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The objective of this study was to evaluate the effects of glycolic acid (GA) (with pH 1.2 and 5) and ethylenediaminetetraacetic acid (EDTA) on the chemical and mechanical properties of dentin to investigate the potential use of GA as final irrigant in the root canal therapy. Specifically, changes in microhardness, smear layer removal, erosion, mineral content distribution, apatite/collagen ratio and flexural strength of mineralized dentin treated with GA were assessed. Saline solution was used as a negative control. Knoop microhardness (KHN) was measured on the root canal lumen of root segments. Dentin beams were used for 3-point flexural strength (σ) test. Scanning electron microscopy (SEM) images of root sections were obtained for evaluation of smear layer removal and dentin erosion on root segments and energy dispersive X-ray spectroscopy (EDS) was used for mineral content distribution. The apatite/collagen ratio (A/C) in dentin powder were examined by Fourier transform infrared (FTIR) spectroscopy. KHN, σ and A/C results were statistically analyzed with ANOVA and Tukey tests (α = 0.05). Smear layer and dentin erosion scores were analyzed with Kruskal-Wallis and Dunn tests (α = 0.05). Root dentin treated with EDTA and GA presented similar KHN regardless of the pH (p > 0.05). However, KHN was significantly reduced in EDTA and GA groups when compared to control group (p<0.001). GA showed the same ability to remove the smear layer and to cause dentin erosion as EDTA. EDS results showed that the GA and EDTA solutions did not alter the dentin mineral content distribution. The apatite/collagen ratio reduced with all irrigant solution and was the lowest with GA pH 5 (p<0.001), while σ was not significantly affected by the experimental solutions (p = 0.559). It can be concluded that GA has similar ability to remove the smear layer than EDTA. GA does not affect negatively the chemical/mechanical properties and it does not increase dentin erosion. The use of GA with low pH seems to promote less change in collagen/apatite ratio, but further studies are needed to establish an ideal clinical protocol. Therefore, this study supports the potential use of GA as an alternative final irrigation solution for root canal preparation.

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The aim of this study was to investigate the effects of glycolic acid (GA) on the microhardness, roughness, dentin mineral content distribution; smear layer removal and cytotoxicity. One hundred human teeth were randomly divided into six groups: distilled water (control group), 17% EDTA, 10% citric acid (CA), 5% GA, 10% GA, and, 17% GA. Microhardness and roughness were measured in the canal lumen. Scanning electron microscopy (SEM) images (2000×) for smear layer removal evaluation; energy dispersive X-ray spectroscopy (EDS) for chemical analysis. Cell viability assay was made on fibroblast cells. The lowest microhardness and higher roughness were observed for 17% GA. GA showed the ability to remove the smear layer to a similar level as EDTA and CA, with no statistical difference between the concentrations used. GA and CA were cytotoxic in a dose-dependent manner. GA showed potential as an endodontic agent for final irrigation in root canal terapies.

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AIM: The aim of the present study was to evaluate the effect of different polishing methods on the surface roughness of resin-based composites subjected to a thermocycling procedure. METHODS: A total of 192 specimens were divided into 24 groups, according to composite materials (Filtek Z250, Point 4, Renamel Nanofill, Filtek Supreme Plus, Renamel Microfill, and Premise) and finishing and polishing systems (Sof-Lex Pop On, Super Snap, Flexidisc, and Flexidisc+Enamelize). The specimens were subjected to thermocycling (5000 cycles). RESULTS: Filtek Supreme Plus showed the lowest surface roughness values before thermocycling. After thermocycling, Filtek Supreme Plus continued to have the lowest surface roughness, with a statistically-significant difference for the other materials. After thermocycling, there was no statistically-significant difference among all the polishing techniques studied. CONCLUSIONS: The thermocycling was concluded as being able to change composite resins' surface roughness, whereas different finishing and polishing methods did not result in surface roughness changes after thermocycling.

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This study evaluated the effect of dentin biomodification on the bond strength (BS) and sealing ability (SA) of HEMA-free and multi-mode adhesives after 24 h and 6 months of water storage. Four adhesives were tested: two multi-mode (Scotchbond Universal - SU, and Prime & Bond Elect - PB) and two HEMA-free (All-Bond 3 - AB, and G-Aenial - GA). Human third molars were selected and dentin was treated with two cross-linking agents (5% glutaraldehyde and 6.5% proanthocyanidin-rich grape seed extract - PACs) for 10 min or kept untreated (control group) (n=6). Teeth were sectioned and prepared for BS test and SA analysis. The SA measurements were taken with the presence of smear layer (minimum permeability), EDTA treatment (maximum permeability), PACs application, adhesive application and after 6 months of water storage. BS data were analyzed by Proc Mixed and Tukey-Kramer test (α=5%). PACs application increased the BS for all adhesives tested at 24 h. However, BS decreased for SU and AB after six months. In general, multi-mode adhesives (SU and PB) did not differ from AB HEMA-free. GA presented the lowest BS values at both times of evaluation. Dentin permeability was reduced after PACs application and remained the same after 6 months, regardless adhesive application. PACs can increase the BS regardless the type of adhesive, however only for PB and GA the BS kept stable after 6-months of water storage. PACs was able to seal the dentin as the minimum permeability and also remained stable after 6 months.

