Abstract: A device for dilating and propping open a patient's jaws. The device includes a pair of outwardly-extending upper arms and a pair of outwardly extending lower arms. Each of the arms has a respective distal end which has a pad pivotally mounted thereon which contacts the patient's jaws during use thereof, and a respective proximal end which is pivotably secured to the housing. Means is provided for pivoting the distal ends of the upper arms towards and away from the distal end of the lower arms such that the distal ends move substantially arcuately between the open and closed positions. A worm and worm wheel arrangement is provided for pivoting the arms, such that the spacing therebetween is infinitely variable.