Abstract: Objective To disclose the etiologies of class Ⅲ malocclusion in deciduous dentition due to bottle feeding.Methods Sixty children with a history of bottle feeding in six months after birth were chosen as participants,thirty with normal occlusion(control group) and thirty with class Ⅲ malocclusion(case group).A simulation baby was used for mothers to mimic their feeding gesture when they fed their children during lactation period and the baby′s angulation of head,body,and milk bottle from the horizontal plane were recorded by a customed inclination device.Meanwhile,sucking pressure of each child was measured by a negative pressure transducer.The data were statistically analyzed by SPSS 16.0 software and the significance was set at P<0.05.Results No significant difference in the angles of head,body,and milk bottle between the two groups was found,nor the angle value from bottle to head (P＞0.05).The average sucking pressure value in control group was (20.1±2.7)kPa while the sucking negative pressure in case group was (15.3±3.3)kPa,which was statistically lower than its counterpart (P<0.01).The difference was significant.Conclusions For the children with bottle feeding,the sucking force in the case group is significantly lower than the control group while there is no statistical difference in feeding gesture between these two groups.We conclude that the lower sucking force can be one of the etiologies that cause class Ⅲ malocclusion in deciduous dentition due to bottle feeding and its relationship with feeding gesture needs to be further studied.

Key words: bottle feeding, class Ⅲ malocclusion, sucking negative pressure