Application of the QLF technology to monitor recovery rates of enamel caries lesions with human saliva

Purpose: The aim of this in vitro study was to assess changes in remineralization by stimulated human saliva over a short period of 48 hours with quantitative light-induced fluorescence (QLF) technology. Materials and Methods: Bovine incisor surfaces were demineralized for 10 days. Two types of stimulated saliva were collected from 7 healthy persons. 24 hours after tooth brushing (Stimulated saliva group) and immediately after tooth brushing with 1,000 ppm NaF dentifrice (Dentifrice saliva group). The specimens were immersed in saliva and fluorescence images were obtained by QLF-digital (QLF-D biluminatorTM‚) at 2, 4, 6, 12, 24, and 48 hours fluorescence loss (⊿F%) of the lesions. A paired t-test was performed to assess fluorescence differences between before (⊿Fbaseline) and after (⊿Ftreatment time) the remineralization process. Results: Before the remineralization, the mean ⊿Fbaseline of the initial demineralized specimens was -18.42±0.15 (%). In both groups, the ⊿F values obtained at baseline and after 2 hours were statistically significant (P < 0.001), indicating recovery of the lesions by approximately 40% after 2 hours. After 48 hours, remineralization rates were slightly higher (49%) for the stimulated saliva group than for the dentifrice saliva group (41%), but the difference was not statistically significant. Conclusions: With QLF minute degrees of remineralization by saliva can be measured in periods as short as 2 hours. Additionally no significantly higher effects of remineralization were observed in the dentifrice saliva group when compared to the stimulated saliva group.ope