Influência de diferentes agentes isolantes aplicados sobre o selamento dentário imediato na resistência à tração de restaurações provisórias / nfluence of different insulating agents applied on immediate dental sealing on the tensile strength of temporary restorations

Constatação do problema: A possível ineficácia dos agentes isolantes utilizados na proteção da camada de dentina hibridizada na técnica do selamento dentinário imediato contra aderência das restaurações à base de polimetilmetacrilato pode impactar negativamente na resistência de união das futuras restaurações definitivas e comprometer o sucesso da técnica. Objetivos: O objetivo deste estudo foi avaliar a capacidade de diferentes agentes isolantes em impedir a adesão entre as restaurações provisórias à base de polimetilmetacrilato e as superfícies de dentina hibridizadas pela técnica do selamento dentinário imediato. Materiais e Métodos: Quarenta dentes humanos extraídos receberam preparos para laminados oclusais ultrafinos, selamento dentinário imediato (OptiBond FL; Kerr) e proteção com diferentes agentes isolantes antes da provisionalização. Os dentes foram divididos em 3 grupos experimentais, de acordo com o agente isolante: vaselina pastosa, gel de glicerina hidrossolúvel (KY; Johnson & Johnson) e agente isolante hidrossolúvel (Pro-V Coat; Bisco). Restaurações provisórias diretas de resina acrílica foram fabricadas sobre os dentes preparados. Após 2 semanas, foi realizado o teste de tração das restaurações provisórias para análise de resistência à tração. A análise do padrão de falha das superfícies dentinárias foram realizadas por microscopia confocal a laser 3D e microscopia eletrônica de varredura. Os dados foram analisados com o teste de variância de um fator e teste post hoc de Tukey (α=0,05). Resultados: O uso do Pro-V Coat apresentou valores de resistência à tração (30,39 ± 10,01 N) significantemente menores em comparação aos outros agentes isolantes (p<0,05). O padrão de falha mostrou-se do tipo misto em todos os grupos avaliados. Conclusão: Pro-V Coat apresentou a maior capacidade de isolamento da superfície dentinária hibridizada pela técnica do selamento dentinário im

OCT for early quality evaluation of tooth-composite bond in clinical trials.

OBJECTIVES: To evaluate early quality of composite restorations with a universal adhesive in different application modes clinically and with optical coherence tomography (OCT). METHODS: 22 patients with four non-carious cervical lesions each received composite restorations (Filtek Supreme™ XTE, 3 M). The universal adhesive Scotchbond Universal™(SBU, 3 M) was applied with three etching protocols: self-etch (SE), selective-enamel-etch (SEE) and etch-and-rinse (ER). The etch-and-rinse adhesive OptiBond™ FL (OFL, Kerr) served as a control. Restorations were imaged by OCT (Thorlabs) directly after application (t0). After 14 days (t1) and 6 month (t2) OCT imaging (interfacial adhesive defects) was repeated combined with clinical assessment (FDI criteria). Groups were compared by Friedman-/Wilcoxon- and McNemar-Test. RESULTS: No differences were seen clinically between groups (pi ≥ 0.500). OCT assessment revealed more adhesive defects at the enamel interface with SBU/SE at t0-t2 compared to all groups (pi ≤ 0.016). OFL showed more defects than SBU/ER (t1: p = 0.01; t2: p = 0.083). At dentin/cementum interface OFL exhibited more adhesive defects than SBU with all conditioning modes (t0, t1, pi ≤ 0.003) and at t2 to SBU/SE and SBU/ER (p < 0.001). Since t1 defects with SBU were detected more frequently in the SE and SEE modes compared to ER (pi ≤ 0.037). In contrast to SBU defects increased with OFL up to t2 (pi ≤ 0.007). CONCLUSIONS: In contrast to clinical evaluation, OCT revealed subtle adhesive defects directly after application that might interfere with clinical success. It was demonstrated that ER does not decrease initial adhesion of SBU to dentin.

Bond durability of different resin cements to caries-affected dentin under simulated intrapulpal pressure.

