Try to wean her off this as soon as you can and replace it with ordinary tap water. The orange squash is potentially harmful in two respects. It is usually heavily sweetened, so bacteria in plaque can metabolise acid and over time infiltrate the enamel and dentin causing dental decay. The orange squash is also acidic, so this can lead to chemical erosion or wearing away of the tooth enamel causing sensitivity and further risk of dental decay. Fruit juice unsweetened, and diluted one measure to five measures of water given in a cup at mealtimes is the ideal and safest way for a child to receive a fruit juice.