A mouth that can only be opened by two fingers is considered a mild mouth opening restriction, which is less severe than a moderate mouth opening restriction and a severe mouth opening restriction. Generally speaking, the normal degree of opening is the distance between the upper and lower incisal edges of 3.7cm~4.5cm, and the common way of measurement is that the degree of opening is roughly the same as the width of my three fingers, i.e. the width of the index finger, the middle finger, and the ring finger, which are all together. Mouth opening can be categorized as mild, moderate or severe. Mild mouth opening is when the opening is only two fingers, moderate mouth opening is when the opening is only one finger, and severe mouth opening is when the opening is less than one finger, or when the opening is not possible at all. If the mouth opening restriction is severe or continues to be unimproved, it is recommended to go to the hospital in time to identify the cause of the problem with the help of a doctor and receive targeted treatment.