Background: Despite improvements in oral health status, dental caries remains a public concern. This study examines the effectiveness of commercial toothpastes in the prevention of tooth decay, using eggshell powder as a substitute for human tooth material. Methods: Colgate, Aquafresh, Colgate Sensitive, Sensodyne, and Oralwise were tested. An enamel model was simulated by adding eggshell powder to beakers containing dissolved toothpastes. The contents were agitated for eight hours at 800rpm, filtered and oven dried. Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDX) were used to characterise the surface morphology and the calcium and phosphate composition of the toothpastes pre-and post-agitation with eggshell powder. Gas-displacement and pressure sensor tests evaluated the rate of reaction between the substitute "tooth enamel" and acids. results: EDX analysis confirmed the presence of calcium phosphate ions, while SEM revealed the formation of an enamel-like layer after agitation. Pressure sensor tests confirmed Colgate Sensitive as most effective in protection against acid attacks, with Oralwise least effective. conclusions: Eggshell can be used as a substitute for the human tooth in an in vitro experiment. All the tested brands of toothpaste effectively reduced the acid reaction, which would contribute to the prevention of tooth decay.