An actuation assembly (122, 322) for an oral irrigator (100) includes a bezel (166, 366) secured to or formed as part of a housing (103) of the oral irrigator (100), an actuator (162, 362) operably connected to the bezel (166, 366) and moveable relative thereto, and an augmentation fluid (300, 500) positioned between the bezel (166, 366) and the actuator (162, 362). The augmentation fluid (300, 500) modifies a frictional relationship between the bezel (166, 366) and the actuator (162, 362) to provide a predefined resistance force between the actuator (162, 362) and the bezel (166, 366) as the actuator (162, 362) is rotated relative to the bezel (166, 366).