Studies have shown that fruit teas erode dental enamel but, until now, the effect of these teas on dentine has been unknown. Now, a study published in the January edition of the Journal of Dentistry, shows that fruit teas remove the protective smear layer, opening up the dentinal tubules more fully, potentially making exposed dentine more sensitive. The erosive potential (pH and neutralisable acidity) of a variety of Twining infusion fruit teas – including lemon, pear and guava, and 'blackcurrent burst' – was assessed by researchers at the Dental School at the Wales College of Medicine in Cardiff. Smeared dentine specimens were prepared from extracted teeth and the ability of each tea to remove the smear layer was assessed by measuring the diameter and area of the opened tubules and counting the number of patent tubules seen under a microscope. All the fruit teas tested were highly acidic and able to remove the smear layer.