Preservation of immunoexpression of type I collagen, BSP and BMP4 in the dentin-pulp complex of head and neck cancer patients after radiotherapy.

This study tested the hypothesis that head and neck radiotherapy (HNRT) impacts the immunoexpression of type I collagen, bone sialoprotein (BSP) and bone morphogenetic protein 4 (BMP4), thereby leading to micromorphological changes in the dentin-pulp complex (DPC), and promoting the onset and progression of radiation caries (RC). Twenty-two demineralized sections of carious teeth (a group of 11 irradiated teeth and a control group of 11 non-irradiated teeth) extracted from 19 head and neck cancer patients were analyzed by conventional optical microscopy and immunohistochemistry to investigate the micromorphology (cellular layer hierarchy, blood vessels, odontoblasts, fibroblasts, extracellular matrix, calcification, necrosis, reactionary dentin formation, and chronic inflammation), and the patterns of staining/immunolocalization of type I collagen, BSP and BMP4 in the dental pulp of irradiated and control samples. No significant differences attributable to the direct impact of radiotherapy were detected in DPC micromorphology between the groups. In addition, the patterns of immunohistochemical staining and immunolocalization of the proteins studied did not differ between the irradiated and the control samples for type I collagen, BSP or BMP4. This study rejected the hypothesis that HNRT directly damages dentition by changing the organic components and the microstructure of the DPC, ultimately leading to RC.

Preservation of immunoexpression of type I collagen, BSP and BMP4 in the dentin-pulp complex of head and neck cancer patients after radiotherapy

Abstract This study tested the hypothesis that head and neck radiotherapy (HNRT) impacts the immunoexpression of type I collagen, bone sialoprotein (BSP) and bone morphogenetic protein 4 (BMP4), thereby leading to micromorphological changes in the dentin-pulp complex (DPC), and promoting the onset and progression of radiation caries (RC). Twenty-two demineralized sections of carious teeth (a group of 11 irradiated teeth and a control group of 11 non-irradiated teeth) extracted from 19 head and neck cancer patients were analyzed by conventional optical microscopy and immunohistochemistry to investigate the micromorphology (cellular layer hierarchy, blood vessels, odontoblasts, fibroblasts, extracellular matrix, calcification, necrosis, reactionary dentin formation, and chronic inflammation), and the patterns of staining/immunolocalization of type I collagen, BSP and BMP4 in the dental pulp of irradiated and control samples. No significant differences attributable to the direct impact of radiotherapy were detected in DPC micromorphology between the groups. In addition, the patterns of immunohistochemical staining and immunolocalization of the proteins studied did not differ between the irradiated and the control samples for type I collagen, BSP or BMP4. This study rejected the hypothesis that HNRT directly damages dentition by changing the organic components and the microstructure of the DPC, ultimately leading to RC.

The impact of head and neck radiotherapy on the dentine-enamel junction: a systematic review

BACKGROUND: Radiotherapy is widely used in contemporary head and neck cancer treatment protocols. The abil-ity of head and neck radiotherapy (HNRT) to cause direct radiogenic destruction to the teeth is one of the most controversial topics in the field of oral oncology. Therefore, this systematic review aimed to investigate ionising radiation as an independent factor for physical and chemical changes on the dentine-enamel junction (DEJ), a piv-otal dental topography for the onset and progression of radiation-related caries (RRC) and enamel delamination. MATERIAL AND METHODS: Systematic searches were conducted on three databases: Scopus, MEDLINE (Via PubMed) and Embase (Elsevier). Laboratory studies evaluating the effects of simulated or in vivo HNRT on the DEJ were included. The GRADE tool adapted for in vitro studies was used to assess the methodological quality. RESULTS: Of the 154 initially selected studies, eight met the inclusion criteria, from which five studies were graded as high quality of evidence, two studies were graded as moderate quality and one as low quality. Two studies did not demonstrate DEJ alterations following HNRT while the other six articles described several organic and inorganic changes in the DEJ of irradiated teeth samples. These radiogenic events were mostly detected through micro and na-noindentation, Raman micro-spectroscopy, confocal microscopy, Western blotting and optical coherence tomography. CONCLUSIONS: HNRT may have a negative impact on the physical and chemical aspects of the DEJ, predisposing can-cer patients to RRC and enamel delamination