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Abstract This study evaluated the effect of dentin biomodification on the bond strength (BS) and sealing ability (SA) of HEMA-free and multi-mode adhesives after 24 h and 6 months of water storage. Four adhesives were tested: two multi-mode (Scotchbond Universal - SU, and Prime & Bond Elect - PB) and two HEMA-free (All-Bond 3 - AB, and G-Aenial - GA). Human third molars were selected and dentin was treated with two cross-linking agents (5% glutaraldehyde and 6.5% proanthocyanidin-rich grape seed extract - PACs) for 10 min or kept untreated (control group) (n=6). Teeth were sectioned and prepared for BS test and SA analysis. The SA measurements were taken with the presence of smear layer (minimum permeability), EDTA treatment (maximum permeability), PACs application, adhesive application and after 6 months of water storage. BS data were analyzed by Proc Mixed and Tukey-Kramer test (α=5%). PACs application increased the BS for all adhesives tested at 24 h. However, BS decreased for SU and AB after six months. In general, multi-mode adhesives (SU and PB) did not differ from AB HEMA-free. GA presented the lowest BS values at both times of evaluation. Dentin permeability was reduced after PACs application and remained the same after 6 months, regardless adhesive application. PACs can increase the BS regardless the type of adhesive, however only for PB and GA the BS kept stable after 6-months of water storage. PACs was able to seal the dentin as the minimum permeability and also remained stable after 6 months.

Resumo Este estudo avaliou o efeito da biomodificação da dentina na resistência de união (BS) e capacidade de selamento (SA) de adesivos "HEMA-free" e "multi-mode" após 24 horas e 6 meses de armazenamento em água. Quatro adesivos foram testados: dois "multi-mode" (Scotchbond Universal - SU, e Prime & Bond Elect - PB) e dois "HEMA-free" (All-Bond 3 - AB, e G-Aenial - GA). Terceiros molares humanos foram selecionados e a dentina desses dentes foi tratada com dois agentes "cross-linking" (glutaraldeído 5% e extrato de uva contendo proantocianidina 6.5% - PACs) por 10 min ou permaneceram sem tratamento (grupo controle) (n=6). Os dentes foram seccionados e preparados para teste de BS e análise de SA. As mensurações de SA foram adquiridas com a presença de "smear layer" (mínima permeabilidade), tratamento com EDTA (máxima permeabilidade), aplicação dos PACs, aplicação de adesivo e após 6 meses de armazenamento em água. Os dados de BS foram analisados pelo Proc Mixed e teste de Tukey-Kramer (α=5%). A aplicação dos PACs aumentaram a BS para todos os adesivos testados no tempo de 24 h. Entretanto, a BS reduziu para o adesivo SU e AB após 6 meses. Em geral, os adesivos "multi-mode" (SU e PB) não diferiram do AB "HEMA-free". O adesivo GA apresentou o menor valor de BS em ambos tempos de avaliação. A permeabilidade dentinária foi reduzida após a aplicação dos PACs e permaneceu a mesma até 6 meses, independente da aplicação do adesivo. Os PACs podem aumentar a BS independente do tipo de adesivo, entretanto somente para o adesivos PB e GA a BS manteve estável após 6 meses de armazenamento em água. Os PACs foram capazes de selar a dentina como a permeabilidade mínima da dentina, que permaneceram estável após 6 meses.

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AIM: To evaluate the effects of sodium hypochlorite (NaOCl), chlorhexidine (CHX), and two naturally derived reducing agents on the bond strength of epoxy resin-based sealer to root dentin. MATERIALS AND METHODS: A total of 60 single-rooted human teeth were prepared using ProTaper (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA) and an irrigation protocol including 5% NaOCl or 2% CHX gel, and ethylenediaminetetraacetic acid (EDTA), for smear layer removal. The following subgroups (n = 10) were also assessed according to the naturally derived reducing agent used: no agent (control group); grape seed extract (GSE); and green tea. Root canals were filled with gutta-percha and AH Plus (Dentsply DeTrey, Konstanz, Germany). Bond strength was measured using the push-out test, and statistical analyses were performed using ANOVA; failure patterns (modes) were classified as adhesive, cohesive, or mixed. The types of failure modes were evaluated using the Chi-squared test at α =0.05. RESULTS: The irrigation protocols demonstrated similar bond strength values (P > 0.05). However, the Chi-squared test revealed significant differences in failure mode among the groups (P < 0.05). An increase in the incidence of adhesive failures was observed for the NaOCl and EDTA groups. The other groups demonstrated a prevalence of mixed and cohesive failures. CONCLUSION: The irrigation protocols and use of naturally derived reducing agents had no effect on the bond strength of the resin-based sealer to dentin; however, improvement was evident in the adhesion quality of AH Plus to NaOCl-treated root dentin, due to the prevalence of cohesive failure.