OBJECTIVE: To evaluate the durability of the bond of different resin cement systems to normal dentin (ND) and caries-affected dentin (CAD) with and without simulated intrapulpal pressure (IPP). METHODS AND MATERIALS: Molars with midcoronal caries were used. Occlusal enamel was cut to expose both dentin substrates (ND and CAD). Dentin substrates were differentiated using visual, tactile, caries-detecting dye, and dye-permeability methods. Prepared crown segments were equally divided according to the tested resin cement systems: etch-and-rinse resin cement, self-etch resin cement containing methacryloyloxydecyl dihydrogen phosphate (MDP), and self-adhesive resin cement. In addition to the dentin substrates and the resin cement types, the effect of application/storage conditions (with or without simulated IPP and with or without thermocycling) were tested. A microtensile bond strength test was done using a universal testing machine. Failure modes were determined using a scanning electron microscope. RESULTS: Etch-and-rinse resin cement strength values were significantly affected by the difference in the dentin substrates as well as the different application/storage conditions. Self-etch adhesive containing MDP bonded equally to ND and CAD and remained stable under all tested conditions. Self-adhesive resin cement revealed a similar bond to ND and CAD; however, its values were the lowest, especially when IPP and thermocycling were combined. Mixed failure was the predominant failure mode. CONCLUSIONS: Etch-and-rinse resin cement was sensitive to dentin substrate and application/storage conditions. Resin cement with self-etch adhesive containing MDP revealed more reliable bonding to ND/CAD even when IPP and thermocycling were combined. The bonding of the self-adhesive resin cement could not compete with other resin cements.

In vitro longevity of bonding properties of universal adhesives to dentin.

PURPOSE: To evaluate the immediate and 6-month resin-dentin bond strength (µTBS) and nanoleakage (NL) of universal adhesives that contain or do not contain methacryloyloxydecyl dihydrogen phosphate (MDP) and are used in the etch-and-rinse and self-etch strategies. METHODS AND MATERIALS: Forty caries-free extracted third molars were divided into eight groups for µTBS (n=5). The groups were bonded with the Clearfil SE Bond (CSE) and Adper Single Bond 2 (SB) as controls; Peak Universal, self-etch (PkSe) and etch-and rinse (PkEr); Scotchbond Universal Adhesive, self-etch (ScSe) and etch-and-rinse (ScEr); and All Bond Universal, self-etch (AlSe) and etch-and-rinse (AlEr). After composite restorations, specimens were longitudinally sectioned to obtain resin-dentin bonded sticks (0.8 mm(2)). The µTBS of the specimens was tested immediately (IM) or after 6 months of water storage (6M) at 0.5 mm/min. Some sticks at each storage period were immersed in silver nitrate and photo developed, and the NL was evaluated with scanning electron microscopy. Data were analyzed with two-way repeated-measures analysis of variance and Tukey test (α=0.05). RESULTS: At the IM period, PkSe and PkEr showed µTBS similar to the control adhesives (p>0.05) but increased NL pattern and lower µTBS after 6M (p<0.05). ScSe and ScEr showed intermediary µTBS values at the IM period but remained stable after 6 months (p>0.05). AlSe showed the lowest µTBS (p<0.05), but µTBS and NL remained stable after 6M (p>0.05). AlEr showed higher IM µTBS but showed higher degradation after 6M (p<0.05). CONCLUSIONS: Universal adhesives that contain MDP showed higher and more stable µTBS with reduced NL at the interfaces after 6 months of water storage.

