Conceiving a molecule as being composed of smaller molecular fragments, or subunits, is one of the pillars of the chemical and physical sciences and leads to productive methods in quantum chemistry. Using a fragmentation scheme, efficient algorithms can be proposed to address problems in the description of chemical bond formation and breaking. We present a formally exact time-dependent density ...

introduction: debonding is a common cause of failure encountered with fiber-reinforced composite (frc) posts, and usually occurs along the post space-dentin adhesive interface. the aim of this in vitro study is to evaluate the regional push-out bond strength of a fiber-reinforced post system, using two resin cements. materials and methods: in this in vitro study 20 maxillary central incisors we...

The concept of Resonance Assisted Hydrogen Bond (RAHB), which usually occurs in b diketons, has a remarkable role in chemistry. These molecules, which contain heteroatom particularly O and N, are species with biological interest in protein folding and DNA pairing. Therefore, the amplification of hydrogen bonds strength by substituents may be important in life scie...

statement of the problem: the bond strength of composites with different adhesive systems with dentin is an important factor in long term durability of composite restorations. the effect of titanium tetrafluoride (tif4) as anti caries agent and sodium hypochlorite (naocl) as disinfectant on the shear bond of nanofilled and silorane based composite resins have not been investigated in previous s...

ethanol wet-bonding (ewb) technique has been stated to decrease degradation of resin-dentin bond. this study evaluated the effect of two ewb techniques on composite resin-to-enamel bond strength.silicon carbide papers were used to produce flat enamel surfaces on the buccal faces of forty-five molars. optibond fl (ofl) adhesive was applied on enamel surfaces in three groups of 15 namely: enamel ...

statement of problem: shear bond strength (sbs) of home and office bleached enamel will be compromised by immediate application of composite restoration. antioxidant agent may overcome this problem. objectives: this in vitro study assessed the effect of green tea extract on shear bond strength of resin composite to in-office and home-bleached enamel. materials and methods: in this experimental ...

conclusions this study suggested that chlorhexidine had no negative effect on the bond strengths of mta-treated dentin. results there were no statistically significant differences between all the experimental groups. the mode of bond failure was predominantly mixed for distilled water groups and cohesive for chx groups. materials and methods sixty dentin disks with a thickness of 1.5 ± 0.2 mm a...

abstract background and aim: one of the major problems with resin composite restorations is the weakness of bonding between the new and aged composites. since appropriate micromechanical retention is necessary for the repair of aged resin composite restorations, the level of surface roughness after sandblasting can be influential in this regard. considering the diverse composition of available ...

background. failure of orthodontic bracket bonds is a common occurrence during orthodontic treatment. different tech-niques have been suggested in the literature to remove resin residues from the bracket bases and enamel surfaces to prepare the surfaces again after debonding. this study attempted to compare multiple rebond shear strengths (sbs) of debonded brackets following preparation with sa...