An unusual presentation of dental transposition caused by digit-sucking

The development of facial and dental structures are dependent on genetic and environmental factors.¹ The effects of environmental factors can be more severe the earlier the interaction with the dento-facial complex occurs. Early digit-sucking habits can influence development of the occlusion and several studies have suggested that prolonged digit-sucking can lead to anterior open bites, posterior crossbites, proclination of the upper incisors and retroclination of lower incisors (Table 1).^2,3,4,5,6 It is theorized that, during prolonged thumb-sucking, the tongue is depressed. This change in the balance of forces between the tongue and the cheeks, in addition to the negative pressure caused by the sucking action, can cause constriction of the upper arch form, leading to posterior crossbites. Prolonged digit pressure leads to intrusion and proclination of the upper incisors and retroclination of the lower incisors. The effect is often characterized by an asymmetric anterior open bite, depending on the digit that is being sucked (Figure 1).