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UNLABELLED: Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries. OBJECTIVE: The aim of this in vitro study was to evaluate the efficacy of a treatment with grape seed extract, under cariogenic challenge, to minimize or even prevent the onset of caries in the enamel and dentin. MATERIAL AND METHODS: Blocks of enamel and dentin (6.0x6.0 mm) were obtained from bovine central incisors, polished, and selected by analysis of surface microhardness (SH). The blocks were randomly divided into 3 groups (n=15), according to the following treatments: GC (control), GSE (grape seed extract), GF (fluoride - 1,000 ppm). The blocks were subjected to 6 daily pH cycles for 8 days. Within the daily cycling, the specimens were stored in buffered solution. The blocks were then analyzed for perpendicular and surface hardness and polarized light microscopy. RESULTS: The means were subjected to statistical analysis using the ANOVA and Fisher's PLSD tests (p<0.05). For enamel SH, GF showed the highest hardness values. In the dentin, GF was also the one that showed higher hardness values, followed by GSE. Regarding the cross-sectional hardness values, all groups behaved similarly in both the enamel and dentin. The samples that were treated with GSE and fluoride (GF) showed statistically higher values than the control. CONCLUSION: Based on the data obtained in this in vitro study, it is suggested that grape seed extract inhibits demineralization of artificial carious lesions in both the enamel and dentin, but in a different scale in each structure and in a smaller scale when compared to fluoride.

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Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries. Objective The aim of this in vitro study was to evaluate the efficacy of a treatment with grape seed extract, under cariogenic challenge, to minimize or even prevent the onset of caries in the enamel and dentin. Material and Methods Blocks of enamel and dentin (6.0x6.0 mm) were obtained from bovine central incisors, polished, and selected by analysis of surface microhardness (SH). The blocks were randomly divided into 3 groups (n=15), according to the following treatments: GC (control), GSE (grape seed extract), GF (fluoride – 1,000 ppm). The blocks were subjected to 6 daily pH cycles for 8 days. Within the daily cycling, the specimens were stored in buffered solution. The blocks were then analyzed for perpendicular and surface hardness and polarized light microscopy. Results The means were subjected to statistical analysis using the ANOVA and Fisher's PLSD tests (p<0.05). For enamel SH, GF showed the highest hardness values. In the dentin, GF was also the one that showed higher hardness values, followed by GSE. Regarding the cross-sectional hardness values, all groups behaved similarly in both the enamel and dentin. The samples that were treated with GSE and fluoride (GF) showed statistically higher values than the control. Conclusion Based on the data obtained in this in vitro study, it is suggested that grape seed extract inhibits demineralization of artificial carious lesions in both the enamel and dentin, but in a different scale in each structure and in a smaller scale when compared to fluoride. .

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OBJECTIVE: This study aimed to investigate the surface roughness of composite resins subjected to thermal cycles procedure. MATERIALS AND METHODS: Two microfill, four microhybrid and four nanofill composites were used. The surface roughness (Ra) was initially measured in a profilometer using a cut-off 0f 0.25 mm, after 3000 and 10,000 thermal cycles. Data were subjected to ANOVA and Fischer's test (α = 0.05). RESULTS: Overall, 3000 thermal cycles increased the surface roughness values for all materials and there was a trend in all groups to decrease the roughness after 10,000 thermal cycles. CONCLUSIONS: The composition of material, including the type of organic matrix, could be more relevant to roughness maintenance over time than the general behavior of composites based on particles fillers. The maintenance of smooth surface in resin-based composite restorations is totally dependent of organic composition of the material.

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The aim was to assess the nanohardness (H) and the reduced modulus of elasticity (Er ) of 2.5% titanium tetrafluoride (TiF4 ) modified dentin, before and after an erosive challenge with 0.3% citric acid (CA). Exposed dentin surfaces were divided into two groups (n = 5): (1) Control-no dentin pretreatment with TiF4 prior to etching with CA, and (2) Experimental-dentin pretreatment with TiF4 + CA. The H and the Er of intertubular dentin were measured using a triboindenter at different time points: baseline for both groups, after using 2.5% TiF4 for the experimental group, and after using CA for both the experimental and the control groups. Scanning electron microscope and energy dispersive X-ray spectroscopy (EDS) analysis of the dentin surfaces were undertaken at the same time points for both groups. Two-way ANOVA for randomized block design was applied. There was significant interaction between the application of the TiF4 solution and different time points (p = 0.001 for H and p < 0.001 for Er ), identified by Tukey's test. Erosive challenge provided a significant decrease in H and Er mean values. The TiF4 solution caused a significant increase in H and Er values, but no significant differences were found between post-TiF4 and post-CA application. TiF4 application produced a precipitate surface layer on intertubular and intratubular dentin. EDS analysis indicated the presence of titanium. The H and Er of the dentin surface were greatly increased after application of 2.5% TiF4 . TiF4 may modify the micromorphology of the dentin surface and produces an erosive resistance surface.

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