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Solubilidade de cimentos de ionômero de vidro indicados para o Tratamento Restaurador Atraumático / Solubility of Glass Ionomer Cements Indicated for Atraumatic Restorative Treatment

O objetivo deste estudo foi avaliar e comparar a solubilidade de quatro cimentos de ionômero de vidro disponíveis comercialmente e indicados para a técnica do Tratamento Restaurador Atraumático (ART), quando expostos ao meio ácido (tampão lactato) e neutro (água). Para cada cimento de ionômero de vidro, 8 corpos-de-prova foram obtidos em matrizes plásticas com dimensões especificadas pela ISO 7849. Dois corpos-de-prova suspensos por fios de aço inoxidável dentro de cada frasco "pesa filtro", foram imersos em 50 mL de água deionizada ou 50 mL de solução tampão lactato (pH 2,74), preparada segundo as recomendações da ISO 9917. Para cada série de experimento, outro frasco "pesa filtro" contendo apenas os 50mL de solução tampão lactato ou água destilada foi usado como controle. Nestas condições, os frascos "pesa filtro" foram armazenados sob temperatura de 37oC, durante 23 horas. O conteúdo solúvel para cada par de corpos-de-prova, em porcentagem, foi calculado seguindo a especificação da ISO 7849. O cimento de ionômero de vidro Ketac Molar Easymix apresentou valor percentual de solubilidade significantemente (p< 0,05) menor tanto no tampão lactato (8,70%) como em água (0,06%), em relação aos demais materiais Vitro Molar (12,17% e 0,10%), Vidrion R (13,29% e 0,26%) e Maxxion R (30,07% e 1,85%). Os quatro cimentos de ionômero de vidro foram significativamente mais solúveis em meio ácido do que em água e o material Ketac Molar Easymix apresentou menor solubilidade em ácido e água.

This study evaluated and compared the solubility of four commercially available glass ionomer cements indicated for Atraumatic Restorarative Treatment (ART), after immersion in acid and water environments. Eight specimens for each brand were obtained using a plastic ring mold with dimensions specified by ISO 7849. Two specimens of the same material were suspended by a platinum wire inside weighing bottles containing 50 mL of water or a lactate buffer solution (pH=2.74) prepared according to ISO 9917. Simultaneously, a clean weighing bottle with either lactate buffer or distilled water was used as a blank estimation for each specimen pair. The weighing bottles were stored at 37oC for 23 hours. The leachable content of each specimen pair in acid or water was calculated as a percentage by mass, according to ISO 7849. Ketac Molar Easymix revealed the statistically lowest solubility in acid (8.70%) and neutral water environments (0.06%) compared to Vitro Molar (12.17% and 0.10%), Vidrion R (13.29% and 0.26%) and Maxxion R (30.07% e 1.85%). All glass ionomer cements showed statically higher solubility in acid compared to water. Ketac Easy Mix cement presented the lowest solubility in both environments.

Effect of replacing a component of a self-etch adhesive by chlorhexidine on bonding to dentin.

The purpose of this study was to evaluate the effect of replacing a component of the self-etch adhesive Adper Scotchbond SE (liquid A + liquid B) by 2% chlorhexidine (CHX) on bond strength to dentin after 1 day, 3 months or 6 months of water storage. Eight human teeth were sectioned to expose a flat dentin surface and were then randomly assigned to 2 groups. In the control group, the dentin surfaces were treated with the adhesive according to the manufacturer's instructions. In the experimental group, liquid A was replaced by 2% CHX. Next, a 6-mm-high resin composite block was incrementally built on the bonded surfaces. The restored teeth were then sectioned to produce stick-shaped specimens (cross-sectional area - 0.8 mm2). The microtensile bond strength (µTBS) was recorded, and the failure modes were assessed. Data were analyzed by two-way repeated measures ANOVA (α=0.05). Four additional teeth were processed in order to conduct a micromorphological analysis of the resin-dentin interface. The µTBS values did not significantly decrease after water storage in either the control or the experimental group, whose values did not differ significantly irrespective of storage time. The morphological aspect of the bonding interface appears not to have been affected by CHX. A higher incidence of cohesive failures within the adhesive and mixed failures (cohesive within adhesive and resin composite) was observed for both groups. It may be concluded that dentin pre-treatment with 2% CHX did not influence significantly the bonding performance of the evaluated adhesive.

