Development of a New Intraoral Demineralization Test

Blocks of bovine enamel covered with a layer of Streptococcus mutans cells were mounted in specially-designed holders in a prosthesis and carried intraorally for 2 h. Measurements of the iodide permeability (Ip) of the blocks before and after intra-oral exposure showed an increase in Ip (+ΔIp), suggesting demineralization when the mouth was rinsed with a 10% sucrose solution at 0 and 60 min, but a decrease in Ip (––ΔIp), suggesting remineralization, after interoral exposure without rinsing. Repeated tests with sucrose rinses in 5 subjects showed good within and between-subject reproducibility of ΔIp. Acid production in the S. mutans cells layer from sucrose caused a typical decrease and subsequent increase in pH (‘Stephan’ curve). S. mutans cells released from the appliance during the test became eliminated from the mouth within 1 to 2 weeks.