To prepare removable dentures, border molding using an impression compound has been employed for a long time to obtain a denture border morphology harmonized with perioral muscle movement. However, border molding using impression compound is performed following practitioner's empirical rule. The objective of this study is to clarify the optimum softening conditions of impression compound for border molding, for which we measured the pressure assumed to be loaded on impression compound during border molding.

The pressure assumed to be loaded on an impression compound during border molding was measured using a tongue pressure-measuring device. Based on the measured pressure, appropriate softening conditions were investigated (softening temperature and water immersion time) for three types of impression compound: Red (Impression com- pound Red, Kerr, USA), green (Peri Compound, GC, Japan), and pink (Iso Compound, GC, Japan).

The measured pressure was significantly different between those in the oral vestibule in the lower anterior tooth region during tugging the mouth corner, and in the gingivobuccal fold of the lower first molar during large mouth opening. Regarding the impression compound softening condition, red was deformed by all measured muscle pressures after immersion in 60°C water for 30 seconds and 65°C water for 20, 25, and 30 seconds. Green was deformed by all measured muscle pressures after immersion in 60°C water for 30 seconds, and 65°C water for 25 and 30 seconds. In contrast, pink was deformed by all measured muscle pressures after immersion in 55°C water for 25 and 30 seconds.

It was clarified that for border molding, muscle pressures of all regions during the functional movements can be registered using red and green softened by immersion in 60°C water for 30 seconds and pink softened by immersion for 20 seconds.

Takano T, Kugimiya Y, Koike T, Ueda T, Sakurai K. Softening Condition of Impression Compound for Border molding of Removable Dentures. Int J Prosthodont Restor Dent 2016;6(2):37-42.