Effect of Replacing a Component of a Self-Etch Adhesive by Chlorhexidine on Bonding to Dentin

The purpose of this study was to evaluate the effect of replacing a component of the self-etch adhesive Adper Scotchbond SE (liquid A + liquid B) by 2% chlorhexidine (CHX) on bond strength to dentin after 1 day, 3 months or 6 months of water storage. Eight human teeth were sectioned to expose a flat dentin surface and were then randomly assigned to 2 groups. In the control group, the dentin surfaces were treated with the adhesive according to the manufacturer's instructions. In the experimental group, liquid A was replaced by 2% CHX. Next, a 6-mm-high resin composite block was incrementally built on the bonded surfaces. The restored teeth were then sectioned to produce stick-shaped specimens (cross-sectional area - 0.8 mm2). The microtensile bond strength (µTBS) was recorded, and the failure modes were assessed. Data were analyzed by two-way repeated measures ANOVA (α=0.05). Four additional teeth were processed in order to conduct a micromorphological analysis of the resin-dentin interface. The µTBS values did not significantly decrease after water storage in either the control or the experimental group, whose values did not differ significantly irrespective of storage time. The morphological aspect of the bonding interface appears not to have been affected by CHX. A higher incidence of cohesive failures within the adhesive and mixed failures (cohesive within adhesive and resin composite) was observed for both groups. It may be concluded that dentin pre-treatment with 2% CHX did not influence significantly the bonding performance of the evaluated adhesive.

O objetivo deste estudo foi o de avaliar o efeito da substituição de um componente do adesivo autocondicionante Adper Scotchbond SE (líquido A + líquido B) por clorexidina (CHX) a 2% na resistência da união à dentina após 1 dia, 3 meses ou 6 meses de armazenamento em água. Oito dentes humanos foram seccionados para expor uma superfície plana de dentina e, em seguida, foram aleatoriamente divididos em dois grupos. No grupo controle, as superfícies de dentina foram tratadas com o adesivo de acordo com as instruções do fabricante. No grupo experimental, o líquido A foi substituído por CHX a 2%. Em seguida, um bloco de resina composta com 6 mm de altura foi construído sobre a superfície de união. Os dentes restaurados foram então seccionados para produzir espécimes em forma de palito (área transversal - 0,8 mm2). A resistência da união à microtração (µT) foi mensurada e os padrões de fratura avaliados. Os dados foram analisados por meio de teste de ANOVA dois critérios de medidas repetidas (α=0,05). Quatro dentes adicionais foram processados a fim de realizar uma análise micromorfológica da interface resina-dentina. Os valores de µT não diminuíram significativamente após armazenamento em água em ambos os grupos controle e experimental, cujos valores não diferiram significativamente entre si independentemente do tempo de armazenamento. O aspecto morfológico da interface adesiva parece não ter sido afetado pela CHX. Uma maior incidência de falhas coesivas no adesivo e falhas mistas (coesivas no adesivo e na resina composta) foi observada em ambos os grupos. Pode-se concluir que o pré-tratamento da dentina com CHX a 2% não influenciou significativamente o desempenho do adesivo avaliado.

Bond strength and interfacial micromorphology of etch-and-rinse and self-adhesive resin cements to dentin.

PURPOSE: To evaluate the microtensile bond strength and interfacial micromorphology of indirect composite restorations to dentin using three commercial resin cements after 24 hours and 30 days of water storage. MATERIALS AND METHODS: The medium dentin of third human molars was exposed (N = 30, n = 10 per group). Three commercial resin cements were used to cement indirect resin composite restorations to dentin: the auto-cured C&B Cement/All Bond 2, the dual-cured RelyX ARC/Adper Single Bond 2, and the self-adhesive dual-cured RelyX Unicem. Teeth were sectioned after water storage at 37°C (24 hours and 30 days) to obtain beams with a bonded area of 0.8 mm(2) . The specimens were tested in a universal testing machine at a 0.5 mm/min crosshead speed. Scanning electron microscopic fractographic and interfacial micromorphology analyses were performed. Data were analyzed using two-way ANOVA and Tukey's test (α= 0.05). RESULTS: Mean bond strength (MPa) after 24 hours: C&B Cement 19.5 ± 3.8, RelyX ARC 40.8 ± 9.4, RelyX Unicem 31.3 ± 7.4; after 30 days: C&B Cement 24.5 ± 5.1, RelyX ARC 44.2 ± 8.5, RelyX Unicem 28.3 ± 7.1. The mean bond strengths of both dual-cure cements were significantly higher than that obtained with C&B Cement after 24 hours. A significant increase in the bond strength of C&B Cement was verified after 30 days, reaching values statistically equivalent to those produced by RelyX Unicem and RelyX ARC. The self-adhesive cement preserved the same level of bond strength after 30 days. Fractographic analysis revealed a prevalence of cohesive fractures in the hybrid layer for C&B Cement, mixed (cohesive in the cement, hybrid layer, and adhesive) for RelyX ARC, and cohesive in the cement for RelyX Unicem. No distinguishable hybrid layer or resin tags were observed in the interaction of RelyX Unicem with dentin. CONCLUSIONS: The particular interaction of each cement with dentin results in specific bond strength and failure patterns that varied among groups in both evaluation times. Even though the self-adhesive cement tested exhibited no authentic hybrid layer, it was able to promote reliable adhesion with the underlying dentin.

