Prediction of early caries prognosis after fluoride application based on the severity of lesions: An in situ study

Purpose: The aim of this in situ study was to measure baseline fluorescence loss values (ΔF₍₀₎) using the quantitative light-induced fluorescence (QLF) technology to screen enamel lesions for effective remineralization following fluoride application. Methods: In this single-blinded in situ study, 20 adult volunteers wore intraoral appliances containing 4 specimens of human enamel. The surfaces of the specimens were divided into 3 regions: sound, demineralized, and treated regions. After generating 80 artificial enamel lesions with varying ΔF values, all specimens were covered with 1.23% acidulated phosphate fluoride gel for 1 min. Three repeated QLF-digital measures of ΔF values were then obtained for the lesions, immediately after demineralization and at 1 and 4 weeks after fluoride application. Results and conclusion: Fluoride application was found to increase the ΔF values of lesions significantly over time (p < 0.001). The groups with lower ΔF₍₀₎ values showed significantly larger changes in ΔF values over time (p < 0.001). Receiver operating characteristics analysis showed that baseline lesion values of ΔF₍₀₎ = −17.50 and −25.50 would allow for lesion ΔF to recover to −10 at 1 and 4 weeks after fluoride application, respectively (p < 0.001). The findings of this study indicate that clinicians can establish prognostic criteria for early carious lesions using the QLF technology, and hence predict the efficacy of fluoride treatment and devise effective lesion-specific treatment plans.