Special protective device for oral clinical tooth preparation

The invention discloses a special protective device for oral clinical tooth preparation. The special protective device comprises an expansion unit, a tongue protection unit and a fixing unit, whereinthe expansion unit comprises two motors, two fixed blocks, bidirectional lead screws, two movable blocks, supporting rods and a fixing frame; the two fixed blocks correspond to each other left and right; a groove is formed in the inner side surface of each of the two fixed blocks; each bidirectional lead screw is rotationally connected to the inside of the corresponding groove; threads at the twoends of each bidirectional lead screw are opposite; the two motors are arranged at the top ends of the two fixed blocks respectively; output shafts of the two motors are connected with the top ends ofthe bidirectional lead screws; the two movable blocks are in sliding connection with the grooves in the inner side surfaces of the fixed blocks respectively; screw holes in the side surfaces of the two movable blocks are in th