A built in inter dental brush and a visual inter dental brush. The built in inter dental brush comprises an inter dental brush (1) and a delivery device (2). The inter dental brush (1) is movably built in a bent tube (21 1) at the front end of the delivery device (2). After a guiding head (21) is aligned with a slit between the teeth a sliding mechanism (22) on the delivery device (2) is pushed to drive a working portion (11) of the inter dental brush to be automatically bent along the radian of the bent tube aligned with the slit between the teeth and enter the slit. A sliding block (22 2) on the sliding mechanism (22) of the delivery device is pushed and pulled back and forth to enable the working portion (11) of the inter dental brush to move back and forth in the slit and clean the slit. The visual inter dental brush comprises an inter dental brush (1) and a delivery device (2). The delivery device (2) is provided with a guiding head (21) a housing (23) and an illuminating system (24). The inter dental brush (1) is mounted on the guiding head (21). The illuminating system (24) can provide illumination to the inter dental brush. The visual inter dental brush also comprises an observing system (25) that is an observing mirror or a photographing system.
