Whilst finger or thumb sucking is considered a normal and natural activity among very young children, it can sometimes intefere with the normal eruption of permanent teeth. The front teeth may be pushed forwards out of alignment, and open bites can develop. Most children grow out of the habit by the age of five or six, but occasionally the behaviour needs to be corrected.

A thumb guard can discourage the behaviour by making it dificult for the child to find a comfortable position thus breaking the habit over time. In some cases orthodontic symptoms may correct themselves once the behaviour has ceased, where in others the condition needs an appliance to be fitted.