The purpose of this study was to compare maxillary anterior teeth positions and smile appearances between four first premolar extraction and nonextraction in Class I crowding cases. Forty-one participants with moderate Class I crowding who had finished orthodontic treatment were recruited and divided into two groups. The first group consisted of 21 participants who had finished nonextraction orthodontic treatment, and the other group consisted of 20 participants who had finished orthodontic treatment with four first premolars extracted. Smiling pictures in frontal and lateral positions of the participants were taken. In part one, the maxillary anterior teeth positions and smile appearances were measured and analyzed. In part two, the smile esthetic of the cropped frontal smiling pictures was rated by three certificated board orthodontists and ten laypersons using the visual analog scale (VAS), and then the VAS scores were compared between the nonextraction and the extraction groups. In the assessment using smiling pictures, the ratio of the distance between the maxillary dental midline and the distal surface of the maxillary canine to the distance between the maxillary dental midline and the angle of the mouth, as well as the ratio of the distance between the left and right maxillary canine cusp to the distance between the left and right alar of the nose in four first premolar group, was significantly higher than in the nonextraction group. The difference between the horizontal distance of the left and the right alar of the nose to left and right maxillary canine cusp tip in the four first premolar extraction group was significantly lower than the nonextraction group. Maxillary canines in the four first premolar extraction group are significantly closer to the alar of the nose and the labial commissures than the maxillary canines in the nonextraction group. Maxillary teeth positions and smile appearances evaluated from the other smile parameters did not differ significantly between the two groups.