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In the present study a novel approach to caries management based on the application of nanoparticles of different nature to increase the mineral phase of demineralized dentin has been developed. Silver nanoparticles have been tested as a material for dentine matrix infiltration. Research findings clearly show that collagen fibers of demineralized dentine could be considered as a scaffold for mineral component delivery and the place where mineral growth can occur. Keywords : dental research, demineralized dentine, dentin collagen fibers, nanotechnologies, silver nanoparticles, nanoparticle infiltration, scanning electron microscopy 1. INTRODUCTION The first stage of caries developing is characterized by hard tooth tissue demineralization. A series of methods are being developed to manage the caries process; one of the most popular is the application of remineralizing therapy along with demineralized dentine collagen matrix protection. In clinical practice a variety of strategies of dentine and enamel remineralization based on the application of bioactive glasses, calcium hydroxiapatite, fluoride delivering materials, artificial saliva and others are in common use

In the present study nanoparticulate silver filler influence on adhesive system mechanical properties has been researched. In the course of laboratory experiments it has been shown that adhesive system mechanical properties are changing in a different manner as soon as silver percentage in adhesive system is increasing. It has been established that 0,5 –1% silver nanoparticle embedding into adhesive system that is enough to make the material X-Ray-sensitive holds its mechanical properties close to the optimum. Thus, the mechanical properties are enhancing in comparison with those of adhesive system without silver nanoparticles. Research findings point to the opportunity to use nanoparticulate silver as a filler while producing X-ray adhesive systems.

Crystal formations were observed on the surface of etched dentine after it had been exposed to 95% ethanol in solution for 30 days at room temperature. 3D visualization of surface formations was carried out using a scanning electron microscope and Alicona 3D MeX software (Alicona GmbH). Metric characteristics of the mentioned above structures were evaluated and the nature of possible errors on the steps of model design was studied. It was shown that the shape of crystal models were likely to be approximated by ellipsoid segments.

In the present study a new adhesive system with embedded PVP-stabilized nano-particulate silver markers has been designed. Nanosized silver was used as a radio-opaque contrast material in SEM examination of adhesive system in dentine. It was studied the impact of nano-particulate silver fillers on rheological properties of adhesive system and its penetration in dentine volume. A SEM comparative evaluation of resin replicas produced using adhesive system with embedded silver nanoparticles and that without ones was carried out. It was shown that embedding of silver nanoparticles into adhesive system did not make its penetration worse. It was established that embedding of nanosized silver changed adhesive system morphology. The methodology that allows visualizing interfaces and intermediate layers between dentine, adhesive system and restorative material using silver nano-particulate markers was developed and approved. Silver nanoparticles were used to compare the objective depth of penetration of adhesive systems of different generations in root dentine with differently oriented dentinal tubules, bonding resin delivery and gravity.

Laboratory experiments conducted in Saratov State University in the first half of 2012 revealed crystal formations on the surface of etched dentine after it had been exposed to 95% ethanol in solution for 30 days at room temperature. It was discovered that the structures observed were calcium-phosphate crystals. The nature of crystal formation on rough dentine surface was described based on substance diffusion in solution, which resulted in dentine becoming spatially inhomogeneous over time. The crystal formation was established to be determined by the limited ion redistribution in dentine material.

In this study the methodology of biological sample preparation for dental research using SEM/EDX has been elaborated. (1)The original cutting equipment supplied with 3D user-controlled sample fixation and an adjustable cooling system has been designed and evaluated. (2) A new approach to the root dentine drying procedure has been developed to preserve structure peculiarities of root dentine. (3) A novel adhesive system with embedded X-Ray nanoparticulate markers has been designed. (4)The technique allowing for visualization of bonding resins, interfaces and intermediate layers between tooth hard tissues and restorative materials of endodontically treated teeth using the X-ray nano-particulate markers has been developed and approved. These methods and approaches were used to compare the objective depth of penetration of adhesive systems of different generations in root dentine. It has been shown that the depth of penetration in dentine is less for adhesive systems of generation VI in comparison with bonding resins of generation V, which is in agreement with theoretical evidence. The depth of penetration depends on the correlation between the direction of dentinal tubules, bonding resin delivery and gravity.