Physical characterisation of conventional toothpastes for adults in Malaysia / Muhammad Fahmi Azizan

Physical characterization of conventional toothpaste in term of rheological, textural, foaming ability and stability properties are influenced by their compositions and formulations. The objective of this study is to assess the physical characteristics of conventional toothpastes by performing rheology and texture profiling; pH and foaming ability analyses; and accelerated stability study. The proposed project covered, virtually all conventional toothpastes for adults offered for sale in Malaysia. Droplet size distribution of the toothpastes were performed for identification of Droplet size distribution (µm) with polydispersity of the samples reflected by span and uniformity values. The determination of viscosity and mechanical response were done through rheological analysis with response to shear stress analysis and dynamic oscillatory. Textural characterization including firmness, cohesiveness and consistency as parameters was done by using the back extrusion method. Stability of the toothpastes was performed by using accelerated method (32°C; 2500rpm) in order to predict the toothpastes stability for two years. Besides, pH reading of toothpastes were performed at room temperature (25°C). The foaming ability and foam stability analysis were used to determine foam expansion and foam volume stability through cylinder method. Based on the result, 10 toothpastes exhibited thixotropic (pseudoplastic) behaviour. Toothpastes that contain additional flavouring agent exhibited a higher value of viscosity. All the toothpaste exhibited elastic behaviour; G' > G". The stability analysis, only one toothpaste sample exhibit low stability property for a given two stability analysis (Pepsodent). As conclusion, most of conventional toothpastes had different flow properties due to the presence of additives and thickening agents in the formulations. Moreover, the age of conventional toothpastes between manufactured date and expiry date might also influence their stability as well as droplet size, rheological, textural, pH and foam properties.