Composite bond strength improvement with thermal vibration: an experimental non-randomised study

Background. Secondary caries formation is a relevant issue due to poor long-term quality of composite fillings, with inherent subsequent chipping and cracking of the material. We developed a method to improve physical, mechanical and chemical properties of available composites based on thermal vibration imposed on unpolymerised composite in the formed tooth cavity directly prior to polymerisation.Objectives. Effect assessment of thermal vibration exposure on bond strength in composite restorative polymer matrix in various composite brands.Methods. The study used synchronous thermal analysis, including differential scanning calorimetry and thermogravimetry, to estimate and register thermal effects of physical and chemical processes within a temperature programme, as well as determine gaseous release, air contact and decomposition-related sample mass variation, thermal stability, reaction kinetics, polymer and inorganic filler component chemical composition, humidity and softening degree. The study covered 90 specimens 30 mg each prepared of three different composites.Results. Synchronous thermal analysis revealed a statistically significant increase in polymer matrix bond strength in the composites Estelite Sigma Quick (Tokuyama Dental), Filtek Bulk Fill Posterior Restorative (3M Espe) and DentLight (VladMiVa) after thermal vibration exposure vs. classical polymerisation of same composites (p < 0.0001). The bond strength increased by 17.00, 22.51 and 11.31%, respectively.Conclusion. The developed exposure method for altering the composite filling physical and chemical properties has been shown advantageous in a laboratory setting. Thermal vibration-pretreated composite fillings had a higher polymer matrix bond strength vs. same composites polymerised under standard conditions.The pretreatment improves composite filling quality via directly affecting the material physical and mechanical properties of hardness and bending strength.

Investigation of the forms of moisture binding in the grain of triticale of the Gorka variety by the method of thermal analysis

The work carried out experimental studies of Gorka triticale grain using differential scanning calorimetry (DSC) and thermogravimetry (TG) methods. To study the patterns of thermal impact on grain samples, a synchronous thermal analysis device (TG-DTA/DSC) of the STA 449 F3 Jupiter model was used. The importance of sample preparation for analysis with ground and whole grains was noted. The obtained relationships made it possible to distinguish periods of dehydration of water and conversion of dry substances during thermal exposure to triticale grain, as well as to identify temperature zones that correspond to the release of moisture with various forms and energy of communication.

THERMAL STUDY OF SOLID COMPLEXES OF CERIUM, PRASEODIUM AND NEODIUM

Взаимодействием водных растворов хлоридов соответствующих редкоземельных элементов и натриевой соли цефазолина (NaCzl) были получены и выделены в твердом виде комплексные соединения цефазолина. Полученные комплексы имеют состав Me(Czl)•3HO, где Me = Ce+, Pr+, Nd+. Полученные соединения исследованы методом синхронного термического анализа. By the interaction of aqueous solutions of the chlorides of the corresponding rare-earth elements and the cefazolin sodium salt (NaCzl), complex compounds of cefazolin were obtained. The resulting compounds were investigated by synchronous thermal analysis.

Исследование фазовых переходов в кристаллах (Cs,NH-=SUB=-4-=/SUB=-)-=SUB=-4-=/SUB=-(HSO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=-(H-=SUB=-2-=/SUB=-PO-=SUB=-4-=/SUB=-)

The crystals of solid solution (NH4,Cs)4(HSO4)3(H2PO4) were investigate by synchronous thermal analysis and polarization microscopy methods at heating with the purpose of studying phase transitions in these solid solutions. The temperatures of structural modifications are established, and it is shown that the replacement of Cs cations by NH4 in Cs4(HSO4)3(H2PO4) crystals leads to a decrease in the temperature of phase transformations.

SIMULTANEOUS THERMAL ANALYSIS AND RAMAN SPECTROSCOPY AS COMPLEMENTARY METHODS OF DIAGNOSTICS OF CARBON ALLOTROPIC FORMS

Work is devoted to detection of distinctive characteristics of allotropic forms of carbon which would provide their identification from mixes. The complex analysis is offered by methods: the synchronous thermal analysis with studying of composition of the emitted gases and Raman spectroscopy. It was shown that researches of carbon structures and their mixes by the declared methods agree well and complement each other.