Abstract
Objectives: The purpose of this study was to investigate the effect of frequency of drinking of soft drink like Coca-cola on surface microhardness of sound bovine enamel. Materials and Methods: Coca-cola (Coca-cola Co., Ltd) was selected as a experimental drink. Thirty-six sound enamel slabs were obtained from bovine teeth and divided into three groups (Mixed saliva: control, Coca-cola 1 time/day, and Coca-cola 5 times/day). Specimens were treated for ten minutes, triple drinking of Coca-cola(0 ,1 and 5) a day for 8 days (This process used in this study was called the drinks and saliva cycle). Except during treatment time, specimens were immersed in mixed saliva. Surface microhardness was measured before and after treatment of drinks using a microhardness tester (Fm-7, Future-tech Corp, Japan). Statistical method used was one way ANOVA. Results: Surface microhardness changes of sound enamel after cycling of Coca-cola and mixed saliva were significantly different among the 3 groups (p<0.01). Surface microhardness values (VHN) of final day were Mixed saliva group (286.98±20.60), Coca-Cola 1 time/day group (225.95±9.46), Coca-Cola 5 times/day group (154.68±16.93). Conclusion: The surface microhardnesses of bovine enamel treated were not recovered to the baseline microhardness values in Coca-cola 1 time/day and 5 times/day groups, except Mixed saliva group(control). Therefore, the increase of frequency of drinking soft drinks like Coca-cola could reduce surface microhardness and induce tooth erosion on sound enamel.