Incisor protrusion is known as maxillary protrusion. Correction of maxillary protrusion usually requires the extraction of 4 premolar teeth to provide space for the teeth to be retracted internally, as follows. Due to the inconsistency between the degeneration of the jawbone and the degeneration of the tooth volume, resulting in the bone volume of the jawbone being relatively smaller than the tooth volume, the anteriorly protruding maxillary anterior teeth lack sufficient space for internal retraction. The premolar is located between the cuspids and the molars, and functions as an aid to tearing food and mashing food, and removing the premolar has a small impact on the masticatory function of the whole mouth. Usually, one premolar is extracted from the upper, lower, left and right sides, making a total of four premolar extractions, to provide enough space for the maxillary front teeth to be retracted and for the teeth to be aligned and leveled. It is recommended to visit a hospital and receive professional treatment with the help of a doctor.