Planejamento como instrumento de sucesso no restabelecimento do sorriso / Planning as a success tool for recovery of the smile

Dentes anteriores manchados e desgastados podem comprometer a beleza de um sorriso. Independentemente da forma escolhida para restabelecer as características desejadas, o conhecimento da anatomia e proporção dental é fundamental para o planejamento do caso. Além disso, é importante que a projeção do resultado possa ser provada e confirmada antecipadamente, estimulando colaboração e confiança do paciente e segurança na execução, para o profissional. Este artigo relata o planejamento e a previsibilidade de um caso clínico de restabelecimento do sorriso, em que se utiliza resina composta nanoparticulada...

Stained, worn anterior teeth may jeopardize the beauty of a smile. Knowledge about anatomy and tooth proportions is essential for treatment planning, regardless of the technique chosen to restore the desired esthetic characteristics. It is also important that the results of the planning can be checked and approved in advance. This procedure not only encourages the patient to authorize the treatment but also allows for a greater confidence on the treatment outcome. This paper reports the planning and predictabilty of smile recovery using a nanofilled composite resin...

Recuperação da cor em dente escurecido: relato de caso clínico / Shade recovery of anterior discolored teeth: a clinical report

Dentes anteriores escurecidos comprometem a estética do sorriso. Etiologicamente, a alteração de cor, de um ou mais dentes isolados nos arcos dentários está relacionada a trauma mecânico e/ou tratamento endodôntico inadequado. A cor é uma das características mais marcantes dos dentes e pode ser interpretada por meio de três parâmetros: matiz, croma e valor. A visão humana possui grande número de células sensíveis à luminosidade. Assim, além da mudança cromática, a alteração mais perceptível nos dentes escurecidos é a perda de valor. Este artigo mostra dois casos clínicos com resoluções diferentes para recuperação da cor de dentes escurecidos no setor ântero-superior: clareamento e faceta direta de resina composta utilizando cores opacas e de alto valor.

Anterior discolored teeth jeopardize smile esthetics. Etiologically, discoloration of one ormore isolated teeth in dental arches is related to mechanical trauma and/or inadequate en¬dodontic treatment. Color is a unique tooth characteristic, and can be interpreted by three parameters: hue, chroma and value. The human eye has great quantity of cells that are sensitive to light intensity. Hence, although chroma changes, lower values tend to be most frequently noticed. This paper describes two clinical cases with different approaches for the esthetic recovery of upper anterior discolored teeth: bleaching and confection of direct composite resin veneers with opaque and high value shades.

Microtensile bond strength test and failure analysis to assess bonding characteristics of different adhesion approaches to ground versus unground enamel.

This study evaluated the bonding characteristics to ground and unground enamel obtained with different strategies. For this purpose, 24 sound third-molars were bisected mesiodistally to obtain tooth halves. A flat enamel area was delimited in the tooth sections, which were randomly distributed into 8 groups (n=6), according to the enamel condition (ground and unground) and adhesive system (Adper Single Bond 2 - SB2; Adper Prompt L-Pop - PLP; Adper Prompt - AD; Clearfil SE Bond - SE). Each system was applied according manufacturers' instructions and a 6-mm-high resin composite "crown" was incrementally built up on bonded surfaces. Hourglass-shaped specimens with 0.8 mm(2) cross-section were produced. Microtensile bond strength (µTBS) was recorded and the failure patterns were classified. Results were analyzed by two-way ANOVA and Tukey's test (α=0.05). There were no statistically significant differences among the µTBS values of SB2, PLP and AD (p>0.05). SE values were significantly lower (p0.05). There was prevalence of cohesive failure within enamel, adhesive system and resin composite for SB2. The self-etch systems produced higher incidence of cohesive failures in the adhesive system. Enamel condition did not determine significant differences on bonding characteristics for the same bonding system. In conclusion, the bonding systems evaluated in this study resulted in specific µTBS and failure patterns due to the particular interaction with enamel.

