2015 Volume 19 Issue 1 Pages 41-51
Objective: The lip pressure and the lip-upper extremity coordinate motion-induced strain on three different types of spoon were measured upon ingestion to clarify the effects of spoon shape on the injection action.
Subjects and Methods: The subjects were 47 normal young adults (10 men, 37 women, 20.5±0.82 years old). A small lip pressure sensor and a strain sensor were placed at the bowl and the junction between the bowl and handle of the spoon, respectively. The three types of spoon had a different long axis and thickness from the bottom to the lid of the bowl as follows: a, 43/4; b, 34/6; c, 34/4 (mm). All types of spoon had the same width of 28 mm. The lip pressure sensor was placed at 1 mm deep from the lid of the bowl of the tested spoons. Four milliliters of pudding placed on each spoon was ingested by the subjects on their own. Measurement parameters were the lip pressure (integrated pressure, pressure sustained period and maximum pressure), the strain at lower lip contact (integrated contact strain, contact sustained period and maximum strain) and the bending strain upon withdrawal of the spoon (integrated bending strain, bending strain sustained period and maximum bending strain). Time zone analyses were performed in developed waves of lip pressure and strains of lower lip contact and withdrawal bending.
Results and Discussion: Upon ingestion the lip pressures did not significantly differ among the three types of spoon used. Wave analyses showed a common pattern in spoon usage as the initial contact of the bowl to lower lip, then the development of lip pressure, and the final withdrawal of the spoon with contact to the upper lip. In contrast, when the thick bowl spoon was used, the integrated contact strain and the maximum strain during lower lip contact were significantly bigger than those of the thinner spoons, suggesting that the contact to the lower lip stabilizes the spoon-aided ingestion. Also, when using the thick bowl spoon, the maximum bending strain was significantly bigger than when using the others, suggesting that the spoon is withdrawn by slipping the upper lip along the curvature of the bowl in cooperation between the upper extremity and upper lip.
Conclusion: The results indicate that the thickness of the spoon bowl plays a role in self-ingestion.
