2,2mm de diâmetro inferior) foram eletrodepositados em ouro (Au eletr). Dois cimentos resinosos - Variolink II (VAR) e Panavia F (PAN) - foram empregados e manipulados conforme as recomendações dos fabricantes. Após a ciclagem térmica (700 ciclos, 5 e 55°c, 1 minuto), os corpos-de-prova (cps) foram submetidos ao ensaio mecânico de tração. Os resultados foram submetidos à análise de variância e ao teste de Tukey (5%). Os grupos experimentais apresentaram as seguintes médias de resistência adesiva (MPa): Au-Pt + VAR: 5,38 (+/-2,44); Au-Pt + PAN: 5,85 (+/-2,81); Co-Cr + VAR: 7,61 (+/-1,43); Co-Cr + PAN: 9,54 (+/-3,81); Au eletr + VAN: 6,48 (+/-1,98); Au eletr + PAN: 6,56 (+/-2,54). Foi observada diferença significante quando o fator metal foi avaliado isoladamente, com superioridade para a liga de Co-Cr. Não houve diferença estatística entre os cimentos resinosos

Microtensile bond strength of current dentin adhesives measured immediately and 24 hours after application.

PURPOSE: To evaluate the immediate microtensile bond strengths achieved with representative adhesive systems from each of the four current bonding approaches. MATERIALS AND METHODS: Resin composite was bonded incrementally to flat, midcoronal dentin from 33 human molars, using the adhesives (Adper Scotchbond MP; Adper Scotchbond 1; Optibond Solo Plus; Clearfil SE Bond; AdheSE; Tyrian SPE + One Step Plus; Optibond Solo Plus self-etching; One-Up Bond F; iBond; Adper Prompt L-Pop; Xeno III) according to the respective manufacturer's instructions. The bonded specimens were immediately sectioned into sticks and underwent microtensile bond testing either immediately or after 24 h. Data were analyzed with two-way ANOVA and LSD tests. RESULTS: No significant differences were found between immediate and 24-h bond strengths (p > 0.05). However, significant differences were observed among adhesives (p = 0.001). The all-in-one adhesive iBond showed statistically lower values when compared to all the other adhesives. Adper Prompt L-Pop, Xeno III, Tyrian SPE + One Step Plus and One-Up Bond F, all self-etching adhesives, were significantly weaker than AdheSE, Optibond Solo Plus, Adper Scotchbond 1, Optibond Solo Plus self-etching, Clearfil SE Bond, and Adper Scotchbond MP, which did not differ statistically from each other. CONCLUSION: Microtensile bond strengths of representative adhesive systems from the four categories of bonding agents were not equivalent, with the lowest values recorded for the one-step self-etching adhesives. There were no differences in the bond strengths when measured immediately and after 24 h.

Microtensile bond strength of different adhesive systems to primary and permanent dentin.

PURPOSE: The aims of this in vitro study were to: (1) compare bond strength of different adhesive systems to primary and permanent dentin using microtensile test; and (2) evaluate the interaction of these materials to primary and permanent dentin by means of scanning electron microscopy (SEM). METHODS: Middle-coronal dentin surfaces of 18 exfoliated primary and 18 extracted permanent molars were exposed and teeth were randomly divided, according to their adhesive system, into 3 groups (N=6 per group): (1) Clearfil SE Bond (SE); (2) One Up Bond F (OU); and (3) Single Bond (SB). Then, 5-mm high composite blocks were constructed. After bonding procedures, the teeth were stored in distilled water at 37 degrees C for 24 hours prior to the specimens' preparation. For the microtensile test, teeth (N=5 per group) were longitudinally sectioned into 2 axes rendering beam-specimens that were glued to special devices, which were mounted in a Universal Testing Machine to be loaded under a crosshead speed of 1 mm/min until fracture. One tooth of each group was prepared for SEM. RESULTS: Microtensile bond strength mean values (MPa) to primary/permanent dentin were: (1) SE=60.0/61.4; (2) OU=54.5/53.3; and (3) SB=70.1/64.9. Two-way analysis of variance (ANOVA) showed no significant differences (P>.05) for the bond strength values among primary and permanent dentin groups, neither among groups SExSB and SExOU. SEM images of SE and SB showed a well-defined, uniform, and continuous hybrid layer. A continuous hybrid layer, however, was not found for OU. CONCLUSIONS: Bond strength and micromorphologic characteristics of the adhesive systems evaluated were not influenced by the substrate. OU achieved worse results.

Polymerization contraction stress of low-shrinkage composites and its correlation with microleakage in class V restorations.