Efeito de agentes dessensibilizantes na obliteração dos túbulos dentinários / Effect of desensitizing agents on obliteration of dentinal tubules

Introdução: Vários tratamentos são propostos para a hipersensibilidade dentinária sendo consenso que o objetivo principal do tratamento é a obliteração dos túbulos dentinários. Objetivo: Avaliar o número de aplicações necessárias para a completa obliteração dos túbulos dentinários utilizando diferentes agentes dessensibilizantes. Material e Método: A porção do esmalte coronário da face vestibular de 40 incisivos bovinos foi removida com auxílio de lixas para expor a dentina superficial da junção amelo-cementária. Em seguida, as raízes e a porção coronária referente ao terço médio-incisal dos dentes foram removidas. A seguir foi realizada a completa remoção de smear layer, evidenciando os túbulos dentinários. As amostras foram divididas em 4 grupos experimentais conforme o agente dessensibilizante utilizado: verniz fluoretado, adesivo dentinário, dessensibilizante dentinário e creme dental. Os produtos foram aplicados de acordo com as recomendações do fabricante. As amostras foram avaliadas previamente e após o uso dos agentes por microscopia eletrônica de varredura de baixo vácuo. A aplicação do agente e a análise foram realizadas até a completa obliteração dos túbulos dentinários. Os dados foram avaliados estatisticamente em relação ao número de aplicações necessárias utilizando os testes de Kruskal-Wallis e Mann-Whitney (p0,05). Resultado: O verniz fluoretado foi o mais eficaz dos agentes avaliados, sendo necessária uma aplicação para a completa obliteração dos túbulos. Para o adesivo dentinário foram necessárias duas aplicações e para o dessensibilizante e o creme dental foram necessárias cinco aplicações. Conclusão: Os agentes dessensibilizantes testados necessitam de um número variado de aplicações, sendo o mais eficaz o verniz fluoretado, onde apenas uma aplicação possibilitou a completa obliteração dos túbulos. (AU)

Introduction: Several treatments are proposed for dentin sensitivity and the consensus is that the main objective of the treatment is the complete obliteration of the dentinal tubules. Objective: To evaluate the number of applications necessary for the complete obliteration of the dentinal tubules using different desensitizing agents. Material and Methods: a portion of coronary enamel of the buccal surface of 40 bovine incisors was removed with the aid of sandpaper in order to expose the superficial dentin at the dentin-enamel junction. The roots and the coronary portions of the mesial-incisal third of the teeth were also removed. Complete smear layer removal was performed, exposing the dentinal tubules. Samples were divided into 4 experimental groups as desensitizing agents used: fluoride varnish, dentin adhesive, dentin desensitizing and toothpaste. The products were applied in accordance to the manufacturer's recommendation. Samples were evaluated before and after the application of different agents by scanning electronic microscopy of low vacuum. The application the products and analysis was carried out until complete obliteration of dentinal tubules. Data was evaluated statistically in relation to the required number of applications using Kruskal-Wallis and Mann-Whitney (p<0, 05). Results: Fluoride varnish was the most efficient of the tested agents, requiring a single application for the complete dentinal tubule obliteration. For the dentin adhesive, two applications were necessary and for the dentin desensitizing and toothpaste five applications were required. Conclusion: The desensitizing agents tested require distinct number of applications, and the fluoride varnish is the most effective one, which a single application resulted in the complete dentin tubule obliteration. (AU)

Push-out bond strength of self-adhesive methacrylate resin-based sealers to root dentin.

This study examined the adhesive strength of two self-adhesive methacrylate resin-based sealers (MetaSEAL and RealSeal SE) to root dentin and compared them with RealSeal and AH Plus in properties. A total of 48 extracted human single-rooted teeth were used to prepare the 0.9-mm thick longitudinal tooth slice (each per tooth). Standardized simulated canal spaces of uniform dimensions were prepared in the middle of radicular dentin. After treated with 5.25% sodium hypochlorite (NaOCl) and 17% EDTA, tooth slices were allocated randomly to four groups (n=12) in terms of different sealers used: MetaSEAL, RealSeal SE, RealSeal, and AH plus groups. The simulated canal spaces were obturated with different sealers in each group. There were 10 slabs with 20 simulated canal spaces (n=20) used in each group for push-out testing. The failure modes and the ultrastructures of fractured sealer-dentin interfaces were examined. The remaining 2 slabs in each group underwent partial demineralization for observation of the ultrastructure of resin tags. The results showed that the push-out bond strength was 12.01±4.66 MPa in MetaSEAL group, significantly higher than that in the other three groups (P<0.05). Moreover, no statistically significant differences were noted in the push-out bond strength between RealSeal SE (5.43±3.68 MPa) and AH Plus (7.34±2.83 MPa) groups and between RealSeal SE and RealSeal (2.93±1.76 MPa) groups (P>0.05). Mixed failures were predominant in the fractured sealer-dentin interfaces in MetaSEAL and AH Plus groups, while adhesive failures were frequently seen in RealSeal SE and RealSeal groups. In conclusion, after complete removal of the smear layer, MetaSEAL showed superior bond ability to root dentin. The RealSeal SE is applicable in clinical practice, with its adhesive strength similar to that of AH Plus. The self-adhesive methacrylate resin-based sealer holds promise for use in endodontic treatment.

