In vivo rehardening of enamel eroded by a cola drink

There are many concerns about the erosive effects of acidic beverages. In t his study, the effects of Pepsi-Cola (pH 2.41) on bovine enamel and the reh ardening effect resulting from intraoral exposure of the teeth were determi ned by microhardness testing (Vicker's Hardness Number). Bovine enamel spec imens (VHN 380.00 +/- 12.74) were immersed in 100 ml of Pepsi-Cola for five minutes and subsequently exposed to human intraoral environment through th e use of a removable resin plate. Microhardness testing was performed on sp ecimens after one hour, twenty-four hours and forty-eight hours of exposure to an intraoral environment. The microhardness value was significantly (p <0.05) reduced by the cola beverage (VHN 262.13 +/- 20.34), and significant ly (p <0.05) increased after intraoral exposure for one hour (VHN 299.75 +/ - 26.86) and twenty-four hours (VHN 328.00 +/- 18.70). The difference in th e microhardness between the twenty-four-hour group and the forty-eight-hour group (VHN 333.50 +/- 1,5.13) was not significant (p >0.05). The microhard ness value of the forty-eight-hour group was significantly less than the va lues recorded during the initial pre-study measurements p <0.05)