Different biomechanical effects of clear aligners in bimaxillary space closure under two strong anchorages: finite element analysis

Progress in Orthodontics

Table 5 Vertical movement of teeth in the 150 g elastic force group

Tooth	Anterior teeth				Posterior teeth
Tooth	1	2	3		5	6	7
Group				Maxilla
Extrusion/Intrusion (× 10⁻² mm)	− 0.009I	− 0.081I	− 0.045I		0.160E	0.050E	− 0.068I
Relative incisor extrusion to the second premolars				− 0.169I
Relative incisor extrusion to the first molars				− 0.059I

Tooth	Anterior teeth				Posterior teeth
Tooth	1	2	3		5	6	7
Group				Mandible
Extrusion/Intrusion (× 10⁻² mm)	− 0.109I	− 0.141I	− 0.063I		0.162E	0.034E	− 0.124I
Relative incisor extrusion to the second premolars				− 0.272I
Relative incisor extrusion to the first molars				− 0.144I

+ values indicate extrusion of teeth (× 10⁻² mm); − values indicate intrusion of teeth (× 10⁻² mm); E, tooth extrusion based on the occlusal plane; I, tooth intrusion based on the occlusal plane; 1, central incisor; 2, lateral incisor; 3, canine; 5, second premolar; 6, first molar; 7, second molar; the relative incisor extrusion is calculated based on the displacement differences between the central incisors and posterior teeth (the second premolar and the first molar) in the vertical direction