Shear bond strength of seventh generation bonding agents on dentin of primary teeth--an in vitro study.

This controlled, randomized, in vitro study evaluated the shear bond strength of several seventh generation bonding agents on the dentin of primary teeth. Six different adhesives were used: Xeno IV, Clearfil S3 Bond, Adper Prompt-L-Pop, AdheSE One, Bond Force, and Optibond (control). Ninety primary teeth were prepared by wet grinding with a 320-grit silicon carbide paper on a polishing wheel running at 110 RPM. After 24 hours of storage in water, shear bond strengths of each group were determined. The mean shear bond strength of the tested adhesive systems to primary dentin was 12.27 MPa. One-way ANOVA testing showed a statistically significant difference between adhesive products (P < 0.001). Tukey HSD post hoc tests were used to assess which means were significantly different from one another. There was no statistically significant difference between the fifth generation adhesive system (Optibond) and the two seventh generation systems (Xeno IV and Bond Force), with Optibond exhibiting a lower mean shear bond strength compared to Bond Force. Within the limitations of this study, there is a significant difference between seventh generation bonding materials. Bond Force and Optibond appear to exhibit higher shear bond strengths than the other products.

Comparison of resin push-out strength to root dentin of bovine- and human-teeth.

AIM: To compare the push-out strength of bovine- and human-root dentin and, thus, evaluate the suitability of bovine-root dentin to substitute human-root dentin for bond strength testing. MATERIALS AND METHODS: Ten single-rooted human-teeth and ten bovine incisors were prepared using a #3 bur of a fiber post system (12 mm long). The posts were duplicated with resin cement (Duolink). The root canals were treated with All Bond 2 adhesive system and the resin posts were cemented using Duolink. The specimens were cut perpendicular to their long axis, yielding disc-specimens with 1.5 mm thickness, which were submitted to a push-out test (1 mm/min). Ten bond strength values per group (n = 10) were used for statistical analysis (Student t test, alpha =.05). RESULTS: Statistically significant differences were found for the bond strength values between bovine- (4.1 +/- 1.3 MPa) and human-root dentin (8.6 +/- 5.7 MPa) (P =.0001). CONCLUSION: The push-out strengths of bovine- and human-root dentin were statistically different.

O condicionamento ácido prévio ainda é indispensável para a odontologia adesiva? / Is previous total etching still indispensable for the adhesive dentistry?

O objetivo deste trabalho foi avaliar as características dos sistemas adesivos disponíveis atualmente considerando a aplicação ou não do condicionamento prévio com ácido fosfórico. O conhecimento das estruturas e o tratamento adequado do substrato dental são fundamentais para utilização dos adesivos convencionais. Os sistemas adesivos autocondicionantes possuem técnica simplificada dispensando o condicionamento ácido prévio. O profissional deverá ter conhecimento dos mecanismos de adesão ao substrato dental, experiência clínica e domínio da técnica de aplicação do adesivo escolhido. O condicionamento ácido prévio não deve ser considerado indispensável na Odontologia adesiva atual.

