Evaluation of gel evaporation rate and effect of adding humectants to the formulation

• Grant number: 25/10376-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Carlos Rocha Gomes Torres
• Grantee: Camila Pasim Rossini
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Estadual Paulista (UNESP). Campus de São José dos Campos. São José dos Campos , SP, Brazil
• Associated research grant: 22/04270-1 - Development of inovative formulations to optimize the efficacy and safety of dental bleaching, AP.TEM

Abstract

The objective of the first part of this study will be to analyze the mass loss profile of the gel through the evaporation process (Evaporation Loss), and compare it with commercially available products. The second part will analyze the influence of the addition of humectants in the formulation on the evaporation rate of the gel. For the first part, silicone rings with 15 mm internal diameter, 24 mm external diameter and 2 mm thick will be glued to a glass microscope slide, with dimensions of 25 x 75 mm, using a transparent acetic silicone glue. This will create a well with standardized dimensions, which will allow the gels to interact with the environment. After the adhesive has dried for 24 hours, 353 µl of each gel will be placed in the internal portion of the ring. The plate will be placed on a vibrational shaker (Vortex) for 5 seconds so that the gel spreads, standardizing the surface area exposed to the air (176.71 mm2). For each gel, 5 samples will be positioned in the arrangement previously described. The experimental gels developed in this study will be tested, in addition to the commercial gels Whiteness HP (FGM), Pola Office Bulk (SDI), Opalescence Boost (Ultradent), Whiteness HP Blue (FGM), Whiteness HP automix (FGM) and Pola Office + (SDI). The pure peroxide solution will also be tested, at the same concentration present in the whitening agents. To analyze the evaporation rate of the gels, the initial weight of each plate/ring set containing the gel will be measured on an analytical balance with 4 decimal places. They will then be taken to a chamber with a controlled atmosphere, maintained at a temperature of 37°C and relative humidity of 65% for 45 minutes.Weighing will be repeated every 5 minutes. The evaporation rate will be calculated using the equation: % mass loss = (M1-M2 / M1-M3) x 100; where M1, M2 and M3 are, respectively, the initial weight, weight measured at that time and final weight, respectively. The data will be plotted on a graph where the abscissa will be the time and the ordinate will be the percentage of mass loss by evaporation. In the second part, the humectants Glycerol, Polyethylene glycol 300 and Propylene glycol will be added to the experimental gels. The incorporation of each of the three humectants will be done at an initial concentration of 0.5%, in Phase B of all experimental gels. Then the evaporation test will be repeated, using the methodology already described in the first phase. If this quantity is not sufficient to match the evaporation rates of commercial products, a larger volume will be added (1%, 2%, 3%, ...), replacing the water, until this is achieved. The data obtained will be analyzed statistically. (AU)