The utility model discloses a self -locking
oral cavity examines and opens apart with the spreader, related to medical instrument technical field, including
slide plate, handheld board and
damper, the upper connected with lower bracing plate of handheld board, one side of handheld board is installed with
slide plate, the top of
slide plate is connected with upper bracing plate, the inboard of lower bracing plate and upper bracing plate all is installed with disposable
mouthguard, the inner wall of one side of lower bracing plate is installed with gear, and the inner wall of gear one side slide plate is engaged and is installed with rack. The utility model utilizes the disposable
mouthguard to be put into lower bracing plate and upper bracing plate, is positioned through the pressing into positioning groove of elastic rubber block, through the elastic rubber block for elastic rubber, makes the pressing elastic rubber block downwards deformable into positioning groove, and elastic rubber block is not easy to fall off, through the sticking of hair and thorn, the positioning installation of disposable
mouthguard is convenient, has solved the problem of inconvenient positioning installation.