Avaliação da resistência de união de novos sistemas adesivos ao esmalte e dentina / Enamel and dentin bond strength evaluation of new adhesive systems

O estudo avaliou a resistência de união (RU) ao esmalte e à dentina de dois novos sistemas adesivos: Tetric N-Bond (TN), que preconiza o condicionamento ácido separado e o autocondicionante Bond Force. A superfície vestibular de 24 incisivos bovinos foi desgastada para exposição do esmalte e dentina. As amostras foram alatoriamente distribuídas em quatro grupos (n=6). Três cilindros de resina composta foram obtidos por dente. Após, as amostras foram submetidas ao ensaio de microcisalhamento e as médias abalisadas estatisticamente (Anova, p<0.05). O adesivo TN apresentou valores superiores e a RU ao esmalte foi maior para os dois adesivos.

Influência do uso do Papacárie® nas propriedades de sistemas adesivos / Influence of Papacárie® application on adhesive systems properties

O objetivo do estudo foi avaliar o efeito de um método químico-mecânico (Papacárie) de remoção de cárie dentinária sobre sistemas adesivos. Avaliou-se a influência de vestígios do Papacárie na qualidade adesiva de restaurações de resina composta micro-híbrida, utilizando-se um adesivo de quinta geração e um autocondicionante. Não foi observada diferença estatisticamente significante entre os quatro grupos testados. Em seguida, foi analisada a influência do Papacárie na microdureza de um sistema de quinta geração. Também neste experimento ficou demonstrado que vestígios do Papacárie não foram capazes de comprometer a dureza do sistema adesivo.

Influence of pulse repetition rate of Er:YAG laser and dentin depth on tensile bond strength of dentin-resin interface.

The study evaluated the in vitro influence of pulse-repetition rate of Er:YAG laser and dentin depth on tensile bond strength of dentin-resin interface. Dentin surfaces of buccal or lingual surfaces from human third molars were submitted to tensile test in different depths (superficial, 1.0 and 1.5 mm) of the same dental area, using the same sample. Surface treatments were acid conditioning solely (control) and Er:YAG laser irradiation (80 mJ) followed by acid conditioning, with different pulse-repetition rates (1, 2, 3, or 4 Hz). Single bond/Z-250 system was used. The samples were stored in distilled water at 37 degrees C for 24 h, and then the first test (superficial dentine) was performed. The bond failures were analyzed. Following, the specimens were identified, grounded until 1.0- and 1.5-mm depths, submitted again to the treatments and to the second and, after that, to third-bond tests on a similar procedure and failure analysis. ANOVA and Tukey test demonstrated a significant difference (p < 0.001) for treatment and treatment x depth interaction (p < 0.05). The tested depths did not show influence (p > 0.05) on the bond strength of dentin-resin interface. It may be concluded that Er:YAG laser with 1, 2, 3, or 4 Hz combined with acid conditioning did not increase the resin tensile bond strength to dentin, regardless of dentin depth.

Tensile bond strength of glass fiber posts luted with different cements.

Proper selection of the luting agent is fundamental to avoid failure due to lack of retention in post-retained crowns. The objective of this study was to investigate the tensile bond strength and failure mode of glass fiber posts luted with different cements. Glass fiber posts were luted in 40 mandibular premolars, divided into 4 groups (n = 10): Group 1--resin-modified glass ionomer RelyX Luting; Group 2--resin-modified glass ionomer Fuji Plus; Group 3--resin cement RelyX ARC; Group 4--resin cement Enforce. Specimens were assessed by tensile strength testing and light microscopy analysis for observation of failure mode. The tensile bond strength values of each group were compared by ANOVA and Tukey test. The significance level was set at 5%. The failure modes were described as percentages. The following tensile strength values were obtained: Group 1--247.6 N; Group 2--256.7 N; Group 3--502.1 N; Group 4--477.3 N. There was no statistically significant difference between Groups 1 and 2 or between Groups 3 and 4, yet the resin cements presented significantly higher tensile bond strength values than those presented by the glass ionomer cements. Group 1 displayed 70% of cohesive failures, whereas Groups 2, 3 and 4 exhibited 70% to 80% of adhesive failures at the dentin-cement interface. We concluded that resin cements and glass ionomer cements are able to provide clinically sufficient retention of glass fiber posts, and that glass ionomer cements may be especially indicated when the application of adhesive techniques is difficult.

