Flat guides, i.e., flat guide appliances, generally need to be worn for about 3 months to achieve the therapeutic effect, and the exact time varies from person to person. Flat guides are generally used to open the occlusion and eliminate occlusal interference. The mechanism is to help the back teeth to elongate effectively, and at the same time partially depress the lower anterior teeth, so that the lower jaw rotates in the backward and downward direction, and promotes the forward and downward growth of the lower jaw, and at the same time, the condyles and the temporomandibular joints undergo reconstruction, so as to achieve the purpose of opening the occlusion. The whole process usually takes about 3 months, the use of fixed plane guides can continue to play a role, does not depend on the patient’s cooperation, to open the bite faster and more effective. It is recommended to visit a regular medical institution to receive professional treatment.