OBJECTIVE: The aim of this study was to compare the behavior of two new, low-shrinkage hybrid composites (Aelite LS and Inten-S) with a microfilled (Heliomolar) and a hybrid composite (Filtek Z250), in terms of polymerization contraction stress and microleakage. METHODS: Maximum contraction stress after 10 min was recorded in a "tensilometer", using a C-factor (C) of 2.5 and energy density of 26 J/cm(2). For the microleakage test, cylindrical cavities with enamel margins prepared in bovine incisors (4 mm diameter, 1.5 mm depth, C = 2.5) were restored in bulk, applying the same energy density used in the contraction stress test. After immersion in 0.5% methylene blue for 4 h, specimens were sectioned twice, perpendicularly, and the highest dye penetration score was recorded. Contraction stress results were analyzed by one-way ANOVA/Tukey's test and microleakage was analyzed by Kruskal-Wallis test. Regression analysis between the two variables was also performed. RESULTS: Aelite LS showed significantly higher stress than the other composites tested. Inten-S and Filtek Z250 had similar stress levels, statistically higher than Heliomolar. In the microleakage test, a significant difference was observed between Aelite LS and Heliomolar only. Regression analysis showed a good linear correlation between the two variables (R2(adjusted) = 0.811). CONCLUSIONS: The low-shrinkage materials exhibited contraction stress values similar or higher than the hybrid composite. A direct relationship between contraction stress values and microleakage for the composites evaluated was verified. SIGNIFICANCE: The low-shrinkage composites tested did not seem to represent an improvement in terms of reducing contraction stress or microleakage.

Influência da geometria dos espécimes em dentina e esmalte no teste de microtração: análise da resistência de união e microscopia eletrônica de varredura / Influence of specimens' characteristics on dentin and enamel on microtensile bond test: microtensile bond strenght and scanning electron microscopy analysis

Este estudo teve como objetivo verificar a influência da geometria dos espécimes em dentina e esmalte no teste de microtração. 32 molares íntegros foram divididos em dois grupos: dentina [D] ou esmalte [E]. Para o grupo [D], o terço oclusal da coroa foi removido e para o grupo [E], a superfície vestibular foi asperizada, expondo, em ambos os casos, superfícies planas. Após a criação de camada smear padrão, foi aplicado o sistema adesivo experimental ABF (Kuraray Medical Inc.) e um bloco de resina composta (Clearfil APX - Kuraray Medical Inc.) foi construído sobre o dente. Após 24 horas, os dentes foram aleatoriamente divididos em quatro subgrupos (n=4), de acordo com o formato (ampulheta ou palito) e a área de união (0,5x0,5mm ou 1x1mm) dos espécimes. Com um disco diamantado, os conjuntos foram seccionados paralelamente ao longo do eixo do dente, obtendo-se fatias com as espessuras determinadas. Para obtenção das ampulhetas, entalhes foram realizados com uma broca diamantada FF. Para obtenção dos palitos, foram feitos cortes perpendiculares aos primeiros. Três corpos-de-prova (cps) de cada condição experimental foram aleatoriamente selecionados e preparados para microscopia eletrônica de varredura (MEV); os demais foram submetidos ao teste de microtração. Tanto o substrato quanto as dimensões e os formatos dos cps influenciaram estatisticamente os resultados de resistência adesiva (p<0,001). Em MEV, foram freqüentemente observadas linhas de fraturas nas ampulhetas na interface adesiva. Essa ocorrência foi mais comum nos cps em esmalte do que em dentina. O entalhamento, principalmente em esmalte, é bastante crítico e influencia os resultados de adesão

Thermal and mechanical load cycling on microleakage and shear bond strength to dentin.

This study evaluated the influence of mechanical and thermal cycling on microleakage at the cervical margins of proximal slot restorations and shear bond strength on flat dentin surfaces. Microleakage Evaluation: One hundred and twenty slot cavity restorations were performed on bovine incisors. The restorations were randomly divided into four groups (n = 30): control (no thermal and mechanical load cycling), thermal cycling (2,000 cycles, 5 degrees C-55 degrees C), mechanical load cycling (50,000-80N) and thermal and load cycling (2,000 5 degrees C-55 degrees C/50,000-80N). The specimens were sealed with acid resistant varnish, leaving a 1-mm window around the cervical margin interface. To detect marginal leakage, a 2% methylene blue buffered solution was used for four hours. The specimens were sectioned longitudinally and qualitatively evaluated by stereomicroscopy (45x) following a ranked score for the dentin cervical margin. The data were analyzed by Kruskal-Wallis test (alpha = 0.05). Shear Bond Strength Evaluation (SBS): Eighty bovine incisors were embedded and polished to obtain a flat standard surface on dentin. The surfaces were restored with Single Bond adhesive system and a resin composite subsequently inserted in a bipartite Teflon matrix. The specimens were randomly divided into the four groups (n = 20) described above for microleakage. Shear bond strengths were measured in a universal testing machine with a crosshead speed of 0.5 mm/minute. The data were analyzed by one way ANOVA test (alpha = 0.05). No statistically significant influence of thermocycling, mechanical load cycling or the combination was observed for both microleakage and shear bond strength.