Bond strength of adhesive systems to human tooth enamel.

The purpose of this study was to evaluate in vitro three adhesive systems: a total etching single-component system (G1 Prime & Bond 2.1), a self-etching primer (G2 Clearfil SE Bond), and a self-etching adhesive (G3 One Up Bond F), through shear bond strength to enamel of human teeth, evaluating the type of fracture through stereomicroscopy, following the ISO guidance on adhesive testing. Thirty sound premolars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin, polished up to 600-grit sandpapers, and randomly assigned to three experimental groups (n = 20). Composite resin cylinders were added to the tested surfaces. The specimens were kept in distilled water (37 degrees C/24 h), thermocycled for 500 cycles (5 degrees C-55 degrees C) and submitted to shear testing at a crosshead speed of 0.5 mm/min. The type of fracture was analyzed under stereomicroscopy and the data were submitted to Anova, Tukey and Chi-squared (5%) statistical analyses. The mean adhesive strengths were G1: 18.13 +/- 6.49 MPa, (55% of resin cohesive fractures); G2: 17.12 +/- 5.80 MPa (90% of adhesive fractures); and G3: 10.47 +/- 3.14 MPa (85% of adhesive fractures). In terms of bond strength, there were no significant differences between G1 and G2, and G3 was significantly different from the other groups. G1 presented a different type of fracture from that of G2 and G3. In conclusion, although the total etching and self-etching systems presented similar shear bond strength values, the types of fracture presented by them were different, which can have clinical implications.

Tensile bond strength of self-etching versus total-etching adhesive systems under different dentinal substrate conditions.

The use of acid etchants to produce surface demineralization and collagen network exposure, allowing adhesive monomers interdiffusion and consequently the formation of a hybrid layer, has been considered the most efficient mechanism of dentin bonding. The aim of this study was to compare the tensile bond strength to dentin of three adhesive systems, two self-etching ones (Clearfil SE Bond--CSEB and One Up Bond F--OUBF) and one total-etching one (Single Bond--SB), under three dentinal substrate conditions (wet, dry and re-wet). Ninety human, freshly extracted third molars were sectioned at the occlusal surface to remove enamel and to form a flat dentin wall. The specimens were restored with composite resin (Filtek Z250) and submitted to tensile bond strength testing (TBS) in an MTS 810. The data were submitted to two-way ANOVA and Tukey's test (p = 0.05). Wet dentin presented the highest TBS values for SB and CSEB. Dry dentin and re-wet produced significantly lower TBS values when using SB. OUBF was not affected by the different conditions of the dentin substrate, producing similar TBS values regardless of the surface pretreatments.

Bond strength of adhesive systems to human tooth enamel

The purpose of this study was to evaluate in vitro three adhesive systems: a total etching single-component system (G1 Prime & Bond 2.1), a self-etching primer (G2 Clearfil SE Bond), and a self-etching adhesive (G3 One Up Bond F), through shear bond strength to enamel of human teeth, evaluating the type of fracture through stereomicroscopy, following the ISO guidance on adhesive testing. Thirty sound premolars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin, polished up to 600-grit sandpapers, and randomly assigned to three experimental groups (n = 20). Composite resin cylinders were added to the tested surfaces. The specimens were kept in distilled water (37°C/24 h), thermocycled for 500 cycles (5°C-55°C) and submitted to shear testing at a crosshead speed of 0.5 mm/min. The type of fracture was analyzed under stereomicroscopy and the data were submitted to Anova, Tukey and Chi-squared (5 percent) statistical analyses. The mean adhesive strengths were G1: 18.13 ± 6.49 MPa, (55 percent of resin cohesive fractures); G2: 17.12 ± 5.80 MPa (90 percent of adhesive fractures); and G3: 10.47 ± 3.14 MPa (85 percent of adhesive fractures). In terms of bond strength, there were no significant differences between G1 and G2, and G3 was significantly different from the other groups. G1 presented a different type of fracture from that of G2 and G3. In conclusion, although the total etching and self-etching systems presented similar shear bond strength values, the types of fracture presented by them were different, which can have clinical implications.

