Fig. 5

Stress distribution of central incisors with different IMPA values during the intrusion by 0.2 mm. The sequence is A (90°), B (95°), C (100°), D (105°), and E (110°). I. von Mises stress distribution of the central incisor: The crown stress was mainly concentrated in the lingual fossa and incisal ridge, and the root stress was concentrated in the lingual surface and the proximal cervical area. II. The minimum principal stress distribution of the central incisor: The compressive stress of the crown was concentrated in the lingual fossa and the incisal ridge. The compressive stress on the root was concentrated in the lingual surface and root apex when the initial IMPA was 90° and 95°. With the increase in IMPA, the root compressive stress area changed to the labial surface. When the IMPA was 110°, the compressive stress was concentrated in all areas of the root labial surfaces, from the apex to the root cervix. III. The minimum principal stress distribution in the PDL of the central incisor: The compressive stress was mainly concentrated in the apex. With the increase in IMPA, the compressive stress concentration area expanded to the labial middle 1/3 and cervical 1/3 of the PDL