[Application of a universal system of epitesis fixation in the rehabilitation of patients with maxillofacial defects]. / Proizvodstvo i primenenie universal'noi sistemy fiksatsii epitezov pri reabilitatsii patsientov s defektami litsa.

OBJECTIVE: The aim of the study was the creation of a universal epithesis fixation system that increases the reliability of its functioning in prosthetics of patients with maxillofacial defects of various genesis. MATERIAL AND METHODS: After the surgical preparation of patients, in accordance with the indications of the underlying disease, epithesis was made from rigid silicone elastomers using CAD/CAM technologies. For the production of attachments, the VT1-0 titanium alloy common in medicine was used. RESULTS: A universal epithesis fixation system was used for prosthetics of various parts of the patient's face. Depending on the clinical situation and the size of the prosthetics area, an intermediate lattice plate (mesostructure) of the appropriate size and configuration was selected. Two types of attachments were used to fix epithets: magnetic with a counterpart and non-magnetic mushroom-shaped. The universal epithesis attachment system is distinguished by the possibility of using each hole of the lattice, both for attaching it to the bone structure and for installing attachments, which makes it easy to fix the lattice to residual bone fragments and center the position of the transition elements and attachments depending on the aesthetic and functional needs of the structure in whole. CONCLUSION: The success of prosthetics largely depends on the epithesis attachment system. The proposed universal epithesis fixation system allows its use in various clinical situations and also reduces the cost of prosthetics for patients with maxillofacial defects.

[Study of biomimetic apatite formation on dentine surface].

The aim of this study was investigation of the opportunity of biomimetic growth of apatite on a dentine surface at various methods of its processing. Artificial blood human plasma--simulated body fluid (SBF)--was used as a source of ions. According to the scanning electronic microscope (SEM) and confocal laser scanning microscope (CLSM) and energy dispersive X-ray analysis (EDX) they have revealed the growth of crystals of calcium--deficient apatite. The structure of the formed apatite layer differed depending on a kind of processing of a dentine surface. After acid etching the globules of the apatite are located chaotically and the part of a dentine surface remains free. The removal of the collagen fibres by NaClO promotes uniform, controllable growth of crystals, forming a monolithic layer. The hypermineralisated areas of a tooth create the best conditions for growth. The transformation hydroxyl apatite in a superficial dentine layer can be caused by increasing of pressure at preparing with diamond bur. The growth of crystals of brushite in the smear layer is possible at a storage in water at 37 degrees capital ES, Cyrillic. The crystals have lamellar form and are well integrated in a dentin surface.

[Study of wear of restorative materials and teeth-antagonists in vitro].

Since clinical evaluation of wear turns out to be particularly time consuming, a standardized method was developed to model oral mastication. So-called artificial mouth was used to assess the extent of wear caused from different restorative materials in contact with bovine enamel. Ball heads manufactured from modern veneering ceramics, gold alloy, amalgam and resin composite materials were loaded with a contact load of 50 N for 200,000 chewing cycles. Additional thermo-cycling (5 degrees /55 degrees C) for 2,500 cycles was conducted in the artificial mouth. The worn surfaces, both on the material specimens and on the antagonist bovine enamel surfaces were volumetrically scanned under a laser microscope. Negligible wear rates were observed for the veneering ceramics and for the gold alloy. Most veneering ceramics as well as the resin composite materials caused low wear on the antagonist enamel surfaces. In contrast, the antagonist enamel was significantly damaged in contact with amalgam or some of the ceramic materials. However, modern veneering ceramics as well as gold alloys might be recommended in occlusally loaded contact with the antagonist enamel, whereas resin composite materials might be indicated for non load-bearing areas. Ceramics are contraindicated in case of bruxism.

[Evaluation of the modern self-etching adhesives efficacy].

The durability of bonding efficacy of composites with hard tissues of a tooth was investigated at application of one-bottle adhesive with total etching and five self-etching adhesives. The efficiency of etching by 36% orthophosphoric acid and acid components of self-etching adhesives was estimated. The adhesion between substrate and composite was measured by method of microtensile bond strength (mTBS). The control of efficiency of etching and depth of the penetration was carried out with the confocal laser scanning microscopy. It was established, that self-etching adhesives are capable to guarantee bonding of composites with enamel and dentine at a level compared with adhesives of the 5th generation. Deep adhesives penetration in dentine tubules is not the key factor for creation of reliable bonding.

[Study of adhesion of glass-ionomer cements to dentine].

The possibilities to increase adhesion of glass-ionomer cements to dentine with the help of conditioning of dentine surface by 20% orthophosphoric acid were analysed. Adhesion of glass-ionomer cements to dentine was determined by microtenzile strength method (mTSB). It was established that dentine etching for 15 sec led to improved adhesion; etching time increasing did not improve the adhesion.

[Modern method for investigation of filling materials' adhesion]. / Sovremennyi metod issledovaniia adgezii plombirovochnykh materialov.

The potentialities of rupture microtesting were studied as exemplified by the 5th generation binding system. The strength of dentin-composite adhesion was evaluated in 5 groups of samples formed from removed human intact molars using a universal testing device (Zwicki-Modell Z/2.5 Ulm, Germany). The surface at the site of rupture was examined under a scanning electron microscope. The findings indicate high efficiency of the method, due to which the strength of adhesion in cavities with different location was evaluated with high accuracy, selective examination of different sites of the same plane was carried out, and the type of rupture was identified.