Microtensile bond strength test and failure analysis to assess bonding characteristics of different adhesion approaches to ground versus unground enamel

This study evaluated the bonding characteristics to ground and unground enamel obtained with different strategies. For this purpose, 24 sound third-molars were bisected mesiodistally to obtain tooth halves. A flat enamel area was delimited in the tooth sections, which were randomly distributed into 8 groups (n=6), according to the enamel condition (ground and unground) and adhesive system (Adper Single Bond 2 - SB2; Adper Prompt L-Pop - PLP; Adper Prompt - AD; Clearfil SE Bond - SE). Each system was applied according manufacturers' instructions and a 6-mm-high resin composite "crown" was incrementally built up on bonded surfaces. Hourglass-shaped specimens with 0.8 mm² cross-section were produced. Microtensile bond strength (μTBS) was recorded and the failure patterns were classified. Results were analyzed by two-way ANOVA and Tukey's test (α=0.05). There were no statistically significant differences among the μTBS values of SB2, PLP and AD (p>0.05). SE values were significantly lower (p0.05). There was prevalence of cohesive failure within enamel, adhesive system and resin composite for SB2. The self-etch systems produced higher incidence of cohesive failures in the adhesive system. Enamel condition did not determine significant differences on bonding characteristics for the same bonding system. In conclusion, the bonding systems evaluated in this study resulted in specific μTBS and failure patterns due to the particular interaction with enamel.

Este estudo avaliou a união ao esmalte íntegro e desgastado obtida com diferentes estratégias. Para tanto, 24 terceiros molares hígidos foram seccionados ao meio. Um plano de esmalte foi delimitado nos fragmentos de dente, aleatoriamente distribuídos em 8 grupos (n=6) conforme a condição do esmalte (íntegro ou desgastado) e o adesivo (Adper Single Bond 2: SB2; Adper Prompt L-Pop: PLP; Adper Prompt: AD; Clearfil SE Bond: SE). Estes foram aplicados seguindo recomendações dos fabricantes e uma "coroa" de compósito (altura - 6 mm) incrementalmente construída. Espécimes (ampulheta/secção transversal - 0,8 mm²) foram confeccionados. O ensaio de resistência da união à micro-tração (RUµT) foi realizado e os padrões de fratura classificadas. Os resultados analisados pela ANOVA (dois fatores) e teste de Tukey (α=0,05). Os valores de RUµT do SB2, PLP e AD não foram significativamente diferentes entre si (p>0,05); SE foi inferior (p0,05). Houve prevalência de fratura no esmalte, adesivo e compósito no SB2. Nos adesivos autocondicionantes, predominou a fratura no adesivo. A condição do esmalte não influenciou significativamente as características da união, considerando o mesmo adesivo. Em conclusão, os adesivos apresentaram RUµT e padrões de fratura específicos, devido a forma de interação com o esmalte.

Adhesive systems: important aspects related to their composition and clinical use

This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and infuence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classifed according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specifc acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and defciencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplifed ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

Bond strength of a resin cement to dentin using the resin coating technique.

