Table 3.

The von Mises stress of the anterior teeth and premolars root in the three groups

The von Mises stress of root (MPa)	11	12	13	14	15
Without attachment	0.268	0.627	0.316	0.248	0.449
With horizontal attachment	0.198	0.469	0.216	0.181	0.358
With vertical attachment	0.199	0.468	0.213	0.179	0.356

11, the central incisor; 12, the lateral incisor; 13, the canine; 14, the first premolar; 15, the second premolar