O objetivo deste estudo foi avaliar in vitro três sistemas adesivos: um monocomponente com condicionamento ácido total (G1 Prime & Bond 2.1), um "primer" autocondicionante (G2 Clearfil SE Bond) e um adesivo autocondicionante (G3 One Up Bond F), através de resistência ao cisalhamento ao esmalte de dentes humanos, avaliando o tipo de fratura por estereomicroscopia, seguindo as normas ISO para testes adesivos. Trinta pré-molares hígidos foram seccionados ao meio em sentido mésio-distal, incluídos em resina acrílica, polidos até lixa d'água de granulação 600 e aleatoriamente divididos em três grupos (n = 20). Cilindros de resina composta foram adicionados às superfícies de teste. Os espécimes foram armazenados em água destilada (37°C/24 h), termociclados por 500 ciclos (5°C-55°C) e submetidos ao teste de cisalhamento com velocidade de 0,5 mm/min, sendo o tipo de fratura analisado sob estereomicroscopia e os dados submetidos à análise estatística Anova, Tukey e Qui-quadrado (5 por cento). As médias de resistência adesiva foram: G1: 18,13 ± 6,49 MPa, (55 por cento de fraturas coesivas em resina); G2: 17,12 ± 5,80 MPa (90 por cento de fraturas adesivas) e G3 10,47 ± 3,14 MPa (85 por cento de fraturas adesivas). Em termos de resistência adesiva, não houve diferenças significantes entre G1 e G2, tendo G3 apresentado diferença significante em relação aos demais grupos. G1 apresentou tipo de fratura diferente de G2 e G3. Em conclusão, apesar de os sistemas adesivos com condicionamento ácido total e "primer" autocondicionante terem apresentado valores de resistência adesiva similares, o tipo de fratura apresentado por eles foi diferente, o que pode ter implicações clínicas.

Tensile bond strength of self-etching versus total-etching adhesive systems under different dentinal substrate conditions

The use of acid etchants to produce surface demineralization and collagen network exposure, allowing adhesive monomers interdiffusion and consequently the formation of a hybrid layer, has been considered the most efficient mechanism of dentin bonding. The aim of this study was to compare the tensile bond strength to dentin of three adhesive systems, two self-etching ones (Clearfil SE Bond - CSEB and One Up Bond F - OUBF) and one total-etching one (Single Bond - SB), under three dentinal substrate conditions (wet, dry and re-wet). Ninety human, freshly extracted third molars were sectioned at the occlusal surface to remove enamel and to form a flat dentin wall. The specimens were restored with composite resin (Filtek Z250) and submitted to tensile bond strength testing (TBS) in an MTS 810. The data were submitted to two-way ANOVA and Tukey's test (p = 0.05). Wet dentin presented the highest TBS values for SB and CSEB. Dry dentin and re-wet produced significantly lower TBS values when using SB. OUBF was not affected by the different conditions of the dentin substrate, producing similar TBS values regardless of the surface pretreatments.

O uso de condicionadores ácidos para desmineralizar a superfície dental e expor a rede de fibras colágenas para interdifusão dos monômeros adesivos e conseqüente formação da camada híbrida tem sido considerado o mais eficiente mecanismo de adesão dos agentes de união. O objetivo deste estudo foi comparar a resistência de união à dentina de três sistemas adesivos, dois autocondicionantes (Clearfil SE Bond - CSEB e One Up Bond F - OUBF) e um de condicionamento total (Single Bond - SB), sob três diferentes condições de substrato dentinário (úmido, seco e reidratado). Noventa terceiros molares humanos recém-extraídos foram cortados na superfície oclusal, para se remover o esmalte e formar uma parede plana de dentina. Os espécimes foram restaurados com resina composta (Filtek Z250) e submetidos ao teste de resistência de união à tração (TBS) em uma MTS 810. As médias foram submetidas à ANOVA a dois critérios e ao teste de Tukey (p = 0,05). A dentina úmida apresentou os maiores valores de TBS para os sistemas adesivos SB e CSEB. A dentina seca e a reidratada apresentaram TBS significativamente menor quando foi empregado SB. OUBF não apresentou resultados influenciados pela condição do substrato dentinário, tendo produzido TBS similares para os diferentes tratamentos de superfície.