The aim of this study was to evaluate the bond strength of a resin cement to dentin using different adhesive systems (AS) in the presence or absence of a low-viscosity composite liner (Protect Liner F - PLF) applied over the bonded dentin. The adhesive systems selected were: AdheSE/Vivadent (AD); Clearfil Protect Bond/Kuraray (CP); One-Up Bond F/Tokuyama (OU); Single Bond/3M ESPE (SB); Tyrian SPE/One-Step Plus/Bisco (TY); Xeno III/Dentsply (XE) and Unifil Bond/GC (UN). After removing the labial and lingual enamel surfaces of bovine incisors, dentin fragments were prepared and randomly divided into 15 groups (n = 8). The dentin substrates were bonded with the AS and the PLF was applied or not before application of the resin cement (Panavia F, Kuraray). In the control group, the ED Primer (ED) and the resin cement without PLF were used. The AS, PLF and resin cement tested were used according to the manufacturers' instructions, and all treated dentin surfaces were temporized. After water storage for one week, three cylinders of resin cement were applied to each bonded dentin surface, using tygon tubing molds. The specimens were subjected to micro-shear testing and the data were statistically analyzed (two-way ANOVA, Tukey and Dunnett tests, p < 0.05). The observed mean shear bond strengths in MPa were: ED: 20.2 +/- 2.3; AD: 30.3 +/- 6.5; CP: 25.3 +/- 4.4; OU: 28.3 +/- 6.6; SB: 25.6 +/- 6.9; TY: 24.5 +/- 2.5; XE: 17.3 +/- 3.4; UN: 28.4 +/- 6.2; AD+PLF: 32.8 +/- 4.1; CP+PLF: 29.9 +/- 3.9; OU+PLF: 34.1 +/- 4.1; SB+PLF: 29.5 +/- 8.2; TY+PLF: 29.2 +/- 3.9; XE+PLF: 32.8 +/- 6.7; UN+PLF: 32.2 +/- 4.5. The bond strength of the resin cement to dentin using the tested AS was increased when the low-viscosity composite liner was applied.

Correlation between margin fit and microleakage in complete crowns cemented with three luting agents

Microleakage can be related to margin misfit. Also, traditional microleakage techniques are time-consuming. This study evaluated the existence of correlation between in vitro margin fit and a new microleakage technique for complete crowns cemented with 3 different luting agents. Thirty human premolars were prepared for full-coverage crowns with a convergence angle of 6 degrees, chamfer margin of 1.2 mm circumferentially, and occlusal reduction of 1.5 mm. Ni-Cr cast crowns were cemented with either zinc phosphate (ZP) (S.S. White), resin-modified glass-ionomer (RMGI) (Rely X Luting Cement) or a resin-based luting agent (RC) (Enforce). Margin fit (seating discrepancy and margin gap) was evaluated according to criteria in the literature under microscope with 0.001 mm accuracy. After thermal cycling, crowns were longitudinally sectioned and microleakage scores at tooth-cement interface were obtained and recorded at ×100 magnification. Margin fit parameters were compared with the one-way ANOVA test and microleakage scores with Kruskal-Wallis and Dunn's tests (alpha=0.05). Correlation between margin fit and microleakage was analyzed with the Spearman's test (alpha=0.05). Seating discrepancy and marginal gap values ranged from 81.82 µm to 137.22 µm (p=0.117), and from 75.42 µm to 78.49 µm (p=0.940), respectively. Marginal microleakage scores were ZP=3.02, RMGI=0.35 and RC=0.12 (p<0.001), with no differences between RMGI and RC scores. The correlation coefficient values ranged from -0.27 to 0.30 (p>0.05). Conclusion: Margin fit parameters and microleakage showed no strong correlations; cast crowns cemented with RMGI and RC had lower microleakage scores than ZP cement.

Bond strength of a resin cement to dentin using the resin coating technique

The aim of this study was to evaluate the bond strength of a resin cement to dentin using different adhesive systems (AS) in the presence or absence of a low-viscosity composite liner (Protect Liner F - PLF) applied over the bonded dentin. The adhesive systems selected were: AdheSE/Vivadent (AD); Clearfil Protect Bond/Kuraray (CP); One-Up Bond F/Tokuyama (OU); Single Bond/3M ESPE (SB); Tyrian SPE/One-Step Plus/Bisco (TY); Xeno III/Dentsply (XE) and Unifil Bond/GC (UN). After removing the labial and lingual enamel surfaces of bovine incisors, dentin fragments were prepared and randomly divided into 15 groups (n = 8). The dentin substrates were bonded with the AS and the PLF was applied or not before application of the resin cement (Panavia F, Kuraray). In the control group, the ED Primer (ED) and the resin cement without PLF were used. The AS, PLF and resin cement tested were used according to the manufacturers' instructions, and all treated dentin surfaces were temporized. After water storage for one week, three cylinders of resin cement were applied to each bonded dentin surface, using tygon tubing molds. The specimens were subjected to micro-shear testing and the data were statistically analyzed (two-way ANOVA, Tukey and Dunnett tests, p < 0.05). The observed mean shear bond strengths in MPa were: ED: 20.2 ± 2.3; AD: 30.3 ± 6.5; CP: 25.3 ± 4.4; OU: 28.3 ± 6.6; SB: 25.6 ± 6.9; TY: 24.5 ± 2.5; XE: 17.3 ± 3.4; UN: 28.4 ± 6.2; AD+PLF: 32.8 ± 4.1; CP+PLF: 29.9 ± 3.9; OU+PLF: 34.1 ± 4.1; SB+PLF: 29.5 ± 8.2; TY+PLF: 29.2 ± 3.9; XE+PLF: 32.8 ± 6.7; UN+PLF: 32.2 ± 4.5. The bond strength of the resin cement to dentin using the tested AS was increased when the low-viscosity composite liner was applied.

