interdental / interdentile [ɪntɜrˈdɛntəl]
interdental – adj. – 1. situated or placed between the teeth; 2. formed with the tip of the tongue protruded between the upper and lower front teeth
interdentil – n. – the space between two dentils (small, rectangular blocks in a series projecting like teeth, as under the corona of a cornice, especially in the Ionic, Corinthian and composite orders, in architecture)