Tensile bond strength of glass fiber posts luted with different cements

Proper selection of the luting agent is fundamental to avoid failure due to lack of retention in post-retained crowns. The objective of this study was to investigate the tensile bond strength and failure mode of glass fiber posts luted with different cements. Glass fiber posts were luted in 40 mandibular premolars, divided into 4 groups (n = 10): Group 1 - resin-modified glass ionomer RelyX Luting; Group 2 - resin-modified glass ionomer Fuji Plus; Group 3 - resin cement RelyX ARC; Group 4 - resin cement Enforce. Specimens were assessed by tensile strength testing and light microscopy analysis for observation of failure mode. The tensile bond strength values of each group were compared by ANOVA and Tukey test. The significance level was set at 5 percent. The failure modes were described as percentages. The following tensile strength values were obtained: Group 1 - 247.6 N; Group 2 - 256.7 N; Group 3 - 502.1 N; Group 4 - 477.3 N. There was no statistically significant difference between Groups 1 and 2 or between Groups 3 and 4, yet the resin cements presented significantly higher tensile bond strength values than those presented by the glass ionomer cements. Group 1 displayed 70 percent of cohesive failures, whereas Groups 2, 3 and 4 exhibited 70 percent to 80 percent of adhesive failures at the dentin-cement interface. We concluded that resin cements and glass ionomer cements are able to provide clinically sufficient retention of glass fiber posts, and that glass ionomer cements may be especially indicated when the application of adhesive techniques is difficult.

A seleção adequada do agente cimentante é essencial para evitar falhas por perda de retenção em coroas retidas por núcleos. O objetivo deste estudo foi investigar a resistência à tração e o tipo de falha de pinos de fibra de vidro cimentados com diferentes materiais. Cimentaram-se pinos de fibra de vidro em 40 pré-molares inferiores, divididos em 4 grupos (n = 10): Grupo 1 - ionômero de vidro modificado por resina RelyX Luting; Grupo 2 - ionômero de vidro modificado por resina Fuji Plus; Grupo 3 - cimento resinoso RelyX ARC; Grupo 4 - cimento resinoso Enforce. Avaliaram-se os espécimes por teste de resistência à tração e análise por microscopia óptica para observação do tipo de falha. Compararam-se os valores de resistência à tração de cada grupo por análise de variância e teste de Tukey, sendo que o nível de significância estabelecido foi de 5 por cento. Descreveram-se os tipos de falha na forma de porcentagens. Os valores de resistência à tração obtidos foram: Grupo 1 - 247,6 N; Grupo 2 - 256,7 N; Grupo 3 - 502,1 N; Grupo 4 - 477,3 N. Não houve diferença estatisticamente significativa entre os Grupos 1 e 2 ou entre os Grupos 3 e 4, porém os cimentos resinosos apresentaram valores de resistência à tração significativamente maiores do que os apresentados pelos cimentos ionoméricos. O Grupo 1 exibiu 70 por cento de falhas coesivas, enquanto os Grupos 2, 3 e 4 apresentaram 70 por cento a 80 por cento de falhas adesivas na interface dentina-cimento. Concluiu-se que os cimentos resinosos e ionoméricos são capazes de proporcionar retenção clinicamente suficiente de pinos de fibras de vidro, e que os cimentos ionoméricos podem ser indicados principalmente quando houver dificuldades de aplicar técnicas adesivas.