INFLUENCE OF PHYTOEXTRACTS ON THE RHEOLOGY AND DENSITY OF POLYVINYL ALCOHOL/CARBOXYMETHYL STARCH POLYMER MATRICES IN DENTAL FILM TECHNOLOGY

Abstract

Purpose. To establish the effect of aqueous extracts of Matricaria chamomilla, Urtica dioica, and Quercus cortex on the rheological behavior of Polyvinyl Alcohol/Carboxymethyl Starch polymer solutions and the physical parameters of films formed on their basis to substantiate the technology of dental films.

Methodology. The objects of study were compositions of Polyvinyl Alcohol (grade 16/1) and Carboxymethyl Starch CAS: 9063-38-1e cgsddslyjityys 1/1, made on the basis of aqueous extracts of chamomile Matricaria chamomilla, stinging nettle Urtica dioica and oak bark Quercus cortex. Extraction was carried out in a water bath (85–95 °C) with subsequent preparation of 10% Polyvinyl Alcohol solution and 5% Carboxymethyl Starch solution based on aqueous phytoextracts. Rheological parameters were determined using a rotational viscometer NDJ-9S (DSTU 33–2003). The type of flow and constants of the Ostwald–de Villa equation were calculated based on the dependence of shear stress on shear rate. Polymer films were formed by the method of pouring onto organic glass (applicator 750 μm) with subsequent drying for 48 hours. The density of the samples was determined by hydrostatic weighing in air and distilled water at 19.7 °C on a Radwag AS 220.R2 analytical balance with automatic calculation of values.

Findings. It was found that the introduction of phytoextracts significantly changes the rheology of Polyvinyl Alcohol/Carboxymethyl Starch systems. Systems without phytoextracts and based on aqueous extracts of chamomile Matricaria chamomilla and oak bark Quercus cortex are characterized by dilatant behavior of solutions, and the Polyvinyl Alcohol/Carboxymethyl Starch system based on aqueous extract of stinging nettle Urtica dioica is characterized by pseudoplastic behavior, which provides optimal rheological conditions for the formation of dental films by the irrigation method. The use of oak bark extract is most appropriate for the creation of combined Polyvinyl Alcohol/Carboxymethyl Starch films due to the maximum viscosity of the system lnη ≈ 10.2 Pa·s and the density of the films 1.36 g/cm³, which determines stability in the aggressive environment of the oral cavity. Nettle extract contributes to a decrease in the viscosity of the compositions by 20–25% compared to the control, which allows obtaining quickly dissolving forms with a density of 1.31 g/cm³. The viscosity range of the compositions 6.0–10.2 Pa·s provides a variation in the thickness of the films within 0.05–0.25 mm with an average density of about 1.32 g/cm³, which is satisfactory for the creation of elastic therapeutic systems. The results obtained confirm the promising use of plant extracts for the development of modern application dosage forms in dentistry.

Originality. For the first time, the influence of the type of phytoextracts on the change in the type of flow (from dilatant to pseudoplastic) and the consistency constant of Polyvinyl Alcohol/Carboxymethyl Starch systems was established. A direct correlation was found between the degree of structuring of solutions and the density of the formed films.

Practical value. The choice of phytoextracts for creating dental films with specified properties is justified, in particular, strong barrier coatings based on aqueous extract of oak bark Quercus cortex, elastic applications based on aqueous extract of medicinal chamomile Matricaria chamomilla and quick-dissolving forms based on aqueous extract of stinging nettle Urtica dioica with a film thickness of 0.05–0.25 mm.