Objectives This study evaluated the long-term effect of carbodiimide treatments of acid-etched dentin on resin-dentin bond strength of a simplified etch-and-rinse adhesive system. Methods Forty-eight sound third molars were divided into three groups (n=16) according to the dentin treatment: G1: Deionized water; G2: 0.5 mol/L 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) applied for 30 seconds; and G3: 0.5 mol/L EDC applied for 60 seconds. Flat dentin surfaces were produced, etched with 37% phosphoric acid for 15 seconds and then treated with deionized water for 60s or with 0.5 mol/L EDC for 30 or 60 seconds prior to the application of Single Bond 2. Crowns were restored with resin composite and beam specimens were prepared for microtensile testing. The beams from each group were tested 24 hours or 6 or 12 months after the adhesive procedures. One slab from each tooth was prepared and analyzed for nanolaekage. Bond strength (MPa) data were submitted to analysis of variance and Tukey test (α=0.05). Results The treatment of dentin with 0.5 mol/L EDC for 30 seconds (24.1±6.2 MPa) and 60 seconds (25.5±5.1 MPa) did not negatively affect the immediate bond strength of Single Bond 2 when compared to the control group (24.6±7.3 MPa). Additionally, EDC prevented resin-dentin bond degradation after 12 months in artificial saliva for both periods of treatment. An increased accumulation of silver ions was seen for the control group over time, while a much lower amount of silver grains was observed for the EDC-treated groups. Conclusions 0.5 mol/L EDC was able to prevent resin-dentin bond degradation after 12 months, especially when applied for 60 seconds.
ResumoIntrodução: Agentes promotores de ligações cruzadas têm sido investigados como inibidores da atividade enzimática da dentina, o que favoreceria a longevidade das restaurações adesivas. Objetivo: Avaliar o efeito do tratamento da dentina com proantocianidina (PA), em curtos períodos de tempo, na inibição da atividade de MMPs in situ. Material e método: Quarenta espécimes de dentina (1×1×6 mm) foram obtidos de molares hígidos e divididos em quatro grupos (n=10). Os espécimes foram condicionados com ácido fosfórico por 15 s, seguido de lavagem em água deionizada. A dentina condicionada foi tratada com: água, 5% PA por 5 s, 15 s ou 30 s. A atividade de MMP foi analisada colorimetricamente (SensoLyte®) e os dados de absorbância (412 nm) foram submetidos aos testes de ANOVA e Tukey (α=0,05). Resultado: Todos os períodos de tratamento foram capazes de reduzir a atividade de MMPs, sendo que os melhores resultados foram observados para a dentina tratada com PA por 15 s (63,1% redução) e 30 s (70,2%). O tratamento por 5 s foi capaz de inibir 39,9% das MMPs. Conclusão: A aplicação de PA sobre a dentina condicionada foi capaz de reduzir a atividade de MMPs mesmo em períodos de tempo extremamente curtos, como 5 s. No entanto, melhores resultados foram obtidos com os maiores períodos de tratamento.Descritores: Dentina; colágeno; metaloproteinase da matriz; proantocianidina. AbstractIntroduction: Collagen cross-linkers have been investigated as inhibitors of the enzymatic activity of dentin, therefore improving the longevity of adhesive restorations. Purpose: To evaluate the effect of etched dentin treatment with proanthocyanidin (PA) in short periods of time on the inhibition of dentin metalloproteinases (MMP) activity in situ. Material and method: Forty dentin specimens (1x1x6mm) were obtained from sound third molars and divided into 4 groups (n=10). The specimens were etched with 37% phosphoric acid for 15s and rinsed in deionized water. Then they were treated with the following solutions: water, 5% PA for 5s, 15s or 30s. The total MMP activity was analyzed by a colorimetric test (SensoLyte®). Absorbance data (412nm) were submitted to ANOVA and Tukey tests (α=0.05). Result: All treatment periods were able to reduce the total activity of MMPs. The best results were observed for dentine treated with PA for 15s (63.1% reduction) and 30s (70.2%). Treatment for 5s was capable of inhibiting only 39.9% of the total MMP activity. Conclusion: Application of PA on the etched dentin in extremely short periods of time reduced the MMPs activity of dentin, even after 5s. However, the best results were obtained for the longer periods.
Aim. The purpose of this study was to evaluate the MD (marginal discrepancy) on the calcinable copings in abutments for cemented prostheses with three luting agents. Methods. Sixty-four analogs of CeraOne-type abutments (NACONIH code, Titanium Fix Implant Sytem SP, Brazil) were divided into four groups (n = 16). The copings were cast and placed on the CeraOne abutment analogs and cemented with eugenol-free zinc oxide (EfZO) (n = 16), with glass ionomer (GI) (n = 16), and with zinc phosphate (ZP) (n = 16), and as a control group, there were CeraOne plastic copings (NACOC code, Titanium Fix Implant Sytem SP, Brazil) (n = 16) which were not cemented with any material. After 24 hours, the MD of the four groups was measured. MD was evaluated using a stereoscopic microscope (Leica EZ4 W, Leica Microsystems, Germany) with an increase of ×100. MD was measured at four predetermined and equidistant sites with respect to the marginal line of the cast adaptation. The measurement was made from the distance between the free edge of the cast cylinder and the margin of preparation of the titanium abutment, with a level of statistical significance of p<0.05. Results. Of the three fixing agents, the ZP was found to have the highest MD (53.59 ± 14.21 μm); however, the lowest MD (41.72 ± 9.10 μm) was found in the GI group. These differences are statistically significant at p<0.001. Conclusions. In summary, according to our results, it was found that ZP cement showed the highest MD after cementation, followed by the glass ionomer, while EfZO showed the lowest MD.
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