Effect of Powder/Water Ratio Variation on Viscosity, Tear Strength and Detail Reproduction of Dental Alginate Impression Material (In Vitro and Clinical Study)

Abstract

Background: Alginate impression is a common dental polymeric material, presented as powder to be mixed with water. Aim: 1. To analyze the effect of alginate powder/water ratio variation on viscosity, tear strength and detail reproduction by in vitro tests, and 2. To evaluate this variation’s effect on patients’ impressions. Materials and methods: Two commercial alginate products were mixed in different viscosities. Viscosity was measured by a viscometer. For the tear strength test, V-shaped specimens were used. For detail reproduction, a die with three scribed lines was used. Clinical dental impressions were examined by stereomicroscope. Results: The alginate specimens mixed with a higher powder/water ratio showed a higher viscosity and tear strength compared to those with a lower powder/water ratio. Both alginate mixtures reproduced two scribed lines in a detail reproduction test. On the other hand, no clear clinical difference was detected when examining dental impressions mixed with a different powder/water ratio. Conclusion: Although increasing the powder/water ratio of mixed alginate raised the resultant viscosity and tear strength by an in vitro test, clinically, no clear difference in tearing was detected. Detail reproduction was minimally affected by the variation in powder/water ratio.

A Promising Potential of Brown Algae Sargassum polycystum as Irreversible Hydrocolloid Impression Material

“…As a rule of thumb, the concentration value will be greatly influenced by the molecular weight of the alginate. The higher the molecular weight, the higher the viscosity [2,14]. Previously published studies reported that the viscosity of dental impression material can be increased if the extraction of potassium alginate is carried out using freshly harvested seaweed [16,23,24].…”

“…Besides casting time, other factors that contribute to the accuracy and dimensional stability of irreversible hydrocolloid material are the room temperature, the water temperature of the mixture impression, the water-to-powder ratio, and the stirring intensity [1,6,11,14]. Theoretically, a warmer water temperature or general room temperature might hasten the setting time, whereas colder water will slow down the setting time.…”

“…In addition, different powder and liquid compositions will also affect alginate properties. A thin dough will shorten the setting time, while a thicker one will reduce the setting time due to less flexibility [14]. Thus, the water added in the mixing process must be proportional to the powder used so that the ideal gel consistency can be obtained in a short setting time [1,29].…”

“…The main active ingredients of irreversible hydrocolloid impression materials are sodium alginate, potassium alginate, or triethanolamine alginate [5,14]. Both sodium alginate and potassium alginate can be extracted from species of multicellular brown algae, including Sargassum sp., Turbinaria sp., Hormophysa sp., and Padina sp.…”

“…The brown macroalgae are characterized architecturally by an alginophyte cell wall structure composed of ß-D-mannuronic acid and α-L-guluronic acid [16]. Alginate extracted from these species can be homogenized in water to form soluble alginate, which can react with calcium sulfate to generate insoluble alginate [6,14]. Most of the species of brown algae are prevalent in a number of maritime countries, including Indonesia [17].…”