SEM analysis of the acid-etched enamel patterns promoted by acidic monomers and phosphoric acids

ABSTRACT OBJECTIVE: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35 percent and 34 percent phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. MATERIALS AND METHODS: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34 percent FA, 35 percent FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. RESULTS: For both IN and GR enamel surfaces, the EP of 34 and 35 percent FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. CONCLUSION: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces.

OBJETIVO: Apesar dos sistemas adesivos autocondicionantes (SAA) serem indicados para aplicação no esmalte dental, preocupação tem sido relatada com relação a sua efetividade. O objetivo deste estudo foi avaliar o padrão de condicionamento ácido (PCA) promovido por nove SAA e comparar ao PCA produzido pelo ácido fosfórico (35 por cento e 34 por cento - AF) no esmalte intacto (EI) ou abrasionado (EA). MATERIAIS E MÉTODOS: Vinte e dois terceiros molares humanos foram seccionados nos sentidos mésio-distal e vestíbulo-lingual, e quatro fragmentos dentais foram obtidos a partir de cada dente. Metade dos fragmentos tiveram o esmalte abrasionado com lixas de SiC (600) e a outra metade permaneceu intacta. Os fragmentos foram divididos em 22 grupos, de acordo com a textura da superfície do esmalte (EI e EA) e a técnica de condicionar o esmalte (AF 34 por cento, AF 35 por cento, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer e Xeno III). Os agentes condicionadores foram aplicados nos EI e EA, de acordo com as instruções dos fabricantes. Espécimes tratados com AF foram lavados com água, enquanto os dentes tratados com SAA foram tratados com banhos alternados de álcool e acetona. Os espécimes foram secos, metalizados e observados em microscopia eletrônica de varredura. RESULTADOS: Em ambas as superfícies (EI e EA), o PCA dos AF (34 e 35 por cento) foi mais profundo e homogêneo, quando comparados ao PCA produzido pelos SAA, exceto para o adesivo Tyrian SPE. A ação dos monômeros ácidos dos SAA foi mais efetiva no EA. CONCLUSÃO: A maioria dos SAA é menos agressiva que o ácido fosfórico e seus efeitos condicionadores são reduzidos em superfícies de EI.

Evaluation of mechanical properties of Z250 composite resin light-cured by different methods

Este estudo avaliou algumas propriedades mecânicas da resina composta Z250 usando diferentes métodos de fotoativação. Dez amostras foram preparadas para cada grupo, com diferentes dimensões de acordo com o ensaio. Os métodos de fotoativação foram: a) luz contínua (800mW/cm2-40s); b) luz exponencial (0-800mW/cm2-40s); c) luz intermitente (2s-600mW/cm2; 2s sem luz-80s); d) dupla intensidade (10s-150mW/cm2; 30s-650mW/cm2); e) PAC (1320mW/cm2-3s); f) LED (350mW/cm2-40s). Após 24 ± 1 h, as amostras foram carregadas até fraturar (v=0,5 mm/min.). As propriedades mecânicas foram calculadas e os dados analisados estatisticamente (ANOVA e teste de Tukey 5%). Os resultados mostraram que, para resistência à compressão, os maiores valores foram encontrados com os métodos luz contínua, intermitente, exponencial e dupla intensidade, enquanto que PAC e LED obtiveram os menores valores. Os métodos LED, PAC, luz contínua, exponencial e dupla intensidade, mostraram os maiores valores para resistência à tração diametral, enquanto luz intermitente mostrou os menores valores, que diferiram apenas do LED. Para a resistência flexural, não houve diferença entre os métodos. Já, para o módulo de elasticidade, os maiores valores foram obtidos com LED, luz exponencial, contínua e intermitente, enquanto que PAC e dupla intensidade mostraram os menores valores. As propriedades mecânicas podem ser afetadas pelo método de fotativação utilizado.

