Effects of different surface treatments and accelerated artificial aging on the bond strength of composite resin repairs

Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)The purpose of the present study was to assess the bond strength of composite resin repairs subjected to different surface treatments and accelerated artificial aging. 192 cylindrical samples (CSs) were prepared and divided into 24 groups (n = 8). Half of the CSs were stored in water for 24 h, and the other half were subjected to C-UV accelerated aging for non-metallic specimens. The treatments were phosphoric acid + silane + adhesive (PSA); phosphoric acid + adhesive (PA); diamond bur + phosphoric acid + silane + adhesive (DPSA); diamond bur + phosphoric acid + adhesive (DPA); air abrasion + phosphoric acid + silane + adhesive (APSA); and air abrasion + phosphoric acid + adhesive (APA). The repair was performed and the specimens were again aged as described above. A control group (n = 8) was established and did not receive any type of aging or surface treatment. The specimens were loaded to failure in shear mode with a crosshead speed of 0.5 mm/min until fracture. Data were analyzed by one-way ANOVA/Tukey's test (p < 0.05). No statistically significant differences were found among DPSA, DPA, APSA, APA, and the control group. The aged PSA and PA achieved low bonding values and were statistically different from the control group, whereas the non-aged PSA and PA presented no statistically significant difference from the control group. Repairs with the proposed surface treatments were viable on both recent and aged restorations; however, phosphoric acid + adhesive alone were effective only on recent restorations

Facile synthesis and characterization of symmetric N-[(Phenylcarbonyl) carbamothioyl]benzamide thiourea : experimental and theoretical investigations.

A thiourea derivative, N-[(phenylcarbonyl)carbamothioyl]benzamide, was synthesized and characterized by elemental analysis, thermal analysis, spectroscopic methods (Fourier transform infrared (FTIR), UV-Vis, Raman, matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF), tandem mass spectrometry (MS/MS) and nuclear magnetic resonance (NMR)) and quantum-chemical calculations. The synthetic route was simple and efficient, conducted just by one-step and no purification step was needed. The compound crystallizes in a non-centrosymmetric orthorhombic crystal system with a P21 21 21 space group, with a= 5.06220(10) ?, b= 11.8623(3) ?, c= 21.9682(8) ?. The molecular conformation of the solid is stabilized by the N-H???O intramolecular hydrogen bond, which was present in the X-ray structure and was also found in the optimized geometry. The theoretical analysis showed that this strong interaction remains even when molecules are solvated, i.e., the rotation barrier and the hydrogen bond strength are greater than the solvent stabilization energy. In addition to this hydrogen bond effect, the relative position of phenyl groups has a certain influence on the chemical behavior of this thiourea and probably for other phenylthioureas

Bioactive glass containing 90% SiO2 in hard tissue engineering : an in vitro and in vivo characterization study.

Bioactive glass has been proved to have many applications in bioengineering due to its bone regenerative properties. In this work, an innovative, highly resorbable bioactive glass containing 90% SiO2 (BG90) to be used as a bone substitute was developed. The BG90 was synthetized by the sol?gel process with the dry step at room temperature. The biomaterial showed in vitro and in vivo bioactivities even with silica content up to 90%. Moreover, the BG90 presented high porosity and surface area due to its homogenously interconnected porous network. In vitro, it was observed to have high cell viability and marked osteoblastic differentiation of rat bone marrow?derived cells when in contact with BG90 ion extracts. The BG90 transplantation into rat tibia defects was analysed at 1, 2, 3, 4, 7, and 10 weeks post?operatively and compared with the defects of negative (no graft) and positive (autogenous bone graft) controls. After 4 weeks of grafting, the BG90 was totally resorbed and induced higher bone formation than did the positive control. Bone morphogenetic protein 2 (BMP?2) expression at the grafting site peaked at 1 week and decreased similarly after 7 weeks for all groups. Only the BG90 group was still exhibiting BMP?2 expression in the last experimental time. Our data demonstrated that the BG90 could be an attractive candidate to provide useful approaches in hard?tissue bioengineering