Evaluation of mechanical properties of Z250 composite resin light-cured by different methods%Avaliação de propriedades mecânicas da resina composta Z250 fotoativada com diferentes métodos

Este estudo avaliou algumas propriedades mecânicas da resina composta Z250 usando diferentes métodos de fotoativação. Dez amostras foram preparadas para cada grupo, com diferentes dimensões de acordo com o ensaio. Os métodos de fotoativação foram: a) luz contínua (800mW/cm2-40s); b) luz exponencial (0-800mW/cm2-40s); c) luz intermitente (2s-600mW/cm2; 2s sem luz-80s); d) dupla intensidade (10s-150mW/cm2; 30s-650mW/cm2); e) PAC (1320mW/cm2-3s); f) LED (350mW/cm2-40s). Após 24 ± 1 h, as amostras foram carregadas até fraturar (v=0,5 mm/min.). As propriedades mecânicas foram calculadas e os dados analisados estatisticamente (ANOVA e teste de Tukey 5%). Os resultados mostraram que, para resistência à compressão, os maiores valores foram encontrados com os métodos luz contínua, intermitente, exponencial e dupla intensidade, enquanto que PAC e LED obtiveram os menores valores. Os métodos LED, PAC, luz contínua, exponencial e dupla intensidade, mostraram os maiores valores para resistência à tração diametral, enquanto luz intermitente mostrou os menores valores, que diferiram apenas do LED. Para a resistência flexural, não houve diferença entre os métodos. Já, para o módulo de elasticidade, os maiores valores foram obtidos com LED, luz exponencial, contínua e intermitente, enquanto que PAC e dupla intensidade mostraram os menores valores. As propriedades mecânicas podem ser afetadas pelo método de fotativação utilizado

Evaluation of mechanical properties of Z250 composite resin light-cured by different methods.

This study evaluated some mechanical parameters of Z250 composite resin using different light-curing methods. Ten specimens were prepared for each mechanical test group with different dimensions according to the test. Light-curing was performed by: a). continuous light (800mW/cm²-40s); b). exponential light (0-800mW/cm²-40s); c). intermittent light (2s-600mW/cm²; 2s without light-80s); d). stepped light (10s-150mW/cm²; 30s-650mW/cm²); e). PAC (1320mW/cm²-3s); f). LED (350mW/cm²-40s). After 24 ± 1 h, the specimens were loaded at a crosshead speed of 0.5 mm/min until fracture. The mechanical properties were calculated and analyzed by ANOVA and Tukey test (5%). The results showed that the highest compressive strength values were found for the continuous, exponential, intermittent and stepped light methods, whereas PAC and LED obtained the lowest values. LED, stepped light, PAC, exponential and continuous light presented the highest values for diametral tensile strength. The intermittent light showed the lowest value, which was significantly lower than the value obtained for LED only. Flexural strength results were not significantly different between all light-curing methods. Finally, the highest modulus of elasticity values were obtained for LED, exponential, continuous and intermittent light, whereas PAC and stepped light showed the lowest values. The mechanical properties were affected by light-curing methods employed.

Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods

O objetivo deste trabalho foi avaliar a profundidade de polimerização e a dureza Knoop do compósito restaurador P60 fotoativado por diferentes métodos. Uma matriz metálica bipartida (3 mm de diâmetro X 11 mm de altura) foi preenchida com o compósito e fotoativada através da luz contínua, luz exponencial, luz intermitente, plasma de xenônio (PAC) ou luz emitida por diodo (LED). Após a abertura da matriz, o material não polimerizado foi removido com o auxílio de uma espátula metálica e o compósito polimerizado medido com um paquímetro digital. Então os espécimes foram incluídos em resina acrílica autopolimerizável e desgastados longitudinalmente e a dureza foi medida na superfície e nas profundidades de 1, 2, 3, 4 e 5 mm. Os dados foram analisados por ANOVA e teste de Tukey (5%). Os resultados mostraram que a profundidade de polimerização foi maior com a luz intermitente, seguida pela luz contínua, luz exponencial, PAC e LED. Até a profundidate de 2 mm, todos os métodos de fotoativação revelaram valores de dureza similares, porém diferiram a outras profundidades, onde o LED demonstrou os menores